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Raster images come in the form of individual pixels. Each spatial location or resolution element has an associated pixel value, which indicates the coordinates, elevation, and any relevant attribute data, such as a color or ID number.

For GIS, CAD, or other mapping applications, raster image data is acquired by satellite or airborne sensors, such as GeoEye-1, Worldview-2, Worldview-1, QuickBird, or IKONOS, high resolution satellite sensors. The spatial resolution is determined by the resolution of the acquisition device, as well as the quality of the original data source. Because a raster image must have pixels for all spatial locations, the size of the represented spatial area is strictly limited. When the spatial resolution is doubled, the total size of a two-dimensional raster image increases by 400%, as the number of pixels is doubled in both X and Y dimensions. The same is true when a larger area is to be covered using the same spatial resolution.

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