screened color image

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:

  1. putting it in a layer on top of the colored original;
  2. setting the blend mode of the gray top layer to "Luminance";
  3. applying a Median filter or Gaussian blur to the colored original layer.

Example courtesy of Robert Silverwood

fftThis 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.

newspaper pictureThis 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.