[Shiraz (Ray)]

the manual warns against using maximum - suspect the same applies to entropy, which is probably going to try to maximise local contrast in some intelligent way.

"Maximum
This is and ultra simple method which should be use with a lot of care. The maximum value of all the pixels in the stack is computed for each pixel.
It may be useful to find what is wrong in a stack by exhibiting all the defects of all the calibrated image."

ie if you want defects, use this.

maybe the simple solution is don't use it