Help System > Color University > Introduction to Color Spaces
Imagine this: you're on a hike and you spot a bunch of the most gorgeous blue flowers you ever saw, and with a bumblebee, too! You take the photo.
Later, you look at the photo and think, "wow, it looks great," but you know that the photo isn't nearly as beautiful as what you saw in real life.
That's because, when you looked at those flowers in real life, your eyes were seeing colors that only exist in real-life nature. Those flowers had colors that can never be reproduced by any monitor, ink, or printer.
There are huge numbers of colors like that—colors that can only possibly exist in nature.
That's why when you see a real sunset, it takes your breath away. That's why when you see a real bouquet of flowers, you say out loud, "wow!" It's because your eyes are seeing, in real life, colors that you've never seen in any photo, magazine, or website.
See these flowers?
No matter what settings you use in Photoshop, no matter how expensive your printer, monitor or paper, you'll never, never, never be able to come close to reproducing that stunning, intensely vivid yellow-orange you saw in real life. That's because your eyes can see up to ten million different colors1—far, far more than can be produced by any ink or any screen.
Now you know that your eyes can see things that can't possibly be printed on paper or shown on a screen, because there are no inks in the world that can match the vivid, intense beauty of real-life colors.
So what colors can printing inks represent?
The most common way for printers to make colors is to combine four different inks: cyan, magenta, yellow, and black:
You can make a whole lot of different colors by combining different proportions of those four inks. You can't make anywhere near the number of colors that your eyes can see, though.
So, we have a problem: if we have a photo of some flowers, a bumblebee, and green foliage in the background...
How much cyan, magenta, yellow, and black will be needed for each "dot" (pixel) in order to reproduce the color of each dot of the original image?
We somehow have to come up with a formula, or a recipe, to mix together the cyan, magenta, yellow, and black (called CMYK - the "K" means "black") for each different color.
In order to make that "recipe" to convert a particular color in a photo to a particular CMYK combination, we first have to somehow get two lists:
OK, so let's do it! Let's start at the beginning: let's map out every single color that the human eye can see onto a big square, or "space." See! We're starting to talk about "color spaces!"
NEXT: How Color Spaces Work
1 American Academy of Ophthalmology, How Humans See Color