How to compare pixel colors

Question

I have a background image and a new image that I wish to compare pixel by pixel.

I will call these I1 and I2. Suppose the color at x,y in I1 is (r1,g1,b1) and I2 is (r2,g2,b2).

Now I find this empirically of the light settings I had in my room, that when r1 is in the range of r2 +/- 25 or b1 is in the range of b2 +/- 25 or g1 is in the range of g2 +/- 25, pixel at x,y in I1 and I2 are identical.

This 25 is the threshold for my room how do I estimate this threshold dynamically.

Answer 1

Sounds like you're looking towards color quantization. Everyone can see a different " identical. " as far as I know there's no pleasing everyone.

An Overview of Color Quantization Techniques

Ux StackExchange Monitor colors and the human eye