Grayscale mode uses different shades of gray in an image. In 8‑bit images, there can be up to 256 shades of gray. Every pixel of a grayscale image has a brightness value ranging from 0 (black) to 255 (white). In 16 and 32‑bit images, the number of shades in an image is much greater than in 8‑bit images.

Grayscale values can also be measured as percentages of black ink coverage (0% is equal to white, 100% to black).

Grayscale mode uses the range defined by the working space setting that you specify in the Color Settings dialog box.