Affinity Photo Trouble Removing Moire On This Image

[zwilson]

I'm having trouble removing the moire pattern from this scanned image. I watched this tutorial on the FTT Denoise filter but as you can see from my attached screen shot the moire pattern in my image doesn't really match those of the two examples shown in the video and no matter what I try I'm getting less than satisfactory results.

[Greyfox]

3 hours ago, zwilson said:

I'm having trouble removing the moire pattern from this scanned image. I watched this tutorial on the FTT Denoise filter but as you can see from my attached screen shot the moire pattern in my image doesn't really match those of the two examples shown in the video and no matter what I try I'm getting less than satisfactory results.

 

Can you post the actual image itself?

[zwilson]

Here is the affinity file.

Futurhythms.afphoto

[Greyfox]

51 minutes ago, zwilson said:

Here is the affinity file.

Yes, FTT certainly doesn't seem to be able to handle that pattern.
As comparison I ran that image through Topaz DeNoise AI as a plugin, with the result on the upper layer.
It's not perfect but it has done fairly well.

Futurhythms_Mod.afphoto

[h_d]

I zoomed out in the FFT Denoise window, set the brush to 80% hard, full flow and 64px. Dotted around on the brighter areas with some success:

But it's not regular noise so it may be beyond FFT to completely obliterate it.

[Old Bruce]

3 minutes ago, h_d said:

But it's not regular noise so it may be beyond FFT to completely obliterate it.

This is a scan of a printed page. The 'moire' or 'noise' is the halftone. There are probably ways of dealing with halftones.

[h_d]

Back in the days of Photoshop 3/4/5 about 29 million years ago we would Gaussian Blur and then Unsharp Mask to remove clean up scanned halftone dot. It was a bit rough and ready, but ok for local newspaper repro. Not sure how well it would work on this one though.

[h_d]

I've seen worse...

[kaffeeundsalz]

25 minutes ago, h_d said:

Back in the days of Photoshop 3/4/5 about 29 million years ago we would Gaussian Blur and then Unsharp Mask to remove clean up scanned halftone dot. It was a bit rough and ready, but ok for local newspaper repro. Not sure how well it would work on this one though.

We did the something similar, but we additionally made the image smaller so the blur would be even less noticeable. Basically, it was something like this: Scan image at 600 dpi, apply Median Filter with a radius of about 2, apply Gaussian Blur with a radius of about 1 px, scale image down to 300 dpi, tackle unwanted blur with an Unsharp Mask. Problem was, sometimes we didn't have a high resolution version of the image available.

51 minutes ago, h_d said:

I zoomed out in the FFT Denoise window

This. The FFT Denoise filter is an excellent tool for reducing moire patterns, but it's not at all obvious that the standard window of the dialog doesn't show the entire noise distribution. Sometimes only zooming out reveals the critical spots of the diagram.

[zwilson]

Thanks everyone. Topaz looks cool might have to check it out. h_d I did something similar but it wrecks the yellow type so I just masked it and copied it and then put the type down after the denoise. When I started in college we had Photoshop 4 and if I remember correctly that was the last version that did not to have an undo history I think ctr-z was all you had.

[h_d]

15 minutes ago, zwilson said:

I think ctr-z was all you had

Happy days...

[Andy05]

14 hours ago, kaffeeundsalz said:

it was something like this: Scan image at 600 dpi,

Also, we never scanned a halftone print at a degree, which is dividable by 45 (or better 30). As those hit the common angles of at least one of the raster layers for print. The results have been better (read: less moiré), if you scanned at an odd angle (like, turn the sheet by just 3-ish or 7-ish degrees.

[h_d]

2 hours ago, Andy05 said:

3-ish or 7-ish degrees

From what I remember the guy who worked the scanner was so off his head that this was an automatic part of the process.