Sharpening

Hi everyone! I’ve been a happy DXO PL2elite user until recently when I acquired an old vintage manual lens which is not supported (and realistically never will be). As there’s no lens module the only remaining sharpening tools are USM and Micro Contrast. That’s IMHO very insufficient for good sharpening! I would very much like to apply a different lens module but I can’t see a way of doing it. How do other DXO-users deal with sharpening of unsupported lenses? Does DXO have plans of providing other, better sharpening options for sharpening of such lenses? Thanks!

Of course, you can buid your own lens profile.
Palette Detail / Unsharp mask
Pascal

Excuse me but I seem to be missing something here. When I’m telling you that Unsharp mask alone is insufficient for good sharpening then you are telling me I should do just that, use Unsharp mask ??

Because I didn’t know the acronym USM !
USM is therefore the tool that you can use.

The ultimate action is play with the exif of your photo.
I can’t say any more.
Pascal

Kohi - this might help in changing exif

Thanks for your response!
When you say this might help… do you mean you don’t know if it will? -From the thread you linked I can’t see where someone would have succeeded to change the exif of a manual lens in a way PhotoLab would have accepted it as another lens.
And if you’re sure it can work … can I make the changes from within the GUI version of ExifTool ore would I have to use the command line version (which I can’t)? I’m currently running the GUI and even there I’ve not yet succeeded to alter any exif data.

Hello Kohi,

I understand from the thread that Marc has succeeded

Yes. Marc succeeded in adding lens info. But it is IMO not clear if this was only to have any lens info instead of none (for the manual lens) … ore if this was to make PhotoLab think there is a different lens attached to allow the use of modules which wouldn’t be available otherwise (sharpening).

Just send him a message and find out

It is as good as impossible as far as I know, because the important data is written in the “maker notes”, and these cannot be changed, at least not in the exiftools that I tried. Perhaps if the lenstype, lensmodel and lensinfo fields are empty in the maker notes, it may be possible, but otherwise not.

A related question: Supposing that correction parameters for kohi’s lens existed in the lensfun database, is there a mechanism for creating even a minimal profile in PL?

Kohi asks is there anything else that can be done? Well we can’t know because we don’t know what analysis and correction DXO themselves actually apply to a lens profile. As I see it there are two main elements. The first is correction of optical aberrations which are correctable - because not all aberrations are correctable. However the easiest to correct is chromatic aberration, as the colour channels that do not align correctly can be identified and moved into alignment. This substantially improves sharpness in areas where the CA is greater than about 0.5 pixels. As far as I can see DXO PL doesn’t offer a fully automatic tool for correction of CA, unlike for example lightroom. For an unknown, or even a faulty lens, I would preferentialy use lightroom to correct CA. Secondly there is sharpening (“unsharp masking” or USM) which works by identifying edges and increasing local contrast at the edges by a defined amount over a defined pixel distance. Used on its own this is applied to the entire image, and unfortunately ends up sharpening noise and artefacts instead. In lightroom and photoshop you can use a mask to determine which areas are affected by USM - this prevents sharpening being applied to noise (e.g. in the sky or in shadow areas) - again something not present in DXO PL.

Tricking PL into using a different profile by editing the EXIF is not going to help with an unknown lens, except by luck or if an optically identical lens with a different name is already profiled.

For Kohi, therefore, my suggestion is to use the tools available in Lightroom rather than PL. I would also add that it may simply not be possible to make a vintage lens perform like a newer one, and it is often the limitations of vintage lenses that give them their “character” - perhaps better to leave it uncorrected and enjoy the vintage “look”…?

There is a separate tool which deals with CA and PF. The auto CA removal is there but what is missing is the ability to sample the offending PF hues and remove them. So the custom PF removal is missing in PhotoLab.

The USM tool has the Threshold value whose purpose is to prevent sharpening of uniform areas. What PhotoLab is missing is the ability to preview the mask, so to work around that you need to first apply very high sharpening value, then establish appropriate radius, then threshold, and then back off the strength to appropriate values. The PL’s USM actually allows you to apply more sharpening to the corners of your image to compensate for lens softness there.

The difference between USM and Lens Sharpness tools in PhotoLab is that the former uses a plain Gaussian Blur kernel, but the latter relies on some form of deconvolution sharpening (possibly a derivative of Gaussian blur, but only the devs know that).

The application of sharpening in DXO PL is hampered by the fact that it is only applied in the main window at zoom levels of 80% and higher. I do understand that this is how DXO intend it to work! However with high pixel count images (say > 24mp) this means only a relatively small portion of the image is visible, and below 70% most images look really quite soft, which unless you understand this behaviour, can be annoying.

I assumed that “lens sharpness” was more complex than USM, possibly involving masking. I personally doubt that it uses deconvolution, because that can be very slow (eg Topaz labs Sharpen, which is astonishingly good but very slow), and in DXO it is applied seemingly without any extra waiting time.

I do find initial RAW conversions done in DXO PL, with a lens/camera profile applied, are noticeably sharper than initial conversions in Adobe LR or PS, and marginally sharper than Capture One. And they achieve that without adding noise or other artefacts such as halos. So it is my primary RAW converter.

However I find DXO often leaves a little CA in the image, if the lens is subject to it (e.g. the Canon 18-135 STM). LR removes this totally in the initial conversion, and does not require a profile. In other words the two packages are using different methods - DXO relies on the profile, LR analyses the image (but can also use a profile).

Coming back to the original post, I do not see how to create a profile in DXO for an unlisted lens except by using the provided tools and saving as a preset, which is not what the OP is asking for, and probably is not possible.

The Detail slider in Lr uses some form of deconvolution (at least Eric Chan called it so) but it doesn’t slow the program down. The effects look similar to using the Details slider in the Lens Sharpness tool in PhotoLab. Also look how RawTherapee applies the R-L Deconvolution – it’s not much slower than using USM – very workable on my ageing computer. They are now replacing it with Capture Sharpening and it looks much better now because it’s applied at a different point in the imaging pipeline.

Lens Sharpness in PhotoLab guards uniform areas from sharpening by means of the Bokeh slider, but apparently it also uses the lens correction profile so that it can compensate for lens softness in an automatic way. I have seen artefacts in my files, esp. when I use a very sharp lens on a camera without AA filter, and I have to back off the Details slider (zero it out) or reduce the Global value significantly. But those artefacts are probably the result of weak demosaicing rather than the Lens Sharpness module itself.