Joint entropy and histogram calculation for 3D+ images

Reasonably fast. Build for any number of dimensions.

Description

Set up for joint entropy only, but code for joint histogram is in there (just commented out).

This uses no for loops - only index manipulation. For a 512x512x128 image it took about a fourth of the time as the conventional for-loop method, and about a tenth of the time for a 16x16x4 image.

Only two inputs are 'needed,' per say, and those are the two images to be processed. However, it does speed things up to allocate memory outside the function for two other variables (as explained in the code).

• Required Products: Image Processing Toolbox; MATLAB
• MATLAB release: MATLAB 8.1 (R2013a)