I have an Android application that has user contributed images. There are a lot of users that submit black or really dark images to the backend application, that I want to filter out. Best solution would be to filter the images already at the phone and notify the user to make more light and retake the picture. Another solution if easier to achive would be to filter it at the backend written in python. I took a look into opencv, but I do not really have a clue where to start. Any hints where to get information to measure the brightness/color of an image in Android and/or in python ?
What about converting the image into greyscale one, calculate average color of the greyscale image, and filter out images than go over some threshold?
Detecting black images on Android or python