BACKPROJ Implementation Using Filtered and Unfiltered Backprojection Algorithms

BACKPROJ employs filtered or unfiltered backprojection algorithms to execute the inverse Radon transform. The filter is designed directly in the frequency domain and multiplied with the FFT of projections. Projections undergo zero-padding to a power of 2 for optimal FFT performance, with implementation requiring careful frequency response design and projection pre-processing.