Evaluating the Impact of the Variability of D50 Light Booths on the ...

By 

Susan Farnand 

Staff Scientist, Chester F. Carlson Center 

for Imaging Science 

Brian Gamm 

Graduate Student, Munsell Color Science 

Laboratory 

Franziska Frey, Ph.D. 

McGhee Distinguished Pr<strong>of</strong>essor, 

School <strong>of</strong> Print Media 

Simon Muehlemann 

Graduate Student, School <strong>of</strong> Print Media 

Ishtar Laguna-Monroy 


Rochester Institute <strong>of</strong> Technology 

<strong>Evaluating</strong> <strong>the</strong> 

<strong>Impact</strong> <strong>of</strong> <strong>the</strong> 

<strong>Variability</strong> <strong>of</strong> <strong>D50</strong> 

<strong>Light</strong> <strong>Booths</strong> on 

<strong>the</strong> Appearance 

<strong>of</strong> Reproductions 

<strong>of</strong> Monochrome 

Photographs 

A Research Monograph <strong>of</strong> <strong>the</strong> 

Printing Industry Center at RIT 

No. PICRM-2012-05

<strong>Evaluating</strong> <strong>the</strong> <strong>Impact</strong> <strong>of</strong> <strong>the</strong> 

<strong>Variability</strong> <strong>of</strong> <strong>D50</strong> <strong>Light</strong> <strong>Booths</strong> on 

<strong>the</strong> Appearance <strong>of</strong> Reproductions 

<strong>of</strong> Monochrome Photographs 

By 

Susan Farnand 

Staff Scientist, Chester F. Carlson Center for Imaging Science 

Brian Gamm 

Graduate Student, Munsell Color Science Laboratory 

Franziska Frey, Ph.D. 

McGhee Distinguished Pr<strong>of</strong>essor, School <strong>of</strong> Print Media 

Simon Muehlemann 


Ishtar Laguna-Monroy 



A Research Monograph <strong>of</strong> <strong>the</strong> 

Printing Industry Center at RIT 

Rochester, NY 

February 2012 

PICRM-2012-05 

© 2012 Printing Industry Center at RIT— All rights reserved. 

i

With Thanks 

ii 

The research agenda <strong>of</strong> <strong>the</strong> Printing Industry Center at RIT and 

<strong>the</strong> publication <strong>of</strong> research findings are supported by <strong>the</strong> 

following organizations: 

bc 

Farnand, Frey, Gamm, Muehlemann, & Laguna-Monroy (PICRM-2012-05)

Table <strong>of</strong> Contents 

Introduction ................................................................................................................... 3 

Part A: A Survey <strong>of</strong> <strong>D50</strong> Viewing <strong>Booths</strong> Used in <strong>the</strong> Graphic Arts Industry 

Introduction ........................................................................................................... 4 

Background ............................................................................................................ 4 

Method .................................................................................................................. 11 

Data Analysis ........................................................................................................ 13 

Case Study A—<strong>Variability</strong> Within <strong>the</strong> Same Booth ........................................ 25 

Case Study B—An Analysis <strong>of</strong> Antique Monochrome Photographs and 

Their Reproductions Under Five <strong>D50</strong> Viewing <strong>Booths</strong> .................................. 27 

Conclusions .......................................................................................................... 37 

Part B: <strong>Evaluating</strong> <strong>the</strong> <strong>Impact</strong> <strong>of</strong> <strong>the</strong> <strong>Variability</strong> <strong>of</strong> <strong>D50</strong> <strong>Light</strong> <strong>Booths</strong> on <strong>the</strong> 

Appearance <strong>of</strong> Reproductions <strong>of</strong> Monochrome Photographs 

Experimental Method ......................................................................................... 38 

Results and Discussion ........................................................................................ 41 

Conclusion ............................................................................................................ 47 

References ..................................................................................................................... 48 

<strong>Evaluating</strong> <strong>the</strong> <strong>Impact</strong> <strong>of</strong> <strong>the</strong> <strong>Variability</strong> <strong>of</strong> <strong>D50</strong> <strong>Light</strong> <strong>Booths</strong> on <strong>the</strong> Appearance <strong>of</strong> 

Reproductions <strong>of</strong> Monochrome Photographs 

Table <strong>of</strong> Contents 

1

2 


Introduction 

Art reproductions are viewed under various lighting conditions, even during image 

evaluation. These conditions range from light booth to <strong>of</strong>fice to museum shop to living 

room to gallery. Consequently, it is important to understand and to quantify <strong>the</strong> 

significance <strong>of</strong> this effect. A recently completed project sponsored by The Andrew W. 

Mellon Foundation evaluated current practices in fine art image reproduction (see Frey 

& Farnand, 2011). This project consisted <strong>of</strong> a series <strong>of</strong> experiments in which a set <strong>of</strong> 

objective targets and pieces <strong>of</strong> artwork in various media were imaged by participating 

museums and prints were made from <strong>the</strong> delivered image files. One <strong>of</strong> <strong>the</strong>se pieces 

<strong>of</strong> artwork was a platinum print donated by <strong>the</strong> Image Permanence Institute (IPI) at 

RIT. Over <strong>the</strong> course <strong>of</strong> <strong>the</strong> experimentation, it was determined that <strong>the</strong> reproduction 

quality <strong>of</strong> this photographic print was particularly sensitive to <strong>the</strong> viewing illumination. 

Empirical evidence suggested that perceived reproduction quality shifted even among 

different <strong>D50</strong> light booths. Measurement results obtained by Gamm, reported in Part A 

<strong>of</strong> this monograph, indicate that, while some <strong>of</strong> <strong>the</strong> light booths deviated from <strong>the</strong> ISO 

Standard specifications, <strong>the</strong> differences should not have been large enough to result in 

visual differences in <strong>the</strong> reproductions. However, visual differences were observed in <strong>the</strong> 

Mellon study. To fur<strong>the</strong>r explore this result, <strong>the</strong> experiment was repeated with a variety 

<strong>of</strong> monochrome photographs similar to, and including, <strong>the</strong> platinum print used in <strong>the</strong> 

Mellon study. The photographs, selected from IPI’s collection, were imaged by three 

cultural heritage institutions, printed on a variety <strong>of</strong> equipment at RIT, and visually 

assessed under two <strong>D50</strong> lighting set ups. 

Quantifying <strong>the</strong> illumination differences in <strong>D50</strong> viewing booths in use today is 

important for those involved with fine art reproduction workflows. It is useful for 

those attempting to generate what are inherently metameric matches to have an 

understanding <strong>of</strong> how much variation in image appearance may result from differences 

in illumination. Toward this end, a survey <strong>of</strong> <strong>D50</strong> light booths used throughout <strong>the</strong> 

print production workflow was conducted. 




3

Part A: Introduction 

4 

Part A: A Survey <strong>of</strong> <strong>D50</strong> Viewing <strong>Booths</strong> 

Used in <strong>the</strong> Graphic Arts Industry 

by Brian Gamm and Simon Muehlemann 


CIE illuminant <strong>D50</strong> is widely accepted by <strong>the</strong> graphic arts industry worldwide as 

<strong>the</strong> reference illuminant <strong>of</strong> choice for <strong>the</strong> critical evaluation <strong>of</strong> prints. However, CIE 

illuminant <strong>D50</strong> is not physically realizable as a source, and must be simulated for use in 

viewing booths. Illuminant <strong>D50</strong> is most commonly simulated using linear fluorescent 

lamps with correlated color temperatures <strong>of</strong> 5000K. Yet, <strong>the</strong> variability among linear 

fluorescent lamp systems, which include <strong>the</strong> lamp, ballast and reflector, is great. This is 

largely due to variations in <strong>the</strong> use <strong>of</strong> viewing booths, including <strong>the</strong> hours <strong>of</strong> use, <strong>the</strong> 

frequency with which <strong>the</strong>y are turned on and <strong>of</strong>f, <strong>the</strong> environment in which <strong>the</strong>y are 

housed, cleanliness, and maintenance. Ideally, <strong>the</strong> variability among viewing booths 

throughout <strong>the</strong> printing industry is minimal. This ensures that a print viewed in one 

location looks <strong>the</strong> same as that same print viewed in anywhere else in <strong>the</strong> world. 

However, we do not live in an ideal world, and variability is ever-present. 

This report is <strong>the</strong> first part in a series <strong>of</strong> two. In Part B <strong>of</strong> this monograph, Farnand 

sought to determine whe<strong>the</strong>r <strong>the</strong> perceived image quality <strong>of</strong> antique monochrome 

photograph reproductions differed under two <strong>D50</strong> sources. Eight photographs were 

photographed by three cultural heritage institutions and printed using four different 

technologies. Empirical evidence from past research suggested that <strong>the</strong> perceived 

image quality <strong>of</strong> monochrome photograph reproductions with respect to <strong>the</strong> originals 

varied as <strong>the</strong> images were viewed in different <strong>D50</strong> viewing booths. Farnand discusses 

an experiment in which she had 14 observers rank 12 reproductions <strong>of</strong> eight antique 

monograph photographs under two <strong>D50</strong> viewing sources. One source was a typical 

<strong>D50</strong> viewing booth and <strong>the</strong> o<strong>the</strong>r was a small room fitted with four banks <strong>of</strong> <strong>D50</strong> lamps 

and used for conducting large-scale psychophysical studies. While this experiment was 

conducted in a laboratory setting, it was designed to demonstrate <strong>the</strong> possible variation 

in image quality across <strong>D50</strong> viewing booths in general. Before answering this question, 

it is necessary to understand <strong>the</strong> extent to which <strong>D50</strong> viewing booths are controlled 

throughout <strong>the</strong> printing industry. The variability between viewing booths is largely 

dependent upon measurement tolerances for standard viewing booths and <strong>the</strong> diligence 

with which viewing booth owners maintain calibration. 

<strong>D50</strong> viewing booths for <strong>the</strong> graphic arts industry must comply with ISO 3664-2009, 

<strong>the</strong> latest edition <strong>of</strong> ISO 3664. This standard describes specifications for color and 

illuminance to minimize inter-booth variation. The goal <strong>of</strong> this study was to understand 

<strong>the</strong> variability among <strong>D50</strong> viewing booths with regard to ISO 3664-2009 and <strong>the</strong> 

perceptual rendering <strong>of</strong> real printed targets. The first step was to collect data from a 


variety <strong>of</strong> viewing booths used throughout <strong>the</strong> printing industry, compute <strong>the</strong> metrics 

defined in ISO 3664-2009, and determine how well <strong>the</strong> sample viewing booths adhered 

to <strong>the</strong> specifications. The specifications in ISO 3664-2009 do not contain tolerances for 

perceptual judgments <strong>of</strong> prints, but seek to define <strong>the</strong> properties <strong>of</strong> <strong>the</strong> lamp. A second 

analysis was conducted using standard color evaluation targets to determine <strong>the</strong> degree 

<strong>of</strong> perceptual uniformity across <strong>D50</strong> viewing booths. 

Background 

Linear Fluorescent Lamps 

Fluorescent lamps are produced in many different forms. Linear fluorescent lamps, 

such as those used in viewing booths, are commonly specified as ei<strong>the</strong>r T12 or T8. 

Fluorescent lamps operate when low-pressure mercury vapor is energized from an 

electric current inside <strong>of</strong> a lamp. The excited mercury vapor emits UV and visible 

radiation. Phosphors coating <strong>the</strong> inner walls <strong>of</strong> <strong>the</strong> lamp absorb <strong>the</strong> UV radiation and 

re-emit it in <strong>the</strong> visible spectrum (<strong>Light</strong>ing Research Center [LRC], 1999). The type <strong>of</strong> 

phosphors used, along with <strong>the</strong> visible mercury emission, determine <strong>the</strong> spectral power 

distribution <strong>of</strong> <strong>the</strong> light source. 

T12 and T8 linear fluorescent tube lamps are <strong>the</strong> oldest <strong>of</strong> <strong>the</strong> still commonly used 

lamps. 1 T8 lamps became available in 1981 as an alternative to T12 lamps. T8 lamps 

typically run at around 32W. T12 lamps most commonly run at around 40W (N. Lena 2 , 

personal communication, January 18, 2012), while more energy efficient models run 

around 34W (LRC, 2006). The major differences between T12 and T8 lamps are <strong>the</strong> 

types <strong>of</strong> phosphors and <strong>the</strong> type <strong>of</strong> ballasts used. T12 lamps use mostly halophosphors 

and T8 lamps use mostly tri-color rare earth phosphors (U.S. Department <strong>of</strong> Energy 

[DOE], 2009). However, <strong>the</strong>se two types <strong>of</strong> phosphors are <strong>of</strong>ten blended to more 

precisely tune <strong>the</strong> lamp spectral power distribution. T12 are less efficient than T8 

systems (DOE, 2011), requiring more power to run a larger diameter lamp. Ballasts 

are a separate element <strong>of</strong> <strong>the</strong> fluorescent lamp luminaire that provide <strong>the</strong> initial starting 

voltage and regulate current during operation (LRC, 1999). Ballasts can ei<strong>the</strong>r be 

magnetic or electronic. T12 lamps commonly use magnetic ballasts, which contain a 

steel core and a copper coil and operate at a power line frequency <strong>of</strong> 60Hz. T8 lamps 

use electronic ballasts, composed <strong>of</strong> a circuit board and o<strong>the</strong>r electronic components 

(DOE, 2009). Magnetic ballasts are <strong>of</strong>ten recognized by a characteristic buzzing 

sound <strong>the</strong>y make during operation. In addition, magnetic ballasts generate more heat 

during operation, which can cause shifts in lamp color and have a negative impact on 

air-conditioning costs, a concern in large-scale commercial use. Electronic ballasts 

tend to be quieter and also more efficient. However, electronic ballasts can produce 

electromagnetic interference, which, while a non-factor in most cases, may be a 

determining factor in cases where electric field interference is an issue. 

1 - The lamp designation means <strong>the</strong> diameter <strong>of</strong> <strong>the</strong> lamp tube is ei<strong>the</strong>r 8/8 inch or 12/8 inch. 

2 - Nick Lena is <strong>the</strong> Director <strong>of</strong> Technology at GTI Graphic Technology, Inc. 



Part A: Introduction 

5

Part A: Background 

6 

The most common color temperatures for T8 lamps are 3500K and 4100K. However, <strong>the</strong> 

color rendering properties <strong>of</strong> <strong>the</strong>se lamps can vary greatly. T8 lamps are classified within 

<strong>the</strong> industry by <strong>the</strong>ir CRI. Those lamps with CRIs between 70 and 79 are classified as 

RE70 lamps; those with CRIs between 80 and 89 are classified as RE80 lamps, and those 

with CRIs greater than 90 are classified as RE90 lamps. However, it is also important to 

remember that fluorescent lamps are <strong>of</strong>ten tuned to produce a specific CRI value (DOE, 

2008), which only guarantees proper rendering <strong>of</strong> <strong>the</strong> eight CRI samples. Mean light 

output for T8 fluorescent lamps tested by <strong>the</strong> National <strong>Light</strong>ing Product Information 

Program (NLPIP) at <strong>the</strong> <strong>Light</strong>ing Research Center varied between a minimum <strong>of</strong> 2650 

lumens to a maximum <strong>of</strong> 3200 lumens with an average <strong>of</strong> around 2950 lumens. These 

values are descriptive <strong>of</strong> lamps with a variety <strong>of</strong> color rendering classifications. Some 

lamps also include design enhancements for high light output and longer life. 

The operating power for T8 lamps can vary without much difference in operation. It is 

recommended that a standard wattage for T8 lamps—32.5 watts as specified by ANSI 

C78.81-2005—be used in approximating T8 lamp efficacy (LRC, 2006). Measurements 

from <strong>the</strong> NLPIP suggest RE70 lamps had <strong>the</strong> poorest efficacy <strong>of</strong> around 88 LPW, while 

RE80 lamps had average efficacies <strong>of</strong> around 95 LPW. T8 lamps can be operated at 

variable frequency levels. <strong>Light</strong> output decreases for high-frequency operation while 

efficacy increases. 

5000K Fluorescent Lamps 

All <strong>D50</strong> viewing booths use linear fluorescent lamps. However, <strong>the</strong>re are a wide 

variety <strong>of</strong> fluorescent lamps available, and multiple brands may be interchangeable 

for a particular viewing booth. The common thread among all linear fluorescent 

lamp designations is <strong>the</strong> specification <strong>of</strong> operating power and lamp type. As discussed 

above, <strong>the</strong> most prevalent linear fluorescent lamps are T8 and T12. Viewing booths are 

designed for ei<strong>the</strong>r T8 or T12 lamps. Companies, such as GTI, manufacture both T12 

and T8 lamps for <strong>the</strong> same brand (GTI, 2009). Power designations (in Watts) are <strong>of</strong>ten 

proportional to lamp length. 3 Longer lamps require more power to match <strong>the</strong> luminance 

<strong>of</strong> shorter lamps. The power rating for linear fluorescent lamps, designated by <strong>the</strong> code 

‘F,’ is listed as ‘F[Watts].’ For example, a 40 Watt T8 lamp would be designated F40T8. 4 

Lamp manufacturers set <strong>the</strong>ir products apart with brand names. Interestingly, <strong>the</strong> three 

largest lamp manufacturers—Sylvania, GE, and Philips—produce similar products and 

make this known within <strong>the</strong>ir product catalogues. For example, Sylvania’s Design 50® 

product line, designated DSGN50, is comparable to GE’s Chroma 50 (C50) product line, 

and Philips’ Colortone 50 (C50) product line. Charts outlining <strong>the</strong> relationship between 

manufacturer brand names and color designations are shown in Figure A-1, reproduced 

from <strong>the</strong> Osram Sylvania Lamp and Ballast Catalogue (Osram Sylvania, 2011, p. 145). 

3 - Lamp length is a measurement <strong>of</strong> <strong>the</strong> entire lamp unit’s length, including <strong>the</strong> electrical pins on each end. 

4 - Some manufacturers only designate <strong>the</strong> power rating for a particular brand if that brand is <strong>the</strong> only 

manufacturer in <strong>the</strong> T8 or T12 format. Such a designation would list only <strong>the</strong> Power, such as F40, for a 40W 

lamp, and <strong>the</strong> brand. 


FLUORESCENT BRAND NAMES 

Figure A-1. Charts outlining <strong>the</strong> relationship between manufacturer brand names and 

color designations (Osram Sylvania, 2011, p. 132) 

While <strong>D50</strong> lamps manufactured by Sylvania, GE, and Philips are not solely intended 

for use in viewing booths, manufacturers <strong>of</strong> viewing booths <strong>of</strong>ten manufacturer 

proprietary lamps. GTI manufacturers <strong>the</strong> Graphiclite®100 for <strong>the</strong>ir <strong>D50</strong> viewing 

booths. GTI lamps are designated as, F#T#/GL50, with power ratings ranging from 11W 

to 58W, corresponding to 15-inch and 60-inch lengths (GTI, 2009). JUST Normlicht 

manufactures Daylight 5000 proGraphic lamps for <strong>the</strong>ir viewing booths. JUST 




SYLVAN 

IA 

GE* 

PHILIP 

S* 

* 

CURVALUME ® (FB) MOD-U-LINE (U) U-Bent (FB) 

CWX Home <strong>Light</strong> Everywhere (HL Everywhere) 

DESIGN 50 ® (DSGN50) Chroma 50 (C50) Colortone 50 (C50) 

DESIGNER ® Series Speci�cation Series (SP) SPEC or TL700 

DESIGNER 800 Series Speci�cation Series (SPX) Ultralume or TL800 

DESIGNER Cool White SP41 Home <strong>Light</strong> Cool (HL Cool) 

DESIGNER Cool White PLUS SPX41 41U 

DESIGNER Warm White Kitchen and Bath ULTRA (70 CRI) SPEC30 

DESIGNER Warm White PLUS (DWWP) Kitchen and Bath ULTRA (80 CRI) Home <strong>Light</strong> WX (HL WX) 

DESIGNER 700, 3500K (D35) SP35 Home <strong>Light</strong> Warm (HL Warm) 

ECOLOGIC ® (ECO ® ) Ecolux (ECO) ALTO 

GRO-LUX ® Gro & Sho/Plant & Aquarium/Terrarium Agro-Lite (AGRO) 

ICETRON ® --- --- 

OCTRON ® T8 (was Trimline) TL70/TL80 

OCTRON 700 XP ECO SP Ecolux XL T8 Lamps with Starcoat TL700 PLUS ALTO 

OCTRON 800 XP ECO SPX Ecolux XL T8 Lamps with Starcoat TL800 PLUS ALTO 

OCTRON 800 XPS ECO --- --- 

OCTRON 950 --- TL950 

PENTRON ® T5 Starcoat SILHOUETTE --- --- QL (similar to ICETRON, but not interchangeable) 

SAFELINE ® covRguard --- 

SUN STICK ® SUN (Sunshine) C50 

SUPERSAVER ® (SS) Watt-Miser (WM) Econ-o-Watt (EW) 

HO (800mA) HO (800mA) HO (800mA) 

VHO (1500mA) 1500 (1500mA) & Power Grove VHO (1500mA) (was SHO) 

VHO/LT T10/1500MA VHO-0 

XP ® XL Plus 

XPS ® Advantage 

* Trademarks or registered trademarks <strong>of</strong> General Electric Company ** Trademarks or registered trademarks <strong>of</strong> Philips 

FLUORESCENT COLOR CROSS REFERENCE 

SYLVANIA GE PHILIPS SYLVANIA GE PHILIPS 

CW CW CW D41 SP41 Spec 41 

CWX CWX, HL Everywhere SP65 

D D D D830 SPX30 30U 

DX DX DX D835 SPX35 35U 

DSGN50 C50 50 D841 SPX41 41U 

DSGN50 SGN C50 D865 

DCW, D41 SP41 HL Cool 730 SP30 730 

DCWP SPX41 U41 735 SP35 735 

DWW, D30 KB / 70 CRI, SP30 SPEC30 741 SP41 741 

DWWP, D830 KB / 82 CRI, SPX30 HL WX 750 SP50 750 

D35 SP35 HL Warm 765 SP65 

GRO/AQ AGRO 827 SPX27 27 

GRO/WS/AQ PL/AQ 830 SPX30 30, 830 

LW LW LW 835 SPX35 35, 835 

N N N 

841 

SPX41 

41, 

841 

SUN STICK SUN C50 850 SPX50 50, 850 

WW WW WW 865 SPX65 865 

D30 SP30 Spec 

30 

950 

950 

D35 SP35 Spec 35 

7


8 

Normlicht does not use <strong>the</strong> standard lamp designation, but lists <strong>the</strong> lamps by power 

rating and width: 18W, 36W, and 58W, corresponding to 24, 48, and 59 inches in length. 

The CIE specifies 12 illuminants in <strong>the</strong>ir ‘F’ series representative <strong>of</strong> common fluorescent 

lamps. CIE illuminant F8 is representative <strong>of</strong> a linear fluorescent lamp with a 5000K 

color temperature. Specifically, <strong>the</strong> spectral power distribution is based on <strong>the</strong> 

Sylvania F40 Design 50 (F40DSGN50) lamp (HunterLab, 2008). ISO/TC 42 studied 

<strong>the</strong> feasibility <strong>of</strong> using CIE illuminant F8 as <strong>the</strong> reference illuminant for ISO 3664- 

2009 ra<strong>the</strong>r than CIE illuminant <strong>D50</strong> (ISO 3664, 2009). In this analysis, ISO/TC 42 

tested five 5000K lamps against CIE illuminants F8 and <strong>D50</strong> as references. These tests 

included metamerism evaluations for a set <strong>of</strong> eight patches printed using eight imaging 

systems and a set <strong>of</strong> 928 SWOP patches. The results showed that <strong>the</strong> ranking <strong>of</strong> <strong>the</strong> five 

sources, based upon index <strong>of</strong> metamerism and color difference, was <strong>the</strong> same for <strong>the</strong> 

two reference illuminants. This result, coupled with <strong>the</strong> industry-wide use <strong>of</strong> <strong>D50</strong> as a 

reference, led ISO/TC 42 to recommend that CIE illuminant <strong>D50</strong> continue to be used 

as <strong>the</strong> reference illuminant. Fur<strong>the</strong>r details <strong>of</strong> this study can be found in Annex B <strong>of</strong> <strong>the</strong> 

original report (ISO 3664, 2009, p. 15). 

ISO 3664 

ISO 3664 was first ratified in 1975 with <strong>the</strong> purpose <strong>of</strong> standardizing viewing conditions 

for critical judgments <strong>of</strong> prints, photographs, transparencies, and displays within <strong>the</strong> 

graphic arts industry (ISO 3664, 2009). Specifically, this report will discuss only those 

aspects <strong>of</strong> ISO 3664 related to <strong>the</strong> critical judgments <strong>of</strong> prints. An example <strong>of</strong> critical 

print judgment in a <strong>D50</strong> viewing booth is shown in Figure A-2. In this case, <strong>the</strong> viewing 

booth is part <strong>of</strong> a press’s in-line control system. 


Figure A-2. An example <strong>of</strong> critical print comparisons in a <strong>D50</strong> viewing booth 

used for in-line print evaluation 

The metrics used to evaluate viewing conditions include: reference illuminant and 

chromaticity tolerance (CIE 1976 Uniform Chromaticity Scale (UCS) diagram, CIE 

1964 standard observer), illuminance (lux), color rendering index (according to 

CIE 13.3), metamerism index (according to CIE 51 (Commission Internationale 

De L’Eclairage [CIE], 1981), now 051.2-1999 (with Supplement 1-1999, “A Method 

for Assessing <strong>the</strong> Quality <strong>of</strong> Daylight Simulators for Colorimetry”)), illumination 

uniformity, and surround luminous reflectance. Following are <strong>the</strong> tolerances for <strong>the</strong> 

later metrics defined in ISO 3664-2009. 

• Reference Illuminant: CIE Illuminant <strong>D50</strong> 

• Chromaticity Tolerance: 0.005 

• Illuminance: 2000 lux ± 500 lux (should be ± 250 lux) 

• Color Rendering Index: General Index ≥ 90, Special Indices for Samples 1-8 ≥ 80 

• Metamerism Index (Visible): Visual C or better (should be B or better) 

• Metamerism Index (UV): < 1.5, should be less than 1 




9


10 

• Illumination Uniformity (Surfaces up to 1 m 2 ): ≥ 0.75 

• Illumination Uniformity (Surfaces greater than 1 m 2 ): ≥ 0.6 

• Surround Luminous Reflectance: 60% (neutral and matte) 

Ideally, prints viewed in different <strong>D50</strong> viewing booths will look <strong>the</strong> same. These 

tolerances were set to ensure <strong>the</strong> best possible agreement between print evaluations 

conducted in certified <strong>D50</strong> viewing booths. Of course, no two viewing booths are 

exactly alike. Factors such as lamp age, ambient conditions, and surround conditions 

influence <strong>the</strong> variability <strong>of</strong> viewing booths. 

One <strong>of</strong> <strong>the</strong> most important changes made to ISO 3664-2000 for ISO 3664-2009 was <strong>the</strong> 

tightening <strong>of</strong> <strong>the</strong> MI UV tolerances from < 4 to < 1.5. In one case study, a lamp produced 

by GTI adhering to <strong>the</strong> ISO 3664-2000 standards had a MI UV <strong>of</strong> 2.5. Responding to <strong>the</strong> 

tightened tolerances in <strong>the</strong> new standard, GTI reengineered this lamp to have a higher 

UV output, <strong>the</strong>reby reducing <strong>the</strong> MI UV to 0.90 (R. McCurdy, personal communication, 

November 2011). 5 

While a tightening <strong>of</strong> tolerances may increase <strong>the</strong> agreement between prints viewing 

under different viewing booths, problems may occur when comparing prints with 

varying optical brightening agent (OBA) content (Kraushaar, 2011). OBAs are added 

to paper to increase <strong>the</strong> perceived brightness <strong>of</strong> <strong>the</strong> paper. They absorb near-UV and 

short wavelength visible radiation and reemit <strong>the</strong> radiation as “blue-ish” light. When 

viewed alone in a viewing booth, papers containing OBAs are perceived as white due 

to adaptation <strong>of</strong> <strong>the</strong> human visual system to <strong>the</strong> environment. However, when papers 

containing different amounts <strong>of</strong> OBAs are compared in <strong>the</strong> same viewing booth, <strong>the</strong> 

paper containing less OBAs will appear slightly yellow. The human visual system 

will not perceive two white objects as neutral “white” if <strong>the</strong>y are <strong>of</strong> different colors. 

Therefore, <strong>the</strong> human visual system will normalize its perception <strong>of</strong> whiteness to <strong>the</strong> 

brightest <strong>of</strong> <strong>the</strong> white papers. This normalization causes <strong>the</strong> less-bright papers, which 

have less OBAs and thus emit less blue energy, to appear yellow (Kraushaar, 2011). The 

increase in UV content by manufacturers in <strong>the</strong>ir <strong>D50</strong> lamps to meet <strong>the</strong> restricted 

tolerances <strong>of</strong> ISO 3664-2009 accentuates <strong>the</strong> problems associated with OBAs. These 

problems are realized when comparing print pro<strong>of</strong>s, which have minimal OBA content, 

and press prints, which can have large amounts <strong>of</strong> OBAs. The difference between 

pro<strong>of</strong>s and prints viewing under lamps manufactured to ISO 3664-2000 standards 

may appear less different than when viewed under lamps manufactured to ISO 3664- 

2009 specifications. In addition, print judgments made in <strong>D50</strong> viewing booths do 

not correspond to <strong>the</strong> color measurements <strong>of</strong> those prints because <strong>the</strong> lamps used in 

measurements devices—commonly tungsten or LED lamps—do not contain <strong>the</strong> same 

UV content as <strong>D50</strong> lamps. This problem is addressed by <strong>the</strong> M1 measurement condition 

specified in ISO 13655-2006 (ISO 13655, 2006). 

5 - Robert McCurdy is <strong>the</strong> VP <strong>of</strong> Sales and Marketing at GTI Graphic Technology Inc. He was interviewed 

over <strong>the</strong> phone and through e-mail with regards to this research due to his expertise in <strong>the</strong> field. 


Method 

E-mails were sent to contacts at six Rochester-area printing companies requesting 

permission to measure a sample <strong>of</strong> <strong>D50</strong> viewing booths currently in use and to conduct 

a short interview with an employee familiar with <strong>the</strong> operation <strong>of</strong> <strong>the</strong> booths. Of <strong>the</strong> six 

companies, three responded, saying <strong>the</strong>y would like to participate. In addition, three 

viewing booths were measured at <strong>the</strong> Printing Applications Laboratory in <strong>the</strong> Center 

for Integrated Manufacturing Studies at RIT, and one booth was measured in <strong>the</strong> Color 

Management Systems Lab in <strong>the</strong> RIT School <strong>of</strong> Print Media. Thus, a total <strong>of</strong> thirteen 

viewing booths were measured across <strong>the</strong> four institutions. 

The procedure for measuring <strong>the</strong> viewing booths was as follows: 

1. Absolute irradiance was measured using an Ocean Optics USB2000+ positioned 

in <strong>the</strong> center <strong>of</strong> <strong>the</strong> viewing booth table (<strong>the</strong> red square shown in Figure A-3) with 

<strong>the</strong> optical axis <strong>of</strong> <strong>the</strong> cosine collector normal to <strong>the</strong> luminaire. 

2. Lux was measured using a Minolta CS-200 positioned in <strong>the</strong> center <strong>of</strong> <strong>the</strong> 

viewing booth table with <strong>the</strong> optical axis <strong>of</strong> <strong>the</strong> integrating sphere normal to <strong>the</strong> 

luminaire. 

3. A series <strong>of</strong> measurements was made using <strong>the</strong> Photo Research SpectraScan 

PR655. The PR655 was mounted on a tripod with <strong>the</strong> lens at a height <strong>of</strong> five feet six 

inches from <strong>the</strong> floor and a distance <strong>of</strong> one foot from <strong>the</strong> base <strong>of</strong> <strong>the</strong> viewing booth 

unit (see Figure A-3). The PR655 has a one-degree field <strong>of</strong> view. The target is located 

by looking through a viewing optic through which is projected an image from <strong>the</strong> 

measurement optic (similar to an SLR camera, but with a fixed mirror containing a 

hole for <strong>the</strong> measurement light). Each measurement was made <strong>of</strong> light reflecting <strong>of</strong>f 

a polytetrafluoroethylene (PTFE) chip (a near perfect reflecting diffuser). 

a. The viewing booth surface was subdivided into nine sections. The nine 

measurement positions were located at <strong>the</strong> center <strong>of</strong> <strong>the</strong> nine subdivisions. 

b. The tripod was translated across <strong>the</strong> viewing booth for <strong>the</strong> three different 

horizontal measurement positions. 



Part A: Method 

11


12 

Viewing 

Booth 

Table Area 

(sq. m) 

Figure A-3. Diagram <strong>of</strong> <strong>the</strong> measurement device positions and <strong>the</strong> locations <strong>of</strong> <strong>the</strong> 9 

measurements on <strong>the</strong> viewing booth 6 

Specifications for <strong>the</strong> 13 measured viewing booths including table area, table angle, 

distance from <strong>the</strong> front <strong>of</strong> <strong>the</strong> table to <strong>the</strong> front <strong>of</strong> <strong>the</strong> lamps, booth brand, lamp brand, 

and <strong>the</strong> booth’s common use, are shown in Table A-1. 

Table A-1. Specifications for <strong>the</strong> 13 measured viewing booths 

Table 

Angle 

(degrees) 

Dist. 

Lamp to 

Table (m) 

1 1.09 12.26 1.12 

2 1.06 11.31 1.07 

Booth Type Lamp Type 

JUST Normlicht Color Control 

Pr<strong>of</strong>essional 

JUST Normlicht Color Control 

Pr<strong>of</strong>essional 

3 1.05 11.63 1.12 Heidelberg Press Booth 

4 1.09 12.53 1.24 

4a 26.57 

4b 12.53 

Photo Research 655 

5 ft. 

6 in. 

? ft. 

1 ft. 

Measurement 

Positions 

40 W lamp 

Common 

Use 

Customer 

Viewing 

40 W lamp Pre-press 

Philips Master 

TL-D 90 

Heidelberg Prinext Press Center GraphicLite 

100 <strong>D50</strong>00 

5 0.98 7.85 0.86 GTI CVX Color Viewing Station 

<strong>Light</strong> Booth 

GraphicLite 


Press 

Press 

On-Press 

Quality 

Control 

6 - The red position marks <strong>the</strong> measurement location <strong>of</strong> <strong>the</strong> Ocean Optics USB2000+ and <strong>the</strong> Minolta CS- 

200. All 12 positions marked in ei<strong>the</strong>r blue or red were read with <strong>the</strong> PR655. 

Farnand, Frey, Gamm, Muehlemann, & Laguna-Monroy (PICRM-2012-05) 

θ ?

Viewing 

Booth 

Table Area 

(sq. m) 

Table 

Angle 

(degrees) 

Dist. 

Lamp to 

Table (m) 

Booth Type Lamp Type 





10 1.01 5.71 0.89 GTI GraphicLite LiteGuard 

11 1.50 16.70 1.14 Heidelberg Press Booth 

12 0.96 3.95 0.86 GTI ColorMatcher 

13 0.65 4.57 0.91 

Data Analysis 

Survey <strong>of</strong> <strong>Light</strong>ing Practices 

GTI GraphicLite Executive Viewing 

Station 

Representatives from each <strong>of</strong> <strong>the</strong> four organizations participating in this study were 

interviewed regarding <strong>the</strong>ir viewing booth usage practices. Each organization reported 

considerably different practice methods. For ease <strong>of</strong> discussion, <strong>the</strong> organizations will 

be referred to as Organizations 1-4. Notably, Organizations 1-3 reported calibrating 

<strong>the</strong>ir viewing booths. However, each <strong>of</strong> <strong>the</strong> three organizations used a different 

method <strong>of</strong> calibration, and only one <strong>of</strong> <strong>the</strong> three reported calibrating to ISO 3664- 

2009 standards. Viewing booth calibration is <strong>the</strong> verification that a viewing booth 

meets ISO 3664 specifications and includes problem-solving methods should <strong>the</strong> 

booth be out <strong>of</strong> specification (R. McCurdy, personal communication, November 

2011). There is no manual adjustment <strong>of</strong> <strong>the</strong> booth o<strong>the</strong>r than <strong>the</strong> changing <strong>of</strong> lamps 

as necessary. Organization 2 contracted out its calibration to GTI Graphic Technology 

Inc., <strong>the</strong> manufacturer <strong>of</strong> <strong>the</strong> lamps used in <strong>the</strong>ir booths as well as <strong>of</strong> most <strong>of</strong> <strong>the</strong> 

non-GTI booths included in this study, with <strong>the</strong> exception <strong>of</strong> <strong>the</strong> Heidelberg booths 

used on press. The calibration for all three organizations involved changing lamps 

in <strong>the</strong> booth. GTI included lamp replacement in <strong>the</strong> calibration procedure <strong>of</strong> <strong>the</strong> 

booths for Organization 2. In Organization 1, lamp replacement was conducted by 

<strong>the</strong> maintenance department, while Organization 3 employed an in-house standards 

and measurement technician. A sample calibration report provided by one <strong>of</strong> <strong>the</strong> 

organizations is shown in Figure A-4. This memo describes <strong>the</strong> location <strong>of</strong> each viewing 



GraphicLite 


GraphicLite 


GraphicLite 


GraphicLite 


GraphicLite 


JUST Daylight 

5000 Pro- 

Graphic 

GraphicLite 


GraphicLite 



Common 

Use 

Quality 

Control 

PrePress 

In-Line 

Testing 

Digital Press 

Testing 

Customer 

Viewing 

Press Check 

Education 

Education/ 

Research 

13

Part A: Data Analysis 

14 

booth, <strong>the</strong> number and type <strong>of</strong> lamps for each viewing booth (denoted by an internal 

classification system), <strong>the</strong> number <strong>of</strong> hours on <strong>the</strong> lamps when <strong>the</strong>y were changed, and 

<strong>the</strong> date when <strong>the</strong>y were changed. 

Date: February 28, 2010 

To: Calibration Records 

From: [Person Name] 

Re: <strong>Light</strong>bulb Updates 

[Person Name] and [Company Name] have made <strong>the</strong> following lightbulb changes: 

Location Bulbs Hours Date 

[1] 4/5000K 5201 2/18/10 

[2] 4/5000K 9671 2/18/10 

[3] 3/Heidelberg ------- 2/22/10 

[4] 4/5000K 2646 2/22/10 

[5] 5/5000K ------- 2/19/10 

[6] 4/5000K 2706 2/19/10 

Pre-Media 4/5000K 2365 2/19/10 

Customer 

Lounge 

4/5000K 14002 2/20/10 

Conf. Room 4/5000K 9275 2/20/10 

Figure A-4. Sample light booth calibration record report 

All four organizations reported having multiple booths divided among various 

departments. For example, an organization may have had one booth in <strong>the</strong> prepress 

department, one in <strong>the</strong> customer viewing lounge, one in <strong>the</strong> quality control department, 

and one placed by each press. However, <strong>the</strong> number <strong>of</strong> booths was variable across 

organizations. Organization 3, for example, was a single company branch, and was not 

a branch that produced prints requiring critical color comparisons. The main viewing 

booth in use was dedicated to in-line evaluations, though most <strong>of</strong> <strong>the</strong>ir color control 

was evaluated via a hand-held spectrophotometer. 

Standard usage practices also varied among organizations. When asked about warm-up 

time, Organizations 1 and 2 reported not incorporating warm-up time into <strong>the</strong>ir 

procedure, Organization 3 reported never turning <strong>of</strong>f <strong>the</strong>ir booth, and Organization 

4 reported allowing 30 minutes to 1 hour for warm-up before conducting critical 


comparisons. Organizations 1-3 reported tracking lamp lifetime on paper as <strong>the</strong> number 

<strong>of</strong> hours <strong>of</strong> operation since <strong>the</strong> previous lamp replacement, and, if <strong>the</strong> booth contained 

a built-in clock, <strong>the</strong> clock time was used as <strong>the</strong> reference. However, use <strong>of</strong> <strong>the</strong> lamp-life 

data varied. Though Organizations 1 and 2 reported tracking lamp life, both reported 

changing lamps annually ra<strong>the</strong>r than at a specific time <strong>of</strong> use. Organization 3 reported 

purchasing lamps in bulk and replacing lamps as needed after <strong>the</strong>ir maximum rated life. 

Organization 4 reported changing lamps only after <strong>the</strong>y burned out. 

The specifications discussed in ISO 3664-2009 and its earlier editions are designed 

to promote <strong>the</strong> best possible agreement between viewing booths in <strong>the</strong> graphic arts 

industry. There are several companies that certify <strong>D50</strong> viewing booths for <strong>the</strong> graphic 

arts. GTI, a manufacturer <strong>of</strong> <strong>D50</strong> viewing booths, has <strong>the</strong>ir booths certified by Fogra 

e.V., <strong>the</strong> German Graphic Technology Research Association (Fogra, 2011). Ugra, 

<strong>the</strong> Swiss Centre <strong>of</strong> Competence for Media and Printing Technology, is ano<strong>the</strong>r such 

organization that performs ISO 3664 tests as part <strong>of</strong> an ISO 12647 certification. While 

<strong>the</strong> certification process ensures <strong>the</strong> accreditation <strong>of</strong> products produced by GTI and 

o<strong>the</strong>r manufacturers <strong>of</strong> <strong>D50</strong> viewing booths, such as JUST Normlicht, X-Rite, and 

Heidelberg, viewing booth calibration is an important step in ensuring that <strong>D50</strong> 

viewing booths continue to operate within <strong>the</strong> ISO 3664 specifications. Viewing booth 

manufacturers <strong>of</strong>ten employ technicians to conduct calibrations <strong>of</strong> viewing booths 

currently being used in <strong>the</strong> field. However, while <strong>the</strong> certification process ensures <strong>the</strong> 

products rigidly adhere to ISO 3664 standards, <strong>the</strong> calibration procedure focuses on 

key aspects <strong>of</strong> <strong>the</strong> standard that <strong>the</strong> user can easily understand, namely <strong>the</strong> CIE uʹvʹ and 

illuminance tolerances. GTI provides <strong>the</strong> Status <strong>of</strong> Color Viewing Facilities Report, also 

called <strong>the</strong> LiteSupport Survey, to clients following <strong>the</strong> calibration <strong>of</strong> a viewing booth 

(R. McCurdy, personal communication, November 2011). This document describes 

<strong>the</strong> conformity <strong>of</strong> viewing booth chromaticities and illuminances to ISO 3664 in a data 

table and describes both graphically and in words <strong>the</strong> spatial uniformity. However, while 

Organizations 1-4 used GTI products, only Organization 2 contracted with GTI for 

calibrations. The procedure by which Organizations 1 and 2 validated <strong>the</strong>ir calibrations 

is not known, but may be investigated fur<strong>the</strong>r in future research. For reference, <strong>the</strong> 

spectral power distributions for all thirteen viewing booths are shown in Figure A-5. 

CIE illuminants F8 and <strong>D50</strong> are shown for comparison. 




15


16 

Relative Spectral Power 

3 

2.5 

2 

1.5 

1 

0.5 

0 

400 450 500 550 600 650 700 750 

Wavelength (nm) 

Figure A-5. Spectral power distributions for all thirteen viewing booths, 

with CIE illuminants F8 and <strong>D50</strong> shown for reference 

Viewing Booth Measurements 

The lighting analysis was conducted based upon <strong>the</strong> metrics described in Table A.1 <strong>of</strong> 

ISO 3664-2009 (p. 14) for critical comparison between prints. ISO 3664 standardizes 

viewing conductions within <strong>the</strong> graphic arts industry. The metrics used to evaluate 

viewing conditions include: reference illuminant and chromaticity tolerance (CIE 1976 

Uniform Chromaticity Scale (UCS) diagram, CIE 1964 standard observer), illuminance 

(lux), color rendering index (according to CIE 13.3), metamerism index (according to 

CIE 51 (CIE, 1981), now 051.2-1999 (with Supplement 1-1999, “A Method for Assessing 

<strong>the</strong> Quality <strong>of</strong> Daylight Simulators for Colorimetry”)), illumination uniformity, 

and surround luminous reflectance. However, due to <strong>the</strong> variety <strong>of</strong> environments 

surrounding <strong>the</strong> measured viewing booths, surround luminous reflectance was not 

analyzed in this study. The measured ISO 3664-2009 metrics are shown in Table A-2. 

The values in red are outside <strong>of</strong> <strong>the</strong> standard tolerances. 

<strong>D50</strong> 


F8

Table A-2. Measurements <strong>of</strong> ISO 3664 viewing conditions metrics for <strong>the</strong> thirteen 

viewing booths 7 

Viewing 

Booth 

CCT CRI 

Illuminance 

(Lux) 

Illumination 

Uniformity 

uʹvʹ 

Difference 

Visible MI 

(∆E * 

ab ) 

1 4632 86 1740 0.8841 0.0108 0.831 C 

2 4419 84 1623 0.7385 0.0176 1.060 D 

3 4633 96 1985 0.7970 0.0097 0.740 C 

4 4877 88 1725 0.6621 0.0044 1.105 D 

5 4833 92 2041 0.7164 0.0043 0.860 C 

6 4793 88 2152 0.6035 0.0056 0.796 C 

7 4817 91 1400 0.7294 0.0048 0.830 C 

8 4634 90 2448 0.6113 0.0083 0.910 C 

9 4550 88 1817 0.7914 0.0112 0.990 C 

10 4655 89 1920 0.6563 0.0079 1.045 D 

11 4704 97 2197 0.8576 0.0057 0.763 C 

12 4777 90 1460 0.6135 0.0056 1.030 D 

13 4799 90 1852 0.7423 0.0064 1.102 D 

Reference Illuminant 

The correlated color temperature (CCT) was calculated based upon <strong>the</strong> minimal 

distance from <strong>the</strong> source chromaticity (CIE 1976 UCS diagram, CIE 1964 standard 

observer) to <strong>the</strong> Planckian Locus. The color temperature representative <strong>of</strong> <strong>the</strong> 

corresponding point on <strong>the</strong> Planckian Locus was regarded as <strong>the</strong> CCT <strong>of</strong> <strong>the</strong> measured 

source. The measured CCTs for <strong>the</strong> 13 viewing booths are shown in Table A-2. ISO 

3664-2009 specifies that <strong>the</strong> CCT for viewing booths be 5000K. However, <strong>the</strong> standard 

does not provide tolerances for <strong>the</strong> direct measure <strong>of</strong> CCT. Ra<strong>the</strong>r, <strong>the</strong> colorimetric 

attributes <strong>of</strong> <strong>the</strong> lamp are compared to those <strong>of</strong> CIE illuminant <strong>D50</strong>. None <strong>of</strong> <strong>the</strong> 

measured booths had CCTs equal to 5000K, though all but one were within ± 500K. 

Chromaticity Tolerance 

The chromaticity coordinates were calculated based upon <strong>the</strong> CIE 1976 UCS diagram 

with <strong>the</strong> CIE 1964 standard observer. ISO 3664-2009 specifies that lamp chromaticities 

be within 0.005 units <strong>of</strong> magnitude from <strong>the</strong> chromaticity coordinates <strong>of</strong> <strong>the</strong> CIE 

standard illuminant <strong>D50</strong>. Of <strong>the</strong> 13 viewing booths, only three were within <strong>the</strong> ISO 

3664-2009 tolerances. The chromaticity coordinates for <strong>the</strong> thirteen booths are shown 

in Figure A-6. The points are plotted on <strong>the</strong> 1976 UCS diagram. A magnified view <strong>of</strong> <strong>the</strong> 

diagram region containing <strong>the</strong> chromaticity points is shown in <strong>the</strong> inset. 

7 - Table elements in red indicate measurements outside <strong>the</strong> ISO 3664-2009 tolerances. 




Visible MI 

Classification 

17


18 

v′ 

0.6 

0.5 

0.4 

0.3 

0.2 

0.1 

525 550 

500 

475 

0 

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 

u′ 

Illuminance 

CIE 1976 UCS Diagram 

575 

A 

1500K 

F2 2000K 

3000K 

<strong>D50</strong> 4000K 

D65 5000K 

7000K 

10000K 

600 

1000K 

Figure A-6. Chromaticity coordinates plot <strong>of</strong> <strong>the</strong> 13 viewing booths 

on <strong>the</strong> 1976 UCS diagram 8 

Illuminance from <strong>the</strong> center measurement position was measured in lux. ISO 3664- 

2009 sets two tolerances for illuminance: <strong>the</strong> absolute tolerance and <strong>the</strong> recommended 

tolerance (<strong>the</strong> “should be” tolerance, as written in ISO 3664-2009). Two <strong>of</strong> <strong>the</strong> thirteen 

booths had illuminances less than <strong>the</strong> absolute tolerance <strong>of</strong> 2000 ± 500 lux, and four 

additional booths had illuminances outside <strong>of</strong> <strong>the</strong> recommended tolerances <strong>of</strong> 2000 

± 250 lux, but were within <strong>the</strong> absolute tolerances. The illuminances <strong>of</strong> <strong>the</strong> thirteen 

viewing booths are plotted in Figure A-7. The solid black line marks <strong>the</strong> specification <strong>of</strong> 

2000 lux. The dotted gold lines mark <strong>the</strong> recommended tolerances, and <strong>the</strong> solid blue 

lines mark <strong>the</strong> absolute tolerances. 

8 - The region <strong>of</strong> <strong>the</strong> diagram containing <strong>the</strong> points surrounding <strong>D50</strong> is magnified in <strong>the</strong> inset. 

625 

650 

780 

0.19 0.2 0.21 0.22 0.23 0.24 0.25 0.26 


0.52 

0.51 

0.5 

0.49 

0.48 

0.47 

0.46 

0.45 

ISO 3664 

Tolerances 

Measured Lamp 

Chromaticities 

D65 

7000K 

<strong>D50</strong> 

5000K 

ʹʹ 

4000K 

F2 

Planckian Locus 

A 

3000K 

In Tolerance: 3/13

Center Illuminance (lux) 

3000 

2500 

2000 

1500 

1000 

500 

0 

1 2 3 4 5 6 7 8 9 10 11 12 13 

Figure A-7. Illuminances <strong>of</strong> <strong>the</strong> thirteen viewing booths measured 

using a Minolta CS-200 

Color Rendering Index (CRI) 

<strong>Light</strong> Booth 

ISO 3664 Condition 

Recommended Tolerance 

Absolute Tolerance 

CRI was developed by <strong>the</strong> CIE as a metric for evaluating how well chromatic reflecting 

objects are rendered under light sources (DOE, 2008). The metric is calculated by 

comparing <strong>the</strong> colorimetry <strong>of</strong> eight medium chroma test samples under <strong>the</strong> test 

source and a reference source. If <strong>the</strong> CCT <strong>of</strong> <strong>the</strong> test source is less than 5000K, <strong>the</strong>n 

<strong>the</strong> reference source is a blackbody radiator with <strong>the</strong> same CCT. If <strong>the</strong> test source CCT 

is greater than 5000K, <strong>the</strong>n <strong>the</strong> reference source is a daylight source calculated using 

<strong>the</strong> CIE standard eigenvectors. The CRI metric, R a is <strong>the</strong> mean ∆E UV across <strong>the</strong> eight 

reference samples scaled to 100. An additional set <strong>of</strong> seven high chroma reference 

samples is also available to validate <strong>the</strong> CRI metric. The metric, R, is an array <strong>of</strong> ∆E UV 

values for all fifteen reference samples. ISO 3664-2009 specifies that lamps have General 

Index values, R a , greater than 90. Seven <strong>of</strong> <strong>the</strong> thirteen viewing booths had CRI values 

greater than or equal to 90. However, four additional viewing booths had CRIs within 

two points <strong>of</strong> <strong>the</strong> tolerance. 

It should be noted, however, that CRI might be a misleading metric in <strong>the</strong> lighting 

industry. It is common practice for manufacturers to manipulate <strong>the</strong> phosphor formulas 

in <strong>the</strong>ir lamps to maximize CRI (N. Lena, personal communication, January 18, 

2012). Because CRI considers only a few specific reflecting samples with low chroma, 

optimizing spectral power distribution for CRI may lead to unpleasing appearance for 

real-world samples viewed under such lamps. It is possible to optimize lamps for CRI 

using narrow-band phosphors, which are less expensive than wide-band phosphors. The 

greater use <strong>of</strong> narrow-band phosphors may lead to greater color inconstancy in <strong>the</strong> field 

or generally unpleasing color. This practice is more common in <strong>the</strong> realm <strong>of</strong> commercial 

lighting, where cost is an issue. Lamps with a more continuous spectrum may require 




19


20 

<strong>the</strong> more expensive wide-band phosphors and more <strong>of</strong> <strong>the</strong>m to achieve <strong>the</strong> desired 

spectral continuity. However, lamps using more phosphors require more operating 

power due to <strong>the</strong> greater energy absorption. The main demand in lamps manufactured 

for viewing booths is color appearance, and thus, spectral continuity. Cost and energy 

consumption are less <strong>of</strong> an issue. Despite <strong>the</strong>ir differences in quality and cost, both 

lamps are capable <strong>of</strong> being manufactured with identical CRIs. This illustrates <strong>the</strong> caution 

that must be given to evaluating lamps based on <strong>the</strong> CRI metric. 

Illumination Uniformity 

According to ISO 3664-2009, “Uniformity should be evaluated by measuring at least 

9 points, equally distributed on <strong>the</strong> viewing surface” (p. 8). Each viewing booth table 

was divided into a grid <strong>of</strong> nine equal-sized regions. One illuminance measurement was 

made from <strong>the</strong> center <strong>of</strong> each region using <strong>the</strong> PR655 and a PTFE tile (see Figure A-3). 

Illumination uniformity was calculated as <strong>the</strong> ratio between <strong>the</strong> lowest illuminance 

measurement and <strong>the</strong> highest illuminance measurement from among <strong>the</strong> nine positions. 

ISO 3664-2009 sets an illumination uniformity tolerance <strong>of</strong> ≥ 0.75 for tables less than or 

equal to one square meter and an illumination uniformity tolerance <strong>of</strong> ≥ 0.60 for tables 

greater than one square meter in area. Nine <strong>of</strong> <strong>the</strong> 13 viewing booths had areas greater 

than one square meter, and all but one viewing booth was within <strong>the</strong> tolerances for 

illumination uniformity. The distribution <strong>of</strong> luminance around <strong>the</strong> center <strong>of</strong> <strong>the</strong> thirteen 

viewing booths is illustrated in Figure A-8. 


Illuminance Difference from Center Position (cd/m 2 ) 

200 

0 

-200 

200 

0 

-200 

200 

0 

-200 

Figure A-8. Distribution <strong>of</strong> illuminance around <strong>the</strong> center <strong>of</strong> <strong>the</strong> thirteen 

viewing booths 9 

Each <strong>of</strong> <strong>the</strong> eight plots shows <strong>the</strong> difference in luminance from <strong>the</strong> center position 

(outside position minus center position) in units <strong>of</strong> candelas per square meter. In most 

cases, <strong>the</strong> center position had <strong>the</strong> highest luminance, with <strong>the</strong> exception <strong>of</strong> <strong>the</strong> front 

center position. There are a number <strong>of</strong> reasons for this effect. First, all <strong>of</strong> <strong>the</strong> viewing 

booths contained multiple lamps, with <strong>the</strong> middle lamp directed toward <strong>the</strong> center <strong>of</strong> 

<strong>the</strong> table. The center position received a high concentration <strong>of</strong> light directly from <strong>the</strong> 

middle lamp and slightly less energy from <strong>the</strong> o<strong>the</strong>r two lamps. The front and back 

positions on <strong>the</strong> table received more light from <strong>the</strong> nearest lamp, but less light from 

<strong>the</strong> surrounding lamps proportionally to <strong>the</strong> center. In addition, <strong>the</strong> illuminance from 

a linear fluorescent lamp is higher at <strong>the</strong> center than at <strong>the</strong> ends. This, along with <strong>the</strong> 

9 - The illuminance at each position is <strong>the</strong> difference between <strong>the</strong> outer position and <strong>the</strong> center position in 

candelas per square meter. 




Back Left Back Center Back Right 

Middle Left 

200 

Front Left Front Center 

0 

-200 

1 2 3 4 5 6 7 8 9 101112 13 1 2 3 4 5 6 7 8 9 101112 13 1 2 3 4 5 6 7 8 9 101112 13 

1 2 3 4 5 6 7 8 9 101112 13 

1 2 3 4 5 6 7 8 9 101112 13 

200 

0 

-200 

Center 

Position 

1 2 3 4 5 6 7 8 9 101112 13 

<strong>Light</strong> Booth Index 

200 

0 

-200 

200 

0 

-200 

200 

0 

-200 

Middle Right 

1 2 3 4 5 6 7 8 9 101112 13 

Front Right 

1 2 3 4 5 6 7 8 9 101112 13 

21


22 

overall greater flux at <strong>the</strong> center position, explains <strong>the</strong> difference between <strong>the</strong> center 

position and <strong>the</strong> left and right positions. Thus, <strong>the</strong> center position will always have a 

higher luminance if <strong>the</strong> luminaire is aligned parallel to <strong>the</strong> table. However, this is not 

always <strong>the</strong> case. For most <strong>of</strong> <strong>the</strong> measured viewing booths, <strong>the</strong> slope <strong>of</strong> <strong>the</strong> luminaire 

was steeper than that <strong>of</strong> <strong>the</strong> table, which is why <strong>the</strong> front center position <strong>of</strong>ten had a 

slightly higher luminance than <strong>the</strong> center position. 

Index <strong>of</strong> Metamerism 

The CIE document CIE 51-1981 outlines a method for assessing <strong>the</strong> quality <strong>of</strong> viewing 

booths simulating CIE illuminants D55, D65, and D75 (CIE, 1981). This document was 

later expanded to include CIE illuminant <strong>D50</strong> (CIE, 1999a). These documents were later 

combined into a single document, CIE 051.2-1999. The suitability <strong>of</strong> viewing booth 

lamps as simulators <strong>of</strong> <strong>D50</strong> is evaluated by examining <strong>the</strong> index <strong>of</strong> metamerism for a set 

<strong>of</strong> visible metamers and UV metamers. The visible metamer set contains five pairs <strong>of</strong> 

non-fluorescent virtual metameric pairs. The spectral reflectance curves for those five 

pairs are shown in Figure A-9. One reflectance spectrum from each <strong>of</strong> <strong>the</strong> five pairs is 

standard to <strong>the</strong> evaluation <strong>of</strong> any illuminant simulator. The second reflectance spectrum 

for each <strong>of</strong> <strong>the</strong> five pairs is designed to match <strong>the</strong> standard under a specific illuminant. 

The visible index <strong>of</strong> metamerism, MI , is evaluated by calculating <strong>the</strong> mean ∆E VIS * 

ab 

color difference for <strong>the</strong> five metameric pairs. It should be noted that <strong>the</strong> special index 

<strong>of</strong> metamerism was used ra<strong>the</strong>r than <strong>the</strong> Matrix R method because <strong>the</strong> metameric pairs 

were specifically designed to match under illuminant <strong>D50</strong>. 

Spectral Reflectance 

0.9 

0.8 

0.7 

0.6 

0.5 

0.4 

0.3 

0.2 

0.1 

Standard 

Metamers 

0 

400 450 500 550 


600 650 700 

Figure A-9. Spectral reflectance curves <strong>of</strong> <strong>the</strong> five visible metameric pairs from 

CIE 51-1981 and CIE 135/3-1999 

ISO 3664-2009 recommended tolerances for MI VIS based upon <strong>the</strong> coding system 

described in CIE 51-1981 are given below in Table A-3. The standard recommends all 

lamps have MI VIS ratings within a Category B at most, but sets absolute tolerances at 

Category C. 


Table A-3. CIE 51-1981 (extended to ISO 3664-2009) recommended tolerances for MI VIS 

Category ∆E * 

ab 

A < 0.25 

B 0.25 to 0.5 

C 0.5 to 1.0 

D 1.0 to 2.0 

E > 2.0 

The MI values for eight <strong>of</strong> <strong>the</strong> 13 viewing booths were rated in Category C. The 

VIS 

remaining viewing booths were rated in Category D. However, <strong>the</strong> ∆E * values for <strong>the</strong> 

ab 

Category D viewing booths were all between 1.0 and 1.1, values relatively close to being 

categorized as C. 

The calculation <strong>of</strong> <strong>the</strong> UV index <strong>of</strong> metamerism, MI UV , is an important component 

<strong>of</strong> ISO 3664-2009 certification. Unfortunately, it was discovered after surveying <strong>the</strong> 

viewing booths that <strong>the</strong> instrument used to measure spectral power distribution with 

<strong>the</strong> UV component was not working properly. The data from this device was deemed 

inaccurate and discarded. Therefore, no analysis <strong>of</strong> MI UV could be conducted at this 

time. However, because <strong>the</strong> calculation <strong>of</strong> MI UV is important, a short description <strong>of</strong> its 

computation is given. 

The UV metamer set contains three sets <strong>of</strong> data describing <strong>the</strong> spectrophotometric 

properties <strong>of</strong> virtual fluorescent samples. The spectra are similar to those <strong>of</strong> paper 

containing OBAs. Within <strong>the</strong> three sets <strong>of</strong> data are <strong>the</strong> spectra needed to construct 

a fluorescent total radiance factor spectrum: <strong>the</strong> spectral reflectance radiance factor, 

<strong>the</strong> relative spectral distribution <strong>of</strong> radiance emitted by fluorescence; and <strong>the</strong> spectral 

external radiant efficiency. The series <strong>of</strong> calculations used to calculate <strong>the</strong> spectral total 

radiance factor are shown in Equation 1. 

β (λ) = β (λ) + β (λ) 

Τ S L 

where β (λ) = ΝF(λ)/S (λ) 

L n 

and 

Ν = Σ S (λʹ)Q(λʹ)Δ λʹ , 

460 n 

where: 

λ=300 

β (λ): Τ spectral total radiance factor 

β (λ): S spectral reflection radiance factor 

F(λ): relative spectral distribution <strong>of</strong> radiance emitted by fluorescence 

Q(λʹ): spectral external radiant efficiency 

Ν: effective excitation 

S (λ): n normalized spectral power distribution <strong>of</strong> <strong>the</strong> test source 

λ: wavelengths <strong>of</strong> reflection and emission 

λʹ: wavelengths <strong>of</strong> excitation 



(1) 


23


24 

F(λ) is identical for <strong>the</strong> three sets <strong>of</strong> data. Differing among <strong>the</strong> sets are Q(λʹ) and β (λ). S 

MI is evaluated by comparing β (λ) and β (λ). The three β (λ) spectra are specific to 

UV Τ S S 

different illuminants. MI is equal to <strong>the</strong> mean ∆E UV * 

ab color difference between β (λ) and 

T 

β (λ) across <strong>the</strong> three datasets. 

S 

Macbeth ColorChecker Reproduction Analysis 

The only metrics by which reflected samples are analyzed in ISO 3664-2009 are CRI 

and M VIS/UV . Nei<strong>the</strong>r <strong>of</strong> <strong>the</strong>se metrics is based upon commonly printed materials. <strong>D50</strong> 

viewing booths are most commonly used to view commercial prints. The 24-patch 

Macbeth ColorChecker is a target commonly used to evaluate reproduction fidelity in 

an imaging system. Its patches are mixtures <strong>of</strong> a wide variety <strong>of</strong> pigments commonly 

used in paints. The goal <strong>of</strong> this analysis was to analyze <strong>the</strong> color constancy <strong>of</strong> <strong>the</strong> 

Macbeth ColorChecker. However, because printing inks are more commonly viewed 

under <strong>D50</strong> viewing booths than are paint pigments, a printed reproduction <strong>of</strong> <strong>the</strong> 

Macbeth ColorChecker was analyzed as opposed to <strong>the</strong> actual object. The particular 

ColorChecker reproduction was selected from among prints made for <strong>the</strong> Benchmarking 

Art Imaging Interchange Cycles project completed at RIT (Frey & Farnand, 2011). 

The reproduction was a reasonably good visual rendering <strong>of</strong> <strong>the</strong> original Macbeth 

ColorChecker compared to <strong>the</strong> o<strong>the</strong>r available renderings. 

Table A-4. Mean ∆E 00 color inconstancy indices between <strong>the</strong> thirteen viewing booths 

and CIE illuminant <strong>D50</strong> for a reproduction <strong>of</strong> <strong>the</strong> Macbeth ColorChecker (zeros not 

included in means) 

<strong>Light</strong> 

Booth 

1 2 3 4 5 6 7 8 9 10 11 12 13 Mean 

1 0 0.39 0.97 0.76 0.67 0.41 0.59 0.44 0.50 0.56 0.91 0.61 0.79 0.63 

2 0.39 0 0.94 1.10 0.97 0.79 0.94 0.74 0.79 0.89 0.98 0.95 1.13 0.88 

3 0.97 0.93 0 1.50 1.12 1.16 1.19 1.00 0.97 1.16 0.32 1.24 1.45 1.09 

4 0.76 1.11 1.51 0 0.48 0.41 0.38 0.54 0.67 0.38 1.34 0.29 0.16 0.67 

5 0.67 0.97 1.13 0.48 0 0.35 0.25 0.33 0.35 0.27 0.96 0.28 0.43 0.54 

6 0.41 0.79 1.17 0.41 0.35 0 0.19 0.29 0.36 0.23 1.01 0.27 0.42 0.49 

7 0.59 0.94 1.20 0.38 0.24 0.19 0 0.30 0.35 0.16 1.01 0.16 0.30 0.49 

8 0.44 0.74 1.01 0.54 0.33 0.29 0.30 0 0.37 0.20 0.87 0.27 0.49 0.49 

9 0.50 0.79 0.98 0.67 0.35 0.36 0.35 0.37 0 0.36 0.82 0.44 0.60 0.55 

10 0.57 0.89 1.17 0.38 0.27 0.24 0.16 0.20 0.36 0 0.99 0.11 0.31 0.47 

11 0.91 0.97 0.32 1.33 0.95 1.01 1.00 0.86 0.82 0.98 0 1.05 1.25 0.95 

12 0.61 0.95 1.24 0.28 0.28 0.27 0.16 0.27 0.44 0.11 1.06 0 0.23 0.49 

13 0.79 1.13 1.46 0.16 0.43 0.42 0.30 0.49 0.60 0.31 1.26 0.23 0 0.63 

Spectral reflectances <strong>of</strong> <strong>the</strong> 24 patches from <strong>the</strong> reproduction were collected using an X-Rite 

i1 spectrophotometer. CIELAB values were calculated for <strong>the</strong> 24 patches under <strong>the</strong> thirteen 

viewing booth spectral power distributions. Mean ∆E 00 color inconstancy indices between 

each <strong>of</strong> <strong>the</strong> 13 viewing booths and test source CIELAB values across <strong>the</strong> 24 patches were 


calculated and are shown in Table A-4. The mean color inconstancy index for each row 

was calculated from <strong>the</strong> matrix. The value describes <strong>the</strong> average color inconstancy index 

resulting from first viewing <strong>the</strong> image under <strong>the</strong> viewing booth indicated by <strong>the</strong> row header, 

<strong>the</strong>n viewing <strong>the</strong> image under each <strong>of</strong> <strong>the</strong> viewing booths indicated by <strong>the</strong> column headers. 

The maximum color inconstancy index was 1.00. This suggests that <strong>the</strong> ColorChecker 

reproduction is color-constant across all 13 viewing booths. 

Case Study A—<strong>Variability</strong> 

Within <strong>the</strong> Same Booth 

Many viewing booths used for in-line press evaluations allow <strong>the</strong> operator to adjust 

<strong>the</strong> angle <strong>of</strong> <strong>the</strong> table. This is an especially useful and <strong>of</strong>ten necessary tool that allows 

press operators to reduce glare on glossy substrates or wet ink. There is no specification 

for table angle in ISO 3664-2009. The standard accounts for table angle with <strong>the</strong> 

illumination uniformity metric. If increasing <strong>the</strong> table angle brings <strong>the</strong> viewing booth 

out <strong>of</strong> tolerance, <strong>the</strong>n considerations must be made for its use. In addition, some 

viewing booths designed for in-line use now contain electronic monitors on <strong>the</strong> back 

wall. One such booth is <strong>the</strong> Heidelberg Prinect Press Center (Viewing Booth 4 in <strong>the</strong> 

prior analysis). The monitor, which accounts for almost <strong>the</strong> entire rear wall <strong>of</strong> <strong>the</strong> 

viewing booth, displays vital information about <strong>the</strong> press, allowing <strong>the</strong> operator to 

oversee and control automated processes and record information about <strong>the</strong> press run. 

The image most commonly shown on <strong>the</strong> monitor contained a neutral gray background. 

The absolute CIE XYZ values (in candelas per square meter) for <strong>the</strong> Heidelberg Prinect 

Press Center neutral gray display image and <strong>the</strong> GTI CVX Color Viewing Station rear 

wall are shown in Table A-5. The large luminance difference between <strong>the</strong> two surfaces 

was very noticeable. 

Table A-5. CIE XYZ values in candelas per square meter for <strong>the</strong> Heidelberg 

Prinect Press Center neutral gray display image and <strong>the</strong> GTI CVX Color Viewing 

Station rear wall 

CIE 

GTI CVX Color 

Viewing Station 

Heidelberg 

Prinect 

X 219.50 80.24 

Y 227.80 91.44 

Z 179.70 99.38 

The operator <strong>of</strong> Viewing Booth 4 also stated that a blue desktop image is also frequently 

shown on <strong>the</strong> display. ISO 3664-2009 does not specify <strong>the</strong> color <strong>of</strong> surround surface 

viewing booths. However, it is known that <strong>the</strong> surround surfaces have an effect on <strong>the</strong> 

color <strong>of</strong> <strong>the</strong> print being evaluated and <strong>the</strong> overall brightness <strong>of</strong> <strong>the</strong> viewing booth. 

In this case study, three different configurations <strong>of</strong> Viewing Booth 4 were evaluated to 

determine whe<strong>the</strong>r <strong>the</strong>re was a significant difference between ISO 3664-2009 metrics. 




25

Part A: Case Study A 

26 

Viewing 

Booth 

The three configurations are shown in Figure A-10. The subfigure titles indicate <strong>the</strong> 

Viewing Booth code, corresponding to codes in <strong>the</strong> tables throughout this report, and 

<strong>the</strong> degree <strong>of</strong> table tilt. 

Standard Working Position (4) Tilted Working Position (4a) Blue Monitor Working Position (4b) 

Luminaire Luminaire Luminaire 

Display Display Display 

13 deg. Tilt 27 deg. Tilt 

13 deg. Tilt 

Figure A-10. Three viewing configurations analyzed in <strong>the</strong> case study 

The ISO 3664-2009 metrics for <strong>the</strong> three configurations are shown in Table A-6. None <strong>of</strong> 

<strong>the</strong> metrics show any significant change across configurations. 

Table A-6. Measurements <strong>of</strong> <strong>the</strong> ISO 3664-2009 viewing conditions metrics for <strong>the</strong> 

three configurations <strong>of</strong> Viewing Booth 4 

CCT CRI 

Illuminance 

(Lux) 

Illumination 

Uniformity 

u’v’ 

Difference 

Visible MI 

(∆E * 

ab ) 

4 4877 88 1725 0.6621 0.0044 1.105 D 

4a 4920 87 -- 0.6209 0.0040 1.095 D 

4b 4859 88 -- 0.6258 0.0047 1.112 D 

Visible MI 

Classification 

The Macbeth ColorChecker reproduction was also analyzed across configurations. The 

results are shown in Table A-7. There does not appear to be a significant change in <strong>the</strong> 

booth’s rendering ability across configurations. 

Table A-7. Mean ∆E 94 color differences between <strong>the</strong> three configurations <strong>of</strong> Viewing 

Booth 4 and CIE illuminant <strong>D50</strong> for a reproduction <strong>of</strong> <strong>the</strong> Macbeth ColorChecker 

Viewing 

Booth 

Mean ∆E 94 

ColorChecker 

4 1.25 

4a 1.29 

4b 1.25 

In general, <strong>the</strong> viewing booth configuration does not appear to have an effect on ei<strong>the</strong>r 

<strong>the</strong> conformance to <strong>the</strong> ISO 3664-2009 tolerances or <strong>the</strong> perceptual rendering <strong>of</strong> a real 

reflecting target. 


Case Study B—An Analysis <strong>of</strong> 

Antique Monochrome Photographs 

and Their Reproductions Under 

Five <strong>D50</strong> Viewing <strong>Booths</strong> 

Thus far, this section <strong>of</strong> <strong>the</strong> monograph has focused on <strong>the</strong> variability among <strong>D50</strong> 

viewing booths used in <strong>the</strong> printing industry. In this case study, <strong>the</strong> variability <strong>of</strong> 

<strong>D50</strong> viewing booths was analyzed in <strong>the</strong> context <strong>of</strong> Farnand’s analysis <strong>of</strong> antique 

monochrome photograph reproductions. 

Three measurements were made <strong>of</strong> each original photograph and reproductions using 

an X-Rite i1 spectrophotometer. A template was used to ensure that <strong>the</strong> measurement 

positions were <strong>the</strong> same for each original and <strong>the</strong>ir respective reproductions. The three 

measurements included one dark tone area, one medium tone area, and one light tone 

area. The spectral reflectance curves from <strong>the</strong> original photographs are shown in Figure 

A-11. Note <strong>the</strong> flatness <strong>of</strong> <strong>the</strong> spectral reflectance curves. This makes reproduction <strong>of</strong> 

<strong>the</strong> photographs using a four-color printing process difficult. However, <strong>the</strong> flat curve 

shapes also mean <strong>the</strong> photographs are color constant, meaning <strong>the</strong> photographs should 

appear <strong>the</strong> same when viewed under different sources. 

Reflectance 

1 

0.9 

0.8 

0.7 

0.6 

0.5 

0.4 

0.3 

0.2 

0.1 

0 

400 450 500 550 600 650 700 


Figure A-11. Spectral reflectance curves from <strong>the</strong> original photographs 

Among <strong>the</strong> four printing technologies used, two were electrophotographic, <strong>the</strong> HP 

Indigo 7000 and <strong>the</strong> Kodak NexPress S3000, located at <strong>the</strong> RIT Printing Applications 



Part A: Case Study B 

27


28 

Laboratory. The images printed on <strong>the</strong> electrophotographic presses were prepared for 

printing using early binding workflows. The substrate for both presses was Mohawk 

Superfine Smooth White 80lb text. Pr<strong>of</strong>iles were created for each press. The institutions 

provided <strong>the</strong> images as RGB files which were <strong>the</strong>n converted to <strong>the</strong> printer pr<strong>of</strong>ile 

and saved as CMYK files. The files were <strong>the</strong>n sent to <strong>the</strong> printer without fur<strong>the</strong>r color 

management. The remaining two printing technologies included an inkjet printer, an 

HP wide-format printer, and a digital silver halide (DAgX) printer, <strong>the</strong> Durst Lambda, 

located at <strong>the</strong> RIT Imaging Systems Lab. The image files were converted to AdobeRGB, 

<strong>the</strong>n delivered to <strong>the</strong> lab as specified by <strong>the</strong> lab. The lab handled color management from 

that point onward. The inkjet images were printed on Kodak Pro Lustre E paper and 

<strong>the</strong> DAgX images were printed on Kodak Matte paper. The four printer technologies are 

coded, as shown in Table A-8, for ease <strong>of</strong> reference. 

Table A-8. Printers included in <strong>the</strong> study and <strong>the</strong>ir respective codes 

Code Printer Name 

EP 1 HP Indigo 7000 

EP 2 Kodak NexPress S3000 

Inkjet HP Wide Format 

DAgX Durst Lambda 

The spectral reflectance curves for three original photographs (solid lines) are shown 

in Figure A-12, alongside <strong>the</strong> spectral reflectance curves for <strong>the</strong> reproductions (dotted 

lines) captured using Workflow 1 and printed using <strong>the</strong> DAgX process (top) and <strong>the</strong> EP 1 

process (bottom). The spectral reflectance curves shapes for <strong>the</strong> reproductions show <strong>the</strong> 

characteristic “bumpiness” <strong>of</strong> a four-color print process. The uneven shape <strong>of</strong> <strong>the</strong> fourcolor 

process curves make <strong>the</strong>m susceptible to inconstant color, especially when <strong>the</strong>re is 

a drastic difference between sources, such as between daylight and tungsten. However, 

<strong>the</strong> likelihood <strong>of</strong> <strong>the</strong> reproductions being noticeably different when viewed under two 

different <strong>D50</strong> sources is minimal due to <strong>the</strong> similarity between <strong>the</strong> source spectral power 

distributions and <strong>the</strong> fact that most <strong>of</strong> <strong>the</strong> source power is distributed among middle 

wavelengths. The reproduction spectral curves have tales at both <strong>the</strong> long and short 

wavelength regions and are thus more susceptible to sources differing in those regions. 


Reflectance 

Reflectance 

1 

0.9 

0.8 

0.7 

0.6 

0.5 

0.4 

0.3 

0.2 

0.1 

1 

0.9 

0.8 

0.7 

0.6 

0.5 

0.4 

0.3 

0.2 

0.1 

<strong>Light</strong> Patch 

0 

400 450 500 550 600 650 700 


<strong>Light</strong> Patch 

Figlia 

Nelson 

Helen 

0 

400 450 500 550 600 650 700 


DAgX Print Process - Spectral Reflectance Curves 

Figlia 


Helen 

Reflectance 

Reflectance 

0 

400 450 500 550 600 650 700 


Figure A-12. Spectral reflectance curves for three original photographs (solid lines) 

alongside <strong>the</strong> spectral reflectance curves for <strong>the</strong> reproductions (dotted lines), 

captured using Workflow 1 and printed using <strong>the</strong> DAgX process (top) 

and <strong>the</strong> EP 1 process (bottom) 

Five <strong>D50</strong> sources were selected to analyze <strong>the</strong> constancy <strong>of</strong> <strong>the</strong> antique monochrome 

photograph reproductions. The spectral power distributions <strong>of</strong> those sources are shown 

in Figure A-13. Two <strong>of</strong> <strong>the</strong> five sources were <strong>the</strong> Viewing Booth source and Viewing 

Room source used by Farnand in her study as part <strong>of</strong> <strong>the</strong> second half <strong>of</strong> this monograph. 

Three <strong>of</strong> <strong>the</strong> 13 sources analyzed in this document completed <strong>the</strong> set <strong>of</strong> five sources. 

Those three sources corresponded to Viewing <strong>Booths</strong> 5, 10, and 2 (see Table A-1), 

labeled as Test Sources 1-3, respectively in Figure A-13. The Viewing Booth source is 

<strong>the</strong> same as Viewing Booth 13 in Table A-1. Test Sources 1-3 had <strong>the</strong> best conformance, 

moderate conformance, and <strong>the</strong> worst conformance, respectively, to ISO 3664-2009 

from among Viewing <strong>Booths</strong> 1-12. 



1 

0.9 

0.8 

0.7 

0.6 

0.5 

0.4 

0.3 

0.2 

0.1 

0 

400 450 500 550 600 650 700 


1 

0.9 

0.8 

0.7 

0.6 

0.5 

0.4 

0.3 

0.2 

0.1 

Medium Patch 

Medium Patch 

Figlia 


Helen 

EP 1 Print Process - Spectral Reflectance Curves 

Original 

Figlia 


Helen 

Reproduction 

Reflectance 

Reflectance 

1 

0.9 

0.8 

0.7 

0.6 

0.5 

0.4 

0.3 

0.2 

0.1 

1 

0.9 

0.8 

0.7 

0.6 

0.5 

0.4 

0.3 

0.2 

0.1 


Dark Patch 

0 

400 450 500 550 600 650 700 


Dark Patch 

Figlia 


Helen 

Figlia 


Helen 

0 

400 450 500 550 600 650 700 


29


30 

Spectral Power Distribution 

3 

2.5 

2 

1.5 

1 

0.5 

0 

Test Source 1 

Test Source 2 

Test Source 3 

Viewing Booth Source 

Viewing Room Source 

400 450 500 550 


600 650 700 

Figure A-13. Spectral power distributions <strong>of</strong> <strong>the</strong> five <strong>D50</strong> sources 

Colorimetry was calculated for <strong>the</strong> measured patches on <strong>the</strong> eight images, twelve 

reproductions (three institutions and four printers), and original photographs under 

<strong>the</strong> five sources. CIEDE2000 color differences, averaged across press, workflow, and 

image, were calculated between all combinations <strong>of</strong> <strong>the</strong> five sources. These color 

differences represent color inconstancy indices. The mean and standard deviation color 

inconstancy indices for <strong>the</strong> three patches, and <strong>the</strong> overall mean, averaged across patches, 

are shown in Table A-9. The rows and columns are labeled with <strong>the</strong> source number or 

name (‘VB’ for Viewing Booth, and ‘VR’ for Viewing Room). Those elements in green 

are <strong>the</strong> smallest color inconstancy indices and those elements in red are <strong>the</strong> largest color 

inconstancy indices for each patch. Interestingly, for all but <strong>the</strong> dark patch, <strong>the</strong> standard 

deviations were lowest for <strong>the</strong> most and least inconstant source pairs. The least color 

inconstant source pair was Test Source 1 and Test Source 2. The mean color inconstancy 

index was 0.13. These sources also had <strong>the</strong> best conformance to ISO 3664-2009. The 

most inconstant source pair was Test Source 3 and <strong>the</strong> Viewing Booth source. However, 

<strong>the</strong> mean color inconstancy index was only 0.86. It is unlikely, even between <strong>the</strong> most 

inconstant sources, that an observer would notice a change in reproduction color. The 

color inconstancy index between <strong>the</strong> Viewing Booth source and <strong>the</strong> Viewing Room 

source was 0.19, with a standard deviation <strong>of</strong> 0.394. It is unlikely that any differences 

noticed between <strong>the</strong> reproductions under <strong>the</strong>se two sources were due to changes in 

color appearance. 


Table A-9. The mean and standard deviation color inconstancy indices (CIEDE2000) for 

<strong>the</strong> three patches, and <strong>the</strong> overall mean, averaged across patches 10 

Dark Patch Medium Patch 

MEAN 1 2 3 VB VR MEAN 1 2 3 VB VR 

1 0 0.13 0.53 0.26 0.12 1 0 0.15 0.64 0.37 0.21 

2 0 0.60 0.14 0.12 2 0 0.74 0.24 0.17 

3 0 0.73 0.63 3 0 0.97 0.83 

VB 0 0.18 VB 0 0.21 

VR 0 VR 0 

STDEV 1 2 3 VB VR STDEV 1 2 3 VB VR 

1 0 0.332 0.499 0.437 0.321 1 0 0.358 0.480 0.482 0.406 

2 0 0.491 0.352 0.324 2 0 0.437 0.424 0.373 

3 0 0.444 0.484 3 0 0.176 0.372 

VB 0 0.383 VB 0 0.404 

VR 0 VR 0 

Averaged across workflow, printer and image 

<strong>Light</strong> Patch Overall Mean 

MEAN 1 2 3 VB VR MEAN 1 2 3 VB VR 

1 0 0.12 0.61 0.31 0.21 1 0 0.13 0.59 0.31 0.18 

2 0 0.66 0.23 0.22 2 0 0.67 0.20 0.17 

3 0 0.88 0.81 3 0 0.86 0.76 

VB 0 0.19 VB 0 0.19 

VR 0 VR 0 

STDEV 1 2 3 VB VR STDEV 1 2 3 VB VR 

1 0 0.323 0.489 0.464 0.411 1 0 0.338 0.491 0.463 0.384 

2 0 0.474 0.421 0.415 2 0 0.472 0.403 0.375 

3 0 0.320 0.394 3 0 0.346 0.429 

VB 0 0.395 VB 0 0.394 

VR 0 VR 0 

Averaged across workflow, printer, image, and patch 

The nature <strong>of</strong> <strong>the</strong> samples’ color inconstancies is illustrated in Figures A-14 and A-15. 

Figure A-14 shows a plot <strong>of</strong> <strong>the</strong> CIELAB values for <strong>the</strong> three measurements <strong>of</strong> <strong>the</strong> 

images Faraoni, Nelson, and Helen 11 reproduced using Workflow 1 <strong>the</strong> EP 1 printer. 

The top two plots show CIELAB data for <strong>the</strong> patches viewed under <strong>the</strong> least inconstant 

source pair, Test Sources 1 and 2. The bottom two plots show CIELAB data for <strong>the</strong> 

10 - Those elements in green are <strong>the</strong> smallest color inconstancy indices and those elements in red are <strong>the</strong> 

largest color inconstancy indices for each patch. The abbreviation ‘VB’ stands for Viewing Booth and <strong>the</strong> 

abbreviation ‘VR’ stands for Viewing Room. 

11 - Please see Part B <strong>of</strong> this monograph for images <strong>of</strong> Faraoni, Nelson, and Helen. These images 

were highlighted because <strong>the</strong>y were, overall, accurate, moderately accurate, and minimally accurate 

reproductions with respect to <strong>the</strong>ir originals based upon <strong>the</strong> colorimetric data ga<strong>the</strong>red from <strong>the</strong> three 

measurements per photograph. 




31


32 

b* 

b* 

20 

15 

10 

5 

0 

-5 

patches viewed under <strong>the</strong> most inconstant source pair, Test Source 3 and <strong>the</strong> Viewing 

Booth source. 

EP 1 Print Process - Test Sources 1 and 2 - Least Inconstant 

a* vs b* 

-10 

-10 -5 0 5 

a* 

10 15 20 

20 

15 

10 

5 

0 

-5 

0 

0 5 10 

C* 

15 20 

EP 1 Print Process - Test Source 3 and <strong>the</strong> Viewing Booth Source - Most Inconstant 

a* vs b* 

Test Source 1 

Test Source 2 

Test Source 3 


-10 

-10 -5 0 5 

a* 

10 15 20 

L* 

L* 

100 

90 

80 

70 

60 

50 

40 

30 

20 

10 

100 

90 

80 

70 

60 

50 

40 

30 

20 

10 

Chroma vs <strong>Light</strong>ness 


0 

0 5 10 

C* 

15 20 

Figure A-14. Plot <strong>of</strong> CIELAB values for <strong>the</strong> three measurements <strong>of</strong> <strong>the</strong> images Faraoni, 

Nelson, and Helen reproduced using all three workflows with <strong>the</strong> EP 1 printer 

Figure A-15 shows a plot <strong>of</strong> <strong>the</strong> CIELAB values for <strong>the</strong> three measurements <strong>of</strong> <strong>the</strong> 

images Faraoni, Nelson, and Helen reproduced using Workflow 1 <strong>the</strong> DAgX printer. 

The top two plots show CIELAB data for <strong>the</strong> patches viewed under <strong>the</strong> least inconstant 

source pair, Test Sources 1 and 2. The bottom two plots show CIELAB data for <strong>the</strong> 

patches viewed under <strong>the</strong> most inconstant source pair, Test Source 3 and <strong>the</strong> Viewing 

Booth source. 


* 

b* 

20 

15 

10 

5 

0 

-5 

DAgX Print Process - Test Sources 1 and 2 - Least Inconstant 

a* vs b* 

-10 

-10 -5 0 5 

a* 

10 15 20 

20 

15 

10 

5 

0 

-5 

DAgX Print Process - Test Source 3 and Viewing Booth Source - Most Inconstant 

a* vs b* 

Test Source 1 

Test Source 2 

Test Source 3 


-10 

-10 -5 0 5 

a* 

10 15 20 

Figure A-15. Plot <strong>of</strong> CIELAB values for <strong>the</strong> three measurements <strong>of</strong> <strong>the</strong> images Faraoni, 

Nelson, and Helen reproduced using all three workflows with <strong>the</strong> DAgX printer 

The color differences resulting from <strong>the</strong> change in source are illustrated in Figures A-14 

and A-15 by a displacement between <strong>the</strong> hollow and solid circles, which represent data 

viewed under <strong>the</strong> two different sources. As expected, <strong>the</strong>re was very little displacement 

between <strong>the</strong> CIELAB points for <strong>the</strong> data viewed under Test Sources 1 and 2 and a 

noticeable difference between <strong>the</strong> CIELAB points for <strong>the</strong> data viewed under Test 

Source 3 and <strong>the</strong> Viewing Booth source. The color difference was greatest for <strong>the</strong> most 

chromatic patches. Most <strong>of</strong> <strong>the</strong> color differences observed were a result <strong>of</strong> hue shifts, 



L* 

L* 

100 

90 

80 

70 

60 

50 

40 

30 

20 

10 



0 

0 5 10 

C* 

15 20 

100 

90 

80 

70 

60 

50 

40 

30 

20 

10 


0 

0 5 10 

C* 

15 20 

33


34 

Print Orig 

EP 1, 

WF 1 

ra<strong>the</strong>r than shifts in ei<strong>the</strong>r lightness or chroma. However, as discussed earlier, <strong>the</strong> mean 

color inconstancy index for <strong>the</strong> source pair with maximum color inconstancy was 0.86, 

a relatively small value and not likely to result in a noticeable visual difference. 

CIEDE2000 color differences were also calculated between <strong>the</strong> 12 reproductions and 

<strong>the</strong> original. The color differences were averaged across measurement patch and image. 

The results are shown in Table A-10. The first row shows <strong>the</strong> color differences between 

each <strong>of</strong> <strong>the</strong> 12 reproductions and <strong>the</strong> original. Workflows 1 and 2 had similar color 

differences from <strong>the</strong> original when printed on EP 1, EP 2, and on <strong>the</strong> Inkjet printer. 

Workflow 3 had <strong>the</strong> largest color difference for those three devices. However, Workflow 

2 had <strong>the</strong> largest color difference when reproduced using <strong>the</strong> DAgX process. 

Table A-10. CIEDE2000 color differences calculated between <strong>the</strong> 12 reproductions and 

<strong>the</strong> original, averaged across measurement patch and image 12 

EP 1, 

WF 2 

EP 1, 

WF 3 

EP 2, 

WF 1 


EP 2, 

WF 2 

EP 2, 

WF 3 

Inkjet, 

WF 1 

Inkjet, 

WF 2 

Inkjet, 

WF 3 

DAgX, 

WF 1 

DAgX, 

WF 2 

DAgX, 

WF 3 

Orig 0 8.39 8.35 11.39 8.04 8.79 11.37 7.17 7.32 11.41 6.78 12.58 8.70 

EP 1, 

WF 1 

0 5.57 5.05 2.50 6.29 5.61 4.90 7.28 8.14 7.99 10.30 8.45 

EP 1, 

WF 2 

0 7.87 4.63 2.44 7.38 7.99 5.43 10.76 8.99 13.80 11.98 

EP 1, 

WF 3 

0 5.51 8.05 2.31 6.60 8.42 4.97 9.99 8.66 9.89 

EP 2, 

WF 1 

0 5.17 5.49 4.87 6.12 8.14 7.91 10.88 9.13 

EP 2, 

WF 2 

0 6.87 7.73 4.65 10.11 8.65 13.26 11.66 

EP 2, 

WF 3 

0 6.74 7.46 4.86 9.78 9.06 10.28 

Inkjet, 

WF 1 

0 5.51 5.68 4.98 7.03 5.04 

Inkjet, 

WF 2 

0 7.55 4.99 10.13 8.75 

Inkjet, 

WF 3 

0 7.77 4.85 7.73 

DAgX, 

WF 1 

0 7.39 5.22 

DAgX, 

WF 2 

0 5.41 

DAgX, 

WF 3 

0 

12 - Color differences are shown for CIELAB data calculated under <strong>the</strong> Viewing Booth source and <strong>the</strong> 

Viewing Room source. 


Print Orig 

EP 1, 

WF 1 

EP 1, 

WF 2 

EP 1, 

WF 3 

EP 2, 

WF 1 


EP 2, 

WF 2 

EP 2, 

WF 3 

Inkjet, 

WF 1 

Inkjet, 

WF 2 



Inkjet, 

WF 3 


DAgX, 

WF 1 

DAgX, 

WF 2 

Orig 0 8.16 8.05 11.17 7.74 8.44 11.08 7.12 7.21 11.39 6.78 12.63 8.75 

EP 1, 

WF 1 

EP 1, 

WF 2 

EP 1, 

WF 3 

EP 2, 

WF 1 

EP 2, 

WF 2 

EP 2, 

WF 3 

Inkjet, 

WF 1 

Inkjet, 

WF 2 

Inkjet, 

WF 3 

DAgX, 

WF 1 

DAgX, 

WF 2 

DAgX, 

WF 3 

DAgX, 

WF 3 

0 5.57 5.05 2.50 6.28 5.59 4.79 7.26 8.11 7.90 10.30 8.32 

0 7.88 4.65 2.43 7.38 7.85 5.35 10.69 8.86 13.77 11.86 

0 5.53 8.06 2.30 6.42 8.37 4.83 9.84 8.56 9.71 

0 5.17 5.50 4.70 6.09 8.11 7.76 10.85 8.97 

0 6.88 7.55 4.50 10.02 8.48 13.21 11.51 

0 6.50 7.34 4.66 9.58 8.93 10.06 

The mean color differences between reproductions and <strong>the</strong> originals, averaged across 

<strong>the</strong> printing processes and capture workflows, are shown in Table A-11 for <strong>the</strong> Viewing 

Booth source and <strong>the</strong> Viewing Room source. All reproductions were consistently 

different from <strong>the</strong> original. The mean color differences for each printer were similar. 

There was greater disparity between color differences for individual workflows. Workflow 

1 consistently had <strong>the</strong> smallest color difference and Workflow 3 had <strong>the</strong> largest. 

Table A-11. Mean CIEDE2000 color differences between reproductions and <strong>the</strong> 

originals, averaged across <strong>the</strong> printing processes and capture workflows 

0 5.49 5.68 4.98 7.10 5.07 

0 7.54 4.98 10.17 8.74 

Viewing Booth Source Viewing Room Source 

EP 1 9.37 WF 1 7.60 EP 1 9.13 WF 1 7.45 

EP 2 9.40 WF 2 9.26 EP 2 9.09 WF 2 9.08 

Inkjet 8.63 WF 3 10.72 Inkjet 8.57 WF 3 10.60 

DAgX 9.35 DAgX 9.37 

Mean CIEDE2000 color differences between printer pairs are shown in Table A-12 and 

0 7.77 4.93 7.74 

0 7.41 5.22 

0 5.42 

0 

35


36 

mean CIEDE2000 color differences between workflow pairs are shown in Table A-13, 

both calculated under <strong>the</strong> Viewing Booth source and <strong>the</strong> Viewing Room source. Not 

surprisingly, as shown in Table A-12, <strong>the</strong> smallest mean color difference was between 

<strong>the</strong> two electrophotographic printing methods. The color difference between <strong>the</strong> inkjet 

printer and <strong>the</strong> two electrophotographic printer were similar and larger than <strong>the</strong> 

difference between <strong>the</strong> two electrophotographic printers. The DAgX printer was <strong>the</strong> 

most different from <strong>the</strong> o<strong>the</strong>r three printers. There was little difference between <strong>the</strong> 

workflow paired color difference comparisons, shown in Table A-13. 

Table A-12. Mean CIEDE2000 color differences between printer pairs 


PRINTER EP 1 EP 2 Inkjet DAgX 

EP 1 0 2.42 5.10 10.56 

EP 2 0 4.80 10.48 

Inkjet 0 7.61 

DAgX 0 


PRINTER EP 1 EP 2 Inkjet DAgX 

EP 1 0 2.41 4.99 10.46 

EP 2 0 4.62 10.34 

Inkjet 0 7.63 

DAgX 0 

Table A-13. Mean CIEDE2000 color differences between workflow pairs 


WORKFLOW WF 1 WF 2 WF 3 

WF 1 0 6.52 5.91 

WF 2 0 6.55 

WF 3 0 


WORKFLOW WF 1 WF 2 WF 3 

WF 1 0 6.49 5.88 

WF 2 0 6.55 

WF 3 0 


Conclusions 

This report discussed <strong>the</strong> degree to which thirteen <strong>D50</strong> viewing booths meet <strong>the</strong> 

specifications for viewing conditions described in ISO 3664-2009 for <strong>the</strong> critical 

judgment <strong>of</strong> prints. The results showed that (1) most viewing booths exceeded or 

were within close range <strong>of</strong> <strong>the</strong> CRI tolerance, (2) most were within <strong>the</strong> illuminance 

and illumination uniformity tolerances, and (3) all had MI VIS values <strong>of</strong> less than 1.1. 

In addition, a separate analysis was conducted in which <strong>the</strong> difference between <strong>the</strong> 

rendering <strong>of</strong> a Macbeth ColorChecker reproduction by <strong>the</strong> thirteen viewing booths and 

CIE illuminant <strong>D50</strong> was evaluated. The maximum ∆E 00 for <strong>the</strong> Macbeth ColorChecker 

reproduction was 1.25. Thus, <strong>the</strong> data suggests that all thirteen viewing booths had <strong>the</strong> 

ability to acceptably render prints. However, all but three viewing booths were outside 

<strong>of</strong> <strong>the</strong> chromaticity tolerances, though some by only a small margin. 

In Annex B <strong>of</strong> ISO 3664-2009, it was reported that <strong>the</strong> chromaticity tolerances specified 

in <strong>the</strong> first edition <strong>of</strong> ISO 3664—published in 1975—were wider. Users complained 

<strong>of</strong> wide variations between <strong>the</strong> colors <strong>of</strong> viewing booth lamps that were within <strong>the</strong> 

chromaticity tolerances. The opposite appears to be <strong>the</strong> case here. Though many viewing 

booths were outside <strong>of</strong> <strong>the</strong> chromaticity tolerances, all booths provided reasonable 

perceptual rendering <strong>of</strong> <strong>the</strong> Macbeth ColorChecker reproduction and had reasonable 

MI VIS values. There is not enough evidence to come to a definite conclusion as to whe<strong>the</strong>r 

<strong>the</strong> viewing booths provide acceptable color reproduction for all prints, but <strong>the</strong> data 

suggests that this may be <strong>the</strong> case for most prints. Never<strong>the</strong>less, fur<strong>the</strong>r studies must 

be conducted to determine <strong>the</strong> degree <strong>of</strong> rendering variation across a variety <strong>of</strong> printed 

samples and how <strong>the</strong> rendering variation compares to ISO 3664-2009 conformance. 

An additional case study was conducted in which <strong>the</strong> color inconstancy <strong>of</strong> antique 

monochrome photograph reproductions under five <strong>D50</strong> sources was examined. While 

<strong>the</strong>re was consistent difference between <strong>the</strong> original photographs and <strong>the</strong> reproductions, 

varied by capture workflow and printer, <strong>the</strong> color differences were consistent under all 

five sources. Thus, it is unlikely that <strong>the</strong>re would be noticeable differences in <strong>the</strong> color <strong>of</strong> 

<strong>the</strong> reproductions as <strong>the</strong>y are moved from one <strong>D50</strong> source to ano<strong>the</strong>r, considering <strong>the</strong> 

sources are in compliance, or near compliant with <strong>the</strong> specifications described in ISO 

3664-2009. 



Part A: Conclusions 

37

Part B: Experimental Method 

38 

Part B: <strong>Evaluating</strong> <strong>the</strong> <strong>Impact</strong> <strong>of</strong> <strong>the</strong> 

<strong>Variability</strong> <strong>of</strong> <strong>D50</strong> <strong>Light</strong> <strong>Booths</strong> on 

<strong>the</strong> Appearance <strong>of</strong> Reproductions 

<strong>of</strong> Monochrome Photographs 

by Susan Farnand, Franziska Frey, Ph.D., and Ishtar Laguna-Monroy 

Experimental Method 

This research involved <strong>the</strong> ranking <strong>of</strong> printed reproductions <strong>of</strong> eight target photographs. 

The platinum print depicting a portrait <strong>of</strong> a bride that was previously used in <strong>the</strong> 

experimentation on fine art reproduction supported by The Andrew W. Mellon 

Foundation was included in <strong>the</strong> image set. The remaining images were selected from 

<strong>the</strong> collection at <strong>the</strong> Image Permanence Institute at RIT. The intent was to include 

photographs featuring o<strong>the</strong>r content, such as buildings or landscape scenery, as well as 

photographs made using o<strong>the</strong>r early photographic processes. While o<strong>the</strong>r processes 

were well represented in <strong>the</strong> test set, photographs <strong>of</strong> <strong>the</strong> time period were generally 

portraits, making it difficult to obtain o<strong>the</strong>r content. The photographs included in <strong>the</strong> 

experiment are shown in Figure B-1. Table B-1 lists <strong>the</strong> photographs and <strong>the</strong> process 

used to generate each image. 

Table B-1. Photographic processes used in <strong>the</strong> image set 

Photograph Photographic Process Brief Description 

Jeremiah Albumen Print 

Male studio portrait 

Format: Cabinet Card 

Helen Chocolate Platinotype Female studio portrait 

Henrietta 

Matte Collodion Printing-Out Paper 

Gold and platinum toning 

Female studio portrait 

Nelson Collodion Printing-Out Paper 

Male studio portrait 


Sculpture Albumen Print 

Reproduction <strong>of</strong> a sculpture 


Library Developed silver print – handmade paper Circa 1870’s 

Eunice Platinotype Female studio portrait 

Faraoni Carbon print – sepia toning Female portrait 


Jeremiah Helen (used in <strong>the</strong> 

Mellon study) 

Sculpture 

Library 

Faraoni 

Henrietta 

Figure B-1. Image set used in <strong>the</strong> experimentation 

Once <strong>the</strong> target set was identified, image captures were made by three cultural heritage 

institutions. These image files were delivered to RIT for printing, and prints were made 

on a variety <strong>of</strong> equipment at RIT. This equipment included an HP Indigo 7000 and 

a Kodak NexPress S3000 at <strong>the</strong> RIT Printing Applications Lab, and a Durst Lambda 

digital silver halide printer on Kodak Matte paper and an HP wide format ink jet printer 

using Kodak Pro Lustre E paper at <strong>the</strong> Digital and Photographic Imaging Services Lab 

at RIT. 




Eunice 


39


40 

When printing was complete, perceptual experimentation was conducted to examine 

<strong>the</strong> impact <strong>of</strong> variations in <strong>D50</strong> lighting on perceived reproduction quality. The 

experimentation was conducted under two lighting conditions: (1) <strong>the</strong> <strong>D50</strong> light booth 

used in <strong>the</strong> Mellon study (see Figure B-2a), and (2) <strong>the</strong> viewing room used in <strong>the</strong> paper 

study (see Figure B-2b). Spectral measurements <strong>of</strong> <strong>the</strong> lights used in <strong>the</strong> experiment are 

shown in Figure A-13 <strong>of</strong> Part A. 

a) b) 

Figure B-2. Experimental set up for (a) <strong>the</strong> viewing booth and (b) <strong>the</strong> viewing room 

In each illumination condition, a rank order experiment was conducted in which 

participants were shown <strong>the</strong> twelve print renditions for each target photograph. The 

participant was asked to order <strong>the</strong> prints from <strong>the</strong> worst to <strong>the</strong> best representations 

<strong>of</strong> <strong>the</strong> original photograph, which was present throughout <strong>the</strong> ranking process. The 

photographs were presented to <strong>the</strong> participants in random order. When <strong>the</strong> ranking <strong>of</strong> 

<strong>the</strong> test prints was completed, <strong>the</strong> participant was <strong>the</strong>n asked if <strong>the</strong> top-ranked print was 

an acceptable reproduction. If <strong>the</strong> answer was ‘yes’, <strong>the</strong>n <strong>the</strong> same question was asked 

regarding <strong>the</strong> second ranked print and so on, until <strong>the</strong> answer was ‘no’. A total <strong>of</strong> twelve 

observers participated in <strong>the</strong> study. 

Once <strong>the</strong> testing was completed, <strong>the</strong> rankings provided by <strong>the</strong> observers were 

translated into z-scores following procedures outlined in Engeldrum (2000) and based 

on Thurstone’s Law <strong>of</strong> Comparative Judgments – Case V (Thurstone, 1927). This 

transformation from observer rankings to z-scores was conducted to provide an interval 

scale ra<strong>the</strong>r than an ordinal one. An ordinal scale simply orders <strong>the</strong> stimuli but provides 

little information about <strong>the</strong> differences in quality between two stimuli, <strong>the</strong> print 

reproductions, in this case. The interval scale provides this information <strong>of</strong> <strong>the</strong> relative 

distance between two stimuli. In transforming from ranking to z-scores, <strong>the</strong> prints 

perceived to be <strong>of</strong> average quality would receive a z-score <strong>of</strong> about ‘0’. Prints perceived 

as being above average would have positive z-scores and those prints perceived as being 

below average would receive negative z-scores. 


Results and Discussion 

The results <strong>of</strong> this experiment fell into one <strong>of</strong> four categories. The reproductions <strong>of</strong> <strong>the</strong> 

Faraoni photo were <strong>the</strong> only ones that observers ranked consistently in <strong>the</strong> two viewing 

environments, as shown in Figure B-3. This photograph was a postcard from <strong>the</strong> 1920s 

made using carbon printing and sepia toning. Note how all <strong>of</strong> <strong>the</strong> datapoints lie close 

to <strong>the</strong> 45 degree line that represents no change in ranking between <strong>the</strong> two viewing 

conditions. 

Figure B-3. Z-scores for <strong>the</strong> renditions <strong>of</strong> <strong>the</strong> Faraoni photo by viewing condition 

The renditions <strong>of</strong> <strong>the</strong> Jeremiah, Henrietta, and Sculpture photos also ranked fairly 

consistently under <strong>the</strong> two viewing conditions. For each <strong>of</strong> <strong>the</strong>se photos, one <strong>of</strong> <strong>the</strong> 

renditions made on <strong>the</strong> digital silver halide printer was ranked more highly in <strong>the</strong> 

viewing booth than it was in <strong>the</strong> viewing room. For example, <strong>the</strong> data for <strong>the</strong> Henrietta 

photo is shown in Figure B-4. The Jeremiah and Sculpture images were <strong>the</strong> only two 

albumen photos included in <strong>the</strong> experiment, while <strong>the</strong> Henrietta image was a matte 

collodion print with gold and platinum toning. 



Part B: Results and Discussion 

41


42 

Figure B-4. Z-scores for <strong>the</strong> renditions <strong>of</strong> <strong>the</strong> Henrietta photo by viewing condition 13 

For <strong>the</strong> Nelson, Library, and Eunice photos, <strong>the</strong> renditions made using 

electrophotography, and especially those for <strong>the</strong> files from Institutions 1 and 2, ranked 

higher in <strong>the</strong> viewing room than in <strong>the</strong> viewing booth. For example, <strong>the</strong> data for <strong>the</strong> 

Library photo is shown in Figure B-5. These photos represent a range <strong>of</strong> technologies: 

<strong>the</strong> Nelson photo is a collodion print, <strong>the</strong> Library image is a silver print on handmade 

paper, and <strong>the</strong> Eunice image is a platinotype print. 

13 - The digital silver halide print that was more highly ranked in <strong>the</strong> viewing booth than <strong>the</strong> viewing room 

is shown in gold. 


Figure B-5. Z-scores for <strong>the</strong> renditions <strong>of</strong> <strong>the</strong> Library photo by viewing condition 14 

Finally, <strong>the</strong> electrophotographic renditions for <strong>the</strong> Helen photo also ranked higher in <strong>the</strong> 

viewing room than in <strong>the</strong> viewing booth as shown in Figure B-6. For this image, nearly 

all <strong>of</strong> <strong>the</strong> digital silver halide and ink jet renditions ranked higher in <strong>the</strong> viewing booth 

than in <strong>the</strong> viewing room. Similar to <strong>the</strong> results <strong>of</strong> <strong>the</strong> experiment supported by The 

Andrew W. Mellon Foundation, nearly all <strong>of</strong> <strong>the</strong> renditions <strong>of</strong> this photograph ranked 

differently in <strong>the</strong> two viewing conditions. 

14 - The electrophotographic prints made using files from Institutions 1 and 2 are shown in gold. 




43


44 

Figure B-6. Z-scores for <strong>the</strong> renditions <strong>of</strong> <strong>the</strong> Helen photo by viewing condition 15 

The perceptual results averaged over all images are shown by workflow in Figure B-7 

and by printer in Figure B-8. These results indicate that <strong>the</strong>re were few changes in 

perceived quality going from <strong>the</strong> viewing booth to <strong>the</strong> viewing room. The results also 

indicate that <strong>the</strong> reproductions for Workflow 3 were consistently ranked <strong>the</strong> lowest 

and that <strong>the</strong> electrophotographic reproductions were consistently ranked as average, 

while <strong>the</strong> ink jet and digital silver halide were consistently ranked as <strong>the</strong> best or worst, 

depending on workflow. The one exception was <strong>the</strong> digital silver halide print for 

Workflow 2, which was consistently ranked about average. 

15 - The electrophotographic prints are shown as gold squares. Burgundy diamonds represent <strong>the</strong> digital 

silver halide and ink jet prints. The ink jet print made using <strong>the</strong> file from Institution 2 is shown in blue. This 

is <strong>the</strong> only print rendition that ranked similarly in <strong>the</strong> two viewing conditions for <strong>the</strong> photo. 


Figure B-7. Z-score results for <strong>the</strong> viewing booth relative to <strong>the</strong> viewing room 

shown by workflow 




45


46 

Figure B-8. Z-score results for <strong>the</strong> viewing booth relative to <strong>the</strong> viewing room 

shown by printer 


Conclusion 

The results <strong>of</strong> this visual study indicate that <strong>the</strong>re were few changes in <strong>the</strong> way 

reproductions <strong>of</strong> vintage photographs were ranked under two different lighting 

conditions. The information obtained in Gamm’s color constancy analysis, reported in 

Part A, supports <strong>the</strong>se results. The one exception was <strong>the</strong> Helen photo, which had similar 

results in <strong>the</strong> Mellon-sponsored fine art reproduction study. This photo is a ‘chocolate’ 

platinotype. The only o<strong>the</strong>r platinotype in this study was <strong>the</strong> Eunice photo, which was 

considerably closer to neutral in color. It could be that <strong>the</strong>re is something about <strong>the</strong> 

materials used in <strong>the</strong> platinotype process that make <strong>the</strong>se prints more susceptible to 

changes in viewing illumination or geometry, especially for more chromatic prints. In 

this study, <strong>the</strong>re were differences in <strong>the</strong> way that electrophotographic prints and those 

made using <strong>the</strong> wide-format ink jet and digital silver halide printers were ranked under 

<strong>the</strong> two lighting conditions. One <strong>of</strong> <strong>the</strong> key differences between <strong>the</strong> electrophotographic 

prints and <strong>the</strong> ink jet and digital silver halide prints is surface finish. The differences 

in relative image quality for <strong>the</strong> Helen image may have been <strong>the</strong> result <strong>of</strong> differences in 

viewing geometry ra<strong>the</strong>r than viewing illumination. Fur<strong>the</strong>r study should include an 

analysis <strong>of</strong> BRDF measurements for <strong>the</strong> Helen image and its reproductions. 



Part B: Conclusion 

47

References 

48 

References 

Part A 

Commission Internationale De L’Eclairage [CIE]. (1981). A method for assessing <strong>the</strong> 

quality <strong>of</strong> daylight simulators for colorimetry. Publication CIE N° 51 (TC-1.3). Paris, 

France: CIE. 

Commission Internationale De L’Eclairage [CIE]. (1999a). CIE Collection 1999: Vision 

and colour: Physical measurement <strong>of</strong> light and radiation. In Technical Report CIE 

135/3 (pp. 23-26). Paris, France: CIE. 

Commission Internationale De L’Eclairage [CIE]. (1999b). A method for assessing <strong>the</strong> 

quality <strong>of</strong> daylight simulators for colorimetry. In Technical Report CIE 051.2. Paris, 

France: CIE. 

U.S. Department <strong>of</strong> Energy. (2008, January). Color rendering index and LEDs. Retrieved 

from http://www1.eere.energy.gov/library/default.aspx?page=2 

U.S. Department <strong>of</strong> Energy. (2009, January). CALiPER benchmark report: Performance 

<strong>of</strong> T12 and T8 fluorescent lamps and tr<strong>of</strong>fers and LED linear replacement lamps. 

Retrieved from http://www1.eere.energy.gov/library/default.aspx?page=2 

U.S. Department <strong>of</strong> Energy. (2011, May). LED replacements for four-foot linear 

fluorescent lamps. Retrieved from http://www1.eere.energy.gov/library/default. 

aspx?page=2 

Fogra. (2011). Scrutiny <strong>of</strong> your viewing cabinet according to ISO 3664. Retrieved from 

http://www.fogra.org/en/fogra-fogracert-en/prepress/viewing-cabinet/cabinets/ 

Frey, F. & Farnand, S. (2011). Benchmarking art image interchange cycles: Final report 

2011 [Technical report]. Rochester, NY: RIT School <strong>of</strong> Print Media. 

GTI. (2009). graphiclite®100 color viewing lamps for critical color viewing & inspection. 

Retrieved from http://www.gtilite.com/pdf/5000K%20Graphiclite%20100%20 

Lamps.PDF 

HunterLab. (2008). Equivalent white light sources and CIE illuminants. Applications 

Note, 17(5), 1-5. 

ISO 3664 (2009). ISO 3664-2009 Graphic technology and photography — Viewing 


ISO 13655 (2006). ISO 13655-2006. Graphic technology — Spectral measurement and 

colorimetric computation for graphic arts images. 

JUST Normlicht. (n.d.). Daylight 5000 proGraphic fluorescent tube. Retrieved from 

http:// www.just.de/us/media/files/US%20Brochures/proGraphic_5000.pdf 

Kraushaar, A. (2011, October). The new, old ISO standard for image appraisal: About 

excitation and aggravation. Fogra News, 26. 


<strong>Light</strong>ing Research Center. (1999). Screwbase compact fluorescent lamp products. 

Retrieved from http://www.lrc.rpi.edu/programs/nlpip/publicationResults. 

asp?type=1 

<strong>Light</strong>ing Research Center. (2006). T8 fluorescent lamps. Retrieved from http://www.lrc. 

rpi.edu/programs/NLPIP/publicationResults.asp?type=2 

Osram Sylvania. (2011). Lamp and ballast catalogue. Retrieved from http://assets. 

sylvania.com/assets/documents/Complete-Catalog.b176dbb1-d6e0-40f0-ab92e768e58f5dc1.pdf 

Part B 

Arney, J.S., Ye, L., Maggard, E., & Renstrom, B. (2007). Gloss granularity <strong>of</strong> 

electrophotographic prints. Journal <strong>of</strong> Imaging Science and Technology, 51(4), 293. 

Engeldrum, P.G. (2000). Psychometric scaling: A toolkit for imaging systems development. 

Winchester, Massachusetts: Imcotek Press. 

Frey, F. & Farnand, S. (2011). Benchmarking art image interchange cycles: Final report 

2011 [Technical report]. Rochester, NY: RIT School <strong>of</strong> Print Media. 

Gamm, B., Frey, F. & Farnand, S. (2011). An analysis <strong>of</strong> <strong>the</strong> factors influencing paper 

selection for books <strong>of</strong> reproduced fine art printed on digital presses (PICRM-2010-02). 

Rochester, NY: Printing Industry Center at RIT. 

ISO 3664 (2009). ISO 3664-2009 Graphic technology and photography — Viewing 


ISO 13655 (2006). ISO 13655-2006. Graphic technology — Spectral measurement and 

colorimetric computation for graphic arts images. 

Thurstone, L.L. (1927). A law <strong>of</strong> comparative judgment. Psychological Review, 34(4), 

273-286. 



References 

49


College <strong>of</strong> Imaging Arts and Sciences 

55 Lomb Memorial Drive 

Rochester, NY 14623 

Phone: (585) 475-2733 

http://print.rit.edu

Evaluating the Impact of the Variability of D50 Light Booths on the ...

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?