Raw conversion parameter for Leica Q

[TK!]

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Hi all,

none of my cameras made me nearly as happy as my Q does today.  It's a great tool! But there is one thing I that really bothers me from the very beginning: The parameter for lens distortion correction and for colour calibration are not publicly available.  So none of the open source raw converters (darktable, gimp, rawtherapie, libraw, ...) is useable with with the Q-DNGs.

Whereas I think it might be a hard job to derive the values for lens distortion I finally would manage to do this.  But for the colors I do not see a chance for me.  My low cost laptop monitor is not calibrated at all.  So for the final prints I fully rely on the software that generates the Jpegs.

Does anyone see a chance how to get around this, i.e. how can we derive and publish the parameter?  Could we convince Leica to do this? With Lightroom no longer available together with the camera Leica should also be searching for an alternative?

Best wishes

TK
 

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[Bart van Hofwegen]

I see that you have stumbled upon the same issue as I have. I do not like Adobe raw converter (ACR) at all, lousy color, introduces all kinds of shifts if you are not careful. I can give you couple of tips from my own experience.

 

I prefer Raw Photo Processor (RPP, only for mac) as raw converter. This converter does not apply any lens corrections, but it does have a built in color profile for the Q. I you make a donation to the makers (otherwise it is free), the profiling function is unlocked and you can create your own color profile using a color checker card. That works great, but it is not easy to achieve an even and usable exposure of the color checker target. It takes practice and trial and error.

 

If other converters offer profiling this way (ACR does too, through the use of Adobe's DNG profile editor, which in itself is an improvement), you could buy an X-Rite color checker or color checker passport and make your own profiles for different lighting conditions. I found that especially in full summer sunlight, this is well worth it for the Q.

 

As far as lens correction is concerned, the by far the best tool I found is PTLens. You use it after raw conversion. It offers a stand alone tool and photoshop plugin and performs a much better correction than any other tool I have tried, including ACR and DxO... It costs $25 so it is affordable. There is a trial version that you can try for ten photos. Not that much, but enough to try it. It is really excellent. And no, I a not affiliated with the makers in any way...

 

Good luck, and if you make any new discoveries, I would love to hear of them!

[GiantTristan]

DxO Pro has much superior lens correction than any other software and it works great with Leica Q Raw files. They offer a free trial.

[wjgoretsky]

I have been a total fan of CaptureOne software and find that it handles raw files with amazing dexterity. It's available as a trial if you want to test out the full suite of features.

 

I also have a voucher code that can be used to provide a 10 percent savings on purchasing it if anyone is interested.

 

Voucher code: AMBWINSTON

 

PhaseOne.com

 

 

Sent from my iPad using Tapatalk Pro

[Bart van Hofwegen]

DxO Pro has much superior lens correction than any other software and it works great with Leica Q Raw files. They offer a free trial.

Well, I must say that PTlens performed a better correction than DxO Pro AND did not insist on having to open the original DNG when fed a TIFF, like DxO did although all EXIF was available. PTLens is also about half the price... Better in all respects, at least for me.

[jaapv]

Hi all,

 

none of my cameras made me nearly as happy as my Q does today.  It's a great tool! But there is one thing I that really bothers me from the very beginning: The parameter for lens distortion correction and for colour calibration are not publicly available.  So none of the open source raw converters (darktable, gimp, rawtherapie, libraw, ...) is useable with with the Q-DNGs.

 

Whereas I think it might be a hard job to derive the values for lens distortion I finally would manage to do this.  But for the colors I do not see a chance for me.  My low cost laptop monitor is not calibrated at all.  So for the final prints I fully rely on the software that generates the Jpegs.

 

Does anyone see a chance how to get around this, i.e. how can we derive and publish the parameter?  Could we convince Leica to do this? With Lightroom no longer available together with the camera Leica should also be searching for an alternative?

 

Best wishes

 

TK

 

As the digital correction of the lens is an integral part of the lens design and probably covers more than distortion compensation alone, it appears futile to me to try and outguess Leica's lens design department.

[Bart van Hofwegen]

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As the digital correction of the lens is an integral part of the lens design and probably covers more than distortion compensation alone, it appears futile to me to try and outguess Leica's lens design department.

The RAW data in the DNG is without correction. The correction is "described" through DNG opcodes ("instructions") that for instance ACR uses. In ACR, you cannot switch this off and be fooled into thinking that the correction is "baked in" in the RAW data. It is not. Use RPP and see the dark corners and warped image....

 

Actually, the distortion correction that is encoded in the DNG is very straightforward and can easily be improved, as for instance PTlens does. Apart from that there is only one other thing encoded in the DNG, I quote Sandy on the Chromasoft blog:

 

"In addition to the lens correction op code, there is also a "FixBadPixelsConstant" opcode, whose function is exactly as the name states. This is not something that I've seen in a Leica DNG before. It's not clear whether this is sensor specific (i.e., different Q's would have different corrections) or common to all cameras of this model."

 

The full article can be found here: http://chromasoft.blogspot.nl/2015/06/leica-q-typ-116-raw-file-dng-analysis.html

 

So, the distortion correction is simple, the bad pixels is another thing entirely... I use RPP as RAW converter that does NOT perform any opcodes, but I have not seen anything that would deserve the label "bad pixel" yet. I guess that is good...

[jaapv]

Yes, it is correct that the lens corrections are in a sidecar file. However, to correct distortion precisely, especially the "moustache" variant, exact data are needed. It is hard to imagine how a third party, working on a reverse-engineered data set can better or even equal the corrections based on the data provided by the lens designers.

There are many arguments to use a one raw converter or the other, but this can hardly be based on the distortion/vignetting and dead pixel corrections.

[jaapv]

Hi all,

 

none of my cameras made me nearly as happy as my Q does today.  It's a great tool! But there is one thing I that really bothers me from the very beginning: The parameter for lens distortion correction and for colour calibration are not publicly available.  So none of the open source raw converters (darktable, gimp, rawtherapie, libraw, ...) is useable with with the Q-DNGs.

 

Whereas I think it might be a hard job to derive the values for lens distortion I finally would manage to do this.  But for the colors I do not see a chance for me.  My low cost laptop monitor is not calibrated at all.  So for the final prints I fully rely on the software that generates the Jpegs.

 

Does anyone see a chance how to get around this, i.e. how can we derive and publish the parameter?  Could we convince Leica to do this? With Lightroom no longer available together with the camera Leica should also be searching for an alternative?

 

Best wishes

 

TK

 

An uncalibrated laptop. I use one from time to time as well, if in a hurry at work. For colour, all bets are off, even contrast and brightness are a gamble. You bought the camera for a high price, why handicap yourself by skimping on  the postprocessing?

As for the lens corrections, the common misconception is that these are there for to compensate for a medioocre design. The opposite is true. Modern lens design methods give the engineers more degrees of freedom in the optical design by shifting corrections that are better made digitally out of the optical design. In other words: the optical part was designed with ultimate digital corrections in mind to get a better result than by optical correction alone. Removing the digital part from the total camera output is equivalent to the removal of one lens element from a traditionally designed lens. It makes no sense at all and impairs the ultimate result (which you can not see anyway on your laptop).

[Bart van Hofwegen]

Yes, it is correct that the lens corrections are in a sidecar file. However, to correct distortion precisely, especially the "moustache" variant, exact data are needed. It is hard to imagine how a third party, working on a reverse-engineered data set can better or even equal the corrections based on the data provided by the lens designers.

There are many arguments to use a one raw converter or the other, but this can hardly be based on the distortion/vignetting and dead pixel corrections.

But ACR simply uses the "linear warp" opcode that is encoded in the DNG, nothing more, no secret knowledge shared by Leica, no Adobe lens profile. It is nothing more than straightforward "bending", no moustache correction whatsoever. At least, that is what I am seeing.

 

PTLens is calibrated from a target shot with the camera so effectively deals with moustache or sombrero distortion or any other type; ACR does not seem to do that, or not completely correctly. (in case of the Q, that is)... The Leica in camera JPG rendering could be different in this respect, we do not know that of course.

 

The whole point is that while many people seem content with ACR, I do not like the color profiles, even if I create my own. The distortion correction is not bad, I have no problems with that in itself and could live with that... I use RPP as a RAW converter, but that converter does not execute the  WarpRectilinear opcode. That is how I came across PTLens, and it really does a better lens correction than ACR (and DxO pro), it is clearly visible on pictures with many straight lines. Where ACR leaves a slight "wavy" effect, PTlens straightens it completely. Again, for the record: I am not affiliated with PTLens in any way.... Just happy with it!  If ACR would have had better color and detail, I certainly would use it.

[jaapv]

Well. I have found that I need a profile for ANY raw converter, and for different light conditions as well.I have been making them since 2007. It is only a minor hassle, easy and quick.

But it only makes sense in a colour-managed and properly calibrated workflow.

In my experience best colours are achieved in Capture One Pro, with version 9 my favorite right now. A bit unsure about 10.

[Bart van Hofwegen]

Well. I have found that I need a profile for ANY raw converter, and for different light conditions as well.I have been making them since 2007. It is only a minor hassle, easy and quick.

But it only makes sense in a colour-managed and properly calibrated workflow.

In my experience best colours are achieved in Capture One Pro, with version 9 my favorite right now. A bit unsure about 10.

I agree, I make profiles too. Always. Even for RPP, it has a great profiling option.

 

I guess that everyone has his or her own preferences, for good reasons. Everyone's photography is different (fortunately). And whilst post processing is important, it can also be a point of strong contention among different users, which it should not be. That is not what I intended to do here, excuse me if I gave that impression. 

 

Maybe I should give Capture one a try one day, I have done that in the past but not for the Q. I came across RPP for the D810 some time ago and found that it squeezes the most detail out of that camera, gives good color, and less noise when pushed.

[jaapv]

No contention with me. I am basically a Photoshop person, with excursions to Lightroom and C1. Sometimes, with critical work, I will do the raw conversion in C1 and the finishing in PS. Omnivorous.

[wjgoretsky]

I have been a total fan of CaptureOne software and find that it handles raw files with amazing dexterity. It's available as a trial if you want to test out the full suite of features.

 

I also have a voucher code that can be used to provide a 10 percent savings on purchasing it if anyone is interested.

 

Voucher code: AMBWINSTON

 

PhaseOne.com

 

 

Sent from my iPad using Tapatalk Pro

This promotional voucher code also works for upgrades from previous versions of CaptureOne to the current version 10.

 

 

 

 

Sent from my iPad using Tapatalk Pro

[Herve5]

(...) So none of the open source raw converters (darktable, gimp, rawtherapie, libraw, ...) is useable with with the Q-DNGs.

 

From simple geometric images, I find that DarkTable Transform tool -> Distortion correction = - 0,2 fits perfectly...

 

Given that after one full year of comparison with everything on the market including beta versions etc. I also find DarkTable beats everybody hands down when it comes to night noise corrections*, I must say I won't go any further...

 

H.

(*) noise reduction tools : 'profile', strength between 0.3 and 0.7 depending on scenes

[TK!]

Seems the latest version of lensfun, http://lensfun.sourceforge.net/, a library most of the open source converters rely on, now supports the Leica Q-lens.

 

This is a good start, now let's hope the lib is infiltrating current raw conversion packages quickly.

 

The parameters seem quite simple, supporting Herve5's approach.

 

Color profiles still open... :-(

 

- TK

 

Excerpt from the lensfun database, https://github.com/lensfun/lensfun/blob/master/data/db/compact-leica.xml:

 

<lens> <maker>Leica Camera AG</maker> <maker lang="en">Leica</maker> <model>28.0mm f/1.7</model> <mount>leicaQTyp116</mount> <cropfactor>1</cropfactor> <calibration> <!-- results obtained using sample RAW from dpreview.com --> <distortion model="ptlens" focal="28" a="0.00098" b="-0.043" c="0.01683"/> <tca model="poly3" focal="28" br="-0.0000329" vr="1.0002023" bb="0.0000845" vb="0.9999781"/> </calibration>

</lens>

[TK!]

Managed to update the lensfun database on my Ubuntu-Laptop to the latest version from github, http://lensfun.sourceforge.net/manual/dbsearch.html

 

Long story short (I am aware this is not a Linux forum): Lens correction for the Q is available via lensfun 0.3.2 for all major open source tools. :-)

 

- TK

[leetmode]

Whats the best way to use PTLens with Lightroom? Do all your basic, tone, color and detail adjustments first then export to Photoshop and use PTLens plugin for distortion and crop with Photoshop?

 

Or do the same edits in LR, export to PTLens then back to LR for cropping adjustments?

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