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Author Topic: Local Sharpening in Lightroom  (Read 2404 times)

englishm@pacificlight.ca

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Local Sharpening in Lightroom
« on: March 21, 2023, 04:32:51 pm »

If this topic has been covered before, I'll apologize in advance.   In Jeff Schewe's books (Digital Negative and Digital Print) he says the local sharpening controls simply add more or less sharpening to the selected local area based on whatever is set in the detail panel.  But... if you zero out the detail panel, create a local adjustment and move the Sharpness slider right or left, LR is definitely adding or removing sharpening to/from the selected area.  This seems inconsistent with the notion that local sharpening is tied to the settings in the detail panel.  My (uneducated) guess is that despite the global settings in the Detail  Panel, some defined "default" settings are in effect for the local adjustments when the Detail panel Amount is set to Zero.  In other words, even though the global amount is set to zero and the other sliders are greyed out, the default settings of radius 1, Detail 25, and Masking 0 are applied to the local selection.
Does anyone know if this is how Adobe has implemented local sharpening?  (I'm hoping Jeff is still around here and can chime in)
Thanks in advance
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digitaldog

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Re: Local Sharpening in Lightroom
« Reply #1 on: March 21, 2023, 05:36:36 pm »

Localized (fill in the blank, including Sharpening) sliders control the localized brush applied to that part of the image. They add or (depending on setting) reduce local sharpening of that brush. Outside of the local adjustments, the same appearing sliders in panels apply globally.
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englishm@pacificlight.ca

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Re: Local Sharpening in Lightroom
« Reply #2 on: March 22, 2023, 01:19:31 am »

Thanks for your reply, but that is not what I was asking.  Jeff Schewe points out in his books that Local Sharpening simply applies more of whatever is set in the Detail panel as to Radius, Detail, and presumably Masking as well.  In other words, if you have set up a High-frequency approach globally, you can only add more or less local sharpening based on that same high-frequency approach.

When you drop the Global Sharpening Amount slider to 0, all other Detail Panel sharpening sliders are greyed out, which one could interpret to mean that sharpening is turned OFF.   And yet, if you apply any local adjustment and adjust the Local Sharpening slider up or down, it is obvious that sharpening is being added or removed. 

It appears then, that since the global sharpening settings are the basis for local sharpening, even with global sharpening OFF, it likely isn't OFF.  I think the logical conclusion is that even with the Global sharpening Amount set to zero, the radius, detail and (possibly) the Masking settings are still active and form the underlying settings for whatever local sharpening you apply.   And, if this isn't the case, then what are the underlying settings for radius, etc for local sharpening when global sharpening is "OFF"?
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digitaldog

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Re: Local Sharpening in Lightroom
« Reply #3 on: March 22, 2023, 09:17:06 am »

Either Jeff got that wrong (VERY unlikely) or there is some misunderstanding of what he's stating.
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Slobodan Blagojevic

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Re: Local Sharpening in Lightroom
« Reply #4 on: March 22, 2023, 09:24:55 am »

What seems likely is that, even when you zero the global slider first, moving the local slider actually moves the global slider too, just the display remains at zero?

englishm@pacificlight.ca

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Re: Local Sharpening in Lightroom
« Reply #5 on: March 22, 2023, 12:39:59 pm »

Andrew,

>>Jeff got that wrong (VERY unlikely)<<  Agreed!

To be clear, Jeff only says that local sharpening adds or reduces more or less of the sharpening as set in the global Detail panel (at the then current revision level of LR at the time of his writing).  He is silent on what happens when the global sharpening is turned off (my words) ie, when the amount slider is set to zero and the Radius, Detail, and Masking sliders are greyed out.  In this case, it is still possible to add or reduce sharpening with a local adjustment.

I know this is a somewhat esoteric question, and I don't want to beat it to death, but it came up in a class, and I couldn't in all honesty provide an authoritative answer.  I like to be right, rather than guessing.
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digitaldog

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Re: Local Sharpening in Lightroom
« Reply #6 on: March 22, 2023, 12:49:08 pm »

Local and non local (global) are totally separate and independent.
You can crank up Global Sharpness to max and see the effect. Then disable that panel with the 'off' switch. Then paint with a brush and add sharpening. The two panels with sliders look identical as they should. One affects the global, the other the local. Local sharpening can add or reduces more or less of the sharpening as set in the global Detail panel if it's on. And if its off.
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jrsforums

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Re: Local Sharpening in Lightroom
« Reply #7 on: March 22, 2023, 03:55:52 pm »

Local and non local (global) are totally separate and independent.
You can crank up Global Sharpness to max and see the effect. Then disable that panel with the 'off' switch. Then paint with a brush and add sharpening. The two panels with sliders look identical as they should. One affects the global, the other the local. Local sharpening can add or reduces more or less of the sharpening as set in the global Detail panel if it's on. And if its off.

Andrew, not sure what you are saying.  What is “… as set in the global Detail panel…”?  Does this include amount, radius, detail, mask….or are we just talking about amount.  If local is “more or less” of “ as set in the global Detail panel”, you are confirming, I think, what Jeff said.

What does local sharpening do if all global sharpening settings are set to ‘0’….particularly amount?  Is local just increasing/decreasing amount…or something else…or do the other stay the same as global.

I thing, this is what the OP is driving at…but, who knows 😀
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digitaldog

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Re: Local Sharpening in Lightroom
« Reply #8 on: March 22, 2023, 03:59:37 pm »

Andrew, not sure what you are saying.  What is “… as set in the global Detail panel…”?  Does this include amount, radius, detail, mask….or are we just talking about amount.  If local is “more or less” of “ as set in the global Detail panel”, you are confirming, I think, what Jeff said.

What does local sharpening do if all global sharpening settings are set to ‘0’….particularly amount?  Is local just increasing/decreasing amount…or something else…or do the other stay the same as global.

I thing, this is what the OP is driving at…but, who knows 😀
Global (the entire image). Example: move Exposure slider, the entire image gets darker or brighter.
Make a local (brush) adjustment and use the same slider: not global, just the selection (brush stroke).
Lastly, zero seeings for sharpness doesn't mean 'no sharpening'. Some is always applied in this converter.
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jrsforums

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Re: Local Sharpening in Lightroom
« Reply #9 on: March 22, 2023, 04:54:32 pm »

Global (the entire image). Example: move Exposure slider, the entire image gets darker or brighter.
Make a local (brush) adjustment and use the same slider: not global, just the selection (brush stroke).
Lastly, zero seeings for sharpness doesn't mean 'no sharpening'. Some is always applied in this converter.

Good grief 😀 I understand global/local…I didn’t ask that!

I have understood that there was some sharpness ‘pre-applied’ to raw images, I assume to, in some way, ‘normalize’ the images to the default settings, e.g. amount =40, radius=1.0, detail=25…..and, I think you are saying, this may include components of each even if they are set to zero.

The question is….when local sharpening is increase or decreased….what is it doing.  Is it increasing/decreasing the ‘amount’ slider? 
Is it applying more or less of the existing global setting?  For example, if masking is set to 100, is this what local sharpening applies (along with amount, radius, detail)?

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digitaldog

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Re: Local Sharpening in Lightroom
« Reply #10 on: March 22, 2023, 05:37:16 pm »

I have understood that there was some sharpness ‘pre-applied’ to raw images, I assume to, in some way, ‘normalize’ the images to the default settings, e.g. amount =40, radius=1.0, detail=25…..and, I think you are saying, this may include components of each even if they are set to zero.
Normalize to default settings? I don't understand .
Yes, that's what I'm saying.
Quote
The question is….when local sharpening is increase or decreased….what is it doing.
Increasing or decreasing sharpness.
Quote
For example, if masking is set to 100, is this what local sharpening applies (along with amount, radius, detail)?
Local and non local (global) are totally separate and independent. So, same answer.
« Last Edit: March 22, 2023, 05:40:17 pm by digitaldog »
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Chris Kern

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Re: Local Sharpening in Lightroom
« Reply #11 on: March 22, 2023, 07:39:40 pm »

I'll probably regret weighing in here, but it seems to me this is too much ado over nothing.

First of all, the Detail panel is complicated.  Here's Schewe's explanation of how it works:

Quote
The Detail sharpening adjustment is pretty complicated. When adjusted downward toward 0, the Detail slider kicks in a halo suppression algorithm that limits how strong the halos get with your Amount settings. Halos are a result of image-sharpening algorithms, but the idea is to have the halos be invisible at normal viewing distances. Lowering the Detail slider can reduce the halo visibility. Moving toward 100, the Detail kicks in a deconvolution-based sharpening that is very similar to Photoshop’s Smart Sharpen filter when set to remove lens blur. Deconvolution sharpening attempts to deblur an image based on determining what kind of blur is in the image. The processing algorithm uses a point-spread function (PSF) to approximate a mathematical description of the blur and then inverts the PSF to try to sharpen away the blur. Accurately calculating the PSF can be very difficult, but the Detail slider at 100 does a reasonable job of attempting to deblur based on a generic lens-blur PSF. The Detail slider interpolates between these two different sharpening algorithms. The default is 25, but I usually increase this toward the middle of the range (rarely to +100, though). You should be aware that running the Detail slider up on a noisy image would substantially increase the sharpening of the noise.

— Jeff Schewe, The Digital Negative (Second Edition), 2016.

Got that?  He said it was complicated.  Read it again.

Second, it's not clear to me that anyone except the Lightroom developers knows the current semantics of each numerical value for each slider, or why anyone else would want to.  (Not even photographers who advise Adobe like Jeff Schewe and Andrew Rodney.)  Aside from the fact that these may change between versions, even if you did know precisely what they meant, how would you use that information to improve your images?  Isn't the whole point of interactive digital post-processing tools that they allow the user to adjust a source image in real-time to get a visually-desired effect?  I don't see how the numerical values of the sliders offer artistically actionable information.  What you see is what you get.

Finally, the new Lightroom paradigm for masking and local adjustments was introduced long after the second edition of the Schewe book, which may no longer accurately reflect the current software.  I consider myself a reasonably proficient Lightroom user, but I'd pop for a new edition if Jeff chose to produce one.

digitaldog

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Re: Local Sharpening in Lightroom
« Reply #12 on: March 22, 2023, 08:05:03 pm »

Indeed, some of this is rather complicated and unknown (like what the numbers represent under the hood). And simple (the numbers really don't matter, what the image looks like properly previewed does. At least for Capture Sharpening (notice output sharpening is by design not something to see).
Jeff writes (and it's based on his eyes):
The default is 25, but I usually increase this toward the middle of the range (rarely to +100, though). You should be aware that running the Detail slider up on a noisy image would substantially increase the sharpening of the noise.

If you want to ask Jeff, unlikely it will happen here. Head over to:
https://photopxl.com/forums/
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englishm@pacificlight.ca

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Re: Local Sharpening in Lightroom
« Reply #13 on: March 22, 2023, 08:28:37 pm »

Wow, a lot of voices here.  Didn't mean to open a can of worms.

Andrew, You say that Local and Global Sharpening are completely separate and independent.  Agreed, up to a point.  You also confirm that Local Sharpening is applied to the local area being adjusted using the settings currently set in the Global panel.  Which I also agree with, but it is inconsistent with the first statement.  Local and Global Sharpening always share the same settings for Radius, Detail and Masking.  So,  (and I apologize for seeming to beat this to death)  if I have set Global Sharpening appropriately for a high-frequency image, (say for argument, radius 0.7, Detail 35, Masking 0).  Local Sharpening will be applied to the image using those settings.

I think we agree on that.

Now, my original query was, "What happens when I set the Amount slider to 0 in the Detail Panel, leaving all the other sliders greyed out?  I have always assumed, erroneously it seems, that this action completely turned off all Sharpening, period.  Since it is still possible to apply local sharpening with the Global controls "turned off" in this way, clearly Sharpening is NOT turned off completely, it's simply NOT being applied globally.  I think on balance, it's reasonable to assume that any Local Sharpening applied in this situation will be applied using whatever settings existed in the Global controls before the Amount slider was set to 0.  ie. the same high-frequency settings in my example. 

But that was always just a guess on my part.  And I was hoping for some confirmation, or to be set straight.  As I said, I prefer to be correct rather than just guessing when I respond to a student's query.

Chris, thanks for your reply.  And I agree that it is possible that the Sharpening algorithms may have changed somewhat since Jeff last updated his books.  With no basis for an opinion other than knowing that the Capture Sharpening algorithms are based on Bruce Fraser's work, I suspect that is unlikely.  I believe, and Andrew can confirm or refute this, that the Output Sharpening algorithms are (or were) directly licensed from Pixel Genius (also based on Bruce Fraser's work) to Adobe.

I will say, however, that there is indeed actionable information in the Detail Panel sliders, but using them in this way is dependent on understanding what kind of image detail you are trying to sharpen.  High frequency: lower the radius; Low-frequency: raise the radius. etc. 
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digitaldog

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Re: Local Sharpening in Lightroom
« Reply #14 on: March 22, 2023, 11:00:00 pm »

Now, my original query was, "What happens when I set the Amount slider to 0 in the Detail Panel, leaving all the other sliders greyed out?  I have always assumed, erroneously it seems, that this action completely turned off all Sharpening, period. 
All user applied global sharpening is off. You want to now apply local sharpening, fine, you can do this. Its rather simple.

BTW, there are no Bruce Fraser or Pixel Genius sharpening algorithms; it's all 100% Adobe Photoshop algorithm, always was. In Lightroom Classic/ACR, it again is all Adobe proprietary algorithms. The sharpening workflow AND the unique sets of sharpening techniques from Photoshop were used.
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fdisilvestro

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Re: Local Sharpening in Lightroom
« Reply #15 on: March 23, 2023, 06:00:50 am »

I have done some tests after reading this thread as I did not know what was happening. You can repeat the tests for yourself.

In Jeff Schewe's books (Digital Negative and Digital Print) he says the local sharpening controls simply add more or less sharpening to the selected local area based on whatever is set in the detail panel.  But... if you zero out the detail panel, create a local adjustment and move the Sharpness slider right or left, LR is definitely adding or removing sharpening to/from the selected area.

It actually appears to be working just as Jeff Schewe described. What happens is that even if you push all the sliders to the left in the global adjustment detail panel, the minimum value for radius is 0.5 and not 0. So when you apply positive local sharpness, you are actually using radius 0.5.

When you drop the Global Sharpening Amount slider to 0, all other Detail Panel sharpening sliders are greyed out, which one could interpret to mean that sharpening is turned OFF.   And yet, if you apply any local adjustment and adjust the Local Sharpening slider up or down, it is obvious that sharpening is being added or removed. 

Yes they are greyed out, but local sharpening will use whatever you have in those sliders (radius, detail, masking). So make sure you adjust those before turning the amount to 0.

Now, something interesting happens with negative values of local sharpening. From 0 to -50 it will gradually reduce the sharpening you had set in global, and from -50 to -100 it will apply blur (cannot tell what type, if it is Gaussian or other). For positive values +100 will be equivalent to amount of 150 in the global detail panel.

To test this, set a high radius & detail and set the amount to 150 and note how the image looks (lets call this version A). Now reduce the amount 0 in the global detail panel and create a localized brush with sharpness +100 and compare the image to version A. To me they look the same.

Based on these results, my suggestion is to set the global sharpening first, and then apply your localized sharpening.

If you modify the global sharpening after having done localized sharpening, check those local adjustments again since they will have varied.

Manoli

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Re: Local Sharpening in Lightroom
« Reply #16 on: March 23, 2023, 10:54:43 am »

Yes they are greyed out, but local sharpening will use whatever you have in those sliders (radius, detail, masking). So make sure you adjust those before turning the amount to 0.

It does, but not 'Masking'. If you test it, I think you'll find that the masking setting is ignored. Easily checked by applying -100 Sharpness to a local selection.

Also worth pointing out that Lr's Detail (global) slider fronts two different sharpening algorithms. At a setting of 0 it's halo suppression as you move the slider to +100 it morphs to deconvolution (psf) based sharpening. I'm reasonably sure that Jeff clarified this in 'The Digital Negative'.

Not sure if its helps, but to use an audio analogy <Radius and Detail> are akin to <Bass and Treble>, Amount is the <Volume> dial. Masking is a global setting only; I suspect it's ignored when making local sharpness adjustments.

« Last Edit: March 23, 2023, 11:19:24 am by Manoli »
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fdisilvestro

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Re: Local Sharpening in Lightroom
« Reply #17 on: March 23, 2023, 02:28:48 pm »

It does, but not 'Masking'. If you test it, I think you'll find that the masking setting is ignored. Easily checked by applying -100 Sharpness to a local selection.

That's not what I'm experiencing. Masking does affect local sharpening. Remember that local sharpening changes to blur when using a negative value from -50 to -100 (maybe the masking is ignored in this case).

Try this: set global  radius and detail to maximum (for an exaggerated effect) and amount to 1 (to avoid graying out the other dials) then use a localized brush with +100 sharpness and return to the global detail. Now move the masking slider back and forth and you will see the effect in the localized area.

Also worth pointing out that Lr's Detail (global) slider fronts two different sharpening algorithms. At a setting of 0 it's halo suppression as you move the slider to +100 it morphs to deconvolution (psf) based sharpening. I'm reasonably sure that Jeff clarified this in 'The Digital Negative'.

Yes, 100% correct!

mcbroomf

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Re: Local Sharpening in Lightroom
« Reply #18 on: March 24, 2023, 10:05:08 am »

Jeff posted in PhotoPxl in response to this thread

https://photopxl.com/forums/topic/local-sharpening-in-acr-lr/
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Rand47

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Re: Local Sharpening in Lightroom
« Reply #19 on: March 24, 2023, 10:40:49 am »

Jeff posted in PhotoPxl in response to this thread

https://photopxl.com/forums/topic/local-sharpening-in-acr-lr/

Thank, Mike!

I had contacted Jeff about this post on local sharpening.  His response on PhotoPXL is “complete” about what’s going on.  OP, make sure you pop over there and have a look.   

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