In digital imaging, a pixel
, or picture element
is a physical point in a raster image, or the smallest addressable element in an all points addressable display device; so it is the smallest controllable element of a picture represented on the screen
. The address of a pixel corresponds to its physical coordinates. LCD pixels are manufactured in a two-dimensional grid, and are often represented using dots or squares, but CRT pixels correspond to their timing mechanisms .
Each pixel is a sample
of an original image; more samples typically provide more accurate
representations of the original. The intensity of each pixel is variable
. In color
imaging systems, a color is typically represented by three or four component
intensities such as red, green, and blue, or cyan, magenta, yellow, and black.
In some contexts (such as descriptions of camera
sensors), the term pixel
is used to refer to a single scalar
element of a multi-component representation (more precisely called a photosite
in the camera sensor
context, although the neologism sensel
is sometimes used to describe the elements of a digital camera's sensor), while in yet other contexts the term may be used to refer to the set of component intensities for a spatial position, though this is more accurately termed a sample. Drawing
a distinction between pixels, photosite and samples avoids confusion
when describing color systems that use chroma subsampling or cameras that use Bayer filter to produce color components via upsampling.
The word pixel
is based on a contraction
(from word "pictures", where it is shortened to "pics", and "cs" in "pics" sounds like "x") and el
(for "element"); similar formations with 'el'
include the words voxel
(for magnetic pixel