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I found a picture on APOD that I wanted as my background, so I saved it to disk, then opened it in Windows Picture Viewer and made it my background. Inexplicably, the colors in the picture change when it is put on the desktop as a background. Here is a screenshot of my desktop demonstrating the way it looks in Picture Viewer (the correct way) and how the colors change when it is on the Windows desktop:




Does anyone know why this happens?

Picture Viewer is colour profile aware while the Desktop is not?

Weird! I seem to remember having a similar problem with Windows Photo Gallery in Vista I believe, every photo seemed to open with a slightly reddish tint compared to how it appeared in a browser or GIMP, Picasa, etc. The problem wasn't a nuisance to me at the time so I never set about resolving it and then I moved to Windows 7 anyway.

Try using another photo viewer and see what results you get.

I never set color profiles explicitly on my computer, so it's not that -- unless there's an automatic color profile that changes things without my input.

As far as another photo viewer, Picture Viewer, Photoshop, and Firefox all display the picture the same way. The desktop background is the only outlier so far.

There is a slight hint that the Picture Viewer is at least partially colour aware. That may explain it. But this stuff should be evident only on actual monitor display, not a screenshot like that. I am confused as well.

BTW, time to ditch XP, seriously.

Is the image CMYK or in another unusual color space?

Please note that at least Windows 7 always stubbornly (re)applies mediocre quality JPEG compression (80% ish) on backgrounds you set. It shouldn't affect colors a lot, but it's worth checking.

Try viewing the recompressed file here (it should be called TranscodedWallpaper):
%APPDATA%\Microsoft\Windows\Themes\

Not sure what the color space of the image is. Also, the OS in use here is XP, not Win7.

Just checked, and the image is in the ProPhoto color space. That space has VERY saturated primaries, so when XP uses it as the background it seems to assume it's in sRGB and becomes desaturated as a result.

All you need to do is convert the image from ProPhoto to sRGB and it should be fine. Photoshop can do this if you have access to it. I'd post a conversion, but it looks like the image is copyrighted (strange to see that on a NASA site).