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How to use Fast Fourier Transform in color photo

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  #1  
Old 01-31-2014, 12:21 AM
adam701 adam701 is offline
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How to use Fast Fourier Transform in color photo

Hi,
I am using PhotoShop CS3 Extended.I installed FFT plug-in and found this tool very useful in reducing grits/pattern from scanned old photos. There is a page in this website that explained how to use FFT. The instruction is clear I am however at a lost as the output of the FFT/IFFT is mono. The steps used in the conversion from b/w to color is less than intuitive. May be it's just me. Sorry being a newbie to FFT. I would appreciate help on how to convert FFT output to color photos. Thanks.
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  #2  
Old 01-31-2014, 12:44 AM
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chillin chillin is offline
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Re: How to use Fast Fourier Transform in color pho

Use Image Analyzer instead.
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Old 01-31-2014, 02:41 AM
arson arson is offline
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Re: How to use Fast Fourier Transform in color pho

You could just set the FFT output layer to luminance above the original layer.
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Old 01-31-2014, 03:10 AM
adam701 adam701 is offline
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Re: How to use Fast Fourier Transform in color pho

I did set the FFT output layer to luminosity. I made sure the original is 8 bit. My question is once the output layer is set to luminosity and dragged on top of the original and then what? Are they supposed to automatically combine? I still see the B/W picture.Nothing happened.
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Old 01-31-2014, 04:19 AM
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Re: How to use Fast Fourier Transform in color pho

Once you have dragged the b&w image created with FFT above your original colour version and set the FFT image to luminosity your colour should be back.

A mistake often made is to forget to flatten your original i.e. the only layer you should see should be labelled Background. Then duplicate and apply FFT, you should end up with a good B&W version (not a fades low opacity version). Once you have this then drag over to the colour image and change blend mode to luminosity
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Old 01-31-2014, 01:11 PM
adam701 adam701 is offline
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Re: How to use Fast Fourier Transform in color pho

"Once you have dragged the b&w image created with FFT above your original colour version and set the FFT image to luminosity your colour should be back.

A mistake often made is to forget to flatten your original i.e. the only layer you should see should be labelled Background. Then duplicate and apply FFT, you should end up with a good B&W version (not a fades low opacity version). Once you have this then drag over to the colour image and change blend mode to luminosity"

Once scanned into PS, the Layer column/flatten image is grey out. In layers dialogue box it stated "Background" and is partially locked.In addition,the blend mode dialogue box and opacity grey out also. The only way trying to flatten the image is to double click the lock then a "Create new layer" dialogue box appears.I can change blend mode to luminosity. And the name is set to "layer 0".Clicked OK. Then I can go to Layer column flatten the image - if that make any sense at all.

The only difference I can find is in the last part in your reply that the new layer(good B/W version)once dragged on top of the original colour image I should change blend mode to luminosity. Again,at this point,the blend mode dialogue box is grey out. The only way to change to luminosity is to do a "Create new layer". That way,the blend mode dialogue box is working and I can change to luminosity.I can also flatten the image. Unfortunately,it didn't make any difference.The B/W did not change to color photo.

The strange thing is,I thought,once an image is flattened with another I should not be able to drag them apart,right? But in this case I can.So it wasn't flattened.

Last edited by adam701; 01-31-2014 at 01:19 PM.
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Old 01-31-2014, 02:31 PM
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Re: How to use Fast Fourier Transform in color pho

When I said flattened this is in case you have other layers in your image. What you should have is just one layer and it should be named Background and have the lock symbol. If it does not then you can use the flatten command to make it so.

Not sure I understand what you are doing so have a look at the attachment. You have to duplicate your colour image and work on the duplicate with the FFT filter then just drag the new B&W from the duplicate (hold down shift while moving from one image to another). With your new layer added just change the blend mode to Luminosity.

If your new layer mode is greyed out then click on the eyeball symbol next to the layer to turn it on

Hope ByRo does not mind me using his image
Attached Images
File Type: jpg FFTLayers.jpg (197.1 KB, 62 views)
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Old 02-01-2014, 02:48 PM
adam701 adam701 is offline
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Re: How to use Fast Fourier Transform in color pho

Many thanks to Tony W' I've since got this going and photos turned into color. May be it's the version of my PS my steps are somewhat different. But it worked in the end.
I've also tried Image Analyzer,thanks to Chllin's head up,and found it to be much more straight forward and the end result is just as good if not better.

Thanks again to all posters who lent a hand to help.
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Old 08-04-2015, 09:19 PM
TONMENn TONMENn is offline
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Re: How to use Fast Fourier Transform in color pho

FFT can be tricky for amateur user that just want to do family photos. I have tried Photoshop plugins, image analyzer, etc. So far the best results I have obtained is with ImageJ, Is a java application that is very forgiving.
You can paint black most of the four quadrants plus the “stars” in the vertical axis and your image will come out in an acceptable quality. Ready for Photoshop CC or any other program.
Usually there is a small banding left that is not noticeable in printed photos or at full screen and can be easily disguised adding 5% noise in Photoshop. Probably is not a “pro” solution but is all about these old pictures for family and friends.
Another point, if you are serious about fixing your old pictures consider Photoshop CC. Is much better and faster that Photoshop elements. It can save you a lot of time. Also consider an ssd drive and a ramdrive utility (you can get one for free) if you have plenty of RAM.
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Old 08-04-2015, 10:06 PM
klev klev is offline
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Re: How to use Fast Fourier Transform in color pho

Quote:
Originally Posted by TONMENn View Post
Usually there is a small banding left that is not noticeable in printed photos or at full screen and can be easily disguised adding 5% noise in Photoshop.
That's an inherent problem in wavelet based methods of dynamic range compression. Implementations of an algorithm like that can sometimes take some small steps to avoid worsening the problem, but it's ultimately going to show up in some images. It's also possible to build in a post processing stage, but that makes the entire thing somewhat less flexible.
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