Firefox-8.0 Colour Management

As I wrote in my recent post, Firefox has many colour management bugs and one is of special concern toward the Oyranos Colour Management LiveCD III. This bug is now reported upstream and I proposed a patch to fix. It is double color correction with X Color Management, which is in close relation to Hal V. Engels report about Firefox color management does not honor _ICC_PROFILE X11 atoms. It affects all X11 builds and inhibits automatic selection of the system ICC monitor profile. A properly detected system monitor profile in Firefox will show default sRGB colours as well as images with ICC profiles much more in line with other colour managed applications. Getting this bug fixed is a major improvement for presenting colours on the web for Linux.

But why is this bug of so strong concern especially for the Oyranos LiveCD? The CompICC desktop colour server, which is part of the CD, uses sRGB as the assumed document colour space of all non colour managed content on screen. It needs to fool all non X Color Management spec aware applications to think the monitor is exactly in sRGB as long as they do not register with the colour server. In the sense of the X Color Management spec only that content, which is registered through specific per window colour regions is honoured to be colour managed and can use the monitors device ICC profile. This way applications like Inkscape, Krita or eog stay upward compatible and continue to work. However Firefox is not able to fetch the sRGB profile due to the above mentioned bug and falls back to a otherwise clever ICC from EDID generated profile. But Firefox colour corrects under Xorg to the from EDID profile and after that already done compensation assumes CompICC the Firefox window to be in sRGB and colour corrects to the actual setup monitor profile, which might be a from EDID generated profile as well, which leads to double colour correction. The fix of this bug lets Firefox detect the correct system profile. Double colour correction can happen as well if the monitor profile is explicitly set in the client application. So use always the system profile. Setting the system profile is really the job of a CMS like Oyranos.

As I read the code, Firefox honors embedded ICC profiles in JPEGs and PNGs. Great. These bitmaps works even in bitmaps inside SVGs, which is wonderful.

In recent changes Firefox can even handle v4 ICC profiles. These profiles are created by newer ICC profilers and became in recent years pretty widespread. But v4 profiles are not supported by default in Firefox. You need to enable them manually in Firefox´ configuration tab.

The situation for pure vectors graphics in Firefox is not in the same level as with bitmaps. The HTML/CSS color_profile element is completely ignored.

Conclusion, Firefox has after the proposed patch the ability to show with its internal colour management comparable colours of bitmaps like most other colour managed applications.

How to deploy the ICC capabilities of Firefox beyond the WWW´s sRGB as a web artist? You can place JPEG and PNG bitmap images with embedded ICC profiles inside web pages. An other way is to place such images inside SVG. While the freely available SVG editor Inkscape will not show a colour corrected preview of these images, it will not touch the JPEG and PNG images, so Firefox can render them correctly by the SVG standard.

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