pigmented colorants: dependence on media and time - Cornell ...

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Chapter 3 Color Background 3.1 Light and Color Color is my day-long obsession, joy and torment. -Claude Monet The human visual system consists of three major components: eyes, which cap- ture light and convert it into neural messages; visual pathways, which modify and transmit those messages from the eye to the brain; and visual centers of the brain, which interpret the messages in ways useful for guiding behavior [SB02]. Hence, the study of color science is broken down into three areas: physical, quantifying the physical energy which reaches the eye; perceptual, determining the perceptual responses of the human visual system; and interpretive, determining the overall impression. All of these components are crucially involved in seeing. 47
3.1.1 Visible Light Spectrum Light is but just one form of electromagnetic radiation, similar to infrared, ultra- violet, and x-rays. All of these forms of energy are formed by the oscillation of electrically charged material. Electromagnetic radiation travels very rapidly (ap- proximately 186,000 miles per second) and tends to travel in straight lines. The light energy is arranged along a spectrum according to the distance between oscil- lations, or wavelength (λ), measuredinnanometers (nm). High rates of oscillation mean the radiation travels a short distance per cycle–meaning a short wavelength. Figure 3.1: A section of the electromagnetic energy spectrum sowing the range of wavelengths comprising the visible spectrum. Adapted from [GW77]. Figure 3.1 underscores an important point: the visible light that we depend on for sight only occupies a very small portion of the electromagnetic spectrum. The human eye is especially tailored for our environment. The light we see is useful as a medium of information about the world because it interacts (reflects and absorbs) with objects in a manner that gives us information about the surfaces and structure of objects. However, the color sensations we experience are not only of individual wavelengths, but of the summation of the entire visible spectrum. An object is “green” if most of the reflected light from the object is around 500nm. However, some light will also be reflected at all other visible wavelengths (380-700nm) 48
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PIGMENTED COLORANTS: DEPENDENCE ON
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ABSTRACT We present a physically ba
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Acknowledgements This work would no
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Table of Contents 1 Introduction 1
Page 9 and 10: List of Tables 2.1 Average pigment
Page 11 and 12: 3.15 Photoreceptor absorption .....
Page 13 and 14: B.15 Variation of spectral reflecta
Page 15 and 16: corrode the surfaces of materials.
Page 17 and 18: Figure 1.1: Detail of the Azor-Sado
Page 19 and 20: However, since mural artwork is typ
Page 21 and 22: at a very high quality (albeit limi
Page 23 and 24: heterogeneous sum of very different
Page 25 and 26: which linseed oil derives (the most
Page 27 and 28: oration of a rigidly painted layer
Page 29 and 30: ing will hit the ground and reflect
Page 31 and 32: tion of paint tubes in 1841 and the
Page 33 and 34: Figure 2.8: Natural pigments of ant
Page 35 and 36: ecome more common recently. The Ame
Page 37 and 38: A V = O(r2 ) O(r3 ) = 1 O(r) 24 (2.
Page 39 and 40: Table 2.2: Pigment specific gravity
Page 41 and 42: provide the underlying color to a p
Page 43 and 44: though the speed of light in air is
Page 45 and 46: In general, when light travels from
Page 47 and 48: materials while lit from behind. Li
Page 49 and 50: Table 2.4: Index of refraction η f
Page 51 and 52: to completely congeal. Hence, these
Page 53 and 54: ond together to form proteins. Exam
Page 55 and 56: to its original state by any means.
Page 57 and 58: While it has been used since the 19
Page 59: organic binder found in more conven
Page 63 and 64: Figure 3.2: Hue, brightness and sat
Page 65 and 66: measures how much light is reflecte
Page 67 and 68: Figure 3.6: Additive color mixing o
Page 69 and 70: Figure 3.9: The physical amount of
Page 71 and 72: The vascular tunic lies on the wall
Page 73 and 74: Figure 3.11: Cross section of the r
Page 75 and 76: Not all areas have the same sensiti
Page 77 and 78: identify and distinguish between va
Page 79 and 80: that range between zero and full in
Page 81 and 82: spectrum. This insures that the res
Page 83 and 84: Figure 3.19: Graphical representati
Page 85 and 86: X x = (X + Y + Z) Y y = (X + Y + Z)
Page 87 and 88: color into the appropriate RGB colo
Page 89 and 90: components in the image (the smalle
Page 91 and 92: haviors of subtractive mixing and i
Page 93 and 94: of perceptually equal sizes. Unfort
Page 95 and 96: enabling one to transform between t
Page 97 and 98: andwidth as converted signals are s
Page 99 and 100: Figure 3.28: Retinal ganglion recep
Page 101 and 102: example shown in Figure 3.28. Under
Page 103 and 104: Figure 3.31: The work of Josef Albe
Page 105 and 106: sensations for each trial and picke
Page 107 and 108: Chapter 4 Previous Work There is no
Page 109 and 110: different location. Subsurface scat
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describes the scattering and absorp
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only accounts for a small percentag
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σ ′ t = σa + σ ′ s and α
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104 Figure 4.4: A model of an alaba
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effects or are too computationally
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108 Figure 4.6: Results using Kubel
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specifying pigments works adequatel
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color representation, it is not fea
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time. A metallic surface patina is
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the system consisted of wetness and
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or darkening enables the museum per
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in front of a displayed work. Felle
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light exposure. This effect is espe
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over time. Perceptually, these hues
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The rate of change of the concentra
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over white grounds) suffer the grea
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protects the deeper remaining color
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light source. This method is used w
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chemical smog and have been identif
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Chapter 5 Preparation & Measurement
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tending transparent pigments used i
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140 Figure 5.1: Spectral reflectanc
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the requirements of the work at han
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144 Figure 5.2: Left: Magnified vie
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Table 5.2: Relevant data regarding
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historically one of the best grades
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created far too strong of a binder,
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too brittle and cracking. While wor
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154 Figure 5.4: Reflectance values
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5.1.5 Painting After the layers of
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The gray card reflected 18% of the
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160 Figure 5.8: The optical setup f
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Note that harmonics reflect at the
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Note that the calibration factors f
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Chapter 6 Experimental Results 6.1
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168 Figure 6.1: Lapis Lazuli in dif
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(such as CIE standards C, D50, orD6
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172 Table 6.2: Perceptual differenc
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174 Figure 6.3: Munsell plots of La
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and j has a saturation of red rsat,
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178 Figure 6.4: Variation of spectr
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visible spectrum are increasing at
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182 Figure 6.5: Munsell plots of La
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trying to match color ca from the p
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as it ages. This is in direct contr
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teractive viewer. In our applicatio
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190 Figure 7.1: Our simulated canva
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where n is the normal at the curren
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In summary, our implementation prov
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Chapter 8 Conclusion We have studie
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inks are beginning to find their wa
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Appendix A Derivation of K-M theory
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∆i − =(K + S) idx 202 ∆j −
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Equation A.8 is now: Rearranging yi
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and if the paint is infinitely thic
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One concatenates the layers into a
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210 Figure B.1: Cold Glauconite in
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Table B.1: Color conversions from t
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214 Figure B.4: Munsell plots of Co
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216 Figure B.5: Burnt Sienna in dif
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220 Figure B.8: Munsell plots of La
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222 Figure B.9: Red Ochre Tint in d
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226 Figure B.12: Munsell plots of C
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228 Figure B.13: Variation of spect
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230 Figure B.15: Variation of spect
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Table B.13: Color conversions of Bu
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234 Figure B.18: Munsell plots of C
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236 Figure B.20: Munsell plots of R
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References [Alb71] Josef Albers. In
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240 [GLL + 04] Michael Goesele, Hen
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242 [KM31] Paul Kubelka and Franz M
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[Rat72] Floyd Ratliff. Contour and
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