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Author Topic: Sharpening ... Not the Generally Accepted Way!  (Read 45817 times)

digitaldog

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Re: Sharpening ... Not the Generally Accepted Way!
« Reply #40 on: August 10, 2014, 01:39:11 pm »

... all you're doing is saying you can't be bothered to check it out because it doesn't fit in with your workflow.
But in my case I use inkjet printers and I never want to output sharpen with a radius of more than 2 or 3 (for 'creative' sharpening, maybe, but that's another story).  
And that's the problem for some of us. We do output to many other devices than just an ink jet. Heck, output sharpening for display is pretty common for me. Ditto with halftone work. I simply can't have a workflow that is only directed to ink jet output.
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Andrew Rodney
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Mark D Segal

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Re: Sharpening ... Not the Generally Accepted Way!
« Reply #41 on: August 10, 2014, 02:27:28 pm »

"Snappy and Sharp" applies to the final sharpened image, printed or for web or for whatever medium, not for 'capture' sharpening (again, this is consistent with Schewe's workflow, I believe).

Yes, that is what I meant.

Regarding the empirical principles etc., etc., it seems to me that I have been doing a lot of testing and that I've offered not only examples, but actions for you guys to check out my suggestions . But so far no one has actually given an example testing a one-pass sharpen against a two-pass sharpen and shown that the two-pass is clearly superior, and under what conditions.

My suggestion was that since you are proposing this option you should be the one doing the rigorous testing. I could download your action and use it, time permitting - I've got a very full plate - but to give it justice I would need to do a lot of very well-conceptualized testing, which unfortunately I don't have time for just now; recall this is all voluntary. I would feel more compelled to make the time if I saw obvious deficiencies in the LR sharpening workflow, but quite frankly I don't. Maybe that's also why there hasen't been a chorus of volunteers. All the more reason why the onus of proof of concept is on you.

And I have certainly not suggested that a one-pass approach is SYSTEMATICALLY superior ... or even that it is superior at all.  I personally think, both from tests and from logic, that it will be better in some cases and worse in others.  If that is true (which you can check out for yourself if you're interested) then surely that is a useful bit of information?  If you knew that for, let's say, images that are upscaled, that you are better off leaving the 'capture sharpening' to after the resize, and that if you did this you would probably have some improvement in the quality of your output, would you not at least consider sharpening after resize rather than before?

Robert, that is part of the problem with what you are proposing. Why not just use one approach systematically and be done with it? The toolset available in LR/ACR and Photokit Sharpener is designed to handle just about anything, systematically. After learning to handle that toolset very well, I doubt one would need or do much better with anything else - unless a deconvolution approach were needed to handle blur.

Part of the problem with this whole discussion is that some of you seem to think that I am criticizing an established workflow by the gurus of the industry (including Bruce Fraser, who is no longer with us sadly).  That may to some extent be the case, but in reality it boils down to 'do you sharpen before or after resizing?'.  The reason I say that is that if you sharpen after resizing then it gives you the opportunity (if it is appropriate) to sharpen only once.

I'm not part of that problem, nor am I sure who is. But for sake of greater clarity, I have no problem with criticizing established anything from anyone. It only depends on the substance of critique.

Unless the 'before resizing' corrects flaws in the original image (due, for example, to the blurring caused by the anti-aliasing filter) there seems no logical reason to apply it before resizing, and good logical reason to apply it after.  In my testing (admittedly limited) I can see no benefit to applying it before.  Since almost all of our photos will be resized before output to the web or print, it then follows that if this is true, you are better off resizing and then sharpening.

There are always flaw in the original image - as you say, the AA filter being one source of reduced acutance at the capture stage. If you read Chapter Two of Schewe's book you would see the point. Turning to Output sharpening, one is in any case be it PKS or LR, doing output sharpening as a function of pixel size. That happens on the fly in LR and on layers in PKS.

So let's say that the conclusion is that two types of sharpening are typically beneficial with the current 'sharpening' technology: one with a small radius to 'recover' fine detail, and one with a higher radius, to give the output a boosted impression of sharpness and crispness.  I think this may well be so at times.  Then, I, personally, would resize, sharpen with a small radius and then sharpen with a higher radius.  This does not fit in with the Lightroom model, because Lightroom is strictly 1st phase sharpen, followed by resize, followed by (optional) 2nd phase sharpen.

Yes, that is how Lightroom is designed to be normally used, because between the imaging scientists on the Adobe Camera Raw team (photographers who know image quality and are brilliant mathematicians on a world scale) and the highly experienced developers in Pixelgenius, it was their combined evaluation that this is indeed the optimal processing approach for most of what LR is designed to do. But it is not really "followed by, followed by...." from a user perspective, as you undoubtedly know. The user can dial any of this stuff into the metadata in any order and the application applies adjustments in the correct sequence under the hood. We don't need to worry about sequencing - part of the application's design philosophy - it relieves the users of fiddling with that which users definitely need not control.

If you do not sharpen in Lightroom, then, in Photoshop, you can use one-pass sharpen where appropriate, and two-pass sharpen if you think this would be beneficial.  There is nothing that I am aware of in PK Sharpen to prevent you from doing this, since it's a Photoshop set of actions.

Yes agreed, we can handle all this any way we want. As well in LR we have options about what sharpening to use or not use at either stage.

I would have thought that one of the great benefits of a forum like this one is that it has many very experience members, who could take a suggestion like this one and demonstrate that it is nonsense, or that it is sometimes good, or that it's the best thing since sliced bread (as a home baker I would have to question that analogy  :)).  

Robert, I agree - that is one of the benefits of this forum, and it is one of the better ones around. There are highly experienced people who visit here and help each other. You are clearly a serious professional and the "rules" within such a peer group don't call for proving a concept to be nonsense - unless of course it so obviously is. But I for one am not saying that. Others may not agree with my criteria in respect of a sharpening workflow - they happen to be very closely aligned with what Jeff said above, for whatever that is worth -  "repeatable and consistent workflow without a lot of gyrations". I don't want to be bothered even thinking about whether an image deserves a one pass or a two pass solution. Once I know how to handle two pass properly, and understanding what I think I do about the underlying logic, I just do it. From my experience editing countless numbers of photographs for the past 14 years that I've been doing digital imaging whether from scanners or DSLRs, I think it's the most efficient and effective path to sharpness I've ever used. But taking into account the value-added of sacrificing the benefits of a self-contained raw workflow, if you convincingly demonstrate a better mouse-trap in terms of both process and results, that's fine.



Robert - I've responded in italics above for ease of following the conversation.
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Mark D Segal (formerly MarkDS)
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Robert Ardill

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Re: Sharpening ... Not the Generally Accepted Way!
« Reply #42 on: August 10, 2014, 03:14:52 pm »

I'll reply to both of you (Mark and Andrew) at the same time as you are essentially making the same point, I think: you both want a consistent workflow that covers all of the different media and technologies you use, and you're happy with your current workflow, and believe that it is the best workflow for sharpening and resizing.

Well of course I have no issue with that at all.  And I’m sure I would be very resistant to someone telling me that I should change my workflow … without demonstrating that what I was doing was sub-optimal, at any rate.

So, to be clear, I’m not at all suggesting that anyone should change their workflow to cut out capture sharpening. 

My post was more like “Hey, what do you think, could it be that we can sharpen just the once? Could there be some benefit to sharpening as little and as few times as possible?”

The thing is … that leaving out a step in a workflow doesn’t mean that you have abandoned or changed your workflow.  You could think of it like this: “I’m going to stick with my workflow and apply capture sharpening as I always do, but for this image I’m going to set the sharpening strength to 0).

As you are both, no doubt, working on many images a week, perhaps you could try it on one and see how you get on. 

Robert

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Mark D Segal

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Re: Sharpening ... Not the Generally Accepted Way!
« Reply #43 on: August 10, 2014, 03:20:44 pm »

Thanks Robert, that's clear and I could do that, but it would not be determinative unless it were thoroughly tested on a properly stratified sample of photographs. And in LR the only place one has real control over sharpening is at the capture stage.
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Mark D Segal (formerly MarkDS)
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Fine_Art

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Re: Sharpening ... Not the Generally Accepted Way!
« Reply #44 on: August 10, 2014, 03:43:56 pm »

It seems to me that capture sharpening is best done with deconvolution. Output sharpening is to reverse the bleeding of inks from the print process. Someone should be able to take an input image, print, scan, determine the PSF of their printer, then deconvolve that to get back close to the original. Once you know the printer PSF you can correct for it in all your output. Again, deconvolution is the tool.

The only thing left is creative sharpening, which, as Bart says, is mostly contrast/clarity adjustment.

A new photoshop action doesnt seem to advance anything. The main claim to fame is, if I follow the thread, a 1 step sharpening process. IMO people are willing to put a lot of effort into their best images. The average throwaway image usually sits on a hard drive as a raw that never gets printed.
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Robert Ardill

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Re: Sharpening ... Not the Generally Accepted Way!
« Reply #45 on: August 10, 2014, 04:22:32 pm »

It seems to me that capture sharpening is best done with deconvolution.

Yes, exactly ... the problem is we don't currently have the tools to do that (perhaps some of them, but the overall problem is quite complex because there are many reasons for the loss of detail in the image, and these all need to be known for the image to be properly 'fixed' with deconvolution).  Also, I wonder ... and perhaps Bart could answer this ... whether or not a deconvolution function would be any more effective than an unsharp mask, carefully tuned, for blurring due to the AA filter.)

Output sharpening is to reverse the bleeding of inks from the print process.


Weeelll ... is that entirely true?  Emphasizing edges (beyond compensation for ink bleed) will create an impression of sharpness - and that isn't strictly 'creative sharpening' ... although of course there's no reason why you couldn't call it that.

A new photoshop action doesnt seem to advance anything. The main claim to fame is, if I follow the thread, a 1 step sharpening process. IMO people are willing to put a lot of effort into their best images. The average throwaway image usually sits on a hard drive as a raw that never gets printed.

The Ps action I put a link to is just a test tool and it can advance things as it gives an easy mechanism to do some comparative sharpening tests.  

There is no claim to fame at all here - as I've said, it's just a question: "Is a 2-step sharpening process always necessary, given our currently available technology?".  I hardly think I'm the first person to have suggested a one-pass sharpening!!  No doubt this is what everyone did before the 2 or 3 pass sharpening came into vogue.

Robert
« Last Edit: August 10, 2014, 04:47:35 pm by Robert Ardill »
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Mark D Segal

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Re: Sharpening ... Not the Generally Accepted Way!
« Reply #46 on: August 10, 2014, 04:28:15 pm »

It seems to me that capture sharpening is best done with deconvolution. Output sharpening is to reverse the bleeding of inks from the print process. Someone should be able to take an input image, print, scan, determine the PSF of their printer, then deconvolve that to get back close to the original. Once you know the printer PSF you can correct for it in all your output. Again, deconvolution is the tool.

The only thing left is creative sharpening, which, as Bart says, is mostly contrast/clarity adjustment.

A new photoshop action doesnt seem to advance anything. The main claim to fame is, if I follow the thread, a 1 step sharpening process. IMO people are willing to put a lot of effort into their best images. The average throwaway image usually sits on a hard drive as a raw that never gets printed.

There's more to output sharpening than what you say here. Ref. Chapters Two and Three of Schewe's book on the subject.

I would be interested to see comparison testing you've done on the relative merits of deconvolution sharpening versus acutance recovery on a range of images having different frequency of detail, and I'd also be interested to know how much sweat-equity you had to put into determining the "printer PSF".
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Mark D Segal (formerly MarkDS)
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Fine_Art

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Re: Sharpening ... Not the Generally Accepted Way!
« Reply #47 on: August 10, 2014, 04:35:29 pm »

The "Sweat equity" is the same for deconvolving your camera-lens system and for the printer. You need an artificial "star" based on how astronomers do it. Any bright light behind a pinhole will do. The pinhole has to be far enough away that your lens images it as a point (from 1 pixel to 3x3) . The spreading of the point is your PSF from the camera-lens system. It's even easier with the printer to begin with, you can make a graphics point. Of course you have to scan it so the work is about the same.
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Schewe

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Re: Sharpening ... Not the Generally Accepted Way!
« Reply #48 on: August 10, 2014, 04:40:33 pm »

Well at least Andrew gave a reason for why he believes this approach is wrong ... all you're doing is saying you can't be bothered to check it out because it doesn't fit in with your workflow.

Correct...and it's a rabbit hole I've lived in before–no need for me to go back down.

The part you are missing in capture sharpening in ACR/LR is that with the Detail slider moved to the right (above 25) you move towards employing deconvolution sharpening. With the Detail slider at 100, it's all deconvolution (similar to Smart Sharpen's Lens Blur removal). With the type of high frequency and high rez images I usually work on, ACR/LR does a very nice job of capture sharpening and the built in edge masking is quite good!

But, there's a flip side to the coin of sharpening and that's noise reduction. Noise reduction is best done prior to sharpening (and I believe the pipeline ACR/LR puts it there). Anytime you sharpen you need to apply a certain degree of noise reduction. Obviously, you need it with higher ISO shots, but you also need it whenever the base image is lightened to help mitigate the increased shadow noise. Even with low ISO captures on my Phase One IQ180 captures, I generally use a very gentle noise reduction to help smooth out any increased noise perceptibility due to sharpening–particularly with high Detail settings.

In terms of output sharpening, I tend to use image sizes that are near the native capture resolution. Sure I resize a tad to get the print size correct, but it's rather unusual for me to have to make big resolution jumps. This slight resizing is done before the LR output sharpening is done–which again is the reason I print from LR.

So, sorry, I'm just not all that interested in stepping backward into a single sharpening workflow...the tools we have now are just so much better than that.
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Fine_Art

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Re: Sharpening ... Not the Generally Accepted Way!
« Reply #49 on: August 10, 2014, 04:41:31 pm »

There is a thread on comparisons with many images posted by Bart, Roger Clark (with links to his site clarkvision), myself and others.

Post a small crop out of any image. Chances are people using deconvolve methods can beat anything done in LR/ACR. I wont say photoshop because it has a function for a custom PSF. It's biggest issue is it cannot iterate in that dialog box.
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Schewe

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Re: Sharpening ... Not the Generally Accepted Way!
« Reply #50 on: August 10, 2014, 04:45:04 pm »

Chances are people using deconvolve methods can beat anything done in LR/ACR.

I guess you don't remember that with the Detail slider moved to the right ACR/LR employs deconvolution similar to the Lens Blur function of Smart Sharpen. No, you can't change the PSF but you can blend the amount of deconvolution by adjusting the slider number. At 50 it's about 1/2 deconvolution and 1/2 halo suppression...then by adjusting the amount and radius (and masking) you have good control over the capture sharpening.
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digitaldog

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Re: Sharpening ... Not the Generally Accepted Way!
« Reply #51 on: August 10, 2014, 04:46:04 pm »

Chances are people using deconvolve methods can beat anything done in LR/ACR.
Yet the last post by Jeff indicates LR/ACR can do just that. Confused...
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Andrew Rodney
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Fine_Art

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Re: Sharpening ... Not the Generally Accepted Way!
« Reply #52 on: August 10, 2014, 04:50:29 pm »

I guess you don't remember that with the Detail slider moved to the right ACR/LR employs deconvolution similar to the Lens Blur function of Smart Sharpen. No, you can't change the PSF but you can blend the amount of deconvolution by adjusting the slider number. At 50 it's about 1/2 deconvolution and 1/2 halo suppression...then by adjusting the amount and radius (and masking) you have good control over the capture sharpening.

Ok, but there are many deconvolution methods. The one you pick, you may even use several, is based on the image. You DO need control. So based on that I still think it is highly likely I can beat any ACR?LR general function with known deconvolve routines.

I often use a custom PSF, an adaptive Richardson-Lucy, a VanCittert. Also wavelets.
« Last Edit: August 10, 2014, 05:08:35 pm by Fine_Art »
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Fine_Art

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Re: Sharpening ... Not the Generally Accepted Way!
« Reply #53 on: August 10, 2014, 04:53:57 pm »

Yet the last post by Jeff indicates LR/ACR can do just that. Confused...

See the next post then try studying the various methods.
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Mark D Segal

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Re: Sharpening ... Not the Generally Accepted Way!
« Reply #54 on: August 10, 2014, 04:54:24 pm »

Can you post some examples or make some comparison files available for download?
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Mark D Segal (formerly MarkDS)
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digitaldog

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Re: Sharpening ... Not the Generally Accepted Way!
« Reply #55 on: August 10, 2014, 04:57:19 pm »

See the next post then try studying the various methods.
I see that your original text:Chances are people using deconvolve methods can beat anything done in LR/ACR, needed further clarification.
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Andrew Rodney
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Robert Ardill

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Re: Sharpening ... Not the Generally Accepted Way!
« Reply #56 on: August 10, 2014, 04:58:06 pm »

Yet the last post by Jeff indicates LR/ACR can do just that. Confused...

Me too  :).  I don't see how the Lr sharpening can use deconvolution since it doesn't know what the image has been convolved with.  Perhaps at this stage Bart or someone who knows about deconvolution could explain the maths for something relatively known like an AA filter?

RObert
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bjanes

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Re: Sharpening ... Not the Generally Accepted Way!
« Reply #57 on: August 10, 2014, 04:59:15 pm »

Yes, exactly ... the problem is we don't currently have the tools to do that (perhaps some of them, but the overall problem is quite complex because there are many reasons for the loss of detail in the image, and these all need to be known for the image to be properly 'fixed' with deconvolution.  Still, it should be well possible to fix specific issues like the anti-aliasing blurring for each camera model).

That is correct, as our resident deconvolution guru, Bart van der Wolf, has pointed out, since a number of sources of blur are convolved together in blurring a typical image, a Gaussian PSF often works reasonably well for deconvolution. He has produced a PSF generator from which custom PSFs can be geneated. While Bruce, Jeff, and the other PixelGenius workers have done some excellent work, but in the 21st century perhaps it is time to progress beyond the 50 year or older unsharpmask and the slightly newer high pass filter with an overlay blending mode. These processes are described in their sharpening books and I think are used with PhotoKit sharpener and with some of the LR/ACR sharpening algorithms. Eric Chan has implemented some deconvolution algorithms for capture sharpening in ACR/LR, but there is no control of the PSFs used for the deconvolution.

Bill
« Last Edit: August 10, 2014, 05:04:55 pm by bjanes »
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Fine_Art

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Re: Sharpening ... Not the Generally Accepted Way!
« Reply #58 on: August 10, 2014, 05:01:30 pm »

I see that your original text:Chances are people using deconvolve methods can beat anything done in LR/ACR, needed further clarification.

Fair enough.

Here is one page that shows several methods from one blurry image.

http://www.deconvolve.net/bialith/Research/BARclockblur.htm

corrected typo.
« Last Edit: August 10, 2014, 05:03:28 pm by Fine_Art »
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digitaldog

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Re: Sharpening ... Not the Generally Accepted Way!
« Reply #59 on: August 10, 2014, 05:02:08 pm »

USM as it's done in Photoshop and elsewhere is 50 years old?

Maybe Eric and Bart can comment on the lack of control of PSFs.
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Andrew Rodney
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