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Demosaicking

color image sensor solution

Definition: Demosaicking is the process of recovering the color information in the systems, which use only a single image sensor.

Cost-effective consumer electronic devices use only a single image sensor to capture the visual scene. The monochromatic nature of the sensor necessitates covering its surface by a color filter array (CFA) which is used to capture all the three, Red-Green-Blue (RGB) primary colors at the same time. Since the single-sensor allows only one color to be measured at each spatial location, the acquired CFA image data constitute a mosaic-like gray-scale image. To recover the color information (Figure 1), the two missing color components must be determined from the adjacent pixels. This estimation process is commonly termed demosaicking, but it is also known as CFA interpolation or color interpolation.

Demosaicking is an integral, and probably the most common processing step, used in digital cameras. Demosaicking (Figure 2) performs spectral interpolation as it transforms a gray-scale (scalar) image to a three-channel, full color output. Namely, it rearranges the acquired gray-scale sensor data to an RGB vectorial field, and estimates missing color components from the adjacent sensor data using an interpolator operating in the spectral (color) domain.

The demosaicking solution can be implemented in i) a conventional digital camera which stores the demosaicked (RGB) output, or in ii) a companion personal (PC) computer which interfaces with the digital camera which stores the images in the raw CFA format. Both processing pipelines can use the same demosaicking solution, however, the PC based approach allows for the utilization of sophisticated demosaicking schemes which cannot, due to their complexity, be embedded in the conventional camera image processing solution due to its power and real-time constraints. Finally, it should be noted that a high-quality imaging pipeline should utilize both the spatial and spectral characteristics of the acquired input during the demosaicking process and that such a solution may be complemented by a postprocessing step to produce a naturally colored, sharp image.

Demotic Literature - DEFINITION., DIFFICULTY., GENRES., AUDIENCE., RANGE OF MATERIALS., EARLIEST NARRATIVES., ORAL TRADITION., CYCLES., TEACHINGS., CONTINUATION., SOURCES [next] [back] Demosaicked Image Postprocessing

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