Pi filter for phased images
filtered_image = pifilter(image[,filter_name])
Filters a phased image before unwrapping it. The purpose is to keep the phase jumps sharp: a convolution by a lowpass kernel would be catastrophic, because it would smooth these jumps, causing the demodulation algorithm to fail.Principle:
This function uses the mkfilter and imconv functions. Reasonable kernels are: 'low-pass' and 'mean'. A high-pass filter would make no sense as it would burst noise !
You can use pifilter for ordinary grayscale images to smooth them without loosing the edges. This filter is similar to the median filter, but will leave edges even stronger. However, the noise will more often not be removed; just attenuated.