Removing moiré / halftone patterns from scans

[Pseudolus]

Hello everyone,

I recently purchased an iPad and was very excited to try out Affinity in a more mobile setting. My primary task in Affinity Photo (ever since I purchased V1 a few years ago) has been to process and clean up flatbed scans. Unfortunately, it seems that the filter I need the most (the FFT Denoise filter) is not available on iPad.

Does anybody know how I could go about using the iPad version of AP for removing moiré patterns that come from scanning in printed images?

Thanks in advance!

(I am now on V2.)

Edited August 24, 2023 by Pseudolus

[NathanC]

Hi @Pseudolus welcome to the forums,

It is unfortunate that FFT Denoise isn't currently available on iPad as the filter exists for this very purpose with effective results (The lack of this filter on iPad is logged internally). You could use the 'Dust and Scratches' filter as an alternative which does a reasonable job, but the image does lose detail as a result, and at lower radius values the halftone pattern is still somewhat visible.

Example Dust and Scratches Filter Desktop Screenshot (it is also on iPad):

 

[pruus]

You could use the Gaussian Blur filter, perhaps 4 pixels.Rasterise and add later on, if needed, sharpening.

 

[Pseudolus]

Thanks to you both for taking a look! Good to know that, even if the feature isn't available on iPad (yet), that my instincts of using those two options above would be my best course of action. I'm going to try rescanning at an even higher resolution to see if I can crush the moiré through compression and a combination of D&S, Gaussian Blur, masking, and sharpening.

I will say that the laserdisc sleeves I took photographs of (and not scans) worked out just fine in Affinity for iPad. 🙂

[NotMyFault]

You may try this method