Colour Mismatch between Photoshop & Apple screenshot

Has anyone else come across this problem?

Try this test: Open up a new psd using the default photoshop settings (RGB colour/8 bit; Color Settings: North American General Purpose 2; proof setup - working cmyk) and fill the bg with any colour (for example #ff0000) now do a screenshot of anything, then open up the screenshot png in photoshop. Now switch between the psd and the png and watch the colour in your palette in your photoshop toolbar change!

Anyone know what's going on?! It's happened a few times to me, on different macs

Colour Mismatch between PS & Apple screenshot

Well I did what you suggested, but even before doing it I suspected what your problem might be. Your test psd is in CMYK mode, and your screen shot png is in RGB mode. If you switch the RGB on your screen shot to CMYK and then try flipping between the two again, I think you will find that the colours remain true and the same. This is actually a good thing, because now you have a better idea of what your image will look like once it is printed, assuming this is what you planned on doing.

It's only the proof setup that is in cmyk, and changing it to macintoch rgb makes no difference. the document color mode is rgb

For anybody interested, I think I've tracked down what the problem is. Appears to be part of a wider colour issue:

The Mysterious “Save For Web” Color Shift | Web Design Blog: Web Design & Innovation in web standards : Viget Labs