Color filter array demosaicking using optimized edge direction map

Abstract

This paper proposes a new color filter array de-mosaicking method with emphasis on the edge estimation. In many existing approaches, the demosaicking is considered a directional interpolation problem, and thus finding the correct edge direction is a very important factor. However, these methods sometimes fail to determine an accurate interpolating direction because they use local information from neighboring pixels. For the estimation of edge direction using global information, we employ an MRF framework where the energy function is formulated by defining new notions of interpolation risk and pixel connectivity. Minimizing this function gives the edge directions, and the green channel is interpolated along the edges. Then we iterate the luminance update and color correction using the high frequencies from green channel. The algorithm is tested with the commonly used images, and it is shown to yield higher CPSNR than the state-of-the-art methods in many images, up to 2.7dB at maximum and 0.4dB on average. Subjective comparison also shows that the proposed method produces less artifacts on complex structures.