The whole question of lens sharpness...

Started Jun 12, 2013 | Discussions thread
GaryW
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Re: DxO Labs' "Lens Softness" Corrections
In reply to Detail Man, Jun 22, 2013

Detail Man wrote:

GaryW wrote:

I have less luck with countering poor focus, but for slight diffraction, it seems to work fine.

In addition, it's what DxO uses (I think) for their "lens sharpness", to counteract the effects of unsharp lenses, particularly in the corners where they use more intensity to counter the greater softness. This seems to work to a large extent.

...You may be familiar with these concepts if you are familiar with MTF (Modulation Transfer Function) curves. DxO Labs has developed a unique unit called the BxU (Blur eXperience Unit) which is a mathematical way of describing this 'blur'. Reducing the ‘lens softness’ or 'blur' or 'lack of sharpness' means performing local, color-channel dependent and anisotropic deconvolution of the image produced by the camera.

Furthermore, DxO deblurring uses a complex contextual approach taking into account both local noise and local detail level in the image. As a result, deblurring will be automatically reduced in uniform areas (like a pure blue sky.), but increased in a detailed zone....

...

As the DxO RAW Optics Correction Modules for a given camera-lens combination appear (to me) to in general to be significantly more effective than the DxO JPG Optics Correction Modules (for the same camera-lens combination), I think that it (may) be the case that some of the related processes may proceed on a RAW-level prior to de-mosaicing of the RAW image-data.

The "lens sharpness" option does not appear for unsupported lenses.  I am not sure what happens for RAW vs. JPEG.

This approach is distinct from the deconvolution-deblurring that occurs in the sharpening tools of Adobe Lightroom, Camera RAW, Photoshop, the PS/LR plugin Topaz Infocus, as well as RAW Therapee's R-L DD - all of which appear operate on what is already de-mosaiced image-data.

Whatever DxO is doing, they've really got it figured out.  Typical deconvolution tends to produce artifacts if overdone, so they are definitely doing something to control the noise.

I think where DxO has done a good job overall is making their program deceptively simple.  You could probably get good results with RAW Therapee, but RT requires more fiddling.  My thought is that at lower ISO, I liked RT just fine, but at higher ISO, the NR is not the best, and the deconvolution will increase the noise.  I can get pretty good results with DxO at any ISO.

DM ...

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Gary W.

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