If the histogram of an image of a gray scale covers a wide range, distribution, the image with high contrast, gray tones and changing the dynamic range, as shown below [1] .
Histogram equalization can be made uniform distribution of the histogram of the image, the gradation widening intervals facilitate analysis and image recognition.
8 is assumed that a gray scale image, its original histogram as follows:
Histogram equalization principle course be illustrated by the following table, the table n- I represents an image appearing in the gray scale number, n is the total number of pixels in the image represents.