Angular Second Moment (ASM) and Energy (also called Uniformity)
ASM and Energy use each Pij as a weight for itself. High values of ASM or Energy occur when the window is very orderly.
ASM equation
The square root of the ASM is sometimes used as a texture
measure, and is called Energy.
Energy equation
The terms ASM and Energy
The name for ASM comes from Physics, and reflects the similar form of Physics equations used to calculate the angular second moment, a measure of rotational acceleration. If you are interested, look up "moment of inertia" in a Physics textbook. The meaning of "energy" is explained in the entropy link The term Uniformity is perhaps less confusing.
Self
test:
Exercise:
Perform the ASM calculation for the horizontal GLCM.