Why does Preivew.app automatically change the saturation of some images? Some images seem to be automatically modified by preview when you open them - in particular, the color saturation changes. 

For example, I see an image with a certain shade of red in Finder's cover flow, but when I open it in preview, that red is now slightly desaturated. If I save the image, cover flow now shows the desaturated red - so Preview.app is certainly doing something.

Why is it doing this and how do I make it stop?
This seems to have something to do with the color profile.
You can change the used profile to display an image in preview by using View -> Soft Proof with Profile.

Finder uses your displays calibration-profile by default

reference: http://photo.net/digital-darkroom-forum/00TmxN