OpenCV histogram equalization process using cv::equalizeHist():Need help understanding final step for this

2
votes

I've a question regarding Histogram Equalization process using cv::equalizeHist()(a function of OpenCV image processing library). In this website:

Histogram equalization process using opencv explained

the histogram equalization process is explained which is:

  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. [equation is given in the above website]

  4. transform the image using H' as a look-up table. [equation is given in the above website]

I'm having problem understanding step number 4. What did the author mean by this line?

Can anyone kindly help me understand how the author got the final equalization result from step number 4?

What method he/she used for step number4? How did he/she transform the image looking at H'?

1
functionimage-processingopencvprocesshistogram

1 Answers

0
votes

After some googling I found answer to your question.

  1. Read this wikipedia article.

  2. From source code cvhistogram.cpp (you can actually use the code to implement this function in your project or library) I found in function cvEqualizeHist this line:

    CV_CALL( cvLUT( src, dst, lut ));

  3. And finally explanation of function you're looking for in OpenCV: LUT.