image
image
 


Features, ImageLab, Edit FFT
Edit FFT - Newspaper raster example
Use this tool to edit the frequency domain of the FFT with IL internal PaintBox editor or use you favorite external paint program. The internal editor is more powerful in that you can directly see the result as a preview, and fine-tune what you are editing. The low frequency part of the FFT is in the central part of the FFT image, and the high frequency part of the FFT is in the outskirts of the FFT image. Most of the image information is in the central part of the FFT image. Experiment with this tool to learn the characteristic of the FFT.

Below is a restoration sequence in ImageLab where an image from a newspaper is cleaned from artifacts.
The artifacts consists of horizontal/vertical streaks around the center of the FFT. It's possible to remove them by simply adding a Low Pass filer, i.e. block the non center data of the FFT. Don't do this to close to the FFT center however.
 
 
image
image
 
image
image