This example shows the Fourier transform plug-in can effectively remove a screen pattern from an image while retaining the information. The plug-in will remove all color from the image, but you can give the gray result its color back by:
This is an inked fingerprint on a printed document. Filtering in the Fourier domain was used to remove the diagonal pattern as well as the screen (see "How to"). Click on the image to see the result.
This newspaper picture was Fourier transformed, and the peaks from the screen were removed in the frequency domain. The resulting image is quite a bit clearer.