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Mohamed Essam , Acting Director of Administration , Faculty Of Science - Cairo University
RGB is a subjective color space. The fact is, colors shift from one screen to the next. And not just a little bit. Wildly. For example, have you ever walked into a modestly enabled tech store that sells20 or so TVs---presumably playing a football game, cuz that's what they're always playing in this country---and noticed how the green field on one screen looks more yellow or blue on another? That's because the signal contains a series of RGB codes and the TV translates them any which way it likes. Remember that game (not football) of telephone where you whisper a message into your friend's ear? "I love meatballs" comes out "I judge street brawls." It's like that, only worse.
CMYK is a cell phone message from hell. The same thing happens when you print your images. Every printer has its own brand of CMY(MYK)K color. Which means that the old game of telephone transforms into some horribly modernized version of AT&T's freakishly unpredictable iPhone coverage. With "I love meatballs" turning into "I @#_*^ &!*%$^@# %=$ %!#*& ^%&$@ $+#_% ***** what the +&$%#!" Again, only worse.
Colors Settings locks 'em down. Photoshop's Edit > Color Settings command locks down the RGB and CMYK definitions so that the telephone message you hear cognates properly and comes out of your mouth in something closely resembling the same form. That is, my screen and your screen and our printers and all the happy monitors round-and-round the world (god bless 'em) convey similar colors.
