3 ms·
Indeed by applying the "dark circle" (ideal filter or sinc filter) in the frequency domain would introduce other artifacts. The restored image would contain som
by a_c 5y ago
Indeed by applying the "dark circle" (ideal filter or sinc filter) in the frequency domain would introduce other artifacts. The restored image would contain some "ringing" around sharp edges, which might not be perceivable in the image shown. [1]
As of the darkening in restored image, it depends how the software interpret the band-stopping of dark holes. By dark circling in the frequency domain, energy is taken out from the image. Re-normalizing the image might be desired, but then it would turn dark areas brighter.
[1] https://en.wikipedia.org/wiki/Ringing_artifacts https://en.wikipedia.org/wiki/Ringing_artifacts
- colanderman 5y agoI suspect using black instead of grey is the reason for the edge contrast enhancement in the inverse-FFT image. I.e., that's exactly why the tiny areas in between the small letters are darker, and thus the lettering clearer.