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PTLens results. . .

Discussion in 'Image Processing' started by GBarrington, May 16, 2014.

  1. GBarrington

    GBarrington Mu-43 Veteran

    I've been looking to find a way to correct distortion caused by extra wide angled lenses, I'm tired of manual correction with ACDSee Pro but I like how it handles ORF files otherwise. So I thought I'd take a look at PTLens. I realize I can download the free trial, but it is only good for 10 photos, and more subtle, less obvious, issues may not get noticed until several months of extended use.

    The problem I see, is that while the website lists several m4/3s lenses as supported and most of the popular 4/3s DSLR lenses, it list NO m4/3s cameras as being supported, only regular 4/3s cameras are listed as supported. My question is, how important is Camera support? What does this lack of camera support mean in terms of how well PTLens will work overall?

    Also, in terms of workflow, would you suggest the following work flow or something else (or does it matter all that much?)

    1. Set basic raw dev settings, in ACDSee Develop Tab
    2. Convert to 16 bit tiff file
    3. Correct distortion
    4. Finish up with any other plugins,and non raw editing

    What I'm asking in the second question, I guess, is do you correct distortion as a last step, or should it occur before the cropping and other non raw edits? What seems most appropriate to you?

    Edit: I've cross posted this to DPR retouching forum for a more generic response, if you see it there, please forgive me.
     
  2. barry13

    barry13 Super Moderator; Photon Wrangler

    Mar 7, 2014
    Southern California
    Barry
    Hi,

    Distortion correction should be done before cropping, sharpening, ...

    Try RawTherapee.

    Barry
     
  3. GBarrington

    GBarrington Mu-43 Veteran

    So are you saying RawTherapee now comes with lens/Camera distortion support? I've tried RT about 18 months ago when I left Lightroom for ACDSee Pro and it didn't have it then (though I didn't care about that at the time) At the time, I was impressed with RT but I felt ACDSee Pro was a tad bit better in terms of shadow and highlight detail. However, if it offers the ability to automate the distortion correction, I might reconsider.
     
  4. barry13

    barry13 Super Moderator; Photon Wrangler

    Mar 7, 2014
    Southern California
    Barry
    Hi,
    RT does have "lens distortion correction"...
    I'm not sure which lenses are automatically supported, and I haven't tried FishEye correction on it.

    See also http://www.dpreview.com/forums/post/39185648
    "enable to crop tool grid (you can do that without actually cropping), then use the distortion correction slider to straighten the image, watching the straight lines against the grids until you are happy with the correction"

    That is from 2011, so it's possible the automatic method has been improved.

    I've used Hugin for FishEye correction, but it's been quite awhile so I don't remember the details.

    Barry
     
  5. barry13

    barry13 Super Moderator; Photon Wrangler

    Mar 7, 2014
    Southern California
    Barry
    OK... RT supports all lens profiles built into DCRaw, and RT also can load "lens correction files", which need to be in Adobe LCP format:
    http://rawtherapee.com/blog/rawtherapee-4.0.9-released

    Looks like you don't need LCP files though... Apparently Olympus puts lens correction profiles into the RAW files when using Olympus lenses (and the E-M1 supports Pana lenses too), according to
    http://www.dpreview.com/forums/thread/3603393#forum-post-52862144
    Maybe RT processes that directly?

    I'd have to take some more test photos to be sure, as I can't see any distortion in the RAW photo of some bricks I took at 42mm on my kit lens.

    Another option would be to use Olympus Viewer (free) to do the distortion correction, if you're using an Oly camera.

    Barry
     
  6. GBarrington

    GBarrington Mu-43 Veteran

    Thanks I will take a second look a RT, though my goal is to continue to use ACDSee Pro for raw development, because frankly, I think it's better at raw development for Orf files in particular, except for this one little feature! But If I can get the same quality out of RT AND get distortion control, I'd be crazy not to take a second look.
     
  7. GBarrington

    GBarrington Mu-43 Veteran

    A Quick update on my PTLens and perspective correction research.

    I had an interesting and very useful email exchange with Thomas Niemann, the author of PTLens. He recommends that we do the distortion correction before any edits are done to the photo. But if you are doing PTLens, you CAN'T do the correction until you have at least converted the raw file to a bitmapped format. This presents a bit of a problem if you want to use a Raw converter that doesn't have an automated distortion correction feature, and I REALLY like how ACDSee Pro converts my orf files, otherwise.

    Niemann also said that the E-M10 is profiled in his program. Apparently I either misread the web page, or found an older cached page from somewhere. He did stress that one needs to have both the body and the lens profiled to make the whole process work. He didn't go into detail.

    I had mentioned to him that when I compared the results of ACDSee pro against OV3 and PSP X6 (which, to my knowledge, also does not claim to do auto correction) , I could see some difference in both ACDSee Pro and OV3 with what appears to be no change to the image in PSP. Niemann asked me to send him those photos and he said he saw no difference between the three. (BTW, I was really impressed with his willingness to work with me, a non paying user at this point!) This surprised me, since I could see some change in the OV3 sample, and I thought I 'sorta' saw some difference in the ACDSee sample.

    I downloaded PTlens to compare it to OV3 and ACDSee Pro. What really surprised me is that the OV3's changes are VERY subtle compared to PTLens (But they ARE there). Both PTLens and OV3 made the biggest change in my test photo taken with my 4/3s DSLR 14-55 mm lens (at 14 mm), and oddly, less change in the test photo taken with my 4/3s DSLR 9-18 mm lens (at 10 mm). These were not photos designed to test the correction, but merely not very good photos of the sort I am likely to take (Landscapes, and the natural world).

    While the correction of the two programs was clearly there in my eyes, I did not see any difference in visual impact. That is I don't think the correction added to or detracted from the images in any way. It didn't really affect my photos much in any way. I shoot the natural world mostly, this is not to say images made up of strong lines and angles won't benefit from correction.

    I suspect that what I thought I saw in ACDSee Pro was the natural and slight variation in how much of the image is cropped/displayed from one brand of software to another. While I would like ACDSee to implement some sort of automated correction, I don't think for my purposes, it matters all that much. I might buy PTLens eventually, particularly if I continue to use ACDSee Pro (I don't JUST take landscapes after all, and I really like how ACDSee handles my orf files!), but I've come to the conclusion it isn't something I need to obsess over or resolve immediately.

    Based on what I've seen, I also don't think it is an issue that should be a deal breaker in terms of what software one uses. PTLens is available as an add-on, it works well as an external editor for the workflow products, AND it is a tested and known reliable product that doesn't cost much. I would say if this issue has been gnawing at you, you can relax!
     
  8. GBarrington

    GBarrington Mu-43 Veteran

    Apparently, I misread what Mr. Niemann said, aparently he recommends that the distortion correction process occur AFTER other edits. My apologies to anyone who was misled by my inaccurate reading.
     
  9. barry13

    barry13 Super Moderator; Photon Wrangler

    Mar 7, 2014
    Southern California
    Barry
    At least save sharpening and scaling/resizing until after the distortion correction.

    Barry