Two-dimensional histogram specification using two-dimensional cumulative distribution function

Recently developed two-dimensional (2D) histogram specification (HS) methods can improve the contrast in an image by increasing the pixel-value differences among the neighbouring pixels. However, the conventional 2D HS methods use the 1D cumulative distribution function (CDF) for pixel-value mapping, and thus the 2D histogram of an output image largely deviates from a 2D target histogram. A 2D CDF-based pairwise pixel-value mapping method is presented. Experimental results show that the 2D histogram of the output image obtained by the proposed method well approximates the 2D target histogram.