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Sharpening in ACR 7.1

Jun 10, 2012 6:57 PM

Tags: #7 #acr #sharpening

I'm reading the part of Martin Evening's "Adobe Photoshop CS6 for Photographers" dealing with sharpening in ACR.  As in his previous edition for CS5, he seems to be saying that putting the Detail slider at 100 is akin to USM in PS, while placing it at 0 minimizes halos.  I would gather this means the 0 setting is deconvolution sharpening. 

 

As I recall, Eric Chan indicated that the settings were the other way round: 0 was akin to USM and 100 deconvolution. Which is which?

 

thanks,

 

grampus45

 
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  • Currently Being Moderated
    Jun 10, 2012 7:14 PM   in reply to grampus45

    I think you are misreading what Martin wrote...

     

    100 is deconvolution sharpening similar to Smart Sharpen in Photoshop. Zero is no devonvolution and max halo supression. Forget USM as it's no longer a model that is used in ACR/LR.

     
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  • Currently Being Moderated
    Jun 10, 2012 10:17 PM   in reply to grampus45

    The Detail slider is an interpolation between deconvolution at 100 to full halo suppression at zero. The halo suppression reduces the total amount of edge contrast the Amount setting applies. Between zero and 100, it's an interpolation between these two parameters…

     
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  • Noel Carboni
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    Jun 12, 2012 3:41 PM   in reply to grampus45

    My suggestion is to just move 'em around until you like the way it looks.  You're overthinking it.

     

    I prefer, for my own defaults, Sharpening: 15, Radius 0.5, Detail: 100, Masking: 0

     

    I got there by trying different settings on different images from my own equipment and lenses, seeing what I liked and didn't like, and finally choosing what I felt was the best compromise.

     

    -Noel

     
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  • Currently Being Moderated
    Jun 12, 2012 3:51 PM   in reply to Noel Carboni

    Noel Carboni wrote:

     

    Masking: 0…

     

    Hi Noel,

     

    May I ask you to elaborate on the setting for "Masking"?  What detrimental effect(s) do you see happening to the image if you apply increasingly higher values of masking?

     

    Thanks in advance.

     
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  • Noel Carboni
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    Jun 12, 2012 5:04 PM   in reply to station_two

    Back when these controls were first introduced, then again with the 6.7 beta, I did a lot of test conversions where I looked critically at the results, and I just liked this setting the best.  Honestly, I don't remember specifics with regard to this particular setting...  I suppose I must have just felt it made the image seem more natural to leave it at zero.  Touchy feely stuff.

     

    Once I started to home in on what I felt may be a good set of defaults, I actually fully processed a number images for various uses (e.g., large prints, web output, etc.), which led to some additional tweaks to the defaults - for example when I found that the sharpening settings in Camera Raw left a few too many artifacts that later processing steps, such as fractal sharpening for output, would bring out.

     

    In related news, I do dial in a fair amount of luminance noise reduction (40) as a default.

     

    -Noel

     
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  • Currently Being Moderated
    Jun 12, 2012 8:25 PM   in reply to Noel Carboni

    Thank you.

     
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  • Currently Being Moderated
    Jun 12, 2012 9:49 PM   in reply to Noel Carboni

    Noel Carboni wrote:

     

    My suggestion is to just move 'em around until you like the way it looks.  You're overthinking it.

     

    I prefer, for my own defaults, Sharpening: 15, Radius 0.5, Detail: 100, Masking: 0

     

    Noel habitually does in ACR upsampling and a lot of post conversion sharpening which tends to break (alter) the sharpening workflow that ACR/LR was designed to use. So his way is one way but not the ONLY way...

     

    I tend to evaluate my images at 100% zoom and sharpen for an optimal "capture" sharpening in ACR/LR at the native capture resolution. When I go to print I use LR's output sharpening after upsampling (which is an accumulated 2 pass sharpening + final rez upsampling).

     

    Noel is intentionally undersharpening his images in the capture sharpening stages because he's upsampling and then adding substantail post processing sharpening. That is his choice (but not the way I work).

     

    I want to get the raw capture "sharp" at the native resolution and keep that as my digital master and upsampke only at the printing stage with output sharpening applied on top.

     

    In any event, I do view Luminance Noise Reduction as the 5th sharpening slider...while the default is zero, almost ALL raw captures need "some" noise reduction as part of the capture sharpening process.

     
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  • Currently Being Moderated
    Jun 13, 2012 5:34 PM   in reply to station_two

    Sharpening is much a matter of personal taste. Mine:

     

    Defaults:

    * Masking: 0

    The rest depend on ISO range and are bounded thusly:

    Amount: 35 - 50

    Detail: 20 - 0

    Radius 1.0 to 1.3

     

    ( as ISO climbs, I increase amount, decrease detail, and increase radius. At higher ISO's, I introduce luminance noise reduction )

     

    I generally don't like the twinkly stuff that accompanies the masking. In the minority of cases when I do use it, it's typically with lower ISO, and lower sharpening amounts, and especially lower sharpening detail, to minimize said twinkly stuff.

     

    I usually use zero luminance noise reduction unless / until detail has been dropped to zero. Why?

     

    Because it seems detail sharpener can't distinguish noise from real detail, nor can luminance denoiser.

     

    Thus, I almost see luminance noise reduction as a "negative extension" of the sharpening detail slider.

     

    This is like the opposite of Noel, who cranks up luminance noise reduction *and* sharpening detail.

     

    I crank sharpening detail up to enhance real detail in lower ISO shots, or when sharpened noise works like faux image detail (poor man's "grain").

     

    To each their own...

     

    UPDATE: In addition to the ISO-related radius factors, I find radius should, for the most part, track degree of inherent focus. - if photo is taken using the sweet spot with sharp lens, and well focused, then low radius. If not well focused, or very small aperture ( e.g. f/22 - f/56 ...), then +radius. Of course depends on photo and objectives etc, as well.

     

    Cheers,

    Rob

     
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  • Currently Being Moderated
    Jun 14, 2012 3:07 PM   in reply to grampus45

    grampus45 wrote:

     

    Jeff, what's happening at Detail equal to zero?  and how does it (and in what sense) does it provide minimum halos?

     

    Sorry...the best I can tell you is that Detail at zero dampens the edge amount in the sharpening and reduces halos. Somebody on the ACR team would have to decide whether or not the question of exactly HOW it does it could be answered...I wouldn't presume to answer for them. Holding down option/alt when moving the slider will give you a rough preview of the effect.

     
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  • Currently Being Moderated
    Jun 15, 2012 10:37 AM   in reply to grampus45

    It might be helpful if Eric and Jeff could post some suggested Sharpening settings for PV2012:

    perhaps a set of settings  for Portraits; Landscapes; Fine Detail and General Snapshots?

     

    This would at least provide some helpful starting points for Users — and perhaps those settings could be added as Presets to the next ACR upgrade?

     
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  • Currently Being Moderated
    Jun 15, 2012 11:23 AM   in reply to CameraAnn

    Hi Camera Ann,

     

    It might be worth starting another thread to discuss "What are good sharpening settings" for various photos.  Grampus seems to want to keep this thread focused on 'Sharpening Detail' algorithm(s), not "recommended settings"...

     

    Rob

     
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  • Currently Being Moderated
    Jun 15, 2012 5:37 PM   in reply to grampus45

    grampus45 wrote:

     

    I am not the slightest bit interested in what other people do with their sharpening.  What I am trying to find out from Jeff (or some other knowledgable source) is just what the sharpening algorithms in ACR do.

     

    May I ask what is your end game? Strictly curiosity? To be able to better determine optimal sharpener settings? to coordinate sharpening between ACR & other software, or choose between? Investigating on behalf of competing software company?...

     

    ???

     

    Rob

     
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  • Currently Being Moderated
    Jun 15, 2012 6:56 PM   in reply to grampus45

    grampus45 wrote:

     

    Rob Cole wrote:

     

    May I ask what is your end game? Strictly curiosity? To be able to better determine optimal sharpener settings? to coordinate sharpening between ACR & other software, or choose between? Investigating on behalf of competing software company?...

    Simply to understand what's happening under the hood when you move the sliders. To best understand and predict the behavior of what you're doing, it's necssary to have a proper model of what's going on.  The gray-scale images are a big help, but they're an awkward device and a far cry from telling the whole story.

     

    Thanks - it helps some of us to know how to respond, or not, to understand your purpose.

     

     

    grampus45 wrote:

     

    I'm not quite sure how to react to your last sentence: whether to laugh at its insolence or simply to be offended.

     

    Neither. - take it light-heartedly. >90% joke...

     

     

    Cheers,

    Rob

     
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  • Currently Being Moderated
    Jun 15, 2012 7:23 PM   in reply to Rob Cole

    Here are some of Adobe's words describing how the sliders work, from their Help file:

    http://helpx.adobe.com/creative-suite/using/sharpening-noise-reduction -camera-raw.html

     

     

    Amount -- Adjusts edge definition. Increase the Amount value to increase sharpening. A value of zero (0) turns off sharpening. In general, set Amount to a lower value for cleaner images. The adjustment is a variation of Unsharp Mask, which locates pixels that differ from surrounding pixels based on the threshold you specify and increases the pixels’ contrast by the amount you specify. When opening a camera raw image file, the Camera Raw plug-in calculates the threshold to use based on camera model, ISO, and exposure compensation.

     

    Radius -- Adjusts the size of the details that sharpening is applied to. Photos with fine details generally need a lower setting. Photos with larger details can use a larger radius. Using too large a radius generally results in unnatural-looking results.

     

    Detail -- Adjusts how much high-frequency information is sharpened in the image and how much the sharpening process emphasizes edges. Lower settings primarily sharpen edges to remove blurring. Higher values are useful for making the textures in the image more pronounced.

     

    Masking -- Controls an edge mask. With a setting of zero (0), everything in the image receives the same amount of sharpening. With a setting of 100, sharpening is mostly restricted to those areas near the strongest edges. Press Alt (Windows) or Option (Mac OS) while dragging this slider to see the areas to be sharpened (white) versus the areas masked out (black).

     
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  • Noel Carboni
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    Jun 16, 2012 9:35 AM   in reply to grampus45
    Rob Cole wrote:

     

    May I ask what is your end game? Strictly curiosity? To be able to better determine optimal sharpener settings? to coordinate sharpening between ACR & other software, or choose between? Investigating on behalf of competing software company?...

     

    Grampus45, I have to admit I was thinking the same things as Rob. 

     

    I applaud your wanting to know more how it works, to be able to use it most intelligently.  That is a VERY effective way to approach things.  However, in all seriousness Adobe probably isn't going to give you much more.  To do so would be to "spill the beans" about what they're doing inside.  There are a variety of reasons they wouldn't want to do that, not least of which is that they might find a better way to do the same (vaguely described) things in the future.  Describing what they're doing in great detail is that far from promising to continue to do it.

     

    I wasn't really being facetious when I said, about the controls, "move 'em around until you like the way it looks".  This is what seems necessary (to this experienced Camera Raw user) to gain an intuitive visual understanding of what the various controls actually do to your image.  Clearly we're beyond using default or suggested settings here - well into splitting hairs.  The only way you're going to get those hairs split just to YOUR liking is to take all the time you need to try combinations of settings and home in on the ones YOU like best for your defaults AND know what controls to tweak in what situations, based on what you see in an image you're opening.

     

    -Noel

     
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  • Currently Being Moderated
    Jun 16, 2012 9:55 AM   in reply to Noel Carboni

    Noel Carboni wrote:

     

    I wasn't really being facetious when I said, about the controls, "move 'em around until you like the way it looks".  This is what seems necessary (to this experienced Camera Raw user) to gain an intuitive visual understanding of what the various controls actually do to your image.  Clearly we're beyond using default or suggested settings here - well into splitting hairs.  The only way you're going to get those hairs split just to YOUR liking is to take all the time you need to try combinations of settings and home in on the ones YOU like best for your defaults AND know what controls to tweak in what situations, based on what you see in an image you're opening.

    I'm not sure that approach always helps. Like when they introduced all the new NR controls with PV2010. I tried sliding them around and still couldn't work out what they did exactly. Sometimes you need a bit of a clue, so you know what you're looking for, and when to look.

     
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  • Currently Being Moderated
    Jun 16, 2012 5:49 PM   in reply to grampus45

    So, technical details to date:

     

    Detail = 0 => "USM-like".

    Detail = 100 => "Deconvolution-like".

    Detail = 50 => in between...

     

    Now, how to determine optimal settings, for you, and your photo?

     

    In Rob's words:

     

    * Amount - Magnitude of sharpening effect, as dictated by radius, and detail.

    * Radius - How "tightly" the sharpening is "pulled in" around whatever is being considered an edge to be sharpened.

    * Detail - Sharpening algorithm determiner. Algorithm at zero is biased to sharpen object edges, algorithm at 100 is biased to sharpen textural details. In between settings somehow blend or interpolate...

    * Masking: Constructs a "layer mask" which modulates the opacity of the sharpening based on edge analysis... Alt-slider to see mask.

     

    Note: The mask is not influenced by radius nor detail setting.

     

    I have developed what I consider a *very* good feel for how to set these optimally for my taste, through *extensive* trial and error.

     

    Note 2: How you set sharpener sliders is highly influenced by how you set luminance noise reduction sliders.

     

    Rather than recant my own proclivities, I think I'll stop here, except for this:

     

    If you use substantial luminance noise reduction, crank noise reduction detail slider up first to recover detail lost through luminance noise reduction (it can handle going all the way to 100 with no adverse effects), then consider uping the sharpening detail.

     

    Legend: By "you", I mean "if the shoe fits...".

     

    Ciao for now,

    Rob

     
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  • Currently Being Moderated
    Jun 17, 2012 12:32 PM   in reply to Rob Cole

    The complexity of the inter-relationship between the Sliders (as shown in these posts)  is exactly the reason that I suggested that Eric might like to post his suggestions for Sharpening/Detail settings for various kinds of photography and then incorporate those settings as Presets in ACR 7.2..

     

    Providing such Presets would help Users to get a feel for what the sliders actually do, how they relate to each other, and how and when to use particular settings.

     
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  • Currently Being Moderated
    Jun 17, 2012 2:19 PM   in reply to CameraAnn

    Eric's knowledge makes him more qualified to describe sharpening algorithms, obviously, but his preferences for sharpen settings are on a par with any other experienced user's, AFAIK.

     

    Still, I apoplogize for suggesting another thread may be better for such. That was based on Grampus comment that he wasn't interested in suggested settings, but actual algorithms employed.

     

    Anyway, perhaps I've got my nose in where it does not belong again - please forgive.

     

    If the end game is to be able to best sharpen ones photos, then I would think all help for such should be welcome. Eric may or may not come forth here with his words of wisdom...

     

    Cheers,

    Rob

     
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  • Currently Being Moderated
    Jun 17, 2012 8:27 PM   in reply to grampus45

    grampus45 wrote:

     

    The one that indicated that Detail = zero was "USM-like" seems to be old news that Jeff's earlier comment negates.  He now contends that USM is not part of the ACR sharpening model.

     

    Not at all negated. Whatever the algorithm is (and I have *no* idea), it's definitely more like a traditional USM at detail=0, than at detail=100. I said "USM-like" with the quotes as a way to distinguish it from "deconvolution-like", which is at the other end of the spectrum. I really don't think finding the proper "name" for the algorithm, or even reading about how it is "enacted" will help you to determine the settings you like best.

     

    I am a person who craves, and thrives upon understanding what's going on under the hood, but when it comes to sharpening, I think it's entirely academic.

     

    I think Noel nailed this one when he said "play with them until your feel develops" (paraphrased).

     

    I don't think this necessarily applies to all things, but sharpening in ACR: yes.

     

    I think it's best to make your photos look "nicely sharpened" in ACR, but *not* oversharpened. In other words, I don't think it's best practice to stop shy of looking sharp enough in ACR, but I definitely recommend using output sharpening based on output medium, so you are less inclined to oversharpen in ACR (but the proof is in the pudding). Obviously if you are also going to be sharpening using some other software too, or instead, then what I just said does not apply.

     

    I know *exactly* what's going on with that detail slider as it's moved from 0 to 100, from experience, although I'm not qualified to give technical details...

     

    Good luck,

    Rob

     
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    Jun 17, 2012 8:28 PM   in reply to grampus45

    grampus45 wrote:

     

    This would suggest that a significant use of masking would be appropriate in applying capture sharpening.  But many things I read, and many suggested 'presets,' tend to downplay or even ignore masking.

     

    I would argue against the term "significant" and more likely call it a beneficial use of masking. You want to be sharpening edges and generally don't want to sharpen surfaces (which are broad areas of tone/color). The default for masking is zero because, well, Thomas decided that no masking should be applied at default but almost any image will benefit from having some edge masking used.

     

    How much really depends on the edge frequency of the image…if you are shooting portraits you want a fairly high edge masking (40 or above). If you are shooting low ISO landscape images with a high frequency of image texture, you probably want less; 10-25 or so. But…that depends on the amount, radius, detail and noise reduction settings…you really can't give a range of settings for any single parameter because they all depend on each other...

     

    grampus45 wrote:

     

    We know from Bruce Fraser what the general principles of sharpening are.  What we need now is someone like Bruce to write a treatise on how to enact those principles, such as they are possible, with the sharpening facility in ACR. We can attempt to infer what's happening by moving the sliders themselves, but it's really going to take someone with "inside knowledge" to do the job properly. So far we only have vague hand waving.

     

    I did...when I revised Bruce's Real World Image Sharpening book...which came out just before the PV 2010 noise reduction functionality (unfortunately). The aim is to get the image to look good at 1:1. That is the intent and design of the Detail panel in ACR/LR. And yes, it's tough because there are tons of cameras and tons of image types to deal with...yes, it's tough to evaluate just enough sharpening but not too much. You can't accomplish that with a few presets...you need to educate your eyes...no way around that.

     

    And the other 2 phases of image sharpening, creative and output sharpening are further complicating factors. The ACR/LR creative sharpening is primitive but useful. The output sharpening in LR is actually very, very good. It's less good in ACR because of the limitations of the size functionality in ACR. Output sharpening MUST be done at the final output size...and sizing in ACR other than native are problematic.

     

    The bottom line is to make the image look good at 1:1. Don't try to do over/under sharpening in the Detail panel, don't try to sharpen for effect or do creative sharpening and don't worry at all about output sharpening. If you are shooting low ISO on high rez cameras, you can sharpen more aggressively, the smaller the capture size and higher the ISO the more you need to be careful of setting the sharpening and noise reduction correctly.

     

    The only generalizations I can make os that you do want to adjust all of the following; Amount, Radius, Detail, Edge Masking and Luminance Noise Reduction to get an optimal capture sharpening result. The numbers will vary by camera size, lens type, Exposure, ISO and shooting techniques. YMWV...

     
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  • Currently Being Moderated
    Jun 17, 2012 9:20 PM   in reply to grampus45

    Regarding masking:

    ----------------------------

    I know one person who sets default masking at 30, and another who sets it at 70. Optimal setting definitely depends on the image (I use non-zero masking values only occasionally).

     

    I like the priniciple of masking, but not the reality: Unless masking gets 100% in areas of say sky, I think it does more harm than good: there is a dancing (call it: alternation) of unmasked and masked regions that I find more offensive than the noise itself. And in areas where edges meet smooth, sharpening extends just enough beyond the edges into the smooth to produce a twinkling around things that drives me crazy. Some people say they have no idea what I'm talking about, others say "Amen - brother".

     

    Personally, if an image would need masking, I prefer a combination of desharpening (often at exactly -50: details available upon request) and/or now noise reduction in the regions where the noise is offensive, and/or enhanced sharpening in areas of interest (using locals, usually brush).

     

    I'm not disagreeing with Jeff about masking - he's expressed his opinion and his taste - can't be disagreed with... Just saying: I really think each individual needs to discover for themselves how to sharpen things according to their taste.

     

    More regarding detail:

    -------------------------------

    I know some people who always keep detail at zero, never ever above zero. Why? they find it's effect "distasteful". I know some people who often crank it way up. Why? - because they like it's effect. I tend to keep it on the low side usually - that's my taste: I usually like a little (ISO permitting), but not too much... - no right answer me-thinks...

     

    And radius

    ---------------

    To make a long story short, some people tend to prefer smaller ones, others bigger. But also it needs to be balanced with other settings: People who like large amounts and high detail settings, tend to use lower radius... I usually like a larger than average radius, but I often use smaller than average amount and detail.

     

    Cheers,

    Rob

     
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  • Currently Being Moderated
    Jun 18, 2012 9:04 AM   in reply to grampus45

    You're welcome Grampus.

     

    I know my replies did not answer your true question - I can't answer it.

     

    But maybe with some practice you'll find your way to optimal sharpening, even without the understanding you seek.

     

    Or, maybe a satisfying treatise will come along...

     

    Until then,

    Rob

     
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  • Noel Carboni
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    Jun 18, 2012 9:25 AM   in reply to grampus45

    grampus45 wrote:

     

    Thank you, both Jeff and Rob, for replies with some substance. 

     

    I'm not sure whether you meant that as a mild put-down or what, but I find it humorous that Rob has said exactly what I said - basically you have to fool with the settings until you like what you see. 

     

    -Noel

     
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  • Currently Being Moderated
    Jun 25, 2012 8:49 AM   in reply to grampus45

    Hi grampus45 and folks,

     

    Yes, moving Detail towards 100 will use a deconvolution-based method to sharpen the image.  I recommend this only for clean (e.g., high ISO), finely detailed scenes.  It will perform the most detail and texture extraction that it can, with no effort to suppress noise or other anomalies.  Use on portraits at your own peril!   

     

    (The earlier high-detail sharpening method in PV 2003 in Lr 1 and Lr 2 was indeed based on USM.  But that was then and this is now.  )

     
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  • Currently Being Moderated
    Jun 25, 2012 8:55 AM   in reply to MadManChan2000

    MadManChan2000 wrote:

     

    Yes, moving Detail towards 100 will use a deconvolution-based method to sharpen the image.  I recommend this only for clean (e.g., high ISO), finely detailed scenes.

     

     

    I'm pretty sure Eric meant to say (e.g., low ISO)

     

    :~)

     
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  • Currently Being Moderated
    Jun 25, 2012 6:36 PM   in reply to MadManChan2000

    MadManChan2000 wrote:

     

    Yes, moving Detail towards 100 will use a deconvolution-based method to sharpen the image.

    Could someone please explain to me what this "deconvolution-based method" means, and how it differs from other, and what other, methods.

    I've been trying to follow this thread and haven't got a clue what you are all talking about,sorry.

     
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  • Currently Being Moderated
    Jun 25, 2012 7:17 PM   in reply to Andrew_Hart

    Read: Deconvolution on Wikipedia and in particular Richardson-Lucy deconvolution

     

    In basic terms it uses a point spread function (PSF) to "un-blur" a blurred image. ACR's deconvolution processing is very similar to Photoshop's Smart Sharpen when set to the Lens Blur option. It is also the basis for Adobe's tech demo on Image Deblurring that was shown late last year that can be seen on Adobe TV. Note, that demo caused a bit of a controversy because the demo showed a deblurring based on a know synthetic blur that was easier to deblur.

     
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    Jun 25, 2012 7:45 PM   in reply to Jeff Schewe

    Thanks, Jeff.

    Still not completely clear but I'll do your suggested further reading/viewing and see if it then makes more sense.

     
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