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01-14-2020, 12:13 AM   #1
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Image sharpening based on lens optical properties?

I recently exported one out of selected K1 raw files to the print company for a 48" print. After retouching the image (cloning out a few small but unwanted elements) I noticed some elements at the edge of the images were a little fuzzy. Pushing the sharpening sliders improved the situation at edges / corners but the center now looked oversharpned. So I had an idea to have sharpening amount gradually increase from center to edges of the frame to compensate for lens concentric sharpness fall off. To do so I exported two of the same image, with two different sharpening amount, one sharpening amount that suit the center of the image and another sharpening amount to make the image edge look good, then I used a layer mask with gradient transparency so that to mask out the image center of the heavily sharpened image. And that worked great. But that's time consuming. Is there a tool that can gradually sharpen an image from center to edge based on know lens profile such as MTF function at each FL and aperture? (I googled it, and didn't find anything relevant..)

01-14-2020, 12:31 AM - 2 Likes   #2
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QuoteOriginally posted by biz-engineer Quote
Is there a tool that can gradually sharpen an image from center to edge based on know lens profile such as MTF function at each FL and aperture? (
There are plugins that allow for differing sharpening levels in user specified areas of an image, these plugins are rather costly as I recall. Each lens has differing properties, and for pentaxians with the staggering amount of glass we can use on our cameras...rounding up and profiling just one absolutely perfect exemplar of each lens that exists for K mount would be an absolute nightmare... and on top of that, each lens has its own individual optical quirks so even just one profile would be unlikely to provide a 100% perfect solution for all scenarios.

Personally I avoid sharpening the entire image, as it often brings out noise in unwanted areas (especially skies). I use a lot of layers and masking techniques in Photoshop to tweak tonality and sharpening levels on what I think should stand out in the frame.
01-14-2020, 01:22 AM   #3
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My sharpening mindset for large prints is very dependent on the subject. Yes the OPs approach is one I've done and it's not that much extra when other layering and masking is being used normally, but equally a slight drop off in edge sharpness is often needed too. Output sharpening is never a formula, sadly. Sharpening the luminosity only is important as well as sharpening for each type of paper - one paper type will sharpen differently to another, I've found. When I print large I expect to take a lot of time to prepare the master copy for that size. The original is then re-purposed/sharpened differently for a different paper/size. Just my workflow thoughts ...
01-14-2020, 01:27 AM - 1 Like   #4
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..and you have to be really careful when you are sharpening for Gloss paper.

01-14-2020, 02:14 AM - 1 Like   #5
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QuoteOriginally posted by biz-engineer Quote
Is there a tool that can gradually sharpen an image from center to edge based on know lens profile such as MTF function at each FL and aperture? (I googled it, and didn't find anything relevant..)
Rawtherapee's upcoming "Capture Sharpening" at least has an adjustable corner boost to address this. Rawtherapee actually has numerous sharpening options, three distinct ones for distinct purposes: RAW/Capture Sharpening is applied before much of the processing of the image and is, to my understanding, intended to address softness due to diffraction and lens-induced softness. Then there is the Detail/Sharpening for visual accentuation (and for similar purposes wavelet-based sharpening, Detail/Edges ...) and finally sharpening after resizing, to recover losses in e.g. edge sharpness due to interpolation. They do interact in some ways, but with a light-handed approach can be used together.
01-14-2020, 02:15 AM   #6
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... as BarryE and Digitalis said, sharpening with layers is the way to go. Maybe a radial gradiant can you help to control sharpening. Capture One does also a good job with its possibility of using layers with all kind of masks for sharpening.
01-14-2020, 02:21 AM   #7
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I would use a layer in Photoshop to sharpen the image until the edges were acceptably sharp. Then using a layer mask paint over the centre area with a soft brush at low opacity (10%) to reduce the sharpening amount in the centre.

The problem with a profile is that assumes your image is not cropped !
01-14-2020, 02:22 AM - 2 Likes   #8
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DxO's RAW converter PhotoLab Elite (current version is 3.1) employs camera-lens profiles that take into account sharpness fall-off towards the edges as found in DxO's own testing. Those profiles may not be perfect, but they do make it easy to apply a stronger sharpening towards the borders and edges of the frame. Just make sure not to overdo the effect, which can be adjusted, or you end up with artefacts. Piece of cake, really.


Last edited by Madaboutpix; 01-14-2020 at 07:03 AM. Reason: Clarity
01-14-2020, 02:29 AM   #9
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Aside from the Ďtypicalí output sharpening, Iíll sometimes use ACRís selection brush tool to sharpen/emphasise specific areas. I suppose the reverse is also true, in that you could select just the outer portions of an image and selectively sharpen those, but Iím not aware of an automated way of doing it.
01-14-2020, 04:12 AM   #10
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I use several sharpening techniques always on separate layers. I lock the bottom layer as it is my reference point.


QuoteOriginally posted by pschlute Quote
he problem with a profile is that assumes your image is not cropped !
Yes, that can really throw a spanner in the works with automated systems.
01-14-2020, 07:24 AM - 1 Like   #11
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QuoteOriginally posted by Madaboutpix Quote
DxO's RAW converter PhotoLab Elite (current version is 3.1) employs camera-lens profiles that take into account sharpness fall-off towards the edges as found in DxO's own testing. Those profiles may not be perfect, but they do make it easy to apply a stronger sharpening towards the borders and edges of the frame. Just make sure not to overdo the effect, which can be adjusted, or you end up with artefacts. Piece of cake, really.
And you can do selective editing, including sharpening, with photolab. So you could sharpen overall image then if sides needed a little more, just brush on a mask and sharpen only masked area.
01-14-2020, 07:48 AM   #12
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QuoteOriginally posted by 7.62lew Quote
And you can do selective editing, including sharpening, with photolab. So you could sharpen overall image then if sides needed a little more, just brush on a mask and sharpen only masked area.

Exactly. Which helps both with cropped images and less-than-perfect (esp. slightly-decentered) copies of lenses.
01-14-2020, 10:23 AM   #13
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QuoteOriginally posted by JensE Quote
Rawtherapee's upcoming "Capture Sharpening" at least has an adjustable corner boost to address this. Rawtherapee actually has numerous sharpening options, three distinct ones for distinct purposes: RAW/Capture Sharpening is applied before much of the processing of the image and is, to my understanding, intended to address softness due to diffraction and lens-induced softness. Then there is the Detail/Sharpening for visual accentuation (and for similar purposes wavelet-based sharpening, Detail/Edges ...) and finally sharpening after resizing, to recover losses in e.g. edge sharpness due to interpolation. They do interact in some ways, but with a light-handed approach can be used together.
Upcoming as in "I have been using it for months"

There was discussions about auto detection or profiling of corner boost for rawtherapee but I don't know if anything came of it.
01-14-2020, 12:20 PM   #14
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QuoteOriginally posted by house Quote
Upcoming as in "I have been using it for months"There was discussions about auto detection or profiling of corner boost for rawtherapee but I don't know if anything came of it.
Upcoming as in "currently available in development builds". So far (dev branch build dev-5.7_405), I haven't seen any automatic estimation nor profiling.
01-14-2020, 04:24 PM - 1 Like   #15
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QuoteOriginally posted by biz-engineer Quote
I recently exported one out of selected K1 raw files to the print company for a 48" print. After retouching the image (cloning out a few small but unwanted elements) I noticed some elements at the edge of the images were a little fuzzy. Pushing the sharpening sliders improved the situation at edges / corners but the center now looked oversharpned. So I had an idea to have sharpening amount gradually increase from center to edges of the frame to compensate for lens concentric sharpness fall off. To do so I exported two of the same image, with two different sharpening amount, one sharpening amount that suit the center of the image and another sharpening amount to make the image edge look good, then I used a layer mask with gradient transparency so that to mask out the image center of the heavily sharpened image. And that worked great. But that's time consuming. Is there a tool that can gradually sharpen an image from center to edge based on know lens profile such as MTF function at each FL and aperture? (I googled it, and didn't find anything relevant..)
This guy has some interesting videos regarding sharpening and pretty much everything you need when comes to Photoshop. You can start by watching this video and then search for others related to what you want on his channel. I made an action in Photoshop which is structured based on what I shoot, mostly people, but it is adaptable to any kind of images. Among frecvency separation, dodge&burn (2 types of it), color correction, color grade, etc. there's also the sharpening option (it allows me to do local adjustment instead of general sharpening). You can make a few different actions instead of one and apply the one suited for each image. Most of them will be doing local sharpening anyway.

There are some who will sell you the action if you buy their tutorial. I was very interested in learning Photoshop in the last 4 years and the guy from the below video cover in his Youtube videos 70-80% of the methods used by the ones who sell tutorials (like Phlearn for example). If you are interested in buying very good editing tutorials, both Karl Taylor and Michael Woloszynowicz (Vibrant Shot Photography) have great ones. I named them because they shoot both with high resolution medium format cameras and they put more attention to fine details when comes to overall editing than the popular guys from Youtube.

Hope it helps...

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