Is "color quantization" the right name for color quantization in OpenCV?

Question

I'm looking for a way to get a complete list of all the RGB values for each pixel in a given image using OpenCV, now i call this "color quantization".

The problem is that according to what I have found online, at least at this point, this "color quantization" thing is about histograms or "color reduction" or similar discrete computation solutions.

Since I know what I want and the "internet" seems to have a different opinion about what this words mean, I was wondering: maybe there is not a real solution for this ? a workable way or a working algorithm in the OpenCV lib.

Answer 1

Color quantization is the conversion of infinite natural colors in the finite digital color space. Anyway to create a full color 'histogram' you can use opencv's sparse matrix implementation and write your own function to compute it. Of course you have to access the pixels one by one, if you have no other structural or continuity information about the image.

Answer 2

Generally speaking, quantization is an operation that takes an input signal with real (mathematical) values to a set of discrete values. A possible algorithm to implement this process is to compute the histogram of the data, then retaining the n values that correspond to the n bins of the histogram with the higher population.

What you are trying to do would be called maybe color listing. If you ar eworking with 8 bits quantized images (type CV_8UC3), my guess is that you do what you desire by taking the histogram of the input image (bin width equal to 1) then searching the result for non-empty bins.