Digital Color Management: Encoding Solutions, 2nd Edition

11

Colorimetric Color Encoding

Colorimetric color encoding is based on measurements made according to the spectral responses of a human observer. One of the principal advantages of this method of color encoding is that it is based on well-established CIE recommendations for color measurement.

At first glance, colorimetric encoding would seem to offer the perfect method for encoding color, and, in practice, colorimetric encoding sometimes can provide input compatibility where methods based on other forms of measurements cannot. In other cases, however, the use of standard colorimetric techniques alone will not work.

Since colorimetric encoding is the method most often promoted as the ideal “device-independent” solution to color encoding, it is very important to understand its capabilities—and its limitations. The examples given in this chapter should help.

A case where colorimetric encoding works well

Consider a system, such as the one shown in Figure 11.1a, that supports input from an assortment of reflection media having different image-forming colorants—printing inks, photographic dyes, thermal-transfer dyes, etc.—with different spectral absorption characteristics. A color-encoding method based on red, green, and blue densitometric measurements alone, as was described in the previous chapter, will not provide a meaningful representation of color in this multiple reflection-media system.

For example, Figure 11.1b illustrates that a pair of colors on two different media can look ...