% Create 2D scatter-plot of two images after affine transformation
% FORMAT H = spm_hist2(G,F,M,s)
% G - unsigned 8 bit 3D array representing the first volume
% F - unsigned 8 bit 3D array representing the second volume
% M - the affine transformation matrix so that G(x) is plotted
% against F(x)
% s - 3 element vector representing the sampling density (in voxels).
% A value of [1 1 1] means that approximately all voxels are
% sampled, whereas [4 4 4] means that only 1 in 64 voxels are
% sampled.
%
% This function is called by spm_mireg for rapidly computing
% joint histograms for mutual information image registration.
%
% Note that the function jitters the sampling of the data to reduce
% interpolation artifacts.
%
%_______________________________________________________________________
% @(#)spm_hist2.m 2.3 John Ashburner 01/07/06