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bakubo
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LR 4.1 RC: Remove CA reduces in some areas and increases in others?

Apr 3, 2012 3:56 PM

I have 2 screenshots of LR 4.1 RC using the Remove Chromatic Aberration option. The first one is before and the second one is after. Notice that in the before where I have written the number 1 there is the red fringe color and where I have written the number 2 there is not. Then when I select Remove Chromatic Aberration the number 1 area is better but the number 2 area is worse.  Maybe nothing can be done or maybe I did something wrong or maybe I don't understand something or maybe something else?

 

Before:

 

screenshot_before.jpg

 

After:

screenshot_after.jpg

 
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  • Currently Being Moderated
    Apr 3, 2012 4:04 PM   in reply to bakubo

    gotta say that in practical use this new CA tool seems like a downgrade

     
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    Apr 3, 2012 5:10 PM   in reply to bakubo

    hiya - ive also found that CA correction is sometimes overcooked - i would like to have manual control over my CA correction back in a LR4 update version...

     
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    Apr 3, 2012 9:11 PM   in reply to Scooby007

    I have to say I preferred the manula controls. They worked

     
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    Apr 4, 2012 2:50 AM   in reply to John Spacey

    agreed John. manual is better especially if you have taken the time to make precise corrections for lenses at different focal lengths, or exotic lenses, or old manual focus lenses that dont apprear in the lens selection dropdowns.
    also, each lens is slightly different, si even if its perfect for the test lens that the LR guys setup their  profiles with, it might not be spot on for the supposedly identical lens anyone else has. case in point is my Nikon, 14-24 at 14mm, 12-24 at 12mm, 10,5mm fisheye and believe it or not, my 70-200 VR at 70! those are all basically main stream lenses. my nikon 24-70 gets messed up even worse at 24mm. thats not cool.

    once you give someone control, you shouldnt take it away unless its is VERY well explained and the automation works every timewithout fail.

     
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    Apr 4, 2012 5:25 AM   in reply to bakubo

    There are two types of Chromatic Aberrations (CA), Lateral (axial) and Longitudinal (transverse):

     

    http://en.wikipedia.org/wiki/Chromatic_aberration

     

    LR's CA tool(s) are designed to correct only longitudinal aberrations, which is the type that becomes more pronounced as you get further from the center of the image. Axial chromatic aberration (purple fringing) is usually uniform in size across the image, but most noticeable along dark edges in bright highlight areas. Yes, you can correct axial CA in a specific area of an image using LR3's CA tools, but then it will introduce longitudinal CA in the rest of the image. In the picture area you posted I suspect both axial and longitudial CA are present. LR4 automatically corrected the lateral CA, revealing the presence of axial CA.

     

    Both LR3 and LR4 have a 'Defringe' tool located under 'Manual' in the Lens Corrections' panel, which is designed to remove axial CA. Take this same image and try checking the 'Defringe'>'All Edges' option. Try using it both with, and without the 'Remove Chromatic Aberrations' checked. The LR 'Defringe tool does a fairly good job in removing most if not all "purple fringing," including sensor overload based fringing common with smaller sensors (i.e. crop sensor, point&shoot cameras). It does not appear to reduce sharpness or add any viual artifacts, at least for the images I've processed with it. Interestingly, Nikon View NX software actually provides separate tools for lateral and axial CA:

     

    https://nikoneurope-en.custhelp.com/app/answers/detail/a_id/45733/~/wh at-is-the-difference-between-lateral-and-axial-chromatic-aberration%3F

     

    I suspect the NX Axial CA tool performs similar to LR's 'Defringe' tool, but with a slider instead of two settings (Highlight Edges, All Edges).

     

    Message was edited by: trshaner: Corrected Nikon View NX link.

     
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    Apr 4, 2012 5:59 AM   in reply to trshaner

    trshaner wrote:


    LR's CA tool(s) are designed to correct only longitudinal aberrations,

     

    Lateral.

     
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    Apr 4, 2012 6:21 AM   in reply to Lee Jay

    Thanks Lee Jay, I got my lateral and longitudinal reversed. Here's a Chromatic Aberration Decoder:

     

    Transverse (Lateral) CA : Color shifts perpendicular to the optical axis, in the plane of the sensor or film.

    Increases with distance from image center.

    Use LR's Chromatic Aberration tool(s).

     

    Axial (Longitudinal) CA: Color shifts in the direction of the optical axis

    Uniform across image, but most noticeable in bright highlight areas.

    Use LR's Defringe tool.

     
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  • Currently Being Moderated
    Apr 4, 2012 3:27 PM   in reply to bakubo

    I agree that using both CA Removal and Defringe appears to be the best of the four screenshots posted. It's also a good idea to review the images with correction applied at 100% to make your final decision, since that's closer to the worst-case of what the image will actually look like. Also check other areas of the picture for impact to CA.

    Axial CA behaves in a non-linear manner compared to Lateral CA, so it's more difficult to design a tool for correcting it. Lateral CA does not vary with the F stop setting , but Axial CA does. If you have a lens that exhibits Axial CA, a smaller F stop setting (F 5.6, 8) will reduce or completely remove it. Unfortunately the lenses with the worst Axial CA are "fast" lenses (F 1.2, 1.4, 1.8), which you paid a lot of money for to use that wide aperture. So we do the best we can. Keep in mind that at most "normal" print and screen view sizes small amounts of residual CA are practically invisible!

     
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    Apr 4, 2012 3:32 PM   in reply to bakubo

    Science or not, the old tool worked better

     
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    Apr 4, 2012 3:59 PM   in reply to Scooby007

    What do you mean by better? LR4's CA tool is actually better than LR3's Lens Profile tool for CA removal, since it works real-time on "your images," " shot with "your lenses," at whatever F stop, distance, and lighting "you used." I'll grant you there may be some examples where LR3's CA "manual tools" may work better than LR4's "automated" tool, but I haven't seen it myself. Can you post screenshots of an example image that supports what you are saying? I'm not trying to put you on the defensive, just interested in seeing what you are seeing.

     
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    Apr 4, 2012 6:06 PM   in reply to bakubo

    I like the automatic controls but also please give us the manual controls back.  There are many instances where the auto doesn't quite do it.  I would like both - auto and also under manual tab the blue/yellow and red/cyan sliders for times when one needs it on trickier images.  It seems that you are digging your heels in on this even when many are asking for the manual controls back.  Is there a technical reason why they cannot be re-implemented?  Thanks.

     
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  • Currently Being Moderated
    Apr 4, 2012 7:20 PM   in reply to adventure_photo

    Trust me when I tell you I'm not "digging my heels in," and this based on over 45 years of work experience with computer technology and photography. I am sure the LR team reviewed numerous images and with the "automatic" CA algorithms before they made the decision to remove the manual CA controls. Adobe can certainly replace the manual CA controls back in LR4 if it can be proven there is a legitimate need. If you can provide actual image files with details on how LR3's manual CA controls provide better CA correction than LR4, I am sure Adobe will give it consideration. Please see this request that has already been posted:

     

    http://feedback.photoshop.com/photoshop_family/topics/lightroom_4_beta _removes_much_chromatic_aberration_and_defringe_capability

     

    Please also keep in mind that the Adobe enginneers can also make changes and additions to the LR4 automatic CA algorithims to improve performance with "tricky" images. This will only happen if we LR users provide actual evidence that it is needed.

     
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    Apr 4, 2012 7:27 PM   in reply to trshaner

    That wasn't directed at you trshaner, I meant I thought Adobe was digging their heels in on this, so sorry if you took it that way.  I did send an image to MadManChan that was an example of an image that did not work with auto CA fix.  Hopefully they'll either improve the auto fix so that it works every time or give us a little more control with manual sliders.

     
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    Apr 8, 2012 4:19 PM   in reply to trshaner

    > I am sure the LR team reviewed numerous images and with the "automatic" CA algorithms before they made the decision to remove the manual CA controls.

    My impression is you don't trust people writing that the manual controls did work for the problem images while the new auto don't

    I do appreciate the automatic option - this is a highly desired new feature. It is something Nikon has been doing for a while in-camera and in the NX converters, and has worked great most of the time, even with 3rd-party lenses. 

    But auto removal tends to fail with bad cases of lateral CA, like when using add-on macro diopters, wide converters, or with some vintage lenses. It seems the same with LR4 and Nikon. For these, the old manual correction is better. +1 please bring the manual correction back as option.

    > Please also keep in mind that the Adobe enginneers can also make changes and additions to the LR4 automatic CA algorithims to improve performance with "tricky" images.

    Adobe engineers can get themselves a few cheap macro diopters. I doubt auto will work because with bad laCA the smearing gets wider and with softer edges (bad laCA is often accompanied by poor edge sharpness). I think automatic CA removal via lens profile creation from B&W target images has a higher chance of success in such cases. But building profiles doesn't always make sense, if one only takes a few shots with the same setup. 

    I hear CA removal is no longer profile based - does this mean creating a profile wouldn't work anymore (haven't tried)?

    Notice Nikon does also longitudinal (axial) CA in CNX2, which is sometimes effective but mostly not. It tends to be effective where the smearing is narrow around the edges. However, loCA smearing is usually wider, then the removal in CNX2 is not very efficient.

     
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    Apr 9, 2012 8:11 AM   in reply to -Sem-

    -Sem- wrote:

     

    > I am sure the LR team reviewed numerous images and with the "automatic" CA algorithms before they made the decision to remove the manual CA controls.

    My impression is you don't trust people writing that the manual controls did work for the problem images while the new auto don't

    I'm a believer that some people are seeing they can remove CA manually in LR3 that LR4's automatic CA tool can't. This is most likely Axial CA, which is going to be present uniformly across the image, but most obvious in bright highlight areas. Using the manual CA control in LR3 may be able to remove it in a specific highlight area, but will introduce "Lateral CA" across the whole image. It's the wrong type of algorithm for Axial CA. The 'Defringe' tool is a better tool to use even though it may not remove all of the visible Axial CA. IMHO- LR4's CA tools produces the same or better "overall" CA correction than LR3.


    -Sem- wrote:

     

     

    I hear CA removal is no longer profile based - does this mean creating a profile wouldn't work anymore (haven't tried)?

    Notice Nikon does also longitudinal (axial) CA in CNX2, which is sometimes effective but mostly not. It tends to be effective where the smearing is narrow around the edges. However, loCA smearing is usually wider, then the removal in CNX2 is not very efficient.

    LR4's automatic CA tool works independently by analyzing the image real-time for Lateral CA, and then applying correction. It does not use or require the Lens Profile information.

     

    I'm pretty sure NX2's Axial CA tool works similar to LR's Defringe tool, but uses a slider instead of two fixed settings. It may or may not be better depending on the type and severity of the Axial CA. I have no experience with NX2, but you might want to try LR's Defringe tool for a comparison. Axial CA is different than Lateral CA in that it is inability to focus all three RGB light rays on the same plane. It causes different amounts (and perhaps color) of CA to appear 1) at the focus plane, 2) in front of the focus plane, and 3) behind the focus plane. Because of this it is much harder to correct than Lateral CA.

     

    It would help if you can post an example raw image file with Axial CA to Yousendit or other download site. That way we can see first hand what you are telling us and provide feedback.

     
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  • Currently Being Moderated
    Apr 9, 2012 2:57 PM   in reply to trshaner

    https://www.yousendit.com/download/M3BrTkZvNHZTSUJjR05Vag

    Here's one CA sample due to an add-on wide-converter. Pay attention to the antenna near the right edge. I guess this is lateral CA.

    Nikon applies auto lateral CA correction without asking, but fails here. The "axial CA" removal option in ViewNX does a great job on the antenna, although I don't think axial CA is the cause (on the other hand, I've seen samples of obvious green/magenta loCA that weren't helped much by this "defringe" option).

    The Auto CA removal in LR4 does some good work, but not great. The Defringe option makes some improvement. I can't check what LR3 would do manually.

     

    I think the manual sliders should be brought back as an option if users can show they work better for certain purposes than the new auto correction. Even if the better results are obtained by gross misuse

     

    https://nikoneurope-en.custhelp.com/app/answers/detail/a_id/45733/~/wh at-is-the-difference-between-lateral-and-axial-chromatic-aberration%3F

     
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  • Currently Being Moderated
    Apr 9, 2012 4:58 PM   in reply to -Sem-

    Thank you Sem. I downloaded the DSC_1947.NEF and processed in LR3.6 and LR4.1RC. I used the LR3 & 4 Develop default settings and did not change any of the controls except CA and Defringe as shown here:

     

    Double-click on the picture to see full-size

    CA Test LR3 versus LR4.jpg

    The above is a crop from the right bottom corner of the picture clearly exhibiting a large amount of Lateral CA.  No Axial CA is visible anywhere in the image. Using LR3's Manual CA tools the CA is fully corrected, with only a tiny barely visible addition of CA in other areas of the picture closer to the center. Addition of Defringe helps slightly for both LR3 and LR4. There is no question LR3's manual CA tools are doing a better job than LR4's automatic CA tool for this image.

     

    I stand corrected!

     
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  • Currently Being Moderated
    Apr 14, 2012 8:02 AM   in reply to trshaner

    Well, try this one (http://www.barragemaabb.com.br/_DSC2829.nef). I used to correct almost all the CA in LR 3.3, but now, with LR 4.0, it can't be corrected! The problem is that I used a magnification filter with my lens, so I got all this CA. With this filter on, I think LR can't figure out how to correct CA.

     
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    Apr 14, 2012 9:59 AM   in reply to glaucoccastro

    LR3's CA tools can only get rid of about 50% of the CA, and LR4's 0%. Since you're shooting with with Nikon equipment why not give the free Nikon ViewNX 2 CA tools a try:

     

    http://nikonimglib.com/nvnx/

     

    It has a lateral CA tool like LR3&4 and an axial CA tool, which LR3&4 does not have.

     

    http://forums.adobe.com/thread/537198

     
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  • Currently Being Moderated
    Apr 14, 2012 4:09 PM   in reply to trshaner

    > It has a lateral CA tool like LR3&4 and an axial CA tool, which LR3&4 does not have.

    Lateral CA in VNX is the same as in-camera (automatic, can only be turned off), doesn't seem to be effective judging by the embedded jpg. I thought you meant the Nikon's axial CA was in some relation to LR's defringe?

    The manual laCA correction in Raw Therapee approximately removes this CA at max correction.

     
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    Apr 14, 2012 4:13 PM   in reply to -Sem-

    I have no experience with Nikon's NX2 tools, but it appears that its 'Axial CA' tool may work better than LR's 'Defringe' tool. Unlike Nikon's automatic lateral CA correction, it has a slider you control to vary the amount of axial CA compensation it applies. Does it help with the file you linked to?

     
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    Apr 14, 2012 4:47 PM   in reply to trshaner

    Here are the results. I don't have Viewer NX2, but I do have Capture NX2.

     

    without correction: http://www.barragemaabb.com.br/without%20correction.jpg

     

    Only auto lateral color aberration: http://www.barragemaabb.com.br/auto%20lateral%20color%20aberration.jpg

     

    auto lateral color aberration + axial color aberration set to 100: http://www.barragemaabb.com.br/auto%20lateral%20color%20aberration%20a nd%20axial%20color%20aberration%20100.jpg

     

    auto lateral color aberration + axial color aberration set to 0: http://www.barragemaabb.com.br/auto%20lateral%20color%20aberration%20a nd%20axial%20color%20aberration%200.jpg

     

    As you can see, it didn't resolve it, but it did a good job. Anyway, I got a better result with LR 3.

     
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    Apr 18, 2012 3:06 AM   in reply to bakubo

    The old manual CA control was way better to use with lenses without profile like fisheye lenses. I use fisheye images to stitch a panorama, and it is impossible to correct the CA in source images with LR 4.1RC.

     
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    Apr 18, 2012 3:42 AM   in reply to Thomas Krueger

    i agree that CA´s are a weak point in LR4.

     

    tha automatic CA removal may work well for some images (camera lens combinations).

    but the manual option should not have been removed.

     
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    Apr 18, 2012 5:17 AM   in reply to Thomas Krueger

    > The old manual CA control was way better to use with lenses without profile like fisheye lenses. I use fisheye images to stitch a panorama, and it is impossible to correct the CA in source images with LR 4.1RC.

     

    Which lens? Have you got a sample to support the initiative? I've checked a few of samples with the Nikkor 10.5mm and auto worked fine, unlike my sample with the WA converter add-on lens. My impression is auto works fine with moderate laCA up to a certain point, but fails with bad CA. Notice even manual may fail with particularly bad CA (if the slider isn't long enough).

    Btw, AFAIK there were lens profiles for certain fisheyes. Not really meant for removing fisheye distortion, as the fisheye projection is rather an inherent characteristic of the lens and converting to rectilinear causes a considerable degradation of quality. But someone did manage to hack a set of profiles for the Samyang 8mm mFT for conversion to a few different projections, including stereographic, equal area and rectilinear (but unfortunately not to cylindrical and variants like Fisheye Hemi). 

     
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    Apr 18, 2012 7:31 AM   in reply to -Sem-

    I'm using the Nikon 10.5mm fisheye and the Tokina 10-17mm fisheye on a Canon 5D.

    For now I'm switching back to PTLens (works with Panoram Tools) to get rid of the CA on 16bit tiff files.

     
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    Apr 26, 2012 5:47 PM   in reply to bakubo

    bakubo wrote:


    I haven't tried them yet though.

     

    They're quite impressive, especially with localization.

     
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    Apr 27, 2012 9:07 AM   in reply to Lee Jay

    Just downloaded 4.1 RC2 and I'm impressed with the new CA tools – Hats off to the Adobe LR team!

     
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    Apr 28, 2012 12:47 AM   in reply to trshaner

    Yup, RC2 is the bees knees for defringing- I have a Canon 85mm 1.8 which produces the most ghastly purple fringing wide open on contasting edges (I use it mainly for concerts and dance so sequins and tuxedos are a bane of my life). The RC2 fringe correction eats the purple fringing up and spits it out and jumps up and down on it. Brilliant!

     
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    Apr 28, 2012 1:47 AM   in reply to bakubo

    Can I say again how brilliant the new RC2 defringing control is. I've just sped through 200 concert shots all taken with the 85mm 1.8, mostly wide open (lousy school concert lighting). Lots of reflective mike stands, white shirts against dark blue school uniforms, brass instruments. Normally I'd either be spending ages painting out the fringing, or giving up and leaving it. But the new adjustments did a wonderful job of removng both the purple fringing and the axial CA. The only issue I have had is that the eyedropper is very hit and miss - it often tells me it can't find the fringing; manipulating the sliders does it every time. I found the auto CA removal in the first version of lightroom 4 worked well for my wide angles but this really does the trick on what is otherwise really painful to deal with stuff.

     
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    Apr 28, 2012 2:05 AM   in reply to Susan S.

    I can't wait to give this a try. I really wasn't expecting a good fix for axial CA anytime soon, and then here it is! This feels like a second birthday after the release of LR4.

     

    I have Canon's 50mm f/1.4 and get quite a bit of purple & green. Looks like LR 4.1 will give these images a huge boost!

     

    Susan: Do you often need to adjust the hue setting or is it just a matter of adding a few steps of defringing power? How far do you usually need to pull the sliders?

     
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    Apr 28, 2012 2:17 AM   in reply to davidnaylor83

    What I needed to do depended a bit on the focal point of the image, and how much stuff was in front of or behind the focal point. The purple fringing settings was pretty much the same on all of them, so I could just set that with the eyedropper and sync across images. I was very impressed as it managed to distinguish between purple music folders and purple fringing - this isn't mindless at all. 

    The green fringing required a bit more finessing  and the eyedropper wasn't so keen on picking it up, so it required twiddling of both the colour range sliders and the amount. A few images had noticable red fringing and extending the colour range of the purple slider did that OK, but it seemed more inclined to pick up other non-fringe areas, especially mouths and lips.

     
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    Apr 28, 2012 2:25 AM   in reply to Susan S.

    Ok. That sounds pretty promising all in all!

     
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    Apr 28, 2012 2:39 AM   in reply to davidnaylor83

    I've just hit a fringing torture test with a row of saxophone players, so  saxes behind (massive green fringing) and in front (red fringing) of the focal point, all bright polished brass, very high contrast lighting; with a drum kit behind with greenish cymbals and red drums, so I had to be really careful not to affect the drum kit colours or skin tones. The eyedropper totally failed on that, but fiddling with the sliders, holding the option key down to show on screen what is being included as you slide worked pretty well.

     
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    Apr 28, 2012 3:16 AM   in reply to Susan S.

    Could you post before/after screenshots? =)

     

    I'm guessing the eyedropper needs a very well defined fringe to work, such as the fringing you get round blown out areas in contact with dark areas.

     
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    Apr 28, 2012 6:06 AM   in reply to davidnaylor83

    Adobe has posted a nice article written by Eric Chan in the Lightroom Journals with details on how to use the new LR4.1 RC2 Defringe controls:

     

    http://blogs.adobe.com/lightroomjournal/2012/04/new-color-fringe-corre ction-controls.html

     
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