Improvement of interpolated color filter array image using modified mean-removed classified vector quantization

To reduce the cost of digital cameras, the color filter array (CFA) is usually coated upon a single-chip image sensor. Each pixel of the image sensor can sense only one of the R, G, B colors under CFA. The two missing colors of a pixel are estimated using the CFA interpolation algorithm. The interpolation algorithm may generate color distortion and degrade the quality of interpolated images. To improve the quality of interpolated images, a modified mean-removed classified vector quantization algorithm is proposed to reduce the estimation error of interpolated colors. The algorithm extends and modifies vector quantization to discover the relationships between the interpolated images and their corresponding original versions using the information from CFA images. The discovered relationships are stored in codebooks and are used to improve the quality of images interpolated by the existing CFA interpolation algorithms. The experiments reveal that the proposed algorithm can improve the quality of images interpolated by the best CFA interpolation algorithm as far as we know. In terms of PSNR, the average PSNR improvements of R, G, and B channels are 0.89, 0.71, and 0.74 dB, respectively.