Abstract
A smart method for restoring 256 or more gray levels from some reduced gray levels of the given image is proposed. In the method, the restored value is estimated by averaging the neighboring sub-pixels which are generated by Sinc function beforehand. Moreover, the normalized correlation coefficient between the respective density histograms of input and output images is also proposed as the evaluation index that can qualify the outbreak of the degradation such as false contour. The image quality provided by the proposed method was experimentally excellent so that the false contour never occurred.
