Colour management in firefox on Fedora 12

Posted: December 6th, 2009 | Author: | Filed under: Fedora, Photography | 1 Comment »

It has been a long time coming, but the Linux desktop is finally getting to the point where colour management is widely available in applications. At a low level ArgyllCMS is providing support for many colour calibration devices and lCMS provides a nice library for applying colour profile transformations to images. At a high level, the graphics/photos tools DigiKam, GIMP, UFRaw, InkScape, Phatch and XSane are all able to do colour management. Most are even following the X colour management spec to automatically obtain the current monitor profile. In the last few weeks Richard Hughes has filled in another missing piece, writing gnome-colour-manager to provide a UI for driving ArgyllCMS and setting up monitor profiles upon login.

It is great to be able to do photo/graphics work on a fully colour managed Linux desktop….and then you upload the photos to Flickr and they go back to looking awful. After a little googling though, it turns out all is not lost. Firefox does in fact contain some colour management support, hidden away in its truly awful about:config page. If you go to that page and filter on ‘gfx’, you’ll find a couple of settings with ‘color_management’ in their name

gfx.color_management.display_profile
gfx.color_management.mode
gfx.color_management.rendering_intent

The first, display_profile, takes the full path to an ICC profile for your monitor, while mode controls where colour management is applied. A value of ‘2’ will make firefox only apply profiles to images explicitly tagged with a profile. A value of ‘1’ will make firefox apply profiles to CSS and images, assuming an sRGB profile if the image does is tagged. rendering_intent takes values 0, 1, 2, 3 corresponding to ‘perceptual’, ‘relative colourimetric’, ‘saturation’ and ‘absolute colourimetric’ respectively. I configured my firefox for mode=1, set a profile and restarted. Browsing to Flickr to showed an immediate improvement, with my images actually appearing in the correct colours, matching those I see during editing in GIMP/UFRaw/etc. There’s a little more info about these settings at the mozilla developer notes on ICC.

While it is nice to have colour management in firefox, its implementation is rather sub-optimal since it requires the user to manually configure the display ICC profile path. Each display profile is only valid with the monitor against which it was created. So the moment I switch my laptop from its built-in LCD to an external LCD all the colours in firefox will go to hell. If firefox followed the X ICC profile spec it would be able to automatically apply the correct profiles for each monitor. Hopefully someone will be motivated to fix this soon, since the spec is rather easy to comply with only needing a quick look at a particular named property on the root window.