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Author Topic: Noise & Sharpening.  (Read 1064 times)

William Walker

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Noise & Sharpening.
« on: December 10, 2017, 06:54:28 AM »

On page 9 of "Realworld Image Sharpening", Jeff Schewe writes: "...noise reduction must be used with caution, and always should be done prior to sharpening (otherwise we sharpen the noise and the image)."
However, in "The Digital Print", starting at page 101, Jeff goes through the sharpening process on the "Detail Panel" of Lightroom until, on page 105, he writes :"The next step of sharpening is to adjust noise reduction..."

Can anyone clear this up for me please?

Thanks
William.

mlewis

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Re: Noise & Sharpening.
« Reply #1 on: December 10, 2017, 11:46:16 AM »

In LR it doesn't matter what order you perform edits in.  LR will work out what order to actually carry them out internally.  You can't change this and the order you adjust sliders has no effect on this.  Therefore adjusting the noise reduction slider after the sharpening sliders is no issue.
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Tony Jay

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Re: Noise & Sharpening.
« Reply #2 on: December 10, 2017, 05:13:28 PM »

On page 9 of "Realworld Image Sharpening", Jeff Schewe writes: "...noise reduction must be used with caution, and always should be done prior to sharpening (otherwise we sharpen the noise and the image)."
However, in "The Digital Print", starting at page 101, Jeff goes through the sharpening process on the "Detail Panel" of Lightroom until, on page 105, he writes :"The next step of sharpening is to adjust noise reduction..."

Can anyone clear this up for me please?

Thanks
William.
Hi William - long time, no see...

Your confusion is basically an historical one.
In the days before non-destructive photo-editing as done in earlier versions of PS the order of editing was vitally important.
This was particularly so when it came to noise reduction and sharpening.

Currently however, with non-destructive editing based on parametric algorithms - think Lightroom here, the order of editing is not important in the sense that the software itself will correctly order any edits done to produce the optimal result. The user cannot influence this internal process.

The order of editing is still important for the sanity of one's workflow however...

Tony Jay
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jrsforums

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Re: Noise & Sharpening.
« Reply #3 on: December 10, 2017, 06:57:38 PM »

Hi William - long time, no see...

Your confusion is basically an historical one.
In the days before non-destructive photo-editing as done in earlier versions of PS the order of editing was vitally important.
This was particularly so when it came to noise reduction and sharpening.

Currently however, with non-destructive editing based on parametric algorithms - think Lightroom here, the order of editing is not important in the sense that the software itself will correctly order any edits done to produce the optimal result. The user cannot influence this internal process.

The order of editing is still important for the sanity of one's workflow however...

Tony Jay

Sharpening and NR can be iterative...and, I am sure, each person has there own LR workflow.

To avoid having tweaks added to tweaks, I have, for me, found it best to first understand the noise structure of an image by turning off all sharpening, then applying minimum NR, as needed.  After that, any new noise is most likely being introduced by your sharpening, which you can control with proper making or adjustment brush. 

In my view, if you sharpen first, you are not sure whether the noise was in there or introduced.
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BartvanderWolf

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Re: Noise & Sharpening.
« Reply #4 on: December 10, 2017, 08:17:46 PM »

Hi William,

As others have pointed out, in LR the order/sequence of adjustments is fixed under the hood. So one has to assume that a sensible order is chosen between sharpening and denoising.

For non-parametric workflows, things are more complicated. There are (e.g. deconvolution) sharpening algorithms that attempt to increase the signal to noise ratio, by sharpening the detail but also reducing the noise at the same time. Trying to reduce noise may affect the ability to restore resolution in that specific case. Noise reduction can affect the ability to deconvolve and restore resolution.

Another potential issue is connected with distortion correction, and CA correction, which can create a much harder challenge for noise reduction if distortion is corrected first (example of image rotation affecting resolution/noise). I don't know in what order LR addresses distortion correction versus noise reduction (NR should be done first).

Cheers,
Bart
« Last Edit: December 10, 2017, 08:35:53 PM by BartvanderWolf »
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William Walker

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Re: Noise & Sharpening.
« Reply #5 on: December 11, 2017, 01:57:47 AM »

Many thanks to all of you!

It was only the Lightroom workflow that I was interested in....

Regards
William

William Walker

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Re: Noise & Sharpening.
« Reply #6 on: December 11, 2017, 02:01:58 AM »

Hi William - long time, no see...

Hi Tony

Yes, I don't spend as much time here as I used to....!

We have moved from Kwa-Zulu Natal to  a little village, Riebeek Kasteel, in the Western Cape....it's like living in another country!

I hope you are well?
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