Ad Terras Per Aspera

I just found an interesting bug in how ColorSync, Apple’s color profile management framework, functions. This effects (but by far is not limited to) Safari, Finder/Cover Flow, and whatever sets the desktop background.

Any image that does not have a profile is not color managed. I mean, it is completely ignored: in my case, I profiled my Powerbook’s LCD using a Spyder2Pro colorimeter. Using the “2.2 gamma 6500k” profile generated by the Spyder2 software, the desktop background image “Purple Frond” that comes with OSX is actually displayed bluish in color because Apple did not embed profiling data in their background images.

I randomly came across the reason for this because I was editing a different background to fit my monitor differently than the automatic modes did. After saving in Photoshop (which was nice enough to include the sRGB color profile in the JPEG), the colors were different.. or rather, they were correct, matching what Photoshop displayed. Double checking against “Purple Frond” by opening it and saving it in Photoshop with the sRGB color profile makes it correctly display purple instead of blue on my desktop.

The correct behavior of ColorSync should be to assume the data is sRGB and color manage it as such, instead of just not color managing it at all. Many images found on the Internet are “broken” and do not have the proper color profile set, but are obviously sRGB data.

Update: The desktop background is set by Dock, apparently. Set your desktop background to “Change picture every… (time period)” with “Random order”, and run killall Dock in Terminal.app… Dock will automatically restart and change your desktop background.