FFT with ImageMagick

[claus_01]

Hello,

I have an image I want to denoise using the FFT feature of ImageMagick.

The image:



This is btw taken from a film by German director, Rainer Erler ('Die Delegation'). The 'aliens' are actors with a special make-up. Mr. Erler kindly gave me permission to use this still, which is unfortunately very noisy.

After applying

Code: Select all

convert image.jpg -fft  \( +clone  -write image_phase.png +delete \) +delete -write image_magnitude.png  -colorspace gray -auto-level -evaluate log 100000  image_spectrum.png

I got this spectrum



but what areas do I mask out? There are no dots as in the example on the ImageMagick page.

TIA,

Claus

[fmw42]

That FFT denoising technique will only remove noise that has a regular pattern. Your image does not qualify for the approach and is way to randomly grainy. You will have to use typical spatial domain median filtering or averaging. Or you can try -despeckle or -enhance or -kuwahara or -cmeans processing.