Determine all colors in bounding box in OpenCV/Python
It can be done by using a grayscale convertion of your image or of your ROI.
You can weather process the histogram of the ROI extract from the gray scale (or convert to grayscale if extracted from the colour image) and count the non zero value. 
Or you can copy all the gray-scale value of your ROI into a set container, then the lenght of the set is the number of colours presents in your ROI.
Given a bounding box for an image in OpenCV, is there a way to return all the colors inside the box? Ideally, the output would give the information along the lines of "In the bounding box, it is 50% white, 25% blue, 15% green, 10% red." 
Is there any way to do this? At the very least, is there some function that could tell me all the colors in the box? (without percentages or how much of it there is). Any indication would be huge help
Thanks in advance