The word image is a polysemous term and not always well defined. In computing, a bitmap image consists of a matrix of dots (called pixels) with associated color codes. In the field of GIS and geomatics, it is useful to distinguish between images whose pixels are a value from an electromagnetic sensor, often from remote sensing, and images whose color codes were assigned for example by a scanner, or by attribute values, qualitative or quantitative. In GIS, an image often takes the form of a raster grid.

See: Raster (mode)