Date: Tue, 10 Dec 1996 03:31:46 GMT Server: NCSA/1.4.2 Content-type: text/html
A digital image is a two-dimensional array of small square regions known as pixels. In the case of a monochrome (also known as gray-scale or "black-and-white" with shades of gray) image, the brightness of each pixel is represented by a numeric value. Gray-scale images typically contain values in the range from 0 to 255, with 0 representing black, 255 representing white and values in between representing shades of gray. Here is an example of the above picture blown up to show the underlying pixel values.
A color image can be represented by a two-dimensional array of Red, Green and Blue triples. Typically, each number in the triple also ranges from 0 to 255, where 0 indicates that none of that primary color is present in that pixel and 255 indicates a maximum amount of that primary color.