Equalizes the histogram of a grayscale image

dst = cv.equalizeHist(src)

Input

• src Source 8-bit single channel image.

Output

• dst Destination image of the same size and type as src.

The function equalizes the histogram of the input image using the following algorithm:

1. Calculate the histogram H for src.

2. Normalize the histogram so that the sum of histogram bins is 255.

3. Compute the integral of the histogram:

   Hp(i) = sum_{0 <= j < i} H(j)
   

4. Transform the image using Hp as a look-up table:

   dst(x,y) = Hp(src(x,y))
   

The algorithm normalizes the brightness and increases the contrast of the image.