ICC color correction in Firefox
Although support for color correction was introduced in Firefox 3, it was disabled by default, requiring some tinkering about in the about:config window to enable it. Firefox 3.5 addresses the issues that caused it be disabled by default in the previous version, and now images with International Color Consortium (ICC) tagging are, by default, color corrected.
The image below is split into three sections. The top left corner shows the image as rendered by Firefox 2. The top right corner shows how the image renders in Firefox 3. The bottom shows the image rendered in Photoshop.
As you can see, Firefox 3 and Photoshop render the image identically, because both support the embedded color correction profile. Firefox 2 ignores the profile, resulting in mismatched color.
Color correction can be controlled by setting the value of the
gfx.color_management.mode preference, as follows:
|0||Color management disabled. (Default in Firefox 3.)|
|1||Full color management.|
|2||Color management applied only to tagged image. (Default in Firefox 3.5.)|
Full color management means that everything rendered by Firefox, with the exception of plugins, has its colors corrected.
You can also specify a specific color profile to use for your hardware by setting the value of the
gfx.color_management.display_profile preference to be the path to a color profile to use.
If no path is specified for the color profile, Firefox queries the operating system and uses its configured color profile.
In addition, you can choose to set the value of the
gfx.color_management.rendering_intent preference to specify a default rendering intent. By default, the intent specified by images is ignored, unless you specify -1 for this value.
The following table lists the possible values.
|-1||Use embedded intent. By default, the embedded intent on images is ignored.|
|0||Perceptual. Directs Firefox to render the image to preserve detail throughout the tonal range of the image. Useful for general purpose display of images in typical cases, especially for photographs and other pictures.|
|1||Media-relative colorimetric. This rescales the color spectrum so that the white point of the rendering medium (such as the display screen) is mapped to the white point of the reference medium. This is most useful for colors that have been mapped to a medium with a smaller gamut than the reference medium.|
|2||Saturation. This preserves vividness of color at the expense of preservation of precision of hue. This is particularly useful for charts and diagrams, and other media whose colors should "pop" while precise duplication of hue is less important.|
|3||ICC-Absolute colorimetric. This is most useful for spot color and when simulating one medium on another, as it doesn't alter in-gamut colors.|
Note: In Firefox 3.5, perceptual, media-relative, and saturation intents all render the same way.
The new QCMS color management system introduced in Firefox 3.5 currently only supports ICC version 2 color profiles, not version 4. This may result in images being too dark. See bug 488800 and the ICC version 4 profile test.