A demosaicing algorithm is a digital image process used to interpolate a complete image from the partial raw data received from the color-filtered image sensor internal to many digital cameras in form of a matrix of colored pixels.
Demosaicing Algorithms: Color Filtering
A more economical and practical way to record the primary colors is to permanently place a filter called a color filter array over each individual photosite.
DEMOSAICING
Demosaicing is a very processor-intensive step, and so the best demosaicing algorithms require more processing power than is practical within today's digital cameras.
Demosaicing
The process of reconstructing (interpolation) color images captured with CCD or CMOS sensors using color filter arrays (CFA). Different demosaicing algorithms are used by the various raw converter applications.
The other reason that images need to be sharpened is due to color and demosaicing. As mentioned above, each pixel can measure only one color of light. Actually, the pixels don't really even measure color. The pixels are colorblind.
Here's an example: we sharpen in ACR as part of the demosaicing, but do arbitrary rotations later Photoshop to fix an unlevel camera.
AA filter of the sensor, A/D conversion, demosaicing, base sharpening and of course the lens resolution. However, the "front-"factors are all near-linear. Say, e.g. the AA filter has a factor 0.7 whereas the base sharpening has a factor of 1.5.
Conventional sensors using a color filter array have only one photodiode per pixel location and will display some color inaccuracies around the edges because the missing pixels in each color channel are estimated based on demosaicing algorithms.
Larger chromatic variances may result from Bayer pattern demosaicing. Digital sensors typically capture photons with a repeating array of two green, one red and one blue photosite(s) that register separate luminance values for each site.
The process of mapping those megapixels, each a different color, into a traditional computer RGB format is known as "demosaicing". The quality of the algorithm used to demosaic will affect the final image quality.
Thus, at each photosite, only a single color is recorded (red, green or blue rather than all three), and the values for the two that are not present are later filled in through a clever process known as demosaicing.
 See also: Image, Demosaic, Camera, Color, Resolution
  
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