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help!!! color noise

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  #1  
Old 03-11-2003, 06:12 PM
katilla katilla is offline
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help!!! color noise

I have several images that have these green and red dots all over them. They are not on the orginal pictures. Only appear after scanning. The orginals were destroyed in fire so I can not re scan. What is it and how do I get rid of it. This one is not to bad but some are so bad they look posterized
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Old 03-11-2003, 07:38 PM
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Andrew B. Andrew B. is offline
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I haven't had a chance to test your image, but one way I've gotten rid of color noise it copy the picture to a new layer, gaussian blur between 4 and 6. Set layer blending mode to color. This gives you smoother color while retaining luminosity detail.

I've also used a program called Neat Image with success on color noise. And if you have a bunch of pictures from the same scanner with the same problem, it might be possible to create a correction profile in Neat Image that can correct them all, based on only one photo that has good-sized testing area in it.

http://www.neatimage.com/
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Old 03-14-2003, 09:57 PM
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CJ Swartz CJ Swartz is offline
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I tried working in LAB per Dan Margulis via one of Stephen M.'s page links. Blurring the A channel in LAB works on the Red/Green colors, and a bit of blurring on the B (Yellow/Blue) helped revert some of the color change caused by the A blurring. NOT blurring the Lightness channel retains the detail. You can then convert the image to RGB. Doing a Levels adjustment layer plus some dodging and burning will help also.
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Old 03-14-2003, 10:34 PM
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roger_ele roger_ele is offline
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The next time this happens look at the original with a strong magnifier and change the angle of the print to reflect light off of the surface - my guess is that the spots are really there in the original, the scanner light is very sensitive to changes in surface reflections and shows stuff that is hard to see.
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Old 03-16-2003, 05:52 PM
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phili1 phili1 is offline
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I tried several things but the noise is so bad its hard no to degrade it.

Anyway this is the best I can do

Select her face inverse and apply!
Smart blur set 16.2 9.1 high normal
deselect
unsharp mask set at 86% 2.4 0

Then use the blur tool set at 50% opacity and remove the rest of the noise be car3eful around eyes and nose and mouth to keep them sharp.

Problem is you cant blow it up unless you start with a very large meg file.
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  #6  
Old 03-19-2003, 09:05 AM
katilla katilla is offline
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thanks

thank all of you very much for your commits. they were very helpful. I did not know i could edit all of the channels in lab.....dumb me....I am sooooo glad I found all of you. I have another question I am posting. Hope you can help
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Old 03-19-2003, 04:36 PM
sdubose99 sdubose99 is offline
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katilla -- the LAB method will probably work better than most other methods. The key to remember is that you can blur the color channels (A, B) separately to a large degree without affecting the sharpness of the luminosity channel (L). You can also sharpen an image without introducing color artifacts by unsharp masking the L channel without touching the A or B... then convert back to RGB without any loss of image quality.

just something I've found very useful lately.

Scott
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  #8  
Old 03-20-2003, 02:47 AM
Stephen M Stephen M is offline
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http://members.ozemail.com.au/~binar...ctremoval.html

Regards,

Stephen Marsh.
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