Local sharpening in ACR & LR

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    Topic: Local sharpening in ACR & LR Read 2705 Times
  • Jeff Schewe
    Jeff Schewe
    Gold Member
    Posts: 136
    Adobe Lightroom & Adobe Camera Raw
    on: March 24, 2023 at 1:10 am

    So, in that “other” forum a new member asked a question in reference to my books; The Digital Negative & Print about local sharpening. He correctly said that the local control adds or subtracts sharpening “Amount” based on the Detail panel settings. His question was what happens when the Amount slider is set to zero? I was pretty sure of the answer but pinged Eric Chan, an ACR engineer, about the question. His answer was pretty much what I expected…

    When the Amount slider in the Detail panel is set to zero, adding Sharpening from the local controls will add sharpening amount with the Radius and Detail settings at default; Radius of 1.0 and a Detail settings of 25. That’s pretty easy to see in ACR & LR.

    However, if you set the Amount slider in the Detail panel to zero and paint minus (negative) Sharpness amounts, both ACR & Lightroom doesn’t do anything at -1 thru -50, it’s an odd dead zone where the settings don’t do anything other than make the mask.

    If you set the Sharpness setting to a -51 thru -100, you will actually add a Lens Blur effect.

    That’s what Eric said…but I’m not 100% sure that’s completely true.

    EDIT: Actually, I was curious to prove Eric either right or wrong because I thought I was seeings a real subtle difference, so I had to test it. I built multiple sh=napshots in LR with local sharpening set to zero, -25, -49 and -50 & -51 and opening them in layers in Photoshop. I set the zero sharpening as the bottom layer and put the other layers above. I set the layer blend to Difference. There was NO DIFFERENCE between the zero, -25, -49 and -50 layers. There was a very subtle difference in the -51 layer which confirmed the addition of the lens blur. So, Eric was, of course correct.

    I had a friend ping me that somebody on that other forum referenced me and my books but I don’t post on that other forum and only visit when somebody tells me there’s something I might want to see.

    Maybe that guy will come visit this forum and find the answer here. 😎

    • This topic was modified 1 year, 1 month ago by Jeff Schewe. Reason: Confirmation of findings after testing
    Mark D Segal
    Mark D Segal
    Silver Member
    Posts: 935
    Re: Local sharpening in ACR & LR
    Reply #1 on: March 24, 2023 at 9:05 am

    I’m getting very tiny and feint font typing here, don’t know why.
    Anyhow, very interesting post Jeff, thanks. I have a follow-up question about the basics of how local sharpening interacts with the detail panel in general. It has been my understanding that when one triggers an adjustment in a local area using the tools in the masking panel, the adjustment made is some percentage of the power of the underlying setting in the detail panel. For for example with sharpening, if I were to have the Amount set at 40, the Sharpening tool in the masking panel would at its maximum add on something up to no more than 40, i.e. point for point it would do less sharpening than the movement of the Amount slider would do if working in the detail panel without a mask. Is this correct?

    Mark D Segal
    Mark D Segal
    Silver Member
    Posts: 935
    Re: Local sharpening in ACR & LR
    Reply #2 on: March 24, 2023 at 9:08 am

    Oh – and as for the “other site” – me too – anyone who wants to read anything I have to say about digital imaging since the time PhotoPXL was created will need to come here.

    • This reply was modified 1 year, 1 month ago by Mark D Segal.
    Rand Scott Adams
    Rand Scott Adams
    Silver Member
    Posts: 287
    Re: Local sharpening in ACR & LR
    Reply #3 on: March 24, 2023 at 10:35 am

    Jeff,

    Thanks for this post. It’s been cross linked “over there” for the benefit of the OP on this question.

    Rand

    Rand Scott Adams Rand47

    Mark English
    Mark English
    Participant
    Posts: 1
    Re: Local sharpening in ACR & LR
    Reply #4 on: March 24, 2023 at 1:21 pm

    Hi Jeff,
    I’m the “new member” from the “other forum”….. actually not new, I just lost interest in that forum after Michael passed. I followed it religiously for years before that, but I digress.
    Thank you for your detailed reply, and for the testing to confirm what is going on here. The scenario I described is unusual, to say the least, but it came up in a class I teach, and I had to admit I didn’t have an answer. I don’t like to guess… hence my post.
    Lastly… I suspect you are not the kind of person who seeks out, let alone likes fawning adulation. Regardless I have to thank you for your contributions to our collective knowledge. There are very few authors I can think of who have generated more “ah-ha” revelatory moments when something previously inscrutable suddenly became clear.
    And for that I thank you.

    Kevin Raber
    Kevin Raber
    Silver Member
    Posts: 1289
    Re: Local sharpening in ACR & LR
    Reply #5 on: March 24, 2023 at 4:25 pm

    BTW Mark, Welcome. Jeff is full of knowledge and he shares it here as does many others. Hope you find a new home here.

    Kevin Raber
    Owner and Publisher of photoPXL

    Jeff Schewe
    Jeff Schewe
    Gold Member
    Posts: 136
    Re: Local sharpening in ACR & LR
    Reply #6 on: March 24, 2023 at 6:16 pm

    I’m getting very tiny and feint font typing here, don’t know why.
    Anyhow, very interesting post Jeff, thanks. I have a follow-up question about the basics of how local sharpening interacts with the detail panel in general. It has been my understanding that when one triggers an adjustment in a local area using the tools in the masking panel, the adjustment made is some percentage of the power of the underlying setting in the detail panel. For for example with sharpening, if I were to have the Amount set at 40, the Sharpening tool in the masking panel would at its maximum add on something up to no more than 40, i.e. point for point it would do less sharpening than the movement of the Amount slider would do if working in the detail panel without a mask. Is this correct?

    Nope…the local adjustment increases or decreases the settings in the same units that the global settings occur (with the exception noted herein) So, if you had a setting of 40 in the global and you used a setting of +20, that would be the same as having the setting be 60 in those areas. Similarly, if you used a -20, the resulting settings in the global +40 would be 20.

    It should also be noted that the local controls are based on and relate to the same global controls but they are not EXACTLY the same in some of the channels of adjustment. I used to have an explanation of that in an email from Eric or Those, but I can’t recall what the exact differences are. But for all practical purposes, the differences are irrelevant to the normal user.

    Jeff Schewe
    Jeff Schewe
    Gold Member
    Posts: 136
    Re: Local sharpening in ACR & LR
    Reply #7 on: March 24, 2023 at 6:17 pm

    Lastly… I suspect you are not the kind of person who seeks out, let alone likes fawning adulation. Regardless I have to thank you for your contributions to our collective knowledge. There are very few authors I can think of who have generated more “ah-ha” revelatory moments when something previously inscrutable suddenly became clear.
    And for that I thank you.

    Thanks for those kind words…they are appreciated.

    Mark D Segal
    Mark D Segal
    Silver Member
    Posts: 935
    Re: Local sharpening in ACR & LR
    Reply #8 on: March 24, 2023 at 6:56 pm

    I’m getting very tiny and feint font typing here, don’t know why.
    Anyhow, very interesting post Jeff, thanks. I have a follow-up question about the basics of how local sharpening interacts with the detail panel in general. It has been my understanding that when one triggers an adjustment in a local area using the tools in the masking panel, the adjustment made is some percentage of the power of the underlying setting in the detail panel. For for example with sharpening, if I were to have the Amount set at 40, the Sharpening tool in the masking panel would at its maximum add on something up to no more than 40, i.e. point for point it would do less sharpening than the movement of the Amount slider would do if working in the detail panel without a mask. Is this correct?

    Nope…the local adjustment increases or decreases the settings in the same units that the global settings occur (with the exception noted herein) So, if you had a setting of 40 in the global and you used a setting of +20, that would be the same as having the setting be 60 in those areas. Similarly, if you used a -20, the resulting settings in the global +40 would be 20.

    It should also be noted that the local controls are based on and relate to the same global controls but they are not EXACTLY the same in some of the channels of adjustment. I used to have an explanation of that in an email from Eric or Those, but I can’t recall what the exact differences are. But for all practical purposes, the differences are irrelevant to the normal user.

    Interesting, thanks for the clarification Jeff.

    Rand Scott Adams
    Rand Scott Adams
    Silver Member
    Posts: 287
    Re: Local sharpening in ACR & LR
    Reply #9 on: March 24, 2023 at 8:37 pm

    Good stuff….!!!
    Rand

    Rand Scott Adams Rand47

    John Schwaller
    John Schwaller
    Participant
    Posts: 5
    Re: Local sharpening in ACR & LR
    Reply #10 on: March 24, 2023 at 8:54 pm

    Great stuff!! Thanks, Jeff

    Francisco Disilvestro
    Francisco Disilvestro
    Participant
    Posts: 4
    Re: Local sharpening in ACR & LR
    Reply #11 on: March 25, 2023 at 3:27 am

    Hi, new member here, also coming from the “other” forum. I have followed this topic with great interest and would like to share the results of a few tests I performed regarding what happens when the global amount is set to zero.

    According to Jeff Schewe (who I have the utmost respect for) in the first post, when the amount is set to zero, the local controls will add sharpening with the default values of radius=1 and Detail = 25.
    Well, this is not what I am experiencing, so here are a few images to show.

    The first image shows an unfeathered brush stroke with flow=100, Density=100 and an adjustment of Sharpness=100

    Sharpenin-brush_reduced

    Then the remaining images shows different settings of the global detail panel, with amount set to zero.

    Second image: Radius=0.5 & Detail=0

    Sharpening-1-reduced

    Third image: Radius=1 & Detail =25 (default values)

    Sharpening-2-reduced

    Last image: Radius=3 & Detail=100 (to appreciate an exaggerated effect)

    Sharpening-3-reduced

    To me there is a distinct effect on the local sharpening depending on the values of the radius and detail, even if they are greyed out when the amount is set to zero. If the sharpening simply changed to the default values, then I would not see any difference.
    Just in case, Lightroom 12.2.1 on Windows 10.
    Image2: details from .nef file from a Nikon D800 @ 200%

    Sorry if the images are not that great, as I had to reduce the size.
    Thanks!

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