When it comes down to work, most of the times I get my graphics from a talented designer that worked on a mac. If the files happen to be in the PNG image format things get slightly confusing. Mac OS X will render the images using the color profile they got stored, actually png gamma correction would be more exact. This is not immediately apparent because at a glance the files may look identical but using the pngs over a CSS background color often reveals an unpleasant sight on the mac, especially on Safari.
To prevent such a color mismatch either use a different image format or strip the png gamma correction. In the case of the latter, pngcrush
does a pretty good job.
I was pleasantly surprised that I could install it with ease on Fedora
("yum install -y pngcrush
"). To use it run:
pngcrush -rem gAMA -rem cHRM -rem iCCP -rem sRGB <png-file-name> \ <optimized-png-file-name>
Removing that unnecessary meta data will also save you a few KBs, which is quite useful regardless if you have any problems with pngs or not.