In digital imaging, a pixel (or picture element) is the smallest item of information in an image. Pixels are normally arranged in a 2-dimensional grid, and are often represented using dots, squares, or rectangles. Each pixel is a sample of an original image, where more samples typically provide more-accurate representations of the original. The intensity of each pixel is variable; in color systems, each pixel has typically three or four components such as red, green, and blue, or cyan, magenta, yellow, and black.

The word pixel is based on a contraction of pix ("pictures") and el (for "element"); similar formations with el  for "element" include the words: voxel and texel.

Etymology

The word "pixel" was first published in 1965 by Frederic C. Billingsley of JPL (in Pasadena, CA), to describe the picture elements of video images from space probes to the Moon and Mars. However, Billingsley did not coin the term himself. Instead, he got the word "pixel" from Keith E. McFarland, at the Link Division of General Precision in Palo Alto, who did not know where the word originated. McFarland said simply it was "in use at the time" (circa 1963).

The word is a combination of picture and element, via pix. Pix was first coined in 1932 in a Variety magazine headline, as an abbreviation for the word pictures, in reference to movies. By 1938, "pix" was being used in reference to still pictures by photojournalists.

The concept of a "picture element" dates to the earliest days of television, for example as "Bildpunkt" (the German word for pixel, literally picture point) in the 1888 German patent of Paul Nipkow. According to various etymologies, the earliest publication of the term picture element itself was in Wireless World magazine in 1927, though it had been used earlier in various U.S. patents filed as early as 1911.

Some authors explain pixel as picture cell, as early as 1972.

A detailed history of pixel and picture element, with references, is linked below (in External links).

In video processing, pel is often used instead of pixel. For example, IBM used it in their Technical Reference for the original PC.

Words with similar etymologies

Texel (texture element) and luxel (lux element) are words used to describe a pixel when it is used in specific context (texturing and light mapping respectively)

A voxel is a volume element, the 3D analogue of a 2D pixel.

Surfels (surface elements) have the same naming pattern as pixels, but share more similarities with shrunken triangles than expanded pixels.