Monday 28 February 2011

RGB and Color Channels in Photoshop Explained


Did you know that Photoshop is color blind?
When I say "color blind", I don't mean it has a little trouble distinguishing between certain shades of green and purple. I mean it's completely and totally blind when it comes to color. All Photoshop sees is black and white. Well, black, white, and a lot of shades of gray in between, but that's it. The world's most powerful image editor, an industry standard among photographers, designers, and virtually all creative professionals, capable of producing millions, even billions of colors has no idea what color is.
You may be looking at a photo you took on your last vacation of the crystal blue waters on the ocean, but all Photoshop sees is a gray ocean. Did you manage to snap a picture of a rainbow arching across the sky after a summer evening storm? Photoshop sees it as a beautiful assortment of shades of gray. And that famous pot of gold at the end of it? To Photoshop, it's a big ol' pot of gray.
Don't feel sorry for Photoshop though. It's perfectly happy in its colorless world. In fact, the only reason it shows us our images in color at all is because we as human beings expect to see them in color. We wouldn't know what to think if everything was appearing in black and white. But not Photoshop. To it, life just couldn't be sweeter than in black, white and gray.
Alright, so if Photoshop doesn't have a clue what color is, and all it knows and sees is black, white and gray, how does it manage to show our images in color? I mean, here's an image I have open in Photoshop:
An image open in Photoshop
An photo open in a document window in Photoshop.
Obviously, this little guy (or girl) is in color. In fact, I don't think birds come much more colorful than this. But it's not just the bird. The leaves in the background are in color. The piece of wood the bird is standing on is in color. The whole thing is in color! And this image is open in Photoshop, so how can it be that Photoshop doesn't see color? And if it really doesn't see color, how is Photoshop doing such a great job of showing us something it doesn't see?
To answer that question, we need to look at a couple of things. One is color modes and the other is color channels. They're both related to each other in a big way, so once you understand the first one, color modes, the second one, color channels, makes a lot more sense.

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