Accurate Color Filter Array Demosaicking Using High-Order, Direction-Oriented Extrapolation and a Weighted Median Filter

Color-filter-array demosaicking is an essential step in rendering full color images from single-sensor digital cameras. Because each pixel only records one color value, estimates of the missing color information at each pixel must be made. In this paper, extrapolation equations based on higher orders of the Taylor series are proposed for accurate, direction-oriented estimations of missing color information. Four estimations are calculated based on information of pixels in four different directions so that at an edge, there is at least one accurate approximation available for selection as the output. The output estimation is selected using an edge-preserving, weighted-median filter with weights based on a classifying edge orientation map. Because the process avoids interpolation across an edge by using direction-oriented extrapolation, it has been shown that the algorithm performs particularly well even at the edges of objects in an image.