CHAPTER 3
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
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.