How do you describe color to a computer? It can’t see red, green or blue. It can’t see transparency or opacity. In order to make a computer “see”, you have to use numbers. To do that in Photoshop, we use color spaces. A “color space” is a way to model color and translate those colors into numbers. There’s more than one way to model color, based on how we need Photoshop to apply those colors. The goal is not only to interpret color accurately, but to “output” (print or display) those colors just as accurately to paper, film, or onto a computer screen. 

Think about all the times you’ve been to an appliance store and seen rows of televisions, all playing the same thing, but each screen looks a little different. Some are brighter or darker, or the colors may look a little different, and so on. That’s because the settings on each television are a little different. That’s what we DON’T want. As much as possible, designers want the color they chose to be “true”, meaning that the color is displayed accurately and looks the same on every television. That’s not really possible with televisions and computer screens, because you can’t do anything about the user adjusting brightness, contrast, and color balance to suit their tastes. But a professional will not only choose the appropriate color model, but he or she will create a profile so those colors are represented accurately on different devices. That’s what ICC profiles do for you.

If you’ve ever chosen paint for your house or for a room, you’re familiar with the need for color to be true. How a color looks when it’s wet isn’t necessarily how it will look when it’s dry. When you consider how much it costs to paint, you want to be sure that the color you picked is the color you’ll get. Choosing the proper color space will depend on how you intend your image to be used. For images that will be used on the web, use a hexadecimal system to model colors. For printing with four-color separations, we model color using values of cyan, magenta, yellow and black. For images that will be used in video, we model color using values of red, green and blue. Where the image will be used will play a role in what color spaces we choose.