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Forums Lobby MASTER YOUR TOOLS Post-Processing & Workflow (Public) Adobe Post-Processing (Public) topic #10192
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Subject: "Image Processing" Previous topic | Next topic
mawyatt1   US  Registered since 11th Feb 2012 Wed 06-Feb-13 03:07 PM
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"Image Processing"



Would any of you image processing experts that are familiar with the inner workings of jpeg comment on the effects of smaller jpeg files regarding image noise reduction? If one has a larger raw file and selects a smaller jpeg file size in LR4, does this have the same or similar effect as pixel downsampling the image from a noise prespective?

Thanks in advance,

  

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mawyatt1   US  Registered since 11th Feb 2012 Wed 06-Feb-13 07:20 PM
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#1. "RE: Image Processing"
In response to Reply # 0
Wed 06-Feb-13 07:21 PM by mawyatt1


I got an answer on another forum. Evidently LR does do the Noise Reducing downsampling first, then compresses the file into JPEG. Another good reason to use LR for JPEG creation from RAW files.

  

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KenLPhotos Gold Member  Stewartstown, US  Nikonian since 26th Jul 2009 Wed 06-Feb-13 08:54 PM
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#2. "RE: Image Processing"
In response to Reply # 1



Noise reduction also degrades sharpness. It is best if the noise reduction is optional.

KenL

Visit my Nikonians gallery.



There are many 'images of beautiful objects' but few 'beautiful images of objects'.

  

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mawyatt1   US  Registered since 11th Feb 2012 Wed 06-Feb-13 09:35 PM
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#3. "RE: Image Processing"
In response to Reply # 2
Wed 06-Feb-13 09:36 PM by mawyatt1


Hi Ken,

The noise reduction I was referring too is a consequence of the down sampling of the image. Another described this very well as: If the downsampling image is taken to just one pixel, then the noise is eliminated.

In terms that I work with which is electronics and communications, this is effectively equivalent to bandwidth reduction which improves the resulant signal to noise ratio. Narrow band information systems are inherantly more sensitive then wideband information systems.

I was concerned about whether the reduction took place before or after the JPEG compression. Apparantly LR does the reduction then the compression, which is the right sequence.

  

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dagoldst Gold Member  Little Rock, US  Nikonian since 02nd Dec 2012 Tue 12-Feb-13 05:17 PM
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#4. "RE: Image Processing"
In response to Reply # 3



>Apparantly LR does the reduction then the compression, which is the right sequence.

If you think about it, that is the only way it could work - ie - until a file is sampled to its new size, the data that would need to be saved is an unknown.

David

"Sawed that board three times and it is still too short... "

  

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Forums Lobby MASTER YOUR TOOLS Post-Processing & Workflow (Public) Adobe Post-Processing (Public) topic #10192 Previous topic | Next topic