Filter Discretization
Artifact Image
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The picture should show a homogenous disc, but there is a cupping artifact.
Line Plot
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A line plot reveals the artifact in more detail. The intensities in the center of the image are artificially reduced.
Explanation
The problem of discretization is not too often described in literature. But when implementing the filtering step this has to be handled correctly.
Implementing only the ramp filter as absolute value in Fourier domain will lead the above described artifact.
If the discretization is handled correctly, e.g. by using the Ram-Lak-Filter, the artifact disappears.
Correct Reconstruction
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Authors
Magdalena Herbst, Salah Saleh, Michael Dorner