Fast Fourier Transform (FFT) plugins (Windows only)

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photoken
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Fast Fourier Transform (FFT) plugins (Windows only)

Post by photoken » Sat 05 Apr 2014 07:56

Although PL's de-screen filter can do a remarkable job, there are times when it doesn't -- notably when the pattern to be removed has a diagonal component. The Fast Fourier Transform function can do a remarkable job in those cases. In fact, any time an image has a repetitive pattern it's a candidate for using FFT.

Several years ago, A. Chirokov wrote a couple of FFT plugins for Photoshop and I've collected the relevant and most recent files from various user forums and decided to provide them in zipped files.

The main advantage of using FFT is that it retains the original sharpness of the image, unlike various de-screening filters which rely on blurring to remove the pattern.

The main disadvantages of FFT are:
  • It does not remove the pattern all the way out to the image edges. You can mitigate this behavior by first using Layout...Document...Change Layer Size to add additional pixels around the image. I use formulas of w*1.5 and h*1.5 with a medium gray background to do this.
  • Often, it does not remove all the pattern, particularly in the brightest areas of the image. You can use PL's de-screen or blur filter followed by a sharpen filter to correct that. The result will usually be sharper than simply using a blurring filter (without FFT) to de-screen.
The FFT x64 (old).zip file is a somewhat older version of the code, but it is a 64-bit plugin. The FFT x86 (new).zip file is a newer incarnation of his code, but is a 32-bit plugin.

http://en.file-upload.net/download-8785 ... -.zip.html
http://en.file-upload.net/download-8785 ... -.zip.html

Installation (32-bit)
Copy all four files into your 32-bit plugins directory.

Installation (64-bit)
  • Copy the two *.8bf files into your 64-bit plugins directory.
  • Copy the DLL file into your PhotoLine directory (the same directory as the PL executable).
This site
http://dl.dropboxusercontent.com/u/6795 ... n/main.htm
has some sample demonstrations, explains the use of the plugin, and provides an explanation of the theory behind the FFT plugin. N.B.: The 32-bit version of the plugin uses the Green channel as the operative channel.

In subsequent posts, I'll show a sample and provide a mini-tutorial about using the plugins with tips I've learned through experience.

Enjoy!
Ken
Yes, I think it can be eeeeeasily done....
Just take everything out on Highway 61.

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Hoogo
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Re: Fast Fourier Transform (FFT) plugins (Windows only)

Post by Hoogo » Sat 05 Apr 2014 09:19

Cool, I only had the 32bit-plugin so far.
The 64bit version works, though I placed the dll into the plugin folder.
And by the way: The download button was the tiny green button in the right bottom corner. Kaspersky blocked the others, whatever they would do...
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photoken
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Re: Fast Fourier Transform (FFT) plugins (Windows only)

Post by photoken » Sat 05 Apr 2014 09:30

Hoogo wrote:The 64bit version works, though I placed the dll into the plugin folder.
Cool. I read a lot of contradicting statements about that, so I thought I'd play it safe....
Hoogo wrote:And by the way: The download button was the tiny green button in the right bottom corner. Kaspersky blocked the others, whatever they would do...
Yeah, it looks weird here, too, in IE11 with Symantec and AdBlock Plus. First time I've used that site, so I hope they'll keep the links active for a year....
Ken
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Just take everything out on Highway 61.

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photoken
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Re: Fast Fourier Transform (FFT) plugins (Windows only)

Post by photoken » Sat 05 Apr 2014 10:33

OK, here's a mini-tutorial for using FFT.

This is the original image. It's shown here as a reduced quality JPG image to conform to the forum's posting limitations, but I found the original by searching the Web for "patterns on scanned images":
fft original.jpg
The pattern is diagonal in nature, so PL's de-screen filter doesn't work too well on it.

1. Open two copies of the image. One copy will be the colour image, the other copy will be converted by FFT into a black-and-white image.
2. Run the FFT-RGB filter. It will create a bizarre image.
3. 64-bit: Use the Channels panel to hide the Blue and Green channels. Activate the Red channel. (When using the 64-bit plugin, it helps to now create a Histogram adjustment layer above the background image and move the left dark slider to 38% to give some contrast so you can better see the "stars".)
32-bit: Use the Channels panel to hide the Blue and Red channels. Activate the Green channel.
Your target channel will look like this:
fft red channel original.png
4. Use the Replace Brush to knock back the "stars". Do not touch the central star. Most images will also have an obvious horizontal line in the center. You can knock out any extra stars on the two main axes, but leave as much of those axes as possible. When you're done, it will look like this:
fft red channel fixed.png
Continued in the next post>>>
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Last edited by photoken on Sat 05 Apr 2014 11:14, edited 1 time in total.
Ken
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Just take everything out on Highway 61.

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photoken
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Re: Fast Fourier Transform (FFT) plugins (Windows only)

Post by photoken » Sat 05 Apr 2014 10:41

FFT tutorial (continued)...

5. Click on the "RGB" channel in the Channel panel to show all three channels.
(If you added a Histogram adjustment layer, delete that layer.)
6. Run the IFFT-RGB filter. It will create a black-and-white image:
ifft result.png
7. Copy this B/W image to the Clipboard.
8. Switch to the colour copy of your image and paste the B/W image in as a layer above the background (original) image.
9. Change the Blend Mode of the B/W image to "Luminance". You'll get the final result:
fft final.jpg
That's it! You're done! Of course, you can now use any appropriate tool to further clean up the image.... :mrgreen:

Sometimes you can first clean up any remaining pattern on the B/W image before copying it.
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Ken
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Just take everything out on Highway 61.

Twindaddy
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Re: Fast Fourier Transform (FFT) plugins (Windows only)

Post by Twindaddy » Sat 05 Apr 2014 12:21

Usually one gets even better results by blurying (is that an existent word?) the original image under the luminance layer

Lundberg02
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Re: Fast Fourier Transform (FFT) plugins (Windows only)

Post by Lundberg02 » Sun 06 Apr 2014 06:25

I went all through this last year and was unable to find a Mac version. I can run PL in Win through Fusion. Thanks for the files and tut.

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photoken
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Re: Fast Fourier Transform (FFT) plugins (Windows only)

Post by photoken » Sun 06 Apr 2014 08:24

photoken wrote: Sometimes you can first clean up any remaining pattern on the B/W image before copying it.
To further reduce the pattern in the light and medium areas of the girl's face and hands, I used PL's built-in "Frequency Filter" action on the B/W image. This made it easy to use the Remove Brush on the medium frequency layer to smooth out the remaining pattern. Then I did a merged copy of the B/W image to paste into the colour photo:
patterned image.jpg
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Just take everything out on Highway 61.

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photoken
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Re: Fast Fourier Transform (FFT) plugins (Windows only)

Post by photoken » Sat 06 Aug 2016 09:26

Updating this discussion to point to another source for the FFT plugins. The download link to the zip file is in message #27
http://www.retouchpro.com/forums/softwa ... post311209:

That zip file contains both the 32-bit and 64-bit versions of the FFT plugins, the advantage being that each version uses the Red channel for editing.
Ken
Yes, I think it can be eeeeeasily done....
Just take everything out on Highway 61.