(pixel) The smallest resolvable rectangular area of an image, eITher on a screen or stored in memory. Each pixel in a monochrome image has ITs own brightness, from 0 for black to the maximum value (e.g. 255 for an eight-bIT pixel) for whITe. In a colour image, each pixel has ITs own brightness and colour, usually represented as a triple of red, green and blue intensITies (see RGB). Compare voxel. (1998-05-08)