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Author Topic: Selective noise reduction  (Read 4432 times)

Bill Jaynes

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Selective noise reduction
« on: July 24, 2008, 02:06:03 pm »

I've just started to use the Color Replacement Tool in CS3. The way it avoids other colors with the "Discontiguous" setting is really remarkable.
Does anyone know of a way to do something similar for noise? I'm helping someone who scans negs and gets gross noise in skies. If we apply Noise Ninja without deselecting fine tree branches, those branches lose any chance of being clear and sharp. Trying to deselect the branches with the magic wand or color range has not been successful. Lots of artifacts looking like an infestation of tent caterpillars. An ideal would be for the Color Replacement Tool to work as a "Texture Replacement Tool". It could selectively replace texture only in the color sampled. Probably a lot to ask.
Any thoughts on this?
Thanks,
Bill
http://www.montanahi-line.net/
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Best regards,
Bill Jaynes [url=http://ww

mbalensiefer

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Selective noise reduction
« Reply #1 on: July 25, 2008, 11:23:57 pm »

Bill,

 Have you tried using the Neatimage utility instead of NN? Sorry I can't directly answer the other parts of your question.

Michael
« Last Edit: July 25, 2008, 11:27:25 pm by mbalensiefer »
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Panopeeper

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Selective noise reduction
« Reply #2 on: July 26, 2008, 01:29:40 am »

I have been doing this for years; I almost always separate the sky in my panos for de-noising and for excluding from sharpening. I read and tried many suggestions and found none better than I do, but that's very (very) laborous, particularly with leaves and fine branches.

First a course selection with lasso, then with magic wand the rest; with larger tolerance but contiguous at the beginning, then small tolerance, non-contiguous. Sometimes segmented, so that different tolerances can be applied.

Now, the tuning: with refine edge or modify. Do not forget to save the original selection and ADD that to the refined one, so that it only expands.

The infestation of tent caterpillars is a PITA. The fringing makes it practically impossible to select such fine structures; the transition is not sharp.

Did I say, that it is very laborous? Sometimes I spend hours on one pano for a good selection.

Btw, a perfect selection is not necessary for de-noising, but it is important, when I change the tonality, for example make the sky darker than it was originally.
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Gabor

MorganAdam

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Selective noise reduction
« Reply #3 on: July 26, 2008, 08:01:11 am »

I understand you're starting with a scanned negative, but for reference here is a turtotial that deals with this exact problem by averaging images.

http://www.cambridgeincolour.com/tutorials...aging-noise.htm

I'm not sure if noise from a scan is fixed. If not, you could scan it twice to acheive the result. If it is, then you could prepare beforehand by shooting the scene twice and scanning both images.
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SeanBK

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Selective noise reduction
« Reply #4 on: July 26, 2008, 08:55:44 am »

Nikon NX does do localised noise reduction.
 1. New Step > (select adjustment) > selection brush on the top tab panel
 2. Paint away what you want to be localised adjusted (Noise reduction/gaussian blur/tonality....)
 3. This is important - you must select your desired step from the drop down tab of selection from the "select adjustment" in the edit list on the rt side & not the same item from tabs on the top. Adjust to suit.
     Noise reduction is very subtle, if need stronger than use gaussian blur.
         For NEF, Tiff & JPEG files.
« Last Edit: July 26, 2008, 08:59:04 am by SeanBK »
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Arizona

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Selective noise reduction
« Reply #5 on: July 26, 2008, 04:00:28 pm »

This is very easy in Noiseware. There is a tab called Color Range. Go there and zero everything but blue and cyan. Put those at 100%. Save this preset and call it Sky. I run this on a layer for most every shot, especially the ones I will convert to B&W as the sky breaks down fast. If there is any blue in other parts of the image and you do not see noise there or do not want to loose any detail then simply paint a mask over those areas with a large soft brush. It is super fast and very effective.
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Glen

walter.sk

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Selective noise reduction
« Reply #6 on: July 27, 2008, 08:55:49 am »

I have been using Noise Ninja, which does have a brush which can be used to paint in the noise reduction, or, alternately, to protect an area, selectively.  I have not found it easy to use, nor as effective as I would want.

Recently I watched a demo of Nik Dfine 2.0, which uses various strategies for reducing noise.  It has the Color Range capability, and also uses the "U-Point" technology that lets you put control points anywhere in the image to control where you want noise reduction and where you don't.  It also lets you control the intensity of the noise reduction or protection.  

I progressed from Neat Image to Noise Ninja when the latter began to suit my needs more.  I have just bought NikDfine 2.0 and find it much more intuitive and astonishingly effective with difficult images.  I suggest downloading their trial version and viewing the several free instructional videos.  No, I don't work for them nor am I related to them.
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