RawTherapee, in-file lens correction not picked up?

Discussion in 'Image Processing' started by T N Args, Dec 9, 2014.

  1. T N Args

    T N Args Agent Photocateur

    Dec 3, 2013
    Adelaide, Australia
    call me Arg
    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?
     
  2. Serhan

    Serhan Mu-43 Top Veteran

    533
    May 7, 2011
    NYC
    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...
     
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  3. T N Args

    T N Args Agent Photocateur

    Dec 3, 2013
    Adelaide, Australia
    call me Arg
    So, it's not switchable?

    And, no lens profiles on-line, available for download?
     
  4. barry13

    barry13 Super Moderator; Photon Wrangler

    Mar 7, 2014
    Southern California
    Barry
    I haven't found any lens profiles, but there is a slider for distortion correction which works reasonably well.

    Barry
     
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  5. T N Args

    T N Args Agent Photocateur

    Dec 3, 2013
    Adelaide, Australia
    call me Arg
    So the missing corrections, that are available in the raw file but not utilized, include distortion, CA, vignetting? Anything else?
     
  6. barry13

    barry13 Super Moderator; Photon Wrangler

    Mar 7, 2014
    Southern California
    Barry
    I think that's all.
     
  7. pictor

    pictor Mu-43 Top Veteran

    636
    Jul 17, 2010
    In the Tab Transformations there is the group Distortion Correction. Just klick the button Auto Distortion Correction and you are done.
     
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  8. T N Args

    T N Args Agent Photocateur

    Dec 3, 2013
    Adelaide, Australia
    call me Arg
    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. ]​
     
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  9. pictor

    pictor Mu-43 Top Veteran

    636
    Jul 17, 2010
    The tooltip says otherwise and so does the documentation.

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

    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.
     
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  10. T N Args

    T N Args Agent Photocateur

    Dec 3, 2013
    Adelaide, Australia
    call me Arg
    You've been very helpful pictor, I appreciate it. Thank you
     
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  11. T N Args

    T N Args Agent Photocateur

    Dec 3, 2013
    Adelaide, Australia
    call me Arg
    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.
     
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  12. pellicle

    pellicle Mu-43 All-Pro

    Feb 10, 2010
    Southport, OzTrailEYa
    pellicle
    Hi

    out of interest

    which lens?

    also are you checking against in-camera JPG corrections too (as a reference)
     
  13. T N Args

    T N Args Agent Photocateur

    Dec 3, 2013
    Adelaide, Australia
    call me Arg
    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.
     
  14. pellicle

    pellicle Mu-43 All-Pro

    Feb 10, 2010
    Southport, OzTrailEYa
    pellicle
    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
     
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  15. pellicle

    pellicle Mu-43 All-Pro

    Feb 10, 2010
    Southport, OzTrailEYa
    pellicle
    sorry this took longer than expected.

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

    RawTherapee
    16586185899_cfa8ef746a_b.

    in-camera
    16772325135_42465aaeea_b.

    speaks for itself really
     
  16. T N Args

    T N Args Agent Photocateur

    Dec 3, 2013
    Adelaide, Australia
    call me Arg
    Is the RT image (above) with or without RT distortion correction?
     
  17. pellicle

    pellicle Mu-43 All-Pro

    Feb 10, 2010
    Southport, OzTrailEYa
    pellicle
    With ... I thought that was what was desired?
     
  18. T N Args

    T N Args Agent Photocateur

    Dec 3, 2013
    Adelaide, Australia
    call me Arg
    Yes, that's right. Just checking... because it certainly does look uncorrected compared to the out-of-camera jpeg!

    Back in post #9, @pictor@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.
     
  19. pellicle

    pellicle Mu-43 All-Pro

    Feb 10, 2010
    Southport, OzTrailEYa
    pellicle
    indeed!


    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.

    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.

    (it even gives a smidge more on the edges to what the OOC JPG was)
     
    Last edited: Mar 10, 2015
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  20. barry13

    barry13 Super Moderator; Photon Wrangler

    Mar 7, 2014
    Southern California
    Barry
    Hi, did you try the distortion slider in RT?

    Barry