Which distance method will account for positions of observations in arrays?

Question

I am trying to figure out the distance method suited for my problem. I have different arrays of the same length. Each position in the array matters. Let's say ... each array is representing an image, and the value at the last position of the array will tell us that the observation point was found in a far end of an image, etc. And the value in that position of the array is the intensity of the color. What I am trying to do is calculate the similarity distance from one image to another. What distance method would be best suited for this problem?