histogramequalization

代码说明：

  In histogram equalization we are trying to maximize the image contrast by applying a gray level transform which tries to flatten the resulting histogram. The gray level transform is a scaled version of the original image s cumulative histogram. That is, the graylevel transform T is given by T[i] = (G-1)c(i), where G is the number of gray levels and c(i) is the normalized cumulative histogram of the original image.