A digital image generated by a series of bits and bytes, resulting in an image displayed as a grid of pixels, each a specific color and gray scale value. Most images on the Web are bitmaps ? typically JPEGs and GIFs. Also known as a raster image. The alternative sort of image is a vector graphic.Related link: Mike Doughty compares bitmap images to vector graphics, and explains the difference. Also see aliased and anti-aliased.