(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)