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green, and blue CRT phosphors. Moreover, devices with a brightness control allow a wide
range of image intensities. Active Matrix Displays generate images from a back-lighted
grid that activates red, green, and blue LCD pixel elements. For paper, and other print
media, gloss affects brightness, and Black Body Temperature affects hue.
More issues arise with the addition of a color scanner to a system. These devices also differ
between manufacturers. WYSIWYG (what you see is what you get) from scanned picture
to monitor to printer gets complicated because of different device color ranges (Gamuts)
and by the different color systems used. A printed color outside the range of a scanner
cannot make it to a monitor; only a nearby color can. Users that attempt to use a computer
application to edit the image received from a scanner may add colors beyond the range of
their printer. Notably, some applications issue gamut warnings. Both monitors and
scanners use the RGB system, while color printers use the CMY/CMYK system. Additive
systems produce a better range of colors using RGB, while subtractive systems do better
with CMY/CMYK.
An important concern then becomes "how does a device handle color data beyond its
range?" If a device just substituted the best color available, objects filled with blends,
starting from inside the gamut and ending at some point beyond the gamut, would loose
their desired appearance. For example, an object blending from say an orange to a red
beyond its red range would abruptly stop blending at the point the device could no longer
produce a deeper red. The remaining blend would then continue with the same color.
Some devices avoid this effect by compressing (via re mapping) the gamut. While
compression can maintain the desired effect, similar to JPEG data, too much compression
produces posterized images.
Even in nature, different conditions produce different colors. Painters of Seascapes point
out how the ocean reflects the color of the sky. The bright, sunny day colors differ from the
cloudy day colors. Women have more color sensitivity than men. Different colors provoke
different emotional responses, which do not necessarily remain the same from one
country to the next. All-in-all, there is much to consider, but most decisions rely on
subjectivity before they become final.
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CHAPTER 3