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

a change in our perception of the color–our eye integrates the surface reflectance
with the incident light against our color sensitivity matching functions.
In order to manage the dataset, an interactive viewer was made to browse
between the 126 pigment-time combinations. This allowed for easier viewing of
the data as one can quickly see the relationships between different samples. The
online application was written in JavaScript, allowing for instant feedback from a
user-specified pigment and time combination. After selecting the input parameters,
the system presents a spectral reflectance plot of the eight different binding media
for the chosen input data. The setup for the viewer is seen in Figure 6.1 for
Lapis lazuli samples that have been dry for one day. The input data is chosen via
drop-down menus in the top-left of the screen. To tint the chosen pigment, the
checkbox is selected. Updating the graphics with new selections is done with the
display button.
A photograph of the pigment is shown for reference in the top-right (for tints,
titanium dioxide white is also shown). Also presented is the corresponding digital
photograph for each paint sample, as spectral graphs are not a very intuitive way
to analyze subtle color shifts. Yet, it is important to note that the spectral data
is what is critical. Displays have significant limitations: monitors approximate
colors using only three phosphors (red, green and blue), while printers only use
fours inks (cyan, magenta, yellow and black) to create images. As a result, many
real-world colors cannot be captured by these devices. Therefore, any photographic
representation will be an inadequate representation of the actual colors.
The importance of the spectral plots is that they show the behavior of light at
all wavelengths in the visible spectrum. The spectral data combined with an illu-
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minant and the eye’s response curves can be predictive with no loss of information.