Bit Depth

Besides resolution (the number of pixels) and color mode (the way colors are processed) there is one other variable that affects image quality. Bit depth measures how much color is available for display or printing of each pixel. A greater bit depth means each pixel contains more information for describing the color. A pixel with a bit depth of 1 can display the pixel as either black or white. The most common bit depth is 8-bit mode, which has a possible value of 256 intensity levels per color channel. However, depending on the version of Photoshop you are working with, you can access 8, 16, or 32 bits per channel. It's important to note, though, that larger bit depth can limit image adjustment commands.