I'm looking for methods of computing some measure of structure in an image. (I do not have a rigorous definition of "structure" though........) Consider the 15 image blocks below:
Suppose for each pixel black = -1, white = 1 and grey = 0. Anything significantly far from 0 is "interesting".
The ones with significant white regions clearly have some structure to them. One way to identify them is by averaging the absolute values of the pixels then set some minimum threshold.
This works, but it does not take into consideration any spatial patterns. So it is unlikely to detect that the blocks along the bottom, and along right, also arguably have some sort of structure to them.
In either case, arguably the top left two blocks have a low structure measure i.e. they looks mostly noise.
Are there any general measures of structure in images which might help for examples like this? Edge detection, filters, etc..... Where to start?