FFT problem. Some idea?

[Florin]

Hi everybody. I have again one of these damaged picture to retouch. It has a global texture which must be removed so I used very carefuly the FFT filter, like always I'm doing. However, the final resoult still presents some horizontal line patterns as you can see in the attached sample. I did this 3 times again but the lines are always there.
I've upload the high resolution file in this server:
http://www.mediafire.com/i/?3eux60y21b3hati
Maybe someone could give me a hand to solve this.
PS "File not found" is fake. You can download it.
Regards and thank you

[jcr6]

I see where you painted out the pattern.

The rest of your pattern is located almost along the vertical band in the FFT Power Spectrum. You have to block out THOSE frequencies, too.

The danger is that the rest of your horizontal lines in the image will also go away.

Can't find your original, high-quality image.

[Florin]

Thank you for answer.
Open the link http://www.mediafire.com/i/?3eux60y21b3hati and clic above, over "Download this image"
So, you say "You have to block out THOSE frequencies, too..." How should I do this? I used the FFT several times and had no resoult, the lines are still there..

[Tony W]

Hi Florin
I am not at all sure if this is of any help but the image link you posted is a grayscale version.

I have tried with my version of FFT without any success even tried convert to RGB - I was going to try rotating the image and overlaying etc. I think that FFT needs therefore an RGB image to start with.

[unimatrix001]

FFT does require an rgb image to start with. it uses the red channel to remove the texture.

[Florin]

Hi, thank you my friends.
Yes, I've upload it as grey because is "lighter" than RGB. Just convert the mode from grey to rgb.
I always use the green channel for the FFT, should I try with the red one?
I'll make a try now.
I must confess that I was doing this kind of retouch before (to be a member here) painting the image, every single pixel, but it's a damn job. Takes a lot of time. Last year, in ReouchPro I learned about this filter and I'm really saving a lot of working time whenever people are sending me these textured pictures. This is the first time it did not work well.
Cheers

[Florin]

Well, I made a try inverting the image after the first FFT pass (invert + FFT again + re-invert) but the resoult it's not so attractive. The lines went away but the picture is too blurry.
I belive this will be done with manually removing these lines.
Cheers

[jcr6]

Here is the image (JPEG, quality = 95 to stay under the 100KB limit) with the pattern removed.

Also attached is the mask I used to do it. (scaled up to 1024x1024)

Used my software (FoveaPro) because I wanted to see the problem.

If you look at the mask in a vertical line down the center are a number of dots -- those dots represent the frequencies you were unable to remove when you did it by hand, above.

[jcr6]

Another thing you can try if you're willing to rescan the image is to rotate it by about 15° so that none of the pattern falls on a horizontal or vertical line. That trick (rotate the image a little and try again) should be in your repertoire.

The problem here was that you could not distinguish the pattern from the power spectrum + cross shape to identify H & V frequencies that needed to be removed.

[Florin]

Very nice, JCR, much better than the FFT pass. Thank you
How could I get this mask/filter please?

[Florin]

The problem is that picture was sent via internet, I have not the original

[jcr6]

It's called FoveaPro 4 (ReindeerGraphics.com), but I'm no sure you want to pay $800 for a 177 plug-ins of which you'll only use a few.

I wasn't trying to push my software, but rather help you out. That Free FFT stuff you've been using has some limitations.

Something else that I wrote, called ClearID ($995 from OceanSystems.com) has a one-stop plugin for removing patterns (called Pattern Remover). It is intended for Law Enforcement -- again at a price that is not exactly cheap.

[jcr6]

Another trick with Fourier processing -- if you need to rotate, increase the image size to 200%, THEN Rotate, THEN Remove the frequencies, THEN scale it back down.

Normally, rotation causes blur, but if you scale the image up by 200% first...

[Florin]

K, I understand.
I'm always working over very high resolutions, 800 - 1200 dpi, 6 inch wide, this is my standard work space. This is the way I can zoom in and paint even the most smallest details. I'll try to apply this in my work. I was thinking the same about the FFT, sometimes it blures too much the images.
You're really a great professional, congratulations and thank you again for your time.
F

[Repairman]

Interesting stuff. I have never heard of fft - is it a filter hidden somewhere in the PS (CS3) menu. Any links to explanations and other uses for fft appreciated.
R.

[jcr6]

FFT == Fast Fourier Transform.

It is NOT part of CSx.

This transform is a way of describing a signal (1-D, 2-D like an image, 3-D or more) as a summation of sine-waves. Short sine waves denote the "high" frequencies (meaning they repeat often) and long sine waves denote the "low" frequencies (meaning they slowly vary across the image).

In audio (a 1-D signal), the lows are the bass and the highs are the treble. In images (2-D), the highs are the edges of your image and the lows are the gradients and "halos" around things.

It is an interesting and useful mathematical space, especially for describing repeating patterns (like in this thread), but there is also a way to describe focus blur and motion blur and ways to remove it.

Here's a little bit: (link)

But there is a lot of stuff (including math!!) at Wikipedia.

[Repairman]

Fascinating link JCR. Much of the detail goes right over my head but the photo examples get the basic point across and are inspiring. Back in the day I would occasionally be asked to produce a roadside poster from one frame of a TV advert. Removing video scan lines automatically would have saved me heaps of time. Live and learn!
R.

[chillin]

I used Image Analyzer. I filled out the gaps to continue with the pattern, cropped the picture & applied the filter. I can't post the full size of it (it is a 35MB tif), but here is the smaller sample.

[Florin]

Thank you Chillin, this is really much better than my poor FFT resoult.
However, due to the client's hurry, I started this yesterday with my traditional (painting) retouch. Here is a capture. It will take more time but it will look fine, I'm sure.
Thank you a lot again for your time

[chillin]

If you wish, I can give you a link to the full version?

[Florin]

Fine, thank you

[chillin]

I have sent a private message w/a link

[Florin]

Thank you very much

[stormyboy]

jcr6,

Would it be possible for you to offer the advanced FFT plug-in as a download to purchase some day? (Separate from the 177 plug-in FoveaPro 4.) I'm guessing others besides me would be interested. Of course, you probably have some exclusivity clause that prohibits such a thing.

Tom

[jcr6]

It's my stuff, so I can do what I want with it. The problem is how much to charge for something like that and what should be in it.

Clearly a COLOR version would be the way to go. If I were so inclined, I'd use 32-bit mode (can store my transform in the layer!!) which would mean you'd probably want to use Extended for a layer workflow. Not required -- we'd make sure you could get by in non-Extended. CS4 at least.

There are many things to consider adding, like a better rotation (You get blurring when you rotate. A Fourier-space rotation would blur less than a bicubic.) Better interpolation comes to mind, as well. (I addressed this many years ago with Optipix.)

But the problem is that the audience seems small, which means I'd have to charge a lot, which kind of defeats the purpose of your request.

Hmmm.

Now, if we turned the tables the other way and tried to design a RetouchPro plug-in pack, proceeds to be split between maintaining the site and some to me, that could be very interesting. It would have to have 'the right stuff' in it. And it would benefit us all if we could sell it far and wide. Things to help the workflow. Address the missing stuff or the slow stuff in Photoshop. Make it easier to retouch. Hit the right pricepoint.

And I bet I could find a lot of beta testers around here.

[secretagents]

177 plugins for $800 that's only $4.52 per plugin which is rather cheap. I am sure if you'd sell them individually for say $10 each you'd probably have a few takers for some of them round here, not sure it would be rewarding financially enough for you making them all standalone though.

Anyway also just wanted to say thanks for your free plugs, notably the homomorphic compression one which is very cool but isn't listed on your main page and which I found by accident some day (even made a topic about it in the software section after that).

Cheers.

Hmmm.

Now, if we turned the tables the other way and tried to design a RetouchPro plug-in pack, proceeds to be split between maintaining the site and some to me, that could be very interesting. It would have to have 'the right stuff' in it. And it would benefit us all if we could sell it far and wide. Things to help the workflow. Address the missing stuff or the slow stuff in Photoshop. Make it easier to retouch. Hit the right pricepoint.

And I bet I could find a lot of beta testers around here.

Sounds like a good idea to me.

[Florin]

Meanwile, my retouch is ready:

http://i53.tinypic.com/slgx82.jpg

[Gewuerz]

Hello,

the FFT-Filter specially would be very good. I think, i would buy this extra filter.
Is a demo or a test version possible?

Thanks and greetings Wolfgang

[Kraellin]

very nice, florin

[Florin]

Thank you, Craig. Yes, it's nice. Finally I had to paint it as I was doind before to know about the FFT. Here it did not helped too much.