Lightroom/Camera Raw: lens sharpness fall-off correction

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  • Updated 4 years ago
For some photos, having sharpness vary from center to edge/corners detracts from the look/quality of the photo.

I'd be happy with a manual solution that has parameters like for vignette correction, except allows one to increase radius and amount of sharpening in the outward direction. On the other hand, an automated lens profile based solution would be hard to argue with...

(At a minimum please allow independent local sharpen settings so it can be corrected somewhat using a brush)

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Rob Cole

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  • wishing for more even sharpness

Posted 7 years ago

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Lee Jay

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"At a minimum please allow independent local sharpen settings so it can be corrected somewhat using a brush"
I really think that approach is pretty ineffective on this problem. Off-axis blur requires a whole different sharpening approach (deconvolution) to correct with any real effectiveness.
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Rob Cole

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Although theoretically its not as rigorous to correct sharpness falloff by doing ordinary sharpening with increasing radius and amount, one can tell exactly how effective it would be simply by trying it. i.e. sharpen the outside at higher radius and amount (detail to taste...) and compare to the inside (use a virtual copy or before/after for comparison. I've been surprised at how effective it is.
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Rob Cole

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To be clear, this 'Idea' is to correct lens sharpness fall-off, by whatever means makes the most sense, given Lr development budget.

I probably shouldn't have even stated some possibilities for different ways to do that, but now that I have, let me reiterate in priority order:

1. Complete automated lens profile based correction, using whatever algorithms work best, be it deconvolution or some other...
2. Tapping into the existing sharpening algorithm but increasing radius and amount in the outward direction.
(one could save presets for different lenses/focal lengths)
3. Provide more flexible sharpening so we can sharpen things differently for whatever reason as we see fit, including sharpness falloff.

DxO is the only raw converter I know of that can do sharpness falloff correction, yet I can actually get better sharpness falloff correction results using Lightroom alone than using DxO, by re-exporting back into Lightroom multiple times and sharpening different regions differently each time, but its very painstaking. Deconvolution is not a panacea - it has its own limitations and artifacts - try FocusMagic or TopazLabs InFocus and you'll see what I mean (they both use deconvolution-based algorithms). I'm not arguing against a different algorithm for pulling in the corners, I'm just sayin' - do whatever makes sense...

BTW: the Lightroom-only correction technique was just for proof of concept - not practical for real-world application, but there are some ways to do it in Photoshop - more info here: http://forums.adobe.com/message/3421915
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Rob Cole

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A workaround for the meantime if you are using Lr5: a radial gradient which increases sharpness in the outward direction.

Hint: use a double-over-sized elipse (extending way beyond image boundary in all directions) with feathering=100 - you'll need a small view, e.g. 1:8 (not 8:1). Invert Mask must be unchecked, and consider adding some noise reduction to counter-act sharpened noise.

Works pretty good actually.