What is Pixel?

Pixel meaning in Digital terms is An abbreviation of picture element, this term may refer to a component of either a digital image or a digital sensor. In the case of a digital image, the pixel is the smallest discrete unit of information in the image’s structure. Images based in raster data can be thought of as a grid in which each cell is called a pixel. The amount of data recorded for each pixel can vary, and is expressed as bit depth or bits per pixel, often also as per channel in order to indicate the allocation of bits to different color channels. In the case of the sensor in a scanner or digital camera, a pixel is the smallest photosensitive component or cell providing a response to light (or photons). The photons collected at each pixel liberate electrons, which register as an electrical charge. The strength of the charge or signal is proportional to the number of photons collected at the pixel location. A primary measure used in describing a digital imaging device is the number of pixels the sensor comprises, normally expressed as megapixels (MP) or millions of pixels.


reference: Federal Agencies Digital Guidelines Initiative – Glossary