FFFF [css-color] rendering-intent descriptions. · w3c/csswg-drafts@8377703 · GitHub
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[css-color] rendering-intent descriptions.
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‎css-color/Overview.bs‎

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@@ -1779,15 +1779,89 @@ In a very similar way to the ''<@font-face.'' at-rule, the ''<@color-profile>''
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at-rule has a name (which will be used inside the stylesheet),
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and a descriptor to point to the actual
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data (<dfn for="@color-profile/src">src</dfn>, just like
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<dfn for="@font-face/src">src</dfn> in font-face.)
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<!-- not clear how I link to the two different descriptors therte, in bikeshed syntax -->
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<dfn for="@font-face/src">src</dfn> in font-face.) The <dfn for="@color-profile/src">src</dfn>
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descriptor takes a url() as it's value.'
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<!-- should we add a format field to this descriptor, like with font-face src? it is always ICC format
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in practice, but that could change in the future. or we could add format later, once there is
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a need, and make the default ICC if not specified -->
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In adition there is a third, optional descriptor to define the ''rendering intent'' to use.
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This is only needed if the profile linked to has data for multiple rendering intents.
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A third, optional descriptor defines the ''rendering intent'' to use when mapping colors
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from a larger to a smaller gamut.
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This descriptor is only needed if the profile linked to has data for multiple rendering intents.
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There are four values for rendering intent[[ICC]]:
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<dl>
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<dt id="intent-relative">relative-colorimetric</dt>
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<dd>
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<p>
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Media-relative colorimetric is required to leave source colors that fall
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inside the destination medium gamut unchanged relative to the respective
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media white points. Source colors that are out of the destination medium
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gamut are mapped to colors on the gamut boundary using a variety of
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different methods.
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</p>
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<p class="note">Note: the media-relative colorimetric rendering intent is
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often used with black point compensation, where the source medium black point
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is mapped to the destination medium black point as well.</p>
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<p>This method must map the source white point to the desination white point. If
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black point compensation is in use, the source black point must also be
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mapped to the destination black point. Adaptation algorithms should be used
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to adjust for the change in white point. Relative relationships of colors
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inside both source and destination gamuts should be preserved. Relative
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relationships of colors outside the destination gamut may be changed. </p>
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</dd>
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<dt id="intent-absolute">absolute-colorimetric</dt>
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<dd>
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<p>ICC-absolute colorimetric is required to leave source colors that fall
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inside the destination medium gamut unchanged relative to the adopted
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white (a perfect reflecting diffuser). Source colors that are out of the
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destination medium gamut are mapped to colors on the gamut boundary using a
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variety of different methods. This method produces the most accurate
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color matching of in-gamut colors, but will result in highlight clipping
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if the destination medium white point is lower than the source medium
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white point. For this reason it is recommended for use only in applications
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that need exact color matching and where highlight clipping is not a concern.</p>
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<p>This method MUST disable white point matching and black point matching when
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converting colors. In general, this option is not recommended except
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for testing purposes. </p>
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</dd>
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<dt id="intent-perceptual">perceptual</dt>
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<dd>
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<p>This method is often the preferred choice for images, especially when there are
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substantial differences between the source and destination (such as a screen display
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image reproduced on a reflection print). It takes the colors of the source image
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and re-optimizes the appearance for the destination medium using proprietary
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methods. This re-optimization may result in colors within both the source
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and destination gamuts being changed, although perceptual transforms are
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supposed to maintain the basic artistic intent of the original in the
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reproduction. They will not attempt to correct errors in the source image.</p>
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<p class="note">With v2 ICC profiles there is no specified perceptual reference medium,
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which can cause interoperability problems. When v2 ICC profiles are used it may
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be safer to use the media-relative colorimetric rendering intent with black
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point compensation, instead of the perceptual rendering intent, unless the
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specific source and destination profiles to be used have been checked to ensure
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the combination produces the desired result. </p>
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<p>This method should maintain relative color values among the pixels as they
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are mapped to the target device gamut. This method may change pixel values
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that were originally within the target device gamut, in order to avoid
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hue shifts and discontinuities and to preserve as much as possible the
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overall appearance of the scene.</p> </dd>
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<dt id="intent-saturation">saturation</dt>
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<dd>
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<p>This option was created to preserve the relative saturation (chroma) of the original,
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and to keep solid colors pure. However, it experienced interoperability problems like
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the perceptual intent, and as solid color preservation is not amenable to a reference
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medium solution using v4 profiles does not solve the problem. Use of this rendering intent
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is not recommended unless the specific source and destination profiles to be used have
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been checked to ensure the combination produces the desired result.
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This option should preserve the relative saturation (chroma) values of the original
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pixels. Out of gamut colors should be converted to colors that have the same saturation
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but fall just inside the gamut.</p> </dd>
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</dl>
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<pre class="prod">
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<dfn at-rule >FIX ME: MISSING</dfn>

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