3D Gaussian Filter in MATLAB
Is there a 3D eqivalent of imfilter available for MATLAB? I wish to apply Gaussian filtering to a 3D histogram. I was going to implement it myself, by creating a (3D) Gaussian filter, then looping over each element in my histogram, and summing up the corresponding data entries.
However, I didn't want to implement it myself in a slow and inefficient way if there's something already out there, or a cleverer way of doing it.
Answer
There are two ways to solve this in order to do the filtering in an efficient manner:
(1) Use CONVN three times to filter your data with three 1D Gaussians, one x-by-1-by-1, one 1-by-y-by-1, and one 1-by-1-by-z.
(2) If you have the signal processing toolbox, use FFTFILT to perform filtering in inverse space (or use any one of the fft-convolution algorithms on the file exchange).
[(3) Send me an email and I'll send you my fftFilterImage, which does 3D Gauss filtering.]