ISSUE:
We can observe that when the dimension of A is a multiple of 2, pixel information is misplaced (top-left-corner) or lost (bottom-right-corner)
FIGURES:
1st-row L-to-R: Shows an original image GREEN, then its MATLAB's radon transform (a.k.a. sinogram), then its MATLAB's inverse radon transform REED (aka iradon), then the position comparison between the original and reconstructed, NON-MATCHING pixel position: SEPARATE COLORS.
2nd-row L-to-R: Shows my manually modified sinogram, then its MATLAB's iradon REED, then the position comparison between the original and reconstructed, MATCHING pixel position: GREEN+RED=YELLOW.
CODE:
On line 50 I partially "fixed" the RT of the image so iRT would interpret the posiitons of the backprojections (potbp) in the proper place. I say partially because I changed all projection values to a new (better) relative distance for iradon to interpret, which here is enough to show the radon-iradon reconstruction issue.
SINOGRAM
The cross-like pattern surrounding the main FIXED reconstructed pixel (red pixels on 2 row of the figure) because the precise fixed potbp should follow a sinosoidal shifting pattern (with more spare time you can do it, but I suggest to better fix the reconstruction rule on iradon), thus it would give no cross-like pattern. |