1-bit color

1-bit color depth means that only one "bit" of information is saved for each pixel in the image. A "bit" can only have two possible values, 0 or 1. In image formats this means each pixel can be either black or white.

1-bit color is appropriate for text and "line art" -- that is, images that are simply black lines on a white background, with no shades of gray and no colors other than black.

 

U.S. Fish & Wildlife Service

8-bit color

8-bit color means that there are 8 bits of information saved for each pixel. This gives you 256
different choices (28 = 256)

The 256 color choices can be spread across the entire color spectrum, or can be limited to shades of gray. This is usually called "grayscale".

8-bit color should only be used for color images if they are composed of plain, flat blocks of color, like the flower below. It can also be used for what we usually call "black and white" photographs (really grayscale) like the bear image below.

	U.S. Fish & Wildlife Service

24-bit color

24-bit color means that there are 24 bits of information saved for every pixel. This gives you 16.7 million color choices (224 = 16.7 million)

24-bit color is necessary to represent color images with any type of shading. In the example below, the landscape image on the top was scanned at 24-bit color. The image on the bottom was scanned at only 8-bit color. The unattractive "chunkiness" of the sky and river is because there were not enough color choices to represent the subtle shading of the original.

U.S. Fish & Wildlife Service

U.S. Fish & Wildlife Service