Image sensor: Difference between revisions

Revision as of 21:29, 23 February 2023

Revision as of 15:26, 26 February 2023

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[[File:Absorption-X3.svg|right|thumb|200px|Foveon's scheme of vertical filtering for color sensing]]

There are several main types of color image sensors, differing by the type of color-separation mechanism:

* '''Integral color sensors'''<ref>{{Cite journal |last=Dillon |first=Peter |date=Dec 1976 |title=Integral color filter arrays for solid-state imagers |url=https://ieeexplore.ieee.org/document/1478779 |journal=Technical Digest International Electron Device Meeting (IEDM), Washington, DC, Dec 1976 |pages=400-403 |via=IEEE}}</ref> use a [[color filter array]] fabricated on top of a single monochrome CCD or CMOS image sensor. The most common color filter array pattern, the [[Bayer pattern]], uses a checkerboard arrangement of two green pixels for each red and blue pixel, although many other color filter patterns have been developed, including patterns using cyan, magenta, yellow, and white pixels.<ref>{{Cite web |last=Parulski |first=Kenneth |date=August 1985 |title=Color Filters and Processing Alternatives for One-chip Cameras |url=https://ieeexplore.ieee.org/document/1484879}}</ref>. Integral color sensors were initially manufactured by transferring colored dyes through photoresist windows onto a polymer receiving layer coated on top of a monochrome CCD sensor.<ref>{{Cite web |last=Dillon |first=Peter |date=February 1978 |title=Fabrication and performance of color filter arrays for solid-state imagers |url=https://ieeexplore.ieee.org/document/1479439}}</ref> Since each pixel provides only a single color (such as green), the "missing" color values (such as red and blue) for the pixel are interpolated using neighboring pixels.<ref>{{Cite web |last=Dillon |first=Peter |date=February 1978 |title=Color imaging system using a single CCD area array |url=https://ieeexplore.ieee.org/document/1479440}}</ref> This processing is also referred to as [[demosaicing]] or de-bayering.

* '''[[Foveon X3 sensor]]''', using an array of layered pixel sensors, separating light via the inherent wavelength-dependent absorption property of silicon, such that every ___location senses all three color channels. This method is similar to how color film for photography works.

* '''[[Three-CCD camera|3CCD]]''', using three discrete image sensors, with the color separation done by a [[dichroic prism]]. The dichroic elements provide a sharper color separation, thus improving color quality. Because each sensor is equally sensitive within its [[passband]], and at full resolution, 3-CCD sensors produce better color quality and better low light performance. 3-CCD sensors produce a full [[Chroma subsampling|4:4:4]] signal, which is preferred in [[television broadcasting]], [[video editing]] and [[chroma key]] visual effects.