Pixel, in computer science, short for picture element; sometimes called a pel. One spot in a rectilinear grid of thousands of such spots that are individually “painted” to form an image produced on the screen by a computer or on paper by a printer. Just as a bit is the smallest unit of information a computer can process, a pixel is the smallest element that display or print hardware and software can manipulate in creating letters, numbers, or graphics. For example, the letter A is actually made up of a pattern of pixels in a grid such as the one below:

An image can also be represented in more than two colours. If a pixel has only two colour values (typically black and white), it can be encoded by one bit of information. If more than two bits are used to represent a pixel, a larger range of colours or shades of grey can be represented: two bits for four colours or shades of grey, four bits for sixteen colours, and so on. Typically, an image of two colours is called a bit map, and an image of more than two colours is called a pixel map.