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Photography Question 
Wendy Moghadam
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member since: 1/19/2007
 

Noise Reduction


What does reducing noise do to the photo? I noticed if I choose it in IPhoto, it looks different than if I do it in elements. If I go higher than, say, 60%, the photo gets a fake look. Sometimes it's cool, but I just wonder what is it really doing?

10/30/2007 6:40:01 PM

 
W. 

member since: 9/25/2006
 
Hi Wendy,

when you shoot in low light, with high ISO, all kinds of specks and often colored artifacts become visible in the darker parts of your image. That is the socalled 'noise'. Reducing that 'denoising' in post production doesn't come without a penalty: you ultimately get a 'fake look', if you apply too much denoising.

Denoising should be applied to high ISO images only.
Applying it to low ISO images may introduce unwanted effects.

However, you speak of reducing noise in iPhoto and in Photoshop Elements. MY iPhoto (6.0.6), nor my Photoshop Elements (2.0) has that feature afaik. Can you please tell me where/how I can find it in either?

10/30/2007 7:31:31 PM

 
Wendy Moghadam
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member since: 1/19/2007
  Hi,
Thanks for responding. I have IPhoto '08 I think its 7.1 version- you can now do adjustments to saturation noise reduction change coloring etc. In Elements 4.0 when you convert raw- and I'm still learning/playing you can reduce noise.

10/30/2007 8:07:10 PM

 
W. 

member since: 9/25/2006
 
Thanks. I didn't know that.
Different denoising applications employ different algorithms, hence the difference in results.

10/30/2007 9:12:04 PM

 
Richard Lynch
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  Wendy,
I'm oversimplifying slightly here, but generally noise reduction involves a type of blurring (sometimes closer to what the Median filter does in Photoshop than Blur or Gaussian Blur). More sophisticated noise reduction will involve detail detection and masking. That is, it will try and find edges of your obejcts and keep these areas from blurring so you retain detail and just lose the noise where the blur occurs. The more extreme your application, the more obvious it will generally be.
Generally, I avoid noise reduction unless I'd have a spectacular shot with it - which usually only happens if it is a shot that can get away with a lot of detail being removed. Also, my process for reducing noise is one I made up, and involves not only edge detection and blurring, but actually adding noise to avoid some of the flattening and "fake look" that WS refers to.
There are many ways to reduce noise and many hyped tools, but I've yet to see one that can accomplish noise reduction without compromising detail.

10/31/2007 3:11:07 AM

 
Carolyn  M. Fletcher
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member since: 10/6/2001
  www.imagenomic.com has a noise reduction filter for free, and it's not too bad. I have as good luck with it as with the Neat Image. What's nice about the Imagenomic Noiseware Community Edition is it has a lot of different categories you can plug in and it responds differently for them, such as portrait, night scene, etc. Give it a try, you can't lose much since it's free.

10/31/2007 9:57:38 AM

 
Wendy Moghadam
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member since: 1/19/2007
  Thank you- W, Richard and Carolyn
I'm going to give imagenoic a try

10/31/2007 9:17:30 PM

 
Chantelle L. Pacheco
BetterPhoto Member

member since: 4/2/2006
  A cool effect that I have used on My portraits of Babies Is I select the area I want to reduce the noise,(or the mottled effect that newborns often have on their skin) and I make a new layer. If it is a large area. I just copy the whole layer. Then I choose median in the Noise menu (photoshop) for the top layer. Then I go over anything I want sharp. with a fine eraser tool. ie skin creases, edges, lips, nose details. Then flatten the image.viola smooth skin, no detail lost.

11/6/2007 5:42:53 AM

 

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