How to get percentages of colors in an image?

Question

Images

Hello everyone, the task is:
There is an illustration, (png), which will then be applied to the wall. And I would like to calculate the amount of paint needed. How I see this cycle:
1. "Passing" the image through some kind of analyzer that reports the percentage of each color in the image
2. Simply multiplying this color by the area of ​​the wall
3. "Passing" the rgb color into the format of the paint that will be used to paint the wall - to calculate the consumption of Kraki
But I could not find the analyzer on the net :c
Maybe someone faced such a problem and solved it?

Answer 1

IMAGE COLOR SUMMARIZER
PS At first I wanted to offer to quantize the image using lib , but the examples on it are not impressive (the desired colors with small areas are lost)