Digital image processing and manipulation: Norman R. Axford
Ralph Jacobson, Sidney Ray, Geoffrey G Attridge, Norman Axford · 2013
A digital image is a rectangular array of numbers representing the luminance and colour at discrete positions in a scene. The image can be thought of as a matrix of pixels, each pixel carrying three numeric values. The pixel position identifies a spatial coordinate and the pixel values represent luminance and colour at that position. The three values of a pixel depend on the colour model employed. For example, they may represent the primary spectral components of red, green and blue (RGB), or they may represent the luminance and two normalized colour values.