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,
#1. "RE: Image Processing" | In response to Reply # 0Wed 06-Feb-13 05:20 PM | edited Wed 06-Feb-13 05:21 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.
#2. "RE: Image Processing" | In response to Reply # 1
#3. "RE: Image Processing" | In response to Reply # 2Wed 06-Feb-13 07:35 PM | edited Wed 06-Feb-13 07:36 PM by mawyatt1
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.
#4. "RE: Image Processing" | In response to Reply # 3dagoldst Nikonian since 02nd Dec 2012Tue 12-Feb-13 03:17 PM
>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.
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