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Author Topic: Deconvolution sharpening revisited  (Read 110310 times)
eronald
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« Reply #20 on: July 23, 2010, 04:47:43 PM »
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Of course the camera manufacturer may have a very accurate lens and AA filter model ... What Canon DPP's sharpening can do is amazing

Edmund
« Last Edit: July 23, 2010, 04:48:39 PM by eronald » Logged
BartvanderWolf
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« Reply #21 on: July 23, 2010, 05:13:20 PM »
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Quote from: madmanchan
Hi Bart, unfortunately I don't know the answer to that, but I will check with the scientist who does. I believe they limit the number of iterations for speed, so I expect this is the reason it would not be as effective for some parameters as the plug-ins, as you've observed.

Thanks Eric, appreciated. I can imagine that there are a whole lot of other optimizations (e.g. avoiding noise amplification and halo contol) bundled together, so some compromises can be expected. Especially because the user has not the choice of tweaking the inner workings and the PSF shape (other than the 2 basic varieties), those compromises could affect the results. However, even in its current state it's clearly preferable over a regular USM in most cases.

Quote from: madmanchan
Hi Erik, yes, the Gaussian and Lens Blur are different PSFs. The Gaussian is basically just that, and the Lens Blur is effectively simulating a nearly circular aperture (assuming even light distribution within the aperture, very unlike Gaussian). You will get better results with the latter though in many cases they are admittedly subtle.

That's correct. It is underestimated by many how devastating de-focus is for microdetail at the pixel level, and then there's DOF. In fact, most of the image is usually defocused to a certain degree. In addition there is the influence of the residual lens aberrations and diffraction, and it also varies throughout the image. Then there may be a bit of camera shake and motion blur, and we have a pretty messed up PSF. Then to think that the sampling density of Red and Blue is different from Green on sensors with a CFA, and the Raw converter adds it's non-linear adaptive interpolation, it's pretty amazing what we can do. The OLPF is just one parameter in the whole mix, but it does help to create a more predictable (better behaved) signal.

Cheers,
Bart
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BartvanderWolf
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« Reply #22 on: July 23, 2010, 05:25:33 PM »
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Quote from: ejmartin
In a word, no.  Aliasing is a shifting of image content from one frequency band to another that is an artifact of discrete sampling.  Deconvolution doesn't introduce aliasing (ie shift frequencies around) so much as try to reverse some of the suppression of high frequency image content that the AA filter effects in its effort to mitigate aliasing.

While that is correct, there may be aliased spatial frequencies that are rendered as larger detail which happens to correspond to the non-aliased detail we are trying to sharpen. So while it won't introduce aliasing, it will 'enhance' some of the already aliased detail. One also needs to watch out for introducing stairstepping in e.g. powerlines, sharp edges at an angle, and other high contrast fine detail. Working on a luminosity blending layer with blend-if applied to spare the highest contrast edges will help to reduce those artifacts.

Cheers,
Bart
« Last Edit: July 23, 2010, 06:42:26 PM by BartvanderWolf » Logged
hcubell
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« Reply #23 on: July 23, 2010, 07:56:16 PM »
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The R-L Deconvolution sharpening tool in Raw Developer often produces exceptional results. It is so crazy that Adobe, with all its resources, does not offer it as an option in Photoshop.
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BernardLanguillier
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« Reply #24 on: July 23, 2010, 08:23:01 PM »
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Quote from: bjanes
the deconvolution sharpening (more properly image restoration) with the Mac only raw converter Raw Developer markedly improves the micro-contrast of the D3x image to the point that it rivals that of the Leica S2.

Yep, I have been using raw developper deconvolution for a few years now. It works great and was actually one of the reasons why I switched to Mac.

One of the reasons why it works so well with the D3x is the very low amount of noise in mid-tones/shadows at low ISO. With lesser sensor you end up sharpening noise also. This comes on top of an AA filter than is weaker than average (but yet manages to avoid moire in all but the most extreme situations).

Couple this with a lens like the Zeiss 100mm f2.0 that has amazing micro-contrast at f5.6-f8 and you have detail rendition that is a lot closer to non AA filter sensors than many seem to believe. You introduce some artifacts also though, but you have the freedom to tune the sharpness/artifacts ratio which you don't with a AA filter less sensors.

Nothing is new here though, D3x users have been reporting on this for 1.5 years now.  

Cheers,
Bernard
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A few images online here!
deejjjaaaa
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« Reply #25 on: July 23, 2010, 09:39:39 PM »
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Quote from: madmanchan
Yes Photoshop's Smart Sharpen is based on deconvolution (but you will need to choose the "More Accurate" option and the Lens Blur kernel for best results). Same with Camera Raw 6 and Lightroom 3 if you ramp up the Detail slider.

Eric - does it mean that after some certain value (>25, >50, > Huh) set by the Detail Slider in ACR you switch the sharpening completely from some variety of USM to some variety of deconvolution ? can you tell what this value has to be (if it is fixed) or it depends on the specific combination of exif parameters (camera model, iso, aperture value, etc)... or you are somehow blending the output of two methods going gradually from some variety of USM to deconvolution as the slider is moved to the right ?

please clariy, thank you.
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ziocan
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« Reply #26 on: July 23, 2010, 11:26:21 PM »
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Quote from: hcubell
The R-L Deconvolution sharpening tool in Raw Developer often produces exceptional results. It is so crazy that Adobe, with all its resources, does not offer it as an option in Photoshop.
Smart sharpen in Photoshop and the sharpening tool in LR offer the same kind of exceptional results.
IMO they also give slightly better results since they have more parameters.

For some work flows, sharpening during the raw conversion is not an option. In that case Photoshop "smart sharpen" or others plugs in for PS, are the only options.

I often see threads about the marvels made by sharpening plugs in, or raw converters, but I have have hardly seen anything doing it better than photoshop "smart sharpen".
At best they are equal.
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ziocan
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« Reply #27 on: July 23, 2010, 11:32:30 PM »
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Quote from: deja
Eric - does it mean that after some certain value (>25, >50, > Huh) set by the Detail Slider in ACR you switch the sharpening completely from some variety of USM to some variety of deconvolution ? can you tell what this value has to be (if it is fixed) or it depends on the specific combination of exif parameters (camera model, iso, aperture value, etc)... or you are somehow blending the output of two methods going gradually from some variety of USM to deconvolution as the slider is moved to the right ?

please clariy, thank you.
well, if you load up an image in LR and do some tests, you may be able to find it out by yourself.

anyway, how can it be fixed?
How a camera model, iso or aperture determine fixed parameters?

every image needs its own parameters, because every image is focused on its own way, has it is own texture and surfaces. not to mention that two images taken with the exact same equipment but focussed slightly different (they all are) will need different sharpening parameters.

I think trial and error and some experiments will give you the best answer to your question.
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ErikKaffehr
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« Reply #28 on: July 24, 2010, 01:40:19 AM »
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Hi Eric,

I actually tried to forget about Zeiss articles, as I recalled that the shape shown there was quite ugly ;-)

Best regards
Erik



Quote from: madmanchan
Hi Bart, unfortunately I don't know the answer to that, but I will check with the scientist who does. I believe they limit the number of iterations for speed, so I expect this is the reason it would not be as effective for some parameters as the plug-ins, as you've observed.

Hi Erik, yes, the Gaussian and Lens Blur are different PSFs. The Gaussian is basically just that, and the Lens Blur is effectively simulating a nearly circular aperture (assuming even light distribution within the aperture, very unlike Gaussian). You will get better results with the latter though in many cases they are admittedly subtle. The OLP filter can be somewhat complex to model. (I believe the Zeiss articles you've referenced recently have some nice images showing how gnarly they can be. I recall it was in the first of the two MTF articles). Gaussians are handy because they have convenient mathematical properties but not the best for modeling this, unfortunately ...
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Jack Flesher
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« Reply #29 on: July 24, 2010, 02:55:24 AM »
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Quote from: ziocan
I often see threads about the marvels made by sharpening plugs in, or raw converters, but I have have hardly seen anything doing it better than photoshop "smart sharpen".
At best they are equal.

Agreed.  I'd even take it one step further -- on cameras with no AA or OLP filter, some raw converters (my favorite is C1) do such an excellent job with sharpening that nothing further is need in CS until your desired output sharpening step.  I no longer do any initial sharpening in CS with my Phase files for this reason.

Cheers,
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bjanes
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« Reply #30 on: July 24, 2010, 08:19:20 AM »
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Quote from: madmanchan
Yes Photoshop's Smart Sharpen is based on deconvolution (but you will need to choose the "More Accurate" option and the Lens Blur kernel for best results). Same with Camera Raw 6 and Lightroom 3 if you ramp up the Detail slider.
Eric,

Thanks for the information. The behavior of the sliders appears to be quite different from the older versions of ACR. In Real World Camera Raw with Adobe Photoshop CS4, Jeff Schewe states that if one moves the detail slider all the way to the right, the results are very similar but not exactly the same that would be obtained with the unsharp mask.

The following observations are likely nothing new to you, but may be of interest to others. The slanted edge target (a black on white transition at a slight angle) is an ISO certified method of determining MTF and is used in Imatest. Here is an example with the Nikon D3 using ACR 6.1 without sharpening (far right), with and with ACR sharpening set to 50, 1, 50 [amount, radius, detail] (middle) and with deconvolution sharpening using Focus Magic with a blur width of 2 pixels and amount of 100%. The images used for measurement are cropped. so the per picture height measurements are for the cropped images.

[attachment=23291:Comp1_images.gif]

One can analyze the black-white transition with Imatest, which determines the pixel interval for a rise in intensity at the interface from 10 to 90%. Results are shown for Focus Magic and ACR sharpening with the above settings. The results are similar. With real world images with this camera (previously posted in a discussion with Mark Segal), I have not noted much difference between optimally sharpened images using ACR and Focus Magic, contrary to the results reported by Diglloyd using the Richardson-Lucy algorithm. Perhaps the Focus Magic algorithm is inferior to the RL. Diglloyd used Smart Sharpen for comparison and did not test ACR 6 sharpening.

[attachment=23292:CompACR_FM_1.gif]

One can look at the effect of the detail slider by using ACR sharpening settings of 100, 1, 100 (left) and 100, 1, 0 (right). The detail setting of zero dampens the overshoot.

[attachment=23293:CompACR.gif]





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bjanes
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« Reply #31 on: July 24, 2010, 08:24:06 AM »
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Quote from: ziocan
Smart sharpen in Photoshop and the sharpening tool in LR offer the same kind of exceptional results.
IMO they also give slightly better results since they have more parameters.

For some work flows, sharpening during the raw conversion is not an option. In that case Photoshop "smart sharpen" or others plugs in for PS, are the only options.

I often see threads about the marvels made by sharpening plugs in, or raw converters, but I have have hardly seen anything doing it better than photoshop "smart sharpen".
At best they are equal.
That may be your experience, but have you tried Richardson-Lucy with a camera having a blur filter? Digilloyd did compare smart sharpen to RL, and found the latter to be much better. Perhaps he did not use optimal settings, but he is a very careful worker and I would not dismiss his results out of hand.
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madmanchan
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« Reply #32 on: July 24, 2010, 08:29:40 AM »
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Quote from: deja
Eric - does it mean that after some certain value (>25, >50, > Huh) set by the Detail Slider in ACR you switch the sharpening completely from some variety of USM to some variety of deconvolution ? can you tell what this value has to be (if it is fixed) or it depends on the specific combination of exif parameters (camera model, iso, aperture value, etc)... or you are somehow blending the output of two methods going gradually from some variety of USM to deconvolution as the slider is moved to the right ?

please clariy, thank you.

Hi Deja, yes, the sharpening in CR 6 / LR 3 is a continuous blend of methods (with Detail slider being the one used to "tween" between the methods, and the Amount, Radius, & Masking used to control the parameters fed into the methods). As you ramp up the Detail slider to higher values, the deconvolution-based method gets more weight. If you're interested in only the deconv method then just set Detail to 100 (which is what I do for low-ISO high-detail landscape images). Not recommended for portraits, though ...  
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madmanchan
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« Reply #33 on: July 24, 2010, 08:37:43 AM »
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Hi Bill, thanks for doing this; your studies and results match my expectations. At higher Detail settings, CR 6 & LR 3 should be closer in behavior to PS's Smart Sharpen, though a little better IMO. There are some differences due to the raw-based design of the former (we have the luxury applying the sharpening at a stage of the imaging pipeline where the signal characteristics are better understood, whereas PS's SS is necessarily at the mercy of whatever processing has already been done to the image, and hence can't really assume anything).
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deejjjaaaa
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« Reply #34 on: July 24, 2010, 09:46:22 AM »
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Quote from: ziocan
well, if you load up an image in LR and do some tests, you may be able to find it out by yourself.

thank you for the suggestion, but I was interested to hear from the developer himself.

Quote from: ziocan
anyway, how can it be fixed?

very simple :

if (slider < 50)
{
   // code to execute if condition is true
}
else
{
   // code to execute if condition is false
}

Quote from: ziocan
How a camera model, iso or aperture determine fixed parameters?

I was talking about if exif parameters will be used in the following manner -> for example high ISO = more noise detected/expected = lesser blending with deconvolution method, etc

Quote from: ziocan
I think trial and error and some experiments will give you the best answer to your question.

certainly - but now that we have some answer I can do trial & error w/ what Eric said in mind
« Last Edit: July 24, 2010, 09:48:08 AM by deja » Logged
walter.sk
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« Reply #35 on: July 24, 2010, 10:39:03 AM »
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Quote from: madmanchan
Hi Deja, yes, the sharpening in CR 6 / LR 3 is a continuous blend of methods (with Detail slider being the one used to "tween" between the methods, and the Amount, Radius, & Masking used to control the parameters fed into the methods). As you ramp up the Detail slider to higher values, the deconvolution-based method gets more weight. If you're interested in only the deconv method then just set Detail to 100 (which is what I do for low-ISO high-detail landscape images). Not recommended for portraits, though ...  
If one were to set the Detail to 100, would this carry through to the Sharpening slider when using the Adjustment Brush in ACR?  If so, that would go a long way toward selective application of the deconvolution method, possibly as good as painting it in from a layer mask.
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bjanes
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« Reply #36 on: July 24, 2010, 12:50:41 PM »
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Quote from: madmanchan
Hi Deja, yes, the sharpening in CR 6 / LR 3 is a continuous blend of methods (with Detail slider being the one used to "tween" between the methods, and the Amount, Radius, & Masking used to control the parameters fed into the methods). As you ramp up the Detail slider to higher values, the deconvolution-based method gets more weight. If you're interested in only the deconv method then just set Detail to 100 (which is what I do for low-ISO high-detail landscape images). Not recommended for portraits, though ...  
Based on your information, I experimented for sharpening with ACR to reproduce the results posted by Diglloyd in in his blog. I used 41-1-100 (amount, radius, detail). The results are pretty close. I hope that this is fair use of Diglloyd's copyright. If there are any complaints, the post can be deleted. I think that the topic is important, though.

[attachment=23300:ACR_RL.jpg]
« Last Edit: July 24, 2010, 07:42:01 PM by bjanes » Logged
ejmartin
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« Reply #37 on: July 24, 2010, 01:12:31 PM »
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Quote from: bjanes
Based on your information, I experimented for sharpening with ACR to reproduce the results posted by Diglloyd in in his blog. I used 41-1-0 (amount, radius, detail). The results are pretty close. I hope that this is fair use of Diglloyd's copyright. If there are any complaints, the post can be deleted. I think that the topic is important, though.

Sorry, don't you want the detail at 100 if you're trying to use the deconvolution part of ACR sharpening?
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emil
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« Reply #38 on: July 24, 2010, 01:15:31 PM »
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Quote from: bjanes
I used 41-1-0 (amount, radius, detail). The results are pretty close.

Hi Bill,

Based on what I see, the radius 1.0 seems to be a bit too large. This is confirmed by the earlier Imatest SFR output that you posted (SFR_20080419_0003_ACR_100_1_100.tif), where the 0.3 cycles/pixel resolution was boosted. Perhaps something like a 0.6 or 0.7 radius is more appropriate to boost the higher spatial frequencies (lower frequencies will also be boosted by that).

Cheers,
Bart
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madmanchan
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« Reply #39 on: July 24, 2010, 01:39:43 PM »
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Yes, it looks like Bill made a typo in the post (the screenshot values say 43, 1, 100, as opposed to 41,1,0). For this type of image I do recommend a value below 1 for the Radius, though 1 is not a bad starting point.
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