**What I am doing right now**: is calculating the euclidian distance between the pixel intensities of the 2 images. The mean of all the distances (if the image is 500*500 pixels then there are 500^2 distances) gives me a measure of how similar those images are.

**My question is**: is the euclidian distance really the best option when comparing natural numbers that can only range between 0 and 255, or should I use some other measure of distance or transform the pixel intensities first?

**Thanks **in advance!

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CLASS-L list.
Instructions: