RawTherapee, in-file lens correction not picked up?

T N Args

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Hi all

I am playing with RawTherapee Portable 4.1.74 (latest). I notice the lens distortion with raw files. (Lumix lens on Lumix camera)

Isn't the MFT raw file supposed to have the lens correction data in-file? I thought RawTherapee would not need explicit lens correction profiles applied. Am I wrong?

That would make it almost useless for MFT users, yes? You would have to build up manual lens correction profiles, because Adobe LCP profile files wouldn't exist for MFT cameras. Right?

Or is there some way to get RawTherapee to recognize the lens correction data that is embedded in the raw files?
 

Serhan

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As far as I know RawTherapee doesn't use the lens profile and that is the reason I downloaded it. Auto distortion correction w/ m43 lenses works with architecture/landscape but it is bad with people shots esp on the sides/edges where people's faces distort after correction. I prefer to correct it myself manually when it is needed...
 

T N Args

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So the missing corrections, that are available in the raw file but not utilized, include distortion, CA, vignetting? Anything else?
 

pictor

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Or is there some way to get RawTherapee to recognize the lens correction data that is embedded in the raw files?

In the Tab Transformations there is the group Distortion Correction. Just klick the button Auto Distortion Correction and you are done.
 

T N Args

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Thank you pictor.

I had spotted that button and tried it, and it definitely works.

BUT, I assumed it was running an internal software distortion correction algorithm, based on what it sees in the image.

Are you saying that it is actually reading the embedded lens correction data in the raw file, and applying it?

Also, isn't there also some CA and vignetting correction data embedded in MFT raw files? This button wouldn't make those corrections as well, would it?

[edit: oh ho, I just noticed that the pop-up dialog that RawTherapee opens when I hover over the Auto Distortion Correction button, says "Correct lens distortion automatically for some cameras (Micro Four Thirds, some compacts, etc)". Brilliant! I take that to mean it's the embedded data being used. ]​
 

pictor

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BUT, I assumed it was running an internal software distortion correction algorithm, based on what it sees in the image.

The tooltip says otherwise and so does the documentation.

Are you saying that it is actually reading the embedded lens correction data in the raw file, and applying it?

Yes, it does just that. If there isn't any information like that, that button has no effect.

Also, isn't there also some CA and vignetting correction data embedded in MFT raw files? This button wouldn't make those corrections as well, would it?

As far as I know, it does only distortion correction. But there is automatic CA correction: tab Raw -> Sensor with Bayer Matrix -> Chromatic Aberration. Just activate Auto-correction and you are done.
 

T N Args

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When I compared
  • the LR-corrected image from a wide angle lens with
  • RT using its distortion correction tool,
the LR result was much better corrected than the RT result. I find it hard to believe that the RT tool uses the embedded information properly.
 

pellicle

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Hi

out of interest

When I compared
  • the LR-corrected image from a wide angle lens with
  • RT using its distortion correction tool,
the LR result was much better corrected than the RT result. I find it hard to believe that the RT tool uses the embedded information properly.
which lens?

also are you checking against in-camera JPG corrections too (as a reference)
 

T N Args

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I would have to go home and check, but it would have been P14 or O9-18.

JPEG was nicely corrected OOC.

I concluded that it is definitely RT doing a bad job. Bugs me because i like RT.
 

pellicle

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I concluded that it is definitely RT doing a bad job. Bugs me because i like RT.
for what its worth PT lens has good corrections (it is of course not free).

I'll have a dig through RawTherapee myself for lens corrections as I happen to like it as a rendering tool (although I do have PS C6 here at work too ...)

I'll get back to you with some results tomorrow
 

pellicle

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I would have to go home and check, but it would have been P14 or O9-18.

JPEG was nicely corrected OOC.

I concluded that it is definitely RT doing a bad job. Bugs me because i like RT.
sorry this took longer than expected.

So, boring brick wall shot ... (great for observing barrel distortion)

RawTherapee
16586185899_cfa8ef746a_b.jpg
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in-camera
16772325135_42465aaeea_b.jpg
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speaks for itself really
 

T N Args

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Yes, that's right. Just checking... because it certainly does look uncorrected compared to the out-of-camera jpeg!

Back in post #9, @pictor says RT uses the embedded lens correction data. But if it were true, then the two images above should look identical, in terms of distortion.

They are not even close. So, I think RT ignores the embedded lens data and does something very crude. It certainly isn't satisfactory.

And that's a real shame.
 

pellicle

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Yes, that's right. Just checking... because it certainly does look uncorrected compared to the out-of-camera jpeg!

indeed!


...They are not even close. So, I think RT ignores the embedded lens data and does something very crude. It certainly isn't satisfactory.

my observation of using it was that it had a popup saying that it did observe corrections for some cameras. I'm guessing that it doesn't do that for this lens / camera combination at least ... I don't know if its a problem with how RW2 files store it or what ... anyway, its making a "guess" at it and here is a dcraw image made from the rw2 file ...

16153970183_290bbaf070_b.jpg
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clearly much worse.

If anything I think that barrel distortion is not handled well in RT, I suspect that its not even properly doing the corrections, but perhaps just applying a generic algorithm ... PTLens does a much better job.

PTLens transform of the dcraw TIFF (converted to JPG)
16773952355_5d1cbcca6a_b.jpg
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(it even gives a smidge more on the edges to what the OOC JPG was)
 
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