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SECTION 4.5                                                                Color Spaces



See Section 7.6.4, “Rendering Parameters and Transparency,” and in particular
“Rendering Intent and Color Conversions” on page 574, for further discussion of
the role of rendering intents in the transparent imaging model.

                          TABLE 4.20 Rendering intents
NAME                   DESCRIPTION

AbsoluteColorimetric   Colors are represented solely with respect to the light source; no
                       correction is made for the output medium’s white point (such as
                       the color of unprinted paper). Thus, for example, a monitor’s
                       white point, which is bluish compared to that of a printer’s pa-
                       per, would be reproduced with a blue cast. In-gamut colors are
                       reproduced exactly; out-of-gamut colors are mapped to the
                       nearest value within the reproducible gamut. This style of repro-
                       duction has the advantage of providing exact color matches
                       from one output medium to another. It has the disadvantage of
                       causing colors with Y values between the medium’s white point
                       and 1.0 to be out of gamut. A typical use might be for logos and
                       solid colors that require exact reproduction across different me-
                       dia.

RelativeColorimetric   Colors are represented with respect to the combination of the
                       light source and the output medium’s white point (such as the
                       color of unprinted paper). Thus, for example, a monitor’s white
                       point would be reproduced on a printer by simply leaving the
                       paper unmarked, ignoring color differences between the two
                       media. In-gamut colors are reproduced exactly; out-of-gamut
                       colors are mapped to the nearest value within the reproducible
                       gamut. This style of reproduction has the advantage of adapting
                       for the varying white points of different output media. It has the
                       disadvantage of not providing exact color matches from one me-
                       dium to another. A typical use might be for vector graphics.

Saturation             Colors are represented in a manner that preserves or emphasizes
                       saturation. Reproduction of in-gamut colors may or may not be
                       colorimetrically accurate. A typical use might be for business
                       graphics, where saturation is the most important attribute of the
                       color.

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