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RawTherapee and CA correction?

Discussion in 'Image Processing' started by barry13, Aug 24, 2014.

  1. barry13

    barry13 Super Moderator; Photon Wrangler

    Mar 7, 2014
    Southern California
    Barry
    Hi,

    I've got a couple of RAW files from my E-M1 and 12-40mm lens that have some Chromatic Aberration.
    I'm trying to figure out how to fix them in RawThreapee.

    The JPEGs from the camera are OK (wrt CA), and the Oly Viewer is able to correct the CA, but I don't like its interface and want to learn how to use RT fully.

    RT can load LCP Lens Correction Profile files, but I've done some searching and afaict they don't seem to exist, other than that they are supposedly 'built-in' to the RAW files. However RT will only let you choose the auto CA correction setting if you have an LCP file loaded.

    So,
    1. are there any LCP files available for our lenses, or some way to get RT (current version, 4.0.12.60) to recognize the embedded profiles?

    2. without an LCP file, what is the best way to try to remove CA in RawTherapee or Gimp or similar?

    Example, 100% crop from RAW:
    E8204982.

    This part of the image is somewhat over exposed, fwiw.
    Also, the CA isn't quite this bad before hitting 'Auto Levels', etc. in RT but it's still pretty bad.

    Thanks,
    Barry
     
    Last edited: Oct 23, 2015
  2. cireyay

    cireyay Mu-43 Rookie

    23
    Dec 31, 2013
    Hi Barry,

    I'm currently using RT 4.1.1 and it does apply CA correction automatically when you double click on a RAW img and the PP interface shows up. However I don't recall it doing it in previous versions. Hence you could update/download the latest version and give it a shot?

    I'm using a pana GX1 by the way, not sure if that will make a difference
     
  3. barry13

    barry13 Super Moderator; Photon Wrangler

    Mar 7, 2014
    Southern California
    Barry
    Hi, I had searched to see if there was a new version, and Google was linked to an old download page...

    So, I'm now running 4.1.49 on Windows but it's still not doing CA correction...
    Under "Lens/Geometry" the 'Auto-Fill' setting is checked, but further down, under "Lens Correction Profile", there is no file selected and the distortion, vignetting, and CA correction checkboxes are greyed out.

    Can you load my raw file (linked above) and try it in yours?
    Zoom in on the motorcycle, and look for the CA on the chrome bars and letters.

    Are you on a Windows PC or Mac or Linux?
    Which lens are you using?

    Thanks!
    Barry
     
  4. Brian Beezley

    Brian Beezley Mu-43 All-Pro

    Barry, try Defringe. Its default parameter values cleaned up the red/purple on the motorcycle when using Neutral. When using Auto Levels, Highlight compression seems to make the red/purple worse. Try adjusting it and the associated threshold.

    Brian
     
    • Like Like x 1
  5. barry13

    barry13 Super Moderator; Photon Wrangler

    Mar 7, 2014
    Southern California
    Barry
    Brian, thank you... that looks much better!

    Thanks!
    Barry
     
  6. barry13

    barry13 Super Moderator; Photon Wrangler

    Mar 7, 2014
    Southern California
    Barry
    Anyone know why RT isn't loading the lens profile for the 12-40mm?

    Thanks,
    Barry