page_title: Pixel
section_title: Subpixels
hierarchical_section_title: Pixel / Technical / Subpixels
caption_attribution_description: English: Pixel geometries. Clockwise from top left: a standard definition CRT television. "Palsonic" brand. (this image is significantly reduced compared to others) a CRT computer monitor. Diamond View 19" (18" viewable). Model 1995SL. a laptop LCD: Lenovo X61, 12" 1024×768 the OLPC XO-1 LCD display. (Test-B2)
context_page_description: In digital imaging, a pixel, pel, 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.
  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, pixel refers to a single scalar element of a multi-component representation, while in yet other contexts it may refer to the set of component intensities for a spatial position.
context_section_description: Many display and image-acquisition systems are not capable of displaying or sensing the different color channels at the same site. Therefore, the pixel grid is divided into single-color regions that contribute to the displayed or sensed color when viewed at a distance. In some displays, such as LCD, LED, and plasma displays, these single-color regions are separately addressable elements, which have come to be known as subpixels. For example, LCDs typically divide each pixel vertically into three subpixels. When the square pixel is divided into three subpixels, each subpixel is necessarily rectangular. In display industry terminology, subpixels are often referred to as pixels, as they are the basic addressable elements in a viewpoint of hardware, and hence pixel circuits rather than subpixel circuits is used.
  Most digital camera image sensors use single-color sensor regions, for example using the Bayer filter pattern, and in the camera industry these are known as pixels just like in the display industry, not subpixels.
  For systems with subpixels, two different approaches can be taken:
  The subpixels can be ignored, with full-color pixels being treated as the smallest addressable imaging element; or
  The subpixels can be included in rendering calculations, which requires more analysis and processing time, but can produce apparently superior images in some cases.
  This latter approach, referred to as subpixel rendering, uses knowledge of pixel geometry to manipulate the three colored subpixels separately, producing an increase in the apparent resolution of color displays. While CRT displays use red-green-blue-masked phosphor areas, dictated by a mesh grid called the shadow mask, it would require a difficult calibration step to be aligned with the displayed pixel raster, and so CRTs do not currently use subpixel rendering.
  The concept of subpixels is related to samples.
caption: Geometry of color elements of various CRT and LCD displays; phosphor dots in the color display of CRTs (top row) bear no relation to pixels or subpixels.
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