Photoshop Wishes

Suggestions for Adobe Photoshop

FFT-based pattern remover

UPDATE:  

New filters/actions for doing FT-based pattern removal can found HERE.
Go there instead of following the tutorial in this post. The process has been greatly improved and semi-automated since I made this post.


Some applications offer FFT/IFFT-filters that can be used in a tedious process to remove repeating patterns (like raster patterns). I wish Photoshop would become the first application to automate this process.

It would work like a filter that – as if by magic – removes repeating patterns in the image:

A quick sample of what can be achieved with the help of FFT. Here a paper texture is removed.

This is done by performing a “Fast Fourier Transform” (FFT) of the image, splitting it into frequency amplitude and phase (storing it as separate channels). Repeating patterns (frequencies) stand out clearly and can be suppressed by the filter. An Inverse FFT is then performed to convert back to a normal image (now with the repeating patterns removed or reduced).

Note that this only works on a single channel, so normally you would just bother to do this on the Luminosity component. Filtering each RGB-channel separately should be considered. I will leave that up to you Adobe… 😉

For the user, this could be a simple one-click operation, or better yet a slider that affects how aggressively the filter removes frequencies.

Read more to see how to do this in Photoshop manually step by step. Continue reading