What is Gamut?

If you do much digital design or use Photoshop to edit lots of photos, sooner or later you will encounter the term “gamut.” Gamut is a set of colors that can be accurately represented within a given color space or by a printer or other output device. When some colors cannot be reproduced accurately they are said to be “out of gamut.” Colors are rendered using relative colorimetric intent or perceptual rendering. It works best when only a small number of colors are out of gamut. This is what I have my Photoshop set to. To see which rendering intent your copy of Photoshop is set to, open the program and select Edit > Color Settings. In relative colorimetric rendering any colors that are out of gamut are moved back into a printable space. To understand this, think of a circle drawn on the ground. Inside the circle, representing the printable space,  are many colored marbles. Several marbles are outside the circle, so you pick them up and move them inside it. It does change the relationships between colors and may lower print quality, or some marbles may collide with each other.

If you are using perceptual rendering, any colors that are in the way of other colors are moved so that their relationships remain the same. To continue with the marble analogy, no marbles collide. This method works better if lots of colors in your image are out of gamut.