This photograph is a small part of a long panoramic group photo.
It has been scanned following all the suggestions / tutorials on this site and this is the best I can get.

I am not asking for anyone to restore this but I hope to get some suggestions on the golf ball texture.

I think Neat image blurs this picture to much.

FFT which has always worked well for me in the past has let me down with this picture
When I run FFT I can get rid of the grain but I am left with lines on the print which is just as bad.

I suppose my question is
Does anyone understand the Stars that FFT gives? I usually remove all except the big one. Is there perhaps a way of removing some of the stars to avoid getting lines on the picture? When I remove just the 4 stars nearest the big star I seem to get the best results from this picture.

This picture clearly needs some Level / Colour / Sharpen adjustment but this also improves the golf balls so I’ve posted the best original scan.

I did complete this image by eliminating every golf ball on the face with the Clone Stamp and my friend is happy with the finished picture. I’m just hoping to find some suggestions for an easier way next time.

Did you scan this, or was it given to you as is.

If you have the original to scan, try scanning once, then rotate image by 180 degrees and scan again.

In photoshop, copy both scans to seperate layers.
Set blend mode of top layer to either lighten, or darken (whichever gives best results). Because the shadows caused by the bumps are different, due to the change in scanned lighting, they cancel out, and the bumps should be less noticeable.

Hope this helps a little.

Hi Cameraken,

Welcome to RP! :pleased:

The result I got with FFT was acceptable ... It is a bit more blurred than I expected but the resolution of the image posted is very, very low ....

Gary this is scanned from about ¼ inch of the original print. I followed all the tutorials about rotating the image and setting blend modes etc.
This image is already a combination of that process.


Flora.
You have done a wonderful job.
I had to increase the jpg compression to get the file uploaded to retouch pro (100kb max)
I tried again on the compressed file and I still don’t get the results you have.
I am still getting lines across the image.
See attached image


All
If anyone reading this is interested I will move this to a ‘Reverse Tutorial’
As it seems that only a few people here understand it (Duv, Flora,Byro)
Can someone can please tell me where to post it?

The best information I found was here
http://www.retouchpro.com/forums/showpost.php?p=76559&postcount=6
But following this still does not give me the results Flora got.

I think this texture removal is really important to making good images as many old photographs have texture.

FFT has worked OK for me in the past and I can’t understand why I am having problems this time

You might have some success trying the following:
Make 3 copies of your picture. Adjust levels.
On the first, select a small portion of the pic and clean it up by cloning out the balls. Go to Filter:Pattern Maker and click on Generate. Save the pattern with the button at the bottom. Cancel out of Pattern Maker. Go to Healing Brush and set it to pattern. Pick out the one you created and heal out the balls.

On second copy, run FFT. You should end up with a B/W image. Shift drag onto Healed image, change to Luminosity and change opacity to suit. High Pass sharpen and fade back in Soft Light.

Cheers
Dave

Since I sell FFT code, Doug gave me a head's-up on this. The UI for my software is completely INAPPROPRIATE for photography or people that don't want to know about FFTs, and a separate discussion will need to be held over what you'd like for tools (since I'm a plugin writer).

In any case, here's what I was able to do with removing the pattern noise from the Power Spectrum manually (attachment).

I have not attempted to go after the random noise in the image and there is evidence of the top layer of the photograph flaking off and yellowing in the blue channel.

This should give you an indication of what's possible.

-Chris Russ

P.S. there is a 3-week demo of the FoveaPro software available if anyone wants to play with it. I do NOT expect any of you guys to buy it -- you're not the intended audience. If anyone is interested in playing I'll be happy to provide a URL for download.

And, I suppose I could write up a discussion on what you're actually seeing when you look at a PowerSpectrum (the "FFT Stars" that someone was referring to, above).

Gluttons for punishment.

Thanks for the info Chris. Personally, I'd like to play with the FoveaPro if you could provide the URL.

Also, do you have any tips on how much of a star to remove. What I mean is that often, horizontal and vertical lines emanate out from the centre of the star, sometimes for quite a distance. Is it recommended just to remove the centre star or should we be cloning out the lines as well? Or is it, try it and see what happens?

Cheers
Dave

Demo for FoveaPro can be downloaded from:

Mac Version (http://drjohnruss.com/shortcuts/FP3.sit)
PC Version (http://drjohnruss.com/shortcuts/FP3.zip)

(Runs for 3 weeks.)

There is a tutorial on using it for Fourier processing at:

Chapter 4 - Processing in Frequency Space (http://reindeergraphics.com/tutorial/chap4/fourier01.html)

But rather than make this a blatant ad for a product that was designed for a different group of people than y'all, let me instead talk about reading Fourier transforms and some of the things you can look for in them.

#1 - The Fourier Transform. We convert an image (no loss of data) into a summation of sine waves. Each possible sine wave has a strength and those are plotted in the Power Spectrum. This is a map of the direction of the different sine waves and their period/phase -- longer sine waves are in the center of the plot (DC is the center and represents the mean value of the image) with shorter sine waves around the outside.

The center cross-shaped radial lines are a combination of the extra frequencies that it takes to wrap around from the left side of the image to the right side of the image (vertical part) and the top side to the bottom side of the image (horizontal part).

Here is an example Power Spectrum:

http://reindeergraphics.com/tutorial/chap4/fig_4_13_2.jpg

In it you can see the center cross (caused by the edges of the image not matching each other) and a spike in the center which corresponds to the overall image brightness and the gross gradient in the image. As we come out further from the center, the amount of power starts to back off. (This plot shows power as black so the "background" will tend to lighten as we come further out radially from the center.)

You will also notice a number of other spikes. These are caused by a halftone pattern in the original picture:

http://reindeergraphics.com/tutorial/chap4/fig_4_13_1.jpg

If we create a mask to eliminate just those spikes and apply it to the Power Spectrum (like this one):

http://reindeergraphics.com/tutorial/chap4/fig_4_13_3.jpg

We get the following result:

http://reindeergraphics.com/tutorial/chap4/fig_4_13_4.jpg

Actually, to get a very good result, and to blur the image some, we also apply a low-pass filter (in this case a Butterworth) and make the Power Spectrum look like this:

http://reindeergraphics.com/tutorial/chap4/fig_4_13_6.jpg

Notice that it now lightens up a lot toward the outside edges and there are holes where the spikes used to be.

Here is the result image:

http://reindeergraphics.com/tutorial/chap4/fig_4_13_7.jpg

That low-pass filter actually filled in the gaps in the original halftone dots. There are a host of other filters that can be done, but this should give you a small idea of what's possible.

It turns out that you can do very high speed convolution in this mathematical space (especially with large filters), remove pattern noise, make some measurements for periodic shapes, determine the real vs. empty resolution of an image, construct really interesting filters (like this one), and otherwise confuse people.

Enjoy.

P.S. When I was a college student in the early 80's we were challenged to perform a periodic noise removal problem. At that time (less politically correct than today) Cheryl Teigs had posed in a fishnet bathing suit that left little to the imagination. Since that suit was fishnet, and thus periodic, we were challenged to remove the suit. (Obviously there were no women in the class.) Needless to say, the technique works.

You asked whick parts of the "FFT Star" or the cross to remove. I would say NONE. That cross represents the frequencies that it takes to do the step from the top to the bottom and the left to the right -- if you remove it, you'll mess up your image up significantly.

Now, if there is a spike sitting on top of the cross, you can remove THAT. And, lines that are not at the 12, 3, 6, and 9 o'clock positions that do not run through the center of your image you can safely remove.

Other stuff might be problemmatic. Perhaps you should post an image and we'll deconstruct it.

Also, let's start with b&w. Color information can be different in the three channels, so lets deal with one channel at a time.

Well I ran the median filter at 3 then Neat Image on the picture.

I couldn't let another FFT thread pass by without sticking my nose in....

FFT which has always worked well for me in the past has let me down with this picture ...... FFT has worked OK for me in the past and I can’t understand why I am having problems this timeFFT is a mathematical process - as you can see by jcr6's post. It is great for detecting well-defined repetitive frequencies in an image.

To our eyes the "golf balls" seem to be exactly repetitive and using FFT you will be able to remove all the repeating frequencies. What you have got left after that is noise that was superimposed on those frequencies.

Although we can see some sort of pattern in this noise, it doesn't repeat any more - there are some white dots, then a few black ones......

Why is this one different? Because other paper textures are usually less embossed than this one and don't pick up so much dirt (=noise).

The best information I found was here
http://www.retouchpro.com/forums/showpost.php?p=76559&postcount=6
I left a note there advising that there is an easier version available now which doesn't need the HSB stuff.

For those (few, OK) mathematically inclined.. there is actually a way to calculate where the stars will be in the FFT. Something like.. measure the pixel distance between the texture ridges, divide the total image dimension by this number, then count out from the centre. I did have it figured out once and it did work.

Rô
(Yeah, I know - 1.496Km to go)

Duv,

Can you come up with a report on the FoveaPro at some point. Something for non-numbers people to appreciate? Ro?

k

OK, I'm on it :!:
But it's a 22MB download :dizzy: - so only tomorrow.

Rô

I never intended for this to be an ad for Fovea -- it is a general purpose image analysis system for scientific imaging.

Now, some of the things in there (like the Fourier suite) *might* make an interesting product at a more acceptable price, but I need to see what you guys want/need/are willing to learn.

My basic inclination is to completely hide the FFT under-the-hood, whether for deconvolution (Optipix->Refocus), using an ideal inverse (a very neat tool for image enhancement), halftone removal, etc.

The learning curve, for one, is huge. Two, the Fourier suite works in b&w. Three, there are 177 plugins in Fovea. Four, the "tutorial" is 500 pages.

Then, again, it might be interesting to see how he feels after going through it. <evil laughter> :devil:

That's how Chris and I first connected. A couple of years ago I was looking for focus and pattern solutions and came across Fovea Pro. We exchanged some emails and I even printed out the manual and made an attempt at figuring it out. But it was written from the perspective of a place I've never been (technical image analysis), and I was quickly in way over my head.

But I do feel there is a valuable restoration tool waiting to be designed, here. Something without painted stars, with sliders (and a realtime preview). Perhaps something that would internally rank the patterns and let you page through them ("no, don't remove that one, yes, remove that one and that one, but leave that one").

The Cheryl Tiegs assignment was inspired :)

My guess it already exists, in Langley, Virginia, USA

k

Then, again, it might be interesting to see how he feels after going through it. <evil laughter> :devil:I'm a kid in a candy store. :dizzy: :bigthmb:

(I had already read through most of your site, and numbers and formulas don't scare me - I almost majored in maths)

Thanks,

Rô

Phil showed an example of using a radius=3 median filter to remove stuff. If you think about a median filter, let's start with the simplest radius=1 (3x3 neighborhood), it will remove lines that are 1 pixel wide or clusters that are less than 9/2 =4.5 pixels. So a block that is 2x2 will be completely removed as will the thinnest of lines.

As this neighborhood radius gets larger (he used an example of radius=3 - 7x7 neighborhood, lines that are 3 pixels wide or narrower will get removed, blocks that are less than 49/2 or 24.5 pixels will be removed, and corners on objects will be rounded off. This is why you were able to remove the pattern with a median filter. It is a really harsh filter, though, in that it removes all kinds of useful stuff.

There is a variation on the median called a "Hybrid Median" that is nowhere near as harsh. We've implemented it in FoveaPro, but also in Optipix as "Safe Median." Basically it is much more computationally intensive, but can preserve lines and corners. It still does a good job at removing noise (and, regretfully, fine detail).

We probably should have a discussion about noise removal and what is noise and what isn't. It might be fun to write a couple of plugins for you guys to play with to see what we can learn. (I like having guinea pigs!)

-Chris

To Philbach
Thanks for the suggestion of median filter. This is quick and easy and has removed all the texture but has sacrificed detail (look at the eyes)

Duv
You have retained all the detail but have left a little texture (or is this noise byRo)
If FFT had worked perfectly your first step would not be necessary
Your image has more contrast than Jcr6

Flora
Your picture still looks good. You have removed all the texture

Jcr6
Thanks very much for your excellent contribution.
Your picture is great. Although there is still a little texture/noise you have retained all the detail (not that there is much in this image)
Duv has got a similar result but with a little more contrast
I’ve downloaded FoveaPro trial and will read Tutorial5.pdf

What you have written here has already taught me a lot

OK here are my new steps

1) Set background colour to grey 127,127,127 (for Padding)
2) Image > Canvas Size > 512,512 in Pixels (In this case - square with dimension equal to an exact power of two)
3) Image > Adjust > Desaturate
4) Filter > FFT RGB
5) On the Red Channel > clone (using Darken) out the Stars except middle one
6) Blur step here? (Butterworth?)
7) Filter > IFFT RGB


Is this OK? My results Have improved

I have a few Questions
I am (now) Using FFT_RGB_PlugIns_13April_2005. Is this the version everyone else is using? And is this the correct version?

In http://reindeergraphics.com/tutorial/chap4/fig_4_13_6.jpg
The corners are missing. Is this significant?

Step 6) Any suggestions?

You suggest starting with a B&W image. Do you mean Greyscale or RGB>Desaturated. My Fourier Transform Folder is unavailable with a Greyscale Image


In the UK Ilford used to make a paper called Velvet Stipple. This was one of the most textured papers available. Does anyone have a sample for Jcr6 to deconstruct.

Ken

I have a few Questions
I am (now) Using FFT_RGB_PlugIns_13April_2005. Is this the version everyone else is using? And is this the correct version?

In http://reindeergraphics.com/tutorial/chap4/fig_4_13_6.jpg
The corners are missing. Is this significant?

Step 6) Any suggestions?

You suggest starting with a B&W image. Do you mean Greyscale or RGB>Desaturated. My Fourier Transform Folder is unavailable with a Greyscale Image

In the UK Ilford used to make a paper called Velvet Stipple. This was one of the most textured papers available. Does anyone have a sample for Jcr6 to deconstruct.


As you may have guessed, I'm not using FFT RGB... Where do I get it?

The corners are "missing" but aren't really missing. It turns out that they're considerably lighter because they've been reduced so much in power. This is a side-effect of the Butterworth filter. The banding in the image is a result of compression.

The reason I suggested B&W was because there is a different signature in the different color channels -- this is more evident if you're looking at a scanned image from a magazine where different colors have different screen angles.

You might also try scanning a blank piece of Velvet Stipple and performing an FFT on that -- this should give you your definitive map of bad frequencies.

Fovea works on one channel at a time.

As you may have guessed, I'm not using FFT RGB... Where do I get it?This is the Alex Chirakov filter, you'll find it here (http://www.pages.drexel.edu/~avc25/archive.htm#FFT).
It's called RGB because the earlier verison encoded the FFT information into HSB, now it´s a lot easier because the FFT is in the Red and Green channels.

OBS: (for jcr6) it will take any size of input image

Rô

byRo

Thanks for answering jcr6. I was just about to reply
When I follow your link there are 2 Options
Option 1)
Download new version of FFT/IFFT Photoshop plugin - 235Kb (April 2005)
Option 2)
Download RGB version of FFT/IFFT Photoshop plugin - 156Kb (April 2005) (Red and Green channels are used instead of Hue and Light to store complex phase and amplitude information)

I have downloaded the second option which seems to follow what you have been saying. I this correct?

It is important here that we are all talking about the same filter.

I had added steps 1 and 2 (and what is now 4) because of what I read from jcr6. But from what you are saying they are not needed with Alex Chirakov filter (and I did not notice any improvement from this)
So. New Steps

1) Image > Adjust > Desaturate
2) Filter > FFT RGB
3) On the Red Channel > clone (using Darken) out the Stars except middle one
4) Blur step here? (Butterworth?)
5) Filter > IFFT RGB



Proxy has submitted what looks like Velvet Stipple Here
http://www.retouchpro.com/forums/showthread.php?t=10633

I was a Professional Photographer for over 20 years and have copied hundreds of photos. Before digital this was easy I put a print on my copy stand got my trusty H/Blad and made copies without worrying about texture as my lighting eliminated it. The problem is caused by scanners which have directional lighting. Why can’t they invent a scanner with a light around the sensor?

Ken

Sorry for being a bit dense here - but can I just confirm something that is probably bleeding obvious:

6th step - overlay with original image set to color mode? Or is there some other way of getting the colour back?

Ro, tried downloading the RGB version, but can't open it. (its a rar file, can't find any info on it).

Caitlin
Put the repaired B&W layer above your colour layer and set blending mode to Luminocity (thanks Flora)

Gary
A rar file is a compressed file you will need a program called Winrar to open it
There is a demo available here
http://www.rarlab.com/download.htm

Gary, didn't quite understand if you don't know about RAR files or if this one was corrupted.

Anyway - general instructions for all...

- You will need WinRar to open the ".rar" files, homepage here (http://www.rarlab.com/). It's shareware, but doesn't stop working after the time limit (just nags).

- If it's the second, better download again.

- When you've got it open in WinRar, open the "bin" folder and extract the two ".8bf" filters to your PS filters folder.

Rô

I just realized that you're only correcting the brightness information, not the color channels.

(One of those "Aha!" moments!)

In order to do this correctly, you really have to correct ALL THREE CHANNELS. And, there can be a different pattern in each. In the case of the "Golf Balls" they're refracting light, so the PowerSpectrum for each (R, G, B) will be different.

If you don't do this to all of the channels, your colors will be screwy -- and will retain the golf ball pattern.

Morning, Camaraken - beat me by three minutes!

6th step - overlay with original image set to color mode? .......Put the repaired B&W layer above your colour layer and set blending mode to Luminosity
They are in fact exactly the same thing, the Lumosity is more efficient because you don't need another layer.

1) Image > Adjust > Desaturate
I wouldn't do this. When you do the FFT you will be working on a greyscale image (in RGB mode). After the FFT process, as you rightly said, you mix in Luminosity. It would be much better then if you separated the Luminosity and not Desaturated (they are very different). Then you process FFT and mix back in the clean Luminosity.

To get Luminosity: New Layer (<Ctrl><J>), Edit>Fill - 50% grey, color, 100%. (There are other ways, this is the quickest)

4) Blur step here? (Butterworth?)Don't think this would help any.

So summing up...
1) Duplicate original image, right click on title bar (that's a new image, not just a layer);
2) On the new image, get Luminosity (as above);
3) Flatten all, <Alt><L><F> (FFT does not understand layers);
4) Run FFT RGB;
5) Clone out stars in the Red Channel;
6) Select all channels again (easy to forget this bit), and run IFFT RGB;
7) Slide this layer on top of the original image (with <Shift> pressed, to align);
8) Set this new layer's mode to Luminosity.

Rô

In order to do this correctly, you really have to correct ALL THREE CHANNELS. And, there can be a different pattern in each....... If you don't do this to all of the channels, your colors will be screwy -- and will retain the golf ball pattern.The theory is solid, OK. But in practice you'll be doing more than three times as much work (including channel separation and recombination) and the difference in the final result jsut isn't worth the trouble.

I did it and, in fact, I found that the Luminosity way gave a slightly better looking result (but then again, I may be biased because I expected it to)

My litte theory - The eye responds much better to luminosity than to colours (JPEG compression reserves 4 times more space for Luminosity information). If you do FFT separately in each channel then you run the risk of introducing Luiminosity artifacts that weren't in the original

Rô

:scared:You can get pattern noise in any of the channels, especially the blue channel since it has a higher gain setting due to the lower sensitivity of a CCD or CMOS chip. In fact, you probably will notice that different channels have different Nyquist limits because of the interpolation in the Bayer pattern on the sensor.

Your technique will leave behind pattern noise that originates in a given channel (although since the Luminosity equation weights 60% for green, most of the correction will take place in the green channel, but only about 16% in the blue channel).

Furthermore, it won't work with a scanned color halftone.

Look, the whole reason you're even considering processing only one channel is because of the hack that stores the phase information in the color channels -- there really is no place to store the complex FFT information within the image itself. Fovea gets around this by storing high precision data in a buffer on disk. And I'm not even addressing the color problem -- I tell people to do one channel at a time. Ideally, the RGB FFT code should only work in 16-bits because of the extra precision.

It is a fact, however, that the Power Spectra of the three channels are different, that the PSF (Point Spread Functions) of the different wavelengths through your optics can be different, and that trying a one-size-fits-all approach is fundamentally flawed.

That it works in this case is fine, but only processing luminance (or brightness or even the K channel - I don't care which) leaves color artifacts behind. I care about the extra bits in the image, both from the point of view of RAW Camera Workflow (extra bits means better definition, color constancy, etc.) and Science (quantitative image analysis).

To say that the luminance can be affected by removing a noise pattern in a channel is disingenuous. Of course it can, especially if a pattern is being removed. If you don't mess with the DC term (the center of the cross), the overall luminance will not be affected.

So, I think that for now this workflow will work, but it has serious limits. Once we have a better method for dealing with color everyone will benefit.

jcr6, I of course agree with everything that you have written here (and, yes I do care about blue channel noise - I'm a very caring person) however I had understood that you would like to get some feedback from your photo-retouching "guinea-pigs". So...

- The problem that we have to deal with here, and in various other threads, is not channel noise but instead the interference of the texture of the paper used for the original prints when these are scanned. (As Camaraken pointed out, this is a problem only for scanning)
- In medical / scientific / astronomic images the attention to individual channels may be fundamentel, for photos to be viewed by human eyes the colour information is only secondary. (vide JPEG, colour TV..)

You had asked earlier about which tools would be useful for restorers / retouchers - my first thoughts would be: an easy-to-use FFT filter (because this texture problem comes up very often) and the deconvolution - focus filter. But as very few folks around here are maths geeks, the most important part would be a friendly user interface.

Rô

I guess I am a math geek then. :)

2 weeks ago I kuldnt spel injeneer. Now I are 1.

You're right that in this case, there does not appear to be a color refringence problem at this scale, so the luminance trick is a good one.

It turns out that patterns come from a number of sources, including your camera (and scanner!) chip. So how do we solve the larger problem?

First my apologies to Camaraken for the hi-jack. Seems like everytime FFT comes up there's a lot to talk about.

A question for Chris..
I've seen in other places that the FFT can only be applied when the image is exactly sized to multiples of two (as in FoveaPro, too). However, the Alex Chirakov version doesn't have that restriction. Is he being fiendishly clever - or is he cheating??

Rô

Sorry, Cameraken -- we're just having too much fun at your expense

The first Fourier transforms were DFT's - Discrete Fourier Transforms and they would work with any size data set. They were also slow. Then along came the FFT, the Fast Fourier Transform that relied upon a major simplification in the math but also required that the dataset be a power-of-two in size. Then along came a further observation that you could use any prime factor (not just 2), so your dataset could be a multiple of any collection of prime numbers. (Effectively each of these prime stages is a DFT -- larger ones are very slow.)

FFTW and a number of other algorithms use prime factorization and Fourier decomposition in order to achieve speed. If your image size is a nice set of multiples (2's, 3's, 5's, ...) the code will run very fast. If your image is prime in both dimensions or a multiple of large prime numbers, prepare yourself for a long wait.

There are number of other solutions for mean padding, zero padding, sine weighted interpolation, etc. for inserting a small image into a larger one that is a power-of-two in order to take benefit of the power-of-two performance speed up. My FFT is actually a split radix 2,4,8 and will run very fast on both Mac and PC hardware. For 16-bit images it even uses double precision. And, finally, I don't have to license it from anybody and it doesn't fall under the GNU/GPL license. There are some that do have restrictions. I hope that RGB FFT isn't one of those.

Ultimately, I was lazy when I chose the power-of-two requirement. I didn't want to deal with the arbitrary size where 4097 (17x241) might be very slow and 4096 (2^12) would be very fast. Also, in an odd-width FFT, it isn't exactly clear which position the DC term will be placed in. So, I've got a lot of issues.

There is a lot of history for dealing with power-of-two dimensions, so I chose the more conservative route. (Like I said, I'm a LAZY programmer.)

-Chris

Thanks Cameraken and Ro. Suspected it was some sort of compression system, but didn't know which, shouldn't have any problems now.

Spoke too fast, went to the site, and for some reason had trouble downloading, guess I'll try again later.

Wonder why they used such an obscure compression system to compress such a useful tool in.

Thanks Chris, a very clear explication.

I tried the Alex Chirakov filter on a 1024*2048 canvas filled with noise, and a 1023*2047 one too.

Didn't take any longer, but the result was quite different - the first didn't have any central lines at all, but the second did have strong lines.

Rô

ByRo and jcr6
No need to apologise. You are very welcome. Although I must admit you are starting to go over my head a bit.
As I mentioned in an earlier post All I look for is a tool that works and clear instructions on how to use it.

My problems started when I upgraded from the RGB > HSL method (which worked) to the “new” method.

byRo has now provided clear instructions and I think I’m happy again.

I have (Hopefully) taken most of the comment/problems and condensed them to a mini tutorial.
Please let me know what you think of my next posting


Gary
Rar files are very common. In fact they can have a better compression rate than zip files and are very often accompanied with a recovery record which can help repair a corrupted file. I would keep Winrar. You will need it again.
I have had a browser pointed at their web site all night without problem. If you’re having trouble I have added my AIM to my profile. Let me know.

Ken

Texture Removal
How to remove the paper pattern from a scanned image

Using Alex Chirakov filter RGB FFT

The Filter may be downloaded Here
http://www.pages.drexel.edu/~avc25/archive/FFT_RGB_PlugIns_13April_2005.rar

You will need WinRar to open the compressed ".rar" file
It's shareware, but doesn't stop working after the time limit
Download Winrar Here
http://www.rarlab.com/download.htm

When you've got it open in WinRar, open the "bin" folder and extract the two ".8bf" filters
to your PS filters folder (typically C:\Program Files\Adobe\Photoshop 7.0\Plug-Ins\Filters\)

Restart Photoshop and FFT RGB, and IFFT RGB should appear in the Filters list under the category "Fourier Transform"

That’s it for the Install - Now For its Use



1) Duplicate original image, right click on title bar and click Duplicate (that's a new image, not just a layer):
2) On the new image, get Luminosity (New Layer (<Ctrl><J>), Edit>Fill - 50% grey, color, 100%.);
3) Flatten all, <Alt><L><F> (FFT does not understand layers);
4) Run FFT RGB;
5) Clone out stars in the Red Channel;
6) Select all channels again (easy to forget this bit), and run IFFT RGB;
7) Slide this layer on top of the original image (with <Shift> pressed, to align);
8) Set this new layer's mode to Luminosity.

That’s It.

Follow these steps carefully and they become easy after a couple of times
If you are not sure what to clone out then follow the steps but just clone out some of the stars
You can always go back to your luminosity image and clone some more out to build up a stack of layers above the original. Then choose which to keep or Discard

Points to watch
Step 2) colour is set in the edit > Fill box under Blending
Step 5) Don’t touch the big star in the centre

The attached picture numbers correspond to the step numbers

Continued 1

Continued 2

Nice work, Ken. :bigthmb:
Like I say (or maybe it was Doug) - the best way to learn something is to write a tutorial about it.

Rô

Mmmm. I'm finding with the original posted image that I'm getting texture showing thru from the base layer. Luminosity looked pretty clean. Is the texture too strong or something else I can do?

Dave

Hi Ken, still having problems getting Winrar to download. Can get the home page OK, download page OK, but can't get the Winrar file to download. Browser just times out. Have tried using both Firefox and IE.

Gary
Email me camerashop@aol.com
I'll send you the extractec filters
Ken

Hi,

Though the technicalities of FFT is beyond my comprehension, I would like to mention two softwares which I found useful for editing out the unwanted patterns/textures; Astra Image and ImageJ. FFT editing can done only in grayscale mode. The interface is similar to what Cameraken has attached above.

Two samples of fft edited picture is also being attached. The first one has been done in AstraImage with plain FFT editing. The second, done in ImageJ has gone through adjusting of Brightness/Contrast and applying of Median filter at a setting of 2.

--
Krishna

Duv
I agree with you I can’t quite get results as good as jcr6. Perhaps this is the difference between 0$ and 799$
As I said right at the start I thought jcr6 provided the best results
Floras has obviously been manipulated so its hard to compare.

Perhaps someone will have the time to compare FFT RGB with FoveaPro FFT
We may have to rely on byRo and jcr6 for the answers.

As I pointed out this picture is a tiny portion of a much larger image and it was given to me rolled up. I suppose that an invisible crease or stretch in the paper could very easily spoil the mathematics of removing a fixed pattern.

We used to mount a lot of our studio photographs using Ademco dry mounting tissue and an Ademco press. We used to use a tacking iron to tack the photo into place before placing it in the press. I am sure that this process would now cause a problem for FFT. As there will be parts of the print with a slightly different texture


Ken

Rô:

1023 (presumably the horizontal direction) is 3 x 11 x 31, but that would run at nearly full speed since a whole line should fit in the L1 cache on your computer. 2047 is 23 x 89, but there is already a large delay in vertical accesses through the image, so you might not see a delay that is significantly worse than memory accesses already are. (Isn't caching fun!) Perhaps we should do benchmarks and compare.

Low Pass and High Pass Filters

I need to read Alex's document, but here are a couple of quick tricks you can try:

1) After performing the FFT, make a ROUND selection starting at the center.
2) Feather the selection. (try it with a large number and with a small number)
3) Press the Delete key. (This will make a high pass filter because we've just deleted the low frequencies)
4) Perform the inverse FFT

-or-

1) as before
2) as before (you might try a larger feather radius for this test)
3) Select Inverse (now the high frequencies are selected, not the lows in the center)
4) Press the Delete key. (This will make a low pass filter because we've just wiped out the high frequencies.)
5) Perform the inverse FFT

Notes: You can also try going into the QuickMask and making a radial gradient from the center as a method of proportionately selecting frequencies. If you have one that goes from 0 (not selected) in the center to 255 (fully selected) at the outer edge, you've created something very much like an "Ideal Inverse" and that can be useful for contrast adjustment.

You might also try using the Adjust->Levels function on a selection to increase/decrease the relative strength of a selection. By using Delete or Levels, you only affect the magnitude of a frequency. I would recommend AGAINST using the clone tool because then you're remapping stuff from another frequency and probably making extra junk in your image.

Time to read Alex's notes...

Yup.. He's using FFTW. There are license issues with that. I can't sell a product based on it. It is, however, extremely fast even with non-power-of-two dimensions.

Also, because the channels are only 8-bit (unless you're specifically choosing 16-bit) your image will get noiser just from the FFT->IFFT transform. Try it.

One of the things that we're going to have to decide here is what should be in a package that does FFTs. I don't want you guys to be paying $800 for something that you're going to use maybe 5 filters out of 177. That isn't cool. I would rather wrap some nice UI around the kinds of functions that you will do and make it part of Optipix ?4? ($150, but *discounted* to all of you.)

I do have ideas along those lines, but am reluctant to share them yet because they will influence your thinking and I'd like to see what y'all come up with.

I will also provide some FoveaPro serial numbers to this group because we cannot get very far in the discussion once your 3-week demo period has run out.

I would recommend AGAINST using the clone tool because then you're remapping stuff from another frequency and probably making extra junk in your image.This part always had me a bit worried, I've always done it this way, but I'm not easy about it.

I did think once that I should fill with black, then I thunk again that this would be creating new noise - seeing as the original un-textured image would not have little black spots all over the FFT image. Maybe 50% grey? Dunno. In the end cloning (with blending set to Darken) seems the easiest way out.

In practical terms, again, FFT won't usually take out all the texture, and as Camaraken pointed out a little random fluctuation could throw off the FFT completely. So, after going through FFT an image will almost certainly need some more touching up.

What I have recommended has been to take out the worst of the texture with FFT and then use some more conventional techniques (as beautifully explained in Flora's tutorial (http://retouchpro.com/tutorials/?m=show&id=140)) to finish up.

- Didn't know that 1023 factored easily! Oops!! :grin:
- I had tried manipulating the FFT space before, but always ended up with a semi-transparent gooey mess. Will try again.
- Is that really a ROUND selection? I had imagined that it would have to be oval, in the proportions of the canvas.

Rô
PS Now you've put up a photo, people are going to think we're brothers!

Black means zero -- that there is no power to that frequency or that that particular sine wave should not be present. You should erase to black. 50% gray would be a pretty significant amplitude for that frequency. You'd essentially be ADDING a pattern.

Since I'm a mac person, I haven't tried Alex's plugins. I presume that they don't work in 16-bits? That's unfortunate because you loose a lot of (useful/important) precision by only working in 8-.

One of the reasons that you can get into trouble in Fourier space is just that gooey mess you've been talking about. The ONLY safe operation that you can perform by hand on a power spectrum is to change the amplitude (AND NOT THE PHASE) of a frequency. This means lighten or darken. I suspect that a better workflow would be:

1) Do the FFT
2) Go into QuickMask
3) Mark the spikes (stars, whatever you call them) with a paintbrush in the mask -- use a fairly large brush, one that is big enough to completely remove the spike and a little bit of the neighborhood. Also use a brush with soft edges. A hard edge will cause ringing artifacts.
4) exit QuickMask
5) Use Levels to reduce the value to black of the spikes. This will preserve the color information (e.g. the Phase)
6) Do the iFFT

-Chris

P.S. We have a lot of bare forehead between us. -- Should I make my image be B&W?

Krisna
Thanks for the suggestions. It took some finding but I found them
Astra Image
This is available here
http://www.phasespace.com.au/download.htm
This Program can be used Free of charge but with save disabled until you have paid $AU49.95 for it

The next Program looks much more promising.
Image J It is part of The Image Processing Toolkit
Available Here for Free
http://rsb.info.nih.gov/ij/download.html
ImageJ runs on Linux, Mac OS 9, Mac OS X and Windows
The Docs are here
http://rsb.info.nih.gov/ij/docs/
And the bit about FFT is here
http://rsb.info.nih.gov/ij/docs/menus/process.html#fft

It is Not a plugin but a complete program

Just one problem Krishna I can’t get it to work
I loaded my image
Process > FFT > FFT
Painted out the stars with the Paintbrush tool in Black
Process > FFT > InverseFFT

I suppose I could have a Bad copy but the results came back exactly the same as they went in.

Krishna. Does that sound OK.
If it does I’ll try downloading it again

Ken

Thanks for the suggestions. It took some finding but I found them
Astra Image
Ken
I find this software extremely easy to edit the FFT. Moreover the algorithms this programme uses for re-focusing blurred pictures works excellent, sometimes.


Just one problem Krishna I can’t get it to work
I loaded my image
Process > FFT > FFT
Painted out the stars with the Paintbrush tool in Black
Process > FFT > InverseFFT

I suppose I could have a Bad copy but the results came back exactly the same as they went in.

Krishna. Does that sound OK.
If it does I’ll try downloading it again

Ken
Ken, I am surprised at this result. First I thought may be the FFT is not working because of you doing it in RGB mode. So far I have been doing it in grayscale mode. Today, thanks to you, I tried on the colour version of the figure and it worked. The method you used is correct but I am unable to say what is going wrong. Could you check the version of Java running on your machine?

--
thanks
Krishna

Black means zero -- that there is no power to that frequency or that that particular sine wave should not be present. You should erase to black. 50% gray would be a pretty significant amplitude for that frequency. You'd essentially be ADDING a pattern.


I made the attached on Friday and discounted it because of the banding around the edges but given the recent discussions concerning cloning, erasing to black, et al, maybe there's some value. Apart from the outside banding the image to me looks as good or better than Chris's.
All I did was use the Lasso around each of the "stars", deleted, then ran Ifft.
Is there a simple reason to explain the perimeter banding?

Dave

All I did was use the Lasso around each of the "stars", deleted, then ran Ifft.
Dave, when you say 'delete' what do you mean exactly?

Duv: The problem with the lasso method is that you have a sharp cutoff of where there is data to where there isn't. If you feathered your selection (by, say 2 pixels) before you deleted, and made the selection correspondingly larger, I'd say you've got a good method.

That problem you're seeing is well known. Very well known. This is why in mine when people provide pass masks (essentially a quickmask), we "suggest" that they blur them first. This smooths out the step function in frequency space, which in turn prevents ringing.

This is also why I suggested painting in the Quickmask with a soft brush -- you get soft edges to the holes in the frequency map.

Krishna

I uninstalled ij134-jdk15-setup.exe and downloaded ij133-setup.exe now its working fine.
Astral Image needs a greyscale image but image J works in full colour.
Image J will remain on my PC as a quick easy option
Thanks again for the suggestion.
There also appears to be a lot of other useful tools included which I’ll look at later.

Jcr6. You should look at image J. It may be of interest (and it works on a mac as its Java)

Byro
Image J paints out the stars in Black
Astral Image darkens them
Jcr6 recommends Black
It looks like Darker or Black and not cloning is the correct method

Another interesting point
Image J – when I give it my sample image (which is 322 X 442 pixels)
The FFT is 512 x 512 so it’s automatically taken it to a square power of 2

Try This
Image J
Load picture
Process > FFT >FFT
Now before painting And with FFT selected
Process > Enhance Contrast > Saturated Pixels 1%
Good Eh!
Now you see stars that were not visible before
Paint out all the stars except the big one in the middle
Process > FFT > InverseFFT

Ok the picture still isn’t perfect But I believe this is the best this version of FFT will do.
If anybody has got better then I think they have done further manipulation.

Does anyone want to discuss which version of FFT is best?
Byro. Is Alex Chirakov FFT version the best? Or is it the only one you found?

These pictures are a straight before and after with no additional manipulation

Ken

Ken, I still am seeing residual golfballs but not sure why cause I used a similar method. Thanks to Chris's suggestion, I 2 pixeled my Lasso and got these results. Still a bit of "Ringing" at top left but otherwise I'm a pretty happy camper. This was using FFT RGB. Still haven't figured out Chris's method. Well, going to work on some other texture problems.

Caitlin, sorry, when I selected a "star" I just hit the delete button and moved to the next.

Cheers
Dave

Been away a few days and missed vital information about FFT .... Gosh I have a lot to catch up now!!! :dizzy: :dizzy:

Floras has obviously been manipulated so its hard to compare. ... If for 'manipulated' you intend run through FFT/IFFT ... yes .. but no other kind of 'manipulation was done in the middle (grey) picture attached to my previous post.
I've only used the 'old' HSB Alex Chirokov FFT plug-in for Photoshop to get that result .... for what I can see it has become 'old fashioned' already :D but, while I read all this new informations, here is what my HSB channels look like ...

First I 'healed' out the stars in the Blue Channel (figure1), then in the Green Channel (figure 2) and finally I 'cleaned' the 'composite' RGB (figure 3).

One last thing .... I found that the 'banding around the edges' appears whenever the the cross' arms are involved in the 'cleaning' ...

The fast Fourier transform (FFT) is a discrete Fourier transform algorithm which reduces the number of computations needed for N points From 2N^2 to 2NlgN…….
Bla Bla Bla.
Our tests performed on on a variety of platforms, show that FFTW's performance is typically superior to that of other publicly available FFT software, and is even competitive with vendor-tuned codes. In contrast to vendor-tuned codes, however, FFTW'………..
Bla Bla Bla.
Hence the name, "FFTW," which stands for the somewhat whimsical title of "Fastest Fourier Transform in the West."
http://www.fftw.org/

OK FFTW is meant to be the best so lets see if we can improve on my last post.

Duv
Your first post was better. We’re going backwards. Have you upgraded to FFT RGB recently? You have missed a couple of stars on the horizontal line but I’m beginning to think there is something fundamentally wrong with byro’s steps. And which I put in my mini tutorial.

Using Alex Chirokov FFT RGB
I very carefully painted out all the stars with a soft brush on a layer mask, changed it back to a selection and used levels to darken to black. The results were not as good as I just got from Image J.
As I said at the beginning my problems started when I ‘Upgraded’ from FFT HSL to FFT RGB.

Flora
Hi, and my apologies. In your picture you had removed the stains etc so I assumed you may have cleaned it further.

If that’s the case then We Are doing something fundamentally wrong Or FFT RGB is not working as well as FFT HSL.

Ken

FFTs have complex floating point values at every point. It is a MAJOR HACK to try to take 8-bytes of information and encode it into 3. A HUGE loss of information. There is also a 180° symmetry between the top and the bottom of the image, post transform, so you will have funky results if you map out a different set of frequencies on the top than on the bottom. One solution is to copy the layer, rotate it 180°, keep the darker pixels between the layers, then flatten.

Notice how the workflow keeps getting more complex?

I suspect that the RGB encoded version is worse than the HSL encoded version. For one reason, he should have used R & B, not R & G because most of the Luminance information is also stored in G.

He should also have done a logarithmic µ-law encoding on Luminance, because that way you'd see more of the rays coming out from the stars and be able to do more accurate correction. Low intensity values will be overrepresented and high intensity values will have big truncation errors.

#1 - Lobby him for a 16-bit version of the plugin. This will solve most of your woes.

#2 - If your stars are white on a black field, you really need to erase to black and perform the anti-aliasing (feathering on a selection or a soft black brush).

Yes, I know all about Image-J. Your tax dollars at work. :( Prior to that, Wayne Rasband was working on NIH-Image, which had a bad combination of poor science and being free (he's a government employee). Thus, people used it and had no reason to pay for a *real* package that had the requirement of using good science. It also made it really difficult to compete in the early 90's for the low end of the market. Image-J has just been a sport since then. If you can fit it into you workflow, go for it. It is worth exactly what you paid for it. (If you don't consider that your tax money has been spent driving little guys like me out of business.)</rant>

FFTW is just another implementation. Whose implementation is used is largely irrelevant as far as the quality of the result is concerned.

If you look at the attachments first, you'll think that the first should be in Doug's Cloud thread and the second is a very uninspired art work.. read on...

My final year project tutor taught me that when you want to discover something, devise an experiment - so this is what I did.

1) Take an "average" photo (Dunno what is average, but the golf balls ain' t);
2) Separate out Luminosity;
3) Expand canvas to some size multiple of two, fill in with 50% grey ;
4) Run through FFT, then imediately return through inverse FFT;
5) Crop back to the original size;
6) Compare with the original.

The noisy image posted is an amplified (Levels 0 - 8) picture of the difference using the Alex Chirakov filter (average difference 3.5), the clean "art" is the Fovea filter (average difference 0.3).

There was no significant difference between the RGB and HSB flavours of the Chirakov filter.

Conclusions:
-The Chirakov version does introduce a considerable amount of noise, whereas the Fovea process does not introduce any. (There is a 1 pixel difference, but this is uniform and to me that's not noise).
- There's no difference between the two Chirakov filters, so you can use the easier (RGB) one without problems.

Rô
PS Chris - keep it coloured, otherwise the folks will think we're twins!

You both look like you need to crawl out of your cubby holes and hit the beach for a while. Ro, have you taken my advice yet?

Cheers
Dave

Ro, have you taken my advice yet?1,495Km to go - seems like I can already hear the waves ;) ;)

Rô

(Actually, this was a break for me -- I'm supposed to be writing code.)

The test was a good idea, Rô.

Later. Since we're not near the ocean, it's time to go to the YMCA.

Wow! That’s heavy stuff. I feel like I need the beach after trying to understand that lot.
I am not a professional retoucher. I don’t have hundreds of textures to remove. I hit this problem once or twice a year and just want to get the best I can from an odd picture.

Byro
Thanks for doing that comparison I think you are saying
FFT RGB is as good as FFT HSL But FFT Fovea is Better.
But if I’ve read correctly you are comparing the loss between the transfer
What interests me is the end results and how to achieve it. So what probably interests me more is “What do I do to the FFT to improve the Picture?”

The initial picture I supplied is a very poor example to use as a ‘Test picture’
What do you think of jcr6 cat picture – is that a good test picture?

Jcr6
I’ve read chapter 4 and pages 9 and 10 of the pdf.

Filter > IP*Fourier > FFT(Forward)
Filter > IP*Fourier > FFT(Inverse) OR Apply Filter and FFTInverse
The picture comes back different (darker the grey padding goes black)
Could you please explain this?

Also could you please clarify that FoveaPro should be working on a Luminocity Image?
And if so then do you agree that byros method is OK.

1) Duplicate original image, right click on title bar and click Duplicate (that's a new image, not just a layer):
2) Set background colour to grey 127,127,127 (for Padding)
3) Image > Canvas Size > 512,512 in Pixels (In this case - square with dimension equal to an exact power of two)
4) On the new image, get Luminosity (New Layer (<Ctrl><J>), Edit>Fill - 50% grey, color, 100%.);
5) Flatten all, <Alt><L><F> (FFT does not understand layers);
6) Filter > IP*Fourier > FFT(Forward)
7) Paint out the Stars in white with a soft brush
8) Filter > IP*Fourier > Apply Filter and FFTInverse

Does that sound OK?
My suggestion earlier about adjusting brightness and contrast to ‘see the stars easier’
This does not seem to spoil the final image. What do you think?


Flora.
You did ‘cheat’ a little. You added the extra step.
First I 'healed' out the stars in the Blue Channel (figure1), then in the Green Channel (figure 2) and finally I 'cleaned' the 'composite' RGB (figure 3).

'cleaned' the 'composite' RGB (figure 3). Is not in the manual
http://www.retouchpro.com/forums/showpost.php?p=76559&postcount=6
Perhaps you could explain this step then we can find out how to apply.

Ken

Hi everybody ...

Wow! That’s heavy stuff. You can say that again ... I read all the posts ... understood that I don't understand ... :eek: :o: :eek: .... considered taking up knitting as a hobby ... Flora.
You did ‘cheat’ a little. You added the extra step.
First I 'healed' out the stars in the Blue Channel (figure1), then in the Green Channel (figure 2) and finally I 'cleaned' the 'composite' RGB (figure 3).
'cleaned' the 'composite' RGB (figure 3). Is not in the manual
http://www.retouchpro.com/forums/showpost.php?p=76559&postcount=6
Perhaps you could explain this step then we can find out how to apply.I was born a real rebel!!! :devil: :devil: I know the 'mathematicians' here would gladly burn me at the stake after this, but by 'cleaning' the composite RGB I meant just that .... after cloning/healing the stars from the two 'recomended' Channels, the composite RGB still looked a bit 'untidy' ... so .... I cleaned it before performing the IFFT... :D ;) :D

Im going to assume that FFT stands for Fast Fourier Transform. IS this yet another helpful and FREE plugin?
Pete

Just wanted to say this indepth thread made me go back and look at FFT, I had come across this filter in the past but misunderstood it, I had done the classic FFT then IFFT and see no result (of course..doh!) now reading this and going through old threads I have got it working. I still find it easier to use HSL as it shows the issue up clearer I think, I had some good success carefully cloning the vertical and horizontal lines which got rid of small highlights in that area that caused problems in the images.

So thanks for thrashing this subject again, this time it stuck for me :)

Hi Pete,
Im going to assume that FFT stands for Fast Fourier Transform. ... Yep! You assumed right!!
IS this yet another helpful and FREE plugin? It can perform real miracles, but it can also be extremely frustrating .... It can come free ( here (http://www.pages.drexel.edu/~avc25/archive.htm) ) .. or for different fees ... you'll find the links scattered all over this Thread.

It's not much... but I hope this helps....

Fourier image processing is one of those "Magic Bullets" that is almost entirely useless except for those rare (but highly impressive) occassions where they are de rigueur.

Despite the shortcomings of the filter mentioned, I wonder would Cameraken, Flora, or someone else here like to put all this together as a tutorial in the tutorial section? I know that the steps are listed out in several threads already, but having it all in one spot would be good - and I thought the images in Camerakens step by step were very clear and would help someone coming to the process new. In fact I think just taking those posts and putting them in the tut section would be great.

(As an aside I tried using Ro's step by step previously, but without screenshots it mean I became very frustrated when it didn't work. It was only a month later when I tried it on another image I realised it was because the photo I was working on did not have a suitable pattern therefore did not have any 'stars'.)

And just to add to caitlen's suggestion, it would be great if their was a Macintosh tutorial as well. I did see that there are a couple of packages for the Mac, but I'm not sure if there are any tutorials on those.

If nobody beats me to it, I'll put up a tutorial this weekend.
That is, if you can stand me going on and on and on about FFT just a bit more!!

Rô

Thanks byRo,
I look forward to being able to get to grips with this technique. I may only see a couple of photos a year that fall into this category but when you have them sitting on your monitor staring at you, it's good to know there is a solution.

The following attachment was presented to me yesterday. I don't know if it's a good candidate for FFT or not but it would be worth a try.

Thanks for your comments Caitlin.

I started this thread because I was having so much trouble, especially with the newer FFT RGB for which the tutorials are very scarce.

I wrote that tutorial to help everyone else struggling with this new version

I have learnt a lot from this thread and I thank everyone so much for their contributions so far.
As you mentioned FFT is not perfect for all images but as an initial starting point for removing texture IMO there is nothing to beat it.

I hope there is more input regarding FoveaPro as this looks good. But I think we will have to wait for byRo to do this.

I would be happy to re-write the tutorial and move it to the tutorial section. And if any mac users would like to volunteer their services we could perhaps do a version for deadants. But I don’t think there is a mac FFT Alex-Chirokov available.
However as Byro has offered to do this we may be better leaving it to the experts.

Off Topic
The original picture I posted was from a much larger picture. By coincidence I have just been asked to do another so I thought I would show you where it came from.

There may be a copyright issue with posting this so I’ve blurred it but it will give the general idea.

This picture is 24” x 8” and the original photo I posted was from part of one of these – Hardly surprising that texture became a problem.
I have restored a bit. few more hours to go.

I use ExclaimPT Tutorial to Stitch the scans which works great.


Ken

For whoever is planning to do the FFT tutorial, I happened upon this one - Rather nicely done - a shame it's in Greek!

FFT tutorial (http://babelfish.altavista.com/babelfish/trurl_pagecontent?url=http%3A%2F%2Fwww.dpgr.gr%2Findex.php%3Fpage%3DFourierPS&lp=el_en) (Or in this case babelfish English) The original is here: http://www.dpgr.gr/index.php?page=FourierPS

Well found Caitlin.

This is a tutorial on FFT RGB so it is the version we have been talking about here.
Babelfish did a pretty good job of translating this.

This is what I managed to understand from this site

1) Again another confirmation that the stars should be painted out in black
2) They are using a square picture as an example but do not seem to insist on square
3) They use blending mode set to colour to put the colour back.
4) They are using gaussian blur on the final image to clean up further.


Does anyone speak Greek


Ken

Some speak Greek, others speak Geek. Unfortunately, I speak neither.

Dave

Duv
:lol: :lol: :lol:

It would make more sense to me in Double Dutch

Ken

Fourier will be gnw'rjmi significance. ..took the words right out of my mouth!!

1) Again another confirmation that the stars should be painted out in blackYes, but he's painting black in all the channels, not just the Red one;

2) They are using a square picture as an example but do not seem to insist on squareThey're using the Chirakov filter so it can be any size and shape;

4) They are using gaussian blur on the final image to clean up further.I think maybe he's blurring the original "coloured" layer and not the FFT luminosity layer - which is a good tip that we hadn't mentioned before.

Caitlin, I got the hint - now I going to write it in portuguese, OK?

Rô
Yeah Duv, I know........

For whoever is planning to do the FFT tutorial, I happened upon this one - Rather nicely done - a shame it's in Greek!

FFT tutorial (http://babelfish.altavista.com/babelfish/trurl_pagecontent?url=http%3A%2F%2Fwww.dpgr.gr%2Findex.php%3Fpage%3DFourierPS&lp=el_en) (Or in this case babelfish English) The original is here: http://www.dpgr.gr/index.php?page=FourierPS

Well, being greek and thus able to read the original of that post, I can tell you 1 thing for certain.. The person writing the article is clear in that he does NOT want to create a tutorial, but rather he just wants to proove a point, that being that everything is just plain-old maths. The steps mentioned are as Cameraken said, but he also mentiones that one should always try to use a "circular pattern" symetric to the center star when deleting spikes.

"Again another confirmation that the stars should be painted out in black"
Well, actually he says that one should "mask-out, filter-out, delete or whatever" the white stars, claiming it's just a matter of terminology and does not actually make much of a difference... not very precise I'd say :)

If anyone is interested, I could write an exact translation of that article, but I seriously doubt that it would shed any light to the subject. the posts here are much more precise and helpfull than anything I have found on there (and FFT is the one reason I keep coming back to retouchpro over and over again)

Thnx...
Jocker

Hi Jocker,

Welcome to RP! :pleased:

We do hope you'll keep coming back ... and, boy, are we glad you shed some light on this .... :pleased: :D :pleased:

As you can see Rô had nearly finished translating the tutorial...even though, I think he was struggling a bit to stay as close as possible to the original text here... Originally Posted by Greek FFT
Fourier will be gnw'rjmi significance...took the words right out of my mouth!! :lmao: :lmao: :lmao:

Thank you very much for your help!

jocker, :bigthmb: welcome to RetouchPRO!! :bigthmb:

Thank you very much for the help.
:rolleyes: Promise I'll post the tutorial this weekend, promise :rolleyes:

Rô

Welcome Jocker and thanks for your input.
‘Everything is just plain-old maths’
When you scan a picture it just becomes a set of numbers, which can be changed or manipulated. The Alex Chirakov FFT RGB is just a calculation on these numbers.
The whole thing could be done in Excel or Visual Basic in fact I have a visual basic program for removing noise from sound, which uses the same calculation.

The point about symmetry is a good one and makes sense with the maths.

I don’t think it is necessary to translate the whole thing but can you help with the gaussian blur bit. It sounds a bit like Floras 'cleaned the composite' step. But as byRo says it sounds like they are talking about the colour layer.

Ken

Welcome Jocker and thanks for your input.

I don’t think it is necessary to translate the whole thing but can you help with the gaussian blur bit. It sounds a bit like Floras 'cleaned the composite' step. But as byRo says it sounds like they are talking about the colour layer.

Ken

ok, let's try a word-by-word translation of the whole thing, so that noone thinks that he's actually missing some intresting point from that article because it's in greek... ;)

----------------------------
Translating http://www.dpgr.gr/index.php?page=FourierPS
----------------------------

Let's see how a fourier transformation of our ewample looks.
Since the information is pictured through the frequency spectrum, and the noise is periodical, like magic, all the noise is shown on specific places, much easier to process. (we use the filter Fourier Transform->FFT):
[picture of fourier spectrum here]
Doesnt it look odd that from this picture we can go back to the original? Notice how symmetric to the main star the bright points are. These are our noise. So what do we do? We delete, mask-out, filter-out, it's just a matter of terminology
Using paintbrush we blank-out the aforementioned points, as in the picture bellow. The process was delibaretly done roughly so as to show that even this way, the method gives very good results.

[picture of EDITED fourier spectrum here]

Time to go back to the space domain from the frequency domain... (that's what a mathematician would say), we just apply the inverse filter and go back to the original picture: (Fourier Transform->IFFT)

[grayscale transformed picture here]

Look at how clean the picture looks. The fact that it's grayscale (that's how the filter FFT works, at first it transform it into grayscale and then applies the transformation), wont make it more difficult to us, it's enough that the luminocity is cleared.

We take a copy of the original picture, put it over the final one as a new layer with blending mode set to colour and we apply as much gaussion blur needed to get rid of the noise (No detail is lost, as that is in the underlying layer).
Here is the result:

[final picture here]

and a crop of before and after, blown up by 200%:

[blown up crops here]

Frequency domain transformation requires skills and experience. Good thing that there are various filters and utils that hide these dificulties

The reason for this article was not to suggest that one should do this by hand, but to shed some light into how applying such methods can give very good results.

--------------- End translation -----------------

See ya...
Jocker

Thanks Jocker for taking the time to do that.

Byro was right (as usual) :- ‘gaussion blur the colour Layer as much as needed to get rid of the noise No detail is lost, as that is in the underlying layer.’

That’s worth noting in case the info has come too late for byRo tutorial.

Thanks again Jocker.

Ken

jocker,

This is just great!!! Thank you again for your time and help!!!!! :pleased:

Ken,

... about blurring the 'color' Layer ....
it is right you don't lose details ... but, if to fade the noise you use the Gaussian Blur, careful because the colours tend to 'bleed' into each other so you can get 'noise-free' pink teeth or, if you are working on a portrait, the skin around the edges tends to get the background tinge ...etc. So, in this case, I would rather use the Median Filter as noise remover, as the Median Filter tends to 'recognize and respect' the edges between colours .... :)

This is just great!!! Thank you again for your time and help!!!!! :pleased:



You're welcome.. I've been quietly reading the forum since January, originally trying to find a decent way to remove the honeycomb effect as a favor to my girlfriend. I'm not really into photography, thus have not contributed anything all this time... Glad to be of service since you have all helped us quite a bit.

Jocker

[...So, in this case, I would rather use the Median Filter as noise remover, as the Median Filter tends to 'recognize and respect' the edges between colours .... :)Nice one, Flora :thumbsup:
I'd forgotten that.

I've written the FFT tutorial but the "uploader" isn't cooperating with me this weekend, so I haven't been able to post it yet.

Rô

I have all of Chris's IP plugins showing up in Filters but what are they under in the Plugin's folder?

Dave

Duv
I’m not sure I understand your question.
I assume you have downloaded FoveaPro/FFT

You use
Filter > IP*Fourier > FFT(Forward)
This gives you the FFT

Then you use
Filter > IP*Fourier > Apply Filter and FFT(Inverse)
This gives you the Image back

Hope this helps

Ken

Sorry Ken. Mine was a terrible post. I have all the IP*thisandthat's in Filters and I wish to delete it all. But I can't seem to find the appropriate files 8bf in the Plugin Folder. I see nothing called Fovea, IP or anything that seems to relate.

Cheers
Dave

Uninstall FoveaProFFT

If anyone has installed the trial version of FoveaPro and now wishes to uninstall it

The problem is that there is no uninstall program. Not even for users who have purchased one version and need to uninstall it to upgrade to a newer version.
With hindsight we should have created a restore point before installation that we could now go back to. However with the lack of hindsight the uninstall must be done manually.

Here are my suggestions

You originally downloaded FP3.zip or FP3.sit
These extracted to
PC FoveaPro3 Installer.exe
Tutorial5.pdf
PC Readme.txt
So where ever you downloaded these files originally – these can be deleted.


Now for the installed filters
When you originally installed this it would have installed into a default folder something like this
c:\Program Files\Adobe\Photoshop 7.0\Plug-ins\Filters\

The big problem is that all the FoveaPro filters are now mixed up with your other filters. Fortunately all the filters are dated the same so if you sort the folder by date all the FoveaPro filters will be grouped together and can all be deleted.
The date on the Windows version is 14/4/2003 (Mac may be different)

So here is the Easy way for Windows XP users
Click Start > Search
In the All or Part of Name Box Type 8bf Then click Search
Once the search is complete click the date modified tab and all the FoveaPro filters will be grouped together with the date 14/4/2003
Highlight all of them and delete
That’s it.

If any of you are uneasy about deleting any other filters created on the same day here is a list of the FoveaPro filters that need deleting. There ate 171 of them listed alphabetically.


ABSDIFF.8BF
AdaptEq.8BF
ADD.8BF
AlignW2.8BF
alvlbrgt.8BF
alvlcolr.8BF
alvldark.8BF
AplyCLUT.8BF
ApplyMsk.8BF
ASTMGSZ.8BF
AutoCntr.8BF
BandPass.8BF
BiLevel.8BF
BLEND.8BF
BoolGen.8BF
Britness.8BF
c2g.8BF
calibrat.8BF
Centroid.8BF
ClrPlane.8BF
CMedian.8BF
Colocal.8BF
ColorFlt.8BF
ColorMap.8BF
ColrCube.8BF
colrvalu.8BF
Contour.8BF
Contrast.8BF
ConvolFT.8BF
Convolve.8BF
CountGrd.8BF
CountMrk.8BF
CRange.8BF
CrossCor.8BF
CSpace.8BF
Custom.8BF
Cutoff.8BF
CVE.8BF
darker.8BF
Deconvol.8BF
DeIntL.8bf
Dens_Cal.8BF
divide.8BF
DOG.8BF
DrwCycld.8BF
DrwLinGr.8BF
DrwPntGr.8BF
EdgePres.8BF
edm.8BF
EDMMorph.8BF
ElevProf.8BF
Entropy.8BF
Equalize.8BF
extremum.8BF
Extrude.8BF
FeatAND.8BF
FeatDist.8BF
FeatID.8BF
FeatPlot.8BF
Features.8BF
FillHole.8BF
FillRegn.8BF
Fit_BG.8BF
Flatten.8BF
Focus.8BF
ForwrdFT.8BF
FractalDim.8BF
FrameROI.8BF
FreiChen.8BF
FTProfil.8BF
Fusion.8BF
Gaussian.8BF
GenMask.8BF
Global.8BF
Haralck1.8BF
Haralck2.8BF
Harmonic.8BF
HillDale.8BF
Histogrm.8BF
Hit_Miss.8BF
Hough.8BF
HoughInv.8BF
HSIThrsh.8BF
HVLines.8BF
HybridMd.8BF
IntensP.8BF
InteractiveDeconv.8BF
InversFT.8BF
InvFilt.8BF
IsoLines.8BF
Isometric.8BF
ItMidDis.8BF
Kirsch.8BF
Kuwahara.8BF
Lighter.8BF
Limits.8BF
LineLen.8BF
LineProf.8BF
LocalEq.8BF
LogNewLine.8BF
MagBar.8BF
MakOpaq.8BF
Mask.8BF
MatchHue.8BF
Math.8BF
MeasIcpt.8BF
MeasPwSp.8BF
Median5.8BF
MorphGen.8BF
Multiply.8BF
NborDist.8BF
Norm_RGB.8BF
Olympic.8BF
Orient.8BF
Outline.8BF
Peaks.8BF
PerimvsA.8BF
Phase.8BF
Phong.8BF
Prune.8BF
PtIcept.8BF
PwrSpec.8BF
RadLines.8BF
RadProf.8BF
Random.8BF
range5x5.8BF
Rank.8BF
RankColr.8BF
RankGen.8BF
Recall2.8BF
Reconstr.8BF
Regions.8BF
Register.8BF
relief.8BF
Rem_BG.8BF
RollBall.8BF
Seed_Grw.8BF
Select.8BF
Setup_2.8BF
SetupLog.8BF
SetupRecipeFile.8BF
Shift.8BF
ShowFTVal.8BF
showval.8BF
SigmavsA.8BF
SineFunc.8BF
skel.8BF
SlitIsnd.8BF
SobelDir.8BF
SobelMag.8BF
Stereo.8BF
StochEdg.8BF
Subtract.8BF
SurfStat.8BF
Swap2.8BF
Symmetry.8BF
Tangent.8BF
texture.8BF
Thicken.8BF
Thinning.8BF
Thr_HSI.8BF
Thr_Pct.8BF
Thr_Skel.8BF
Thresh.8BF
ThrshPen.8BF
Tophat.8BF
Trim.8BF
TriStim.8BF
UEP.8BF
Var_Adj.8BF
Watershd.8BF



End of List



Ken

Thank you so much Ken for taking the time. I was getting a little anxious and concerned but everything is back to normal now.

Cheers
Dave

ByRo has now posted his tutorial on FFT RGB which can be found here

http://retouchpro.com/tutorials/?m=show&id=185


Thanks ByRo for a very clear Tutorial.

Mac users can follow along using image-J mentioned in this thread



Ken

Well I have had some interesting results paying with imageJ. It definitely works when you erase the centre star. If you make a small erase of the centre star the image is blurred. The bigger the erased circle, the sharper the image becomes. Be careful not to erase the other stars or the image turns black.

Its brilliant. This has made the process so easy and simple. I tried it with 3 images. Thanks for posting this trick.

--
Krishna

Image J is part of The Image Processing Toolkit
Available Here for Free
http://rsb.info.nih.gov/ij/download.html
ImageJ runs on Linux, Mac OS 9, Mac OS X and Windows
The Docs are here
http://rsb.info.nih.gov/ij/docs/
And the bit about FFT is here
http://rsb.info.nih.gov/ij/docs/menus/process.html#fft

Deadants
Thanks for moving threads. I used to be very confused about using FFT RGB and I thought talking about ImageJ in the FFT RGB Tutorial thread may confuse even more.
Maybe we need an ImageJ FFT Tutorial as well.

I quite like ImageJ. It’s easier to use than FFT RGB. The downside is that being a standalone program and not a plug-in you have to come out of PS to use it. However as this should be the first step it’s not that bad.

I am on a PC but the program should be the same on a mac.

OK now your problem.

Here are the steps.

Open ImageJ
File > Open and load the picture
Process > FFT > FFT
The FFT will now open as in attachment 2
Double click the colour Picker and choose Black as your colour
Double click on the brush and choose a brush size of 10 (on this picture)
Now paint out all the stars except the centre one as in the attached picture 3
Process > FFT > Inverse FFT
Save the results

And that’s it. Your picture should now be texture free and ready to load into PS.

There should be no need for a black layer as If done correctly the picture will not be transparent.

If you need any more help just ask and perhaps post your image a bit bigger.

Ken

Hi Ken,
Sorry about the delay in replying but it was a big weekend :)

I tried again as you suggest by crossing out the outer stars while leaving the center star in tact, but all I get is a black image. I have had good results with the erasing centre star technique. As the same people wrote ImageJ you would think it's got to work the same on both PC and Mac the same way. So I'm scratching my head.

Krishna, did you do the erase centre star technique or the black out the outer stars method? Also are you using a Mac?

Has anyone else with a Mac tried imageJ, if so which method are you using?

Krishna, did you do the erase centre star technique or the black out the outer stars method? Also are you using a Mac?
I used to do the black out outer stars method and it used to give good results. But your method is much easier and it gives better results (it is doing the blacking out in a different way). In the blacking out method, my experience has been that even after completing, there will be a few patterns left out. To remove them I used to slightly blur the image. But with this method the masking is so complete and the work is over in a few seconds.

Has anyone else with a Mac tried imageJ, if so which method are you using?
I have been using ImageJ regularly in Mac and have tried in PC also. In PC, I haven't found any difference except sometimes the system hangs. But that cannot be blamed on ImageJ alone.

--
thanks
Krishna.

Deadants

I tried your method of painting the centre star with white. Painting with white is adding to the FFT. This method does not remove the texture. What it does do is blur the image so that you can’t see the texture.

Painting in black removes from the FFT. If your image is going transparent then you must have removed too much.

Post your image and we can work through the steps;

Ken

Hi ken,
I wasn't filling the cenre with white, I actually deleted it. But I take your point that the image is being blurred. I have tried several times at blacking out the surronding stars in ImageJ on the Mac but the results are disapointing. The IFFT doesn't seem to do anything, it returns a picture that looks the same as the original.

Here is a link to a good sized halftoned image that we may be able to walk through the process.
http://tinyurl.com/dg3ph

I tried the following (see screengrab) and got a sufficiently neat picture. Mid grays get cleared up easily while the pattern on black are persistent.

--
Krishna

Deadants

I have downloaded your picture. It is an image made up entirely of black dots (well crosses) in the white areas and white dots in the dark areas.
If you remove the dots you will remove the entire picture.

FFT is a way of removing Texture. And seeing there is No texture in this photograph I would not even use FFT. However, after saying that the way Krishna has used your method is good.
Yes it is blurring the image but only a little and blurring would be the only way to fill in the dots using any other method.

In photoshop you can achieve the same results with Gaussian blur set at 2 (setting at 3 eliminates even more of the dots but is blurring more)

In my attachment I changed the mode from Indexed to RGB
I used Gaussian blur set at 2 on the face and Gaussian blur set at 3 on the rest.
I think this is slightly better than using ImageJ.

I’ve tried using the same method in FFT RGB and it does not work. So this is specific to ImageJ.


Ken

In my attachment I changed the mode from Indexed to RGB
I used Gaussian blur set at 2 on the face and Gaussian blur set at 3 on the rest.
I think this is slightly better than using ImageJ.

I’ve tried using the same method in FFT RGB and it does not work. So this is specific to ImageJ.

In this case what you say is correct, Ken. But I have come across certain other instances where photos with halftone dots will have to be blurred considerably to get an acceptable picture whereas to the result you get using FFT in ImageJ, you need to add only a slight blur to remove vestiges of pattern.

As you say correctly, both the methods are blurring the image, but may be the algorithms being used (or the methods) might be different and hence the different result.

--
Krishna

Krishna

I am not very familiar with halftoned images. But I don’t think Deadants picture was very representative of what we normally see. You may be right about the way imageJ may blur differently, I don’t know.

If you have a picture where you think imageJ has worked better then please post it.


Ken

Here is one sample Ken. You can downloade it from
http://www.ola.in/tmp/photo2-sample.jpg

After FFT processing the picutre has been blurred slightly.

--
Krishna

PS: This is a picture scanned from a magazine.

Krishna

I’ve downloaded your sample Krishna.
Have you scanned this in?
If you have then are you aware of the de-screening options built into the scanner software. I would have thought that you could have got a better scan than this from a magazine.
Try scanning at a much higher resolution than you need, then drop the resolution in PS.
Also try scanning halftones at a 30 degree angle and then straighten up is PS. This can also help.

Anyway, working with what we have got.

This is a halftoned image with a slight texture from the paper it was scanned
The texture could be removed with FFT but I really don’t think it would help much as by far the biggest problem is the well spaced halftone dots.

A halftoned image has information missing which is lost forever. Filling in the dots can only be a guess based on the surrounding pixels. So whatever method you use the detail can not be increased.

Here is what I did

Opened the Sample image and cropped it back to the original
Changed mode to RGB
Duplicated the background twice
On BG Copy2 (the top one) Filter > Other > Offset Horizontal=2 OK, Layer Opacity 50%
Select All > Copy Merged > Paste
L1 Filter > Noise > Dust and Scratches 3,3 OK, Layer Opacity 80%
I then used brightness/Contrast and upped the contrast +30
Done.

I suppose you could try Polaroid Dust and Scratches or Neat Image but I don’t think you will get much better results.

Krishna. Your results are similar to mine. So unless anyone knows a better way I think a rescan is the only way you will improve on this.

Ken

got rid of the 'golf balls', but still have scan lines. just started playing with this FFT stuff. just a bit fussy. one thing i found is, you dont have to split the channels. you can edit the 'stars' in the color image you get after running FFT. and this isnt the FFT RGB one either. run fft, edit the cross marks and lines except the main middle one and then run ifft on that. seems to work just fine.

Craig

Just wanted to say this indepth thread made me go back and look at FFT, I had come across this filter in the past but misunderstood it, I had done the classic FFT then IFFT and see no result (of course..doh!) now reading this and going through old threads I have got it working. I still find it easier to use HSL as it shows the issue up clearer I think, I had some good success carefully cloning the vertical and horizontal lines which got rid of small highlights in that area that caused problems in the images.

So thanks for thrashing this subject again, this time it stuck for me :)

Having revisited this issue I have a sneaking suspicion that despite (or because of) having both filters I may have been using the wrong one. Hence my HSL comment. The examples I have worked on show the same pattern on red channel using the rgb as is seen on the blue channel using HSL version. Slaps forehead repeatedly. :bigthmb:

Well, this thread is so long it probably doesn't need another tail. However, I keep finding ways to get better results. On a duplicate of this image, I reduced the contrast and ran a Discrete Cosine Filter which did a much better job than any of the FFTs I had. I applied the output to a contrast enhanced version of the original and used a luminosity blend. A slight clean up in Neat Image. Finally a quick trip to LAB to attenuate the bright yellow stains.
Regards, Murray