DPL and lens diffraction

DxO PhotoLab
1

Is there any special treatment against diffraction in Lens Sharpness toll ?

I suppose yes, each lens is characterized for all diaphragms !?
On theses examples PhaseOne C1 with eponymous tool seems better than DPL.
… unless contrast difference !

https://www.chassimages.com/forum/index.php/topic,287629.0.html

Pascal

2

Pascal, thanks for the link.

A very interesting discussion and examples about the effect and correction of diffraction.

I would also be interested in learning more about DxO’s approach to dealing with diffraction in the Lens Sharpness Tool,

Joseph

3

Svetlana (@sgospodarenko), could you help us understand how DxO PhotoLab deals with diffraction?

Specifically I am interested in the following points regarding the Lens sharpness tool:

  1. Do the DxO Optics Modules take into account the decrease of sharpness that occurs at smaller apertures?

  2. Does the tool attempt to correct the loss of detail caused by diffraction?

Regards,
Joseph

4

Hello guys,

@Benoit could you, please, have a look on that?

Thank you

Regards,
Svetlana G.

5

Lens sharpness tool is based on a specific calibration made for each lens-camera combination. And for each given lens-camera combination, we measure variation of sharpness across image field, for each combination of focal and aperture. Consequently, as diffraction contributes more and more to lens sharpness when aperture decreases, its effect is taken into account in our dxo modules, and thus lens sharpness tool has an impact on it.

This said, when diffraction is strong (or more generally when input lens sharpness is very poor), our dxo modules limit their correction by default, as fully correcting the picture might lead to artifacts (and when a small detail is very blurry, there’s not that much to do to recover it…). Nonetheless, adjusting manually lens sharpness sliders enables to increase again sharpness.

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6

Merci beaucoup Benoit.
Pascal

7

@Benoit and @sgospodarenko, thank you for helping satisfy my curiosity about DxO’s approach to diffraction correction.
So, if I understand it correctly, you are not using a deconvolution algorithm to mitigate the loss of detail at small aperture, but instead you rely entirely on the information contained in the DxO optics modules.

Does this mean that PhotoLab is not likely to offer in the future an option for diffraction correction that is independent of the optics modules?

Thanks again,
Joseph

8

Hello Joseph,

As lens sharpness correction already includes the action on diffraction, and as it would be quite costly to split in each DxO modules the part of the blur caused by diffraction, we don’t think about such a feature for the short term.

Benoît

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