Raster images can be bilevel, grayscale, or color, but they are always made up of dots (also called pixels). They are created with drawing programs such as Paint, and by scanning pieces of paper.
For bilevel rasters, each pixel is either on (black or foreground or 1) or off (white or background or 0).
Bilevel raster
With grayscale rasters, each pixel is assigned a number from 0 (black) to 255 (white), with each number in between representing an ever-lighter shade of gray.
Grayscale raster
In color rasters, a combination of red, green, and blue (RGB) forms color pixels.
Color raster
