Atomic force microscopy images can be analyzed with the height-height correlation function to determine both long-range (global) roughness, as well as short-range (local, Hurst) roughness and a correlation length related to the crystalline size, or grain size. An example is shown in the publication below:
Thomas Gredig, Evan A. Silverstein, Matthew P. Byrne, Height-Height Correlation Function to Determine Grain Size in Iron Phthalocyanine Thin Films, J. Phys.: Conf. Ser., 417, 012069 (2013).
The code to compute the Height-Height Correlation Function is available via GitHub/ThomasGredig/.