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Another FFT Question...

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  #1  
Old 04-26-2005, 09:14 PM
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Fizzgiz Fizzgiz is offline
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Exclamation Another FFT Question...

Ok, I have a picture that I'm working on that is a photocopy of a newspaper scan. I have read everything on the FFT filter and have downloaded it. I do not have the HSB/HSL filter for some reason. I see that it would be on my Photoshop disk, and that I have to install it specifically, but I can't seem to find it. I'm not sure if I just haven't found it, or I do not have it. I am working with Photoshop6, so maybe it was not on that one. Please advise.
Jessy
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Old 04-26-2005, 10:00 PM
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You can do quite well staying in RGB or changing to Multichannel then changing back.

Dave
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Old 04-27-2005, 01:07 PM
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Unhappy Still don't quite get it...

Thanks Dave. I ran the filter staying in RGB, but I'm not sure that it helped much. Following the instuctions, you are only supposed to work on the Blue and Green channels, not touching the Red. So if I changed to Multichannel, I work on the Cyan only, or Cyan and Yellow, and which channel do I use the clone tool set to lighten and which for darken? I am sorry that I don't understand the details of this filter and what it's actually doing. Very very confused here. And also, what exactly is HSB, and is it not available on Photoshop 6? Thanks in advance for any future help anyone can give me.
Jessy
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Old 04-27-2005, 02:42 PM
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Breathe deeply and relax. I know what you are going thru. I assume you are using ByRo's instructions. Correct me if I'm wrong. There is nothing wrong with his approach, I just don't think you have to do all that to get results. HSL (HueSaturationLuminance) and HSB (HueSaturationBrightness) are on the Extras install disc for PS 7 & 8. I don't think 6 has it. Don't sweat it.
Changing to other modes just makes it easier to see the "stars" in FFT. I find Mulichannel works just dandy.
Forget channels for now, just work on your RGB layer. It's called walking before you run. ByRo was born with running shoes on his feet!
Your looking for "stars" or bright points of light in the 4 quadrants. Don't touch the centre. You can clone out stars that appear on the x,y axis. Just clone out as much as you need at 100%.
This filter is not the easiest to use. Experimentation is the key word. Sometimes your result may be less than desired, for example, the edges of your picture may still have texture. You can even try cloning out the axis except the centre.

If you're still not getting there, try posting your pic or a portion and see what we can do.

Cheers
Dave
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Old 04-27-2005, 04:57 PM
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Quote:
Originally Posted by Fizzgiz
I am sorry that I don't understand the details of this filter and what it's actually doing.
Hi Jessy,

What does it do?
There are many ways that an image can be represented, or encoded if you wish. Common alternatives are RBG, CMYK - these are pretty easy to understand because each channel represents something we can visualize: one is the amount of each coloured light and the other the amount of coloured ink.

Lab colour gets more difficult - "L" is lightness, which is easy, but the "a" and "b" channels are pretty wierd to look at
.
FFT is just another way of representing the image which now considers the frequencies present in the image. If you look at the output you won't be able to understand anything at all, but it does have a very special property - repetitive patterns in the image, correspond to fixed frequencies and these show up as little stars. These stars are easy to see and eliminate.
Quote:
Originally Posted by Fizzgiz
And also, what exactly is HSB
Yet another way to represent an image, now considering Hue (colour tone), Saturation (colour strength) and Brightness.

What's HSB got to do with FFT?
When the guy, Alex Chirakov, made the filter he chose (I don't know why) to put the frequency information (which we want) coded as Brightness. So applying the RGB>HSB filter we can separate out the Brightness component and fix it.

Quote:
Originally Posted by Duv
Forget channels for now, just work on your RGB layer.
Dave, when I saw this I was thumping myself on the head. Of course! If we want to fix the brightness then no need for HSB! I tried, but couldn't get a good result. I've seen some great FFT stuff of yours in other threads. Did you clone out the stars using Luminosty blending? By my logic that ought to work (but it didn't ).

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Old 04-28-2005, 12:57 AM
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Roland, you need to get to the beach and let the sand trickle thru your toes. Watch out for the Sharks though. Having said that, 4 scotches later, I can't feel my toes. In any case, I'm just tryin to help Jessy, God luv "im to see some results from this filter that quite honestly pisses me off on a very regular basis.
Please correct me (I'm sure you will) that most of the info we're concerned about is in the "L"..whatever. Your method is "immaculate" but in terms of FFT, ooch, help me, does the small amount of crap from the "color" channels really impede our progress? We're just tryin to get to first base. However good, bad or indifferent..I only work in RGB or Multichannel. I don't have HSL/B either. Anyhow, it's Pacific, Eastern Standard time and I need to do my stretches. Good night!!
Dave
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  #7  
Old 04-28-2005, 06:19 AM
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Quote:
Originally Posted by Duv
Roland, you need to get to the beach and let the sand trickle thru your toes.
Dave, that's the best advice I've seen on this site .

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  #8  
Old 04-28-2005, 12:46 PM
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Well thank you very much gentlemen.
Dave, I did as you said and it worked very well for me.
Roland, The more detailed explanation was helpful. Sometimes I am lost and feel that I should go back to school and take a basic Photography course. I have been reading some photography mags lately, and they have been helping as well. At the least, I'm taking better pictures.
Anyway, thank you both for your time.
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