Lightroom Classic 9.1: Repair brush - creates a color fringe of about 1 pixel width in the target area

  • 4
  • Problem
  • Updated 1 month ago
  • Acknowledged
  • (Edited)
Unfortunately, the following problem occurs constantly:
If the repair brush is used to paint over an area adjacent to the edge of the image, Lightroom creates a color fringe of about 1 pixel width in the target area.
The error is visible in the preview image and in the exported image, too.
I use Lightroom 9.1 on MacOS 10.14.6.

Add background with repair brush:


Color fringe appears:


Magnified 8 times:


Edit: Changed second image to better show the issue.
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Patrick Itten

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  • frustrated

Posted 1 month ago

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Edmund Gall

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Hi Patrick! When using LR's repair brush on the edges of your photos, you need to ensure it's set to Clone instead of Heal. Otherwise you'll get the result displayed here. Can you confirm if your brush was set to Heal (as it's not included in the screenshot snippets you've attached above)? If yes, then what you observed is not a bug, but the proper function of the brush.

Hope this helps...
Ed
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Patrick Itten

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Hi Ed

Yeah, the repair brush is indeed set to Heal. Sorry, that I didn't specify.
I know it works with Clone. From what I understand, Heal is basically a Clone followed by a low pass filter. (I suppose the actual implementation is a bit more sophisticated.)

I did a lot of numerical simulations during my engineering studies and you always had to put a lot of thought into proper handling of the boundary conditions.

The described color fringes are definitely not the desired function of the repair brush in Heal mode, but an insufficient implementation of these boundary conditions. The pixels at the image border have a different 'neighbourhood' than all the other pixels. This has to be taken into account.

Patrick
(Edited)
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Anthony Blackett

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Tried this in Heal mode on my Windows 10 system with Lr Classic 9.1 and don't see any edge artifacts, even at 11:1 zoom.
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Patrick Itten

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Thanks Anthony for testing. You prove that this is not by design but by accident.

I have to correct myself. The fringes appear even in Clone mode and whether I have gpu acceleration turned on or off does not change anything.

Painting several times over the edges solves the problem partially or in places. But it's a lottery whether it works or not.

It would be helpful if an Adobe engineer could look at this issue.
In the meantime, I will have to perform an action over the exported images to remove the outermost pixels.
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Patrick Itten

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Here you can clearly see, that it's just showing up where the repair brush was applied.(The small image size and the heavy compression in this forum makes it appear less pronounced than it is in reality.)

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Bruce Houstoun

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Can you provide details about the image?
i.e. Camera/filetype ,was there any processing like Pano/HDR /Photoshop done first?

I tried a few images myself LR9.1/Win10 and could not see anything like what you have shown.
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Patrick Itten

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It's a .cr2 raw-image from a Canon 5Dmk4. No processing is done before applying the repair brush, not even any Lightroom adjustment.
(Edited)
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Anthony Blackett

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Patrick, my camera is a Nikon D750. Downloaded a cr2 raw image and tried the test in a dark corner. Resulted in a coloured line down one edge where the spot removal was placed. I'll try more tests later.

Tony
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Anthony Blackett

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Further tests on a CR2 file have shown that it doesn’t matter whether the clone or heal mode is used, the edge artifact is still produced. In fact, for my test it seemed worse in clone mode. The artifact also changes as you drag the sampled area around, but for this image, it only appeared on the right edge (or the left edge if clicking the bottom left corner). To make it more visible, I first pushed the exposure up quite a bit and then clicked the spot removal tool in a dark corner of the image at 11:1 zoom. Here is a screen shot:



Once again, I tried this with one of my NEF files and could not produce any edge artifacts in either the clone or heal mode.

Tony

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Bruce Houstoun

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I was also able to repeat the issue with cloning dark edge areas with files from Canon 5Dmkiv, 5DS R  (cr2) & EOS R (cr3) (using with LR9.1/win10)
I also tried some other sample files from other Nikon and Canon cameras but so far those were the 3 models that I found that had the same problem. (I was using files with no other LR edits applied)

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Patrick Itten

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I ran some more tests and found that the fringe appears only at the outermost border of the cr2 image. If I crop the image just a tiny bit before applying the repair brush, no fringe appears.

And I can reliably reproduce the issue on 5D4 and 5DSR raw files. With raw files from the 5D3 and the 6D2 no fringes appeared so far.
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Patrick Itten

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This is the right forum to get Adobe's attention, right?
So far they haven't reacted and I would be happy if the issue would be looked at.
Or is there another way to submit a bug report?
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Edmund Gall

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It is the right forum, but from what I've seen, I'm guessing there are several degrees of response. If there's a quick workaround/fix, then someone (who may or may not be from Adobe, e.g. a fellow user) will chime in. Especially if the issue is likely to impact a significant proportion of users: that's why if any users are experiencing it, they should click on the Me Too button above so Adobe would know.

If it's a bug (as this seems to be), then someone from Adobe (or one of the forum admins) will need to confirm it as repeatable before change the status (e.g. from Problem to Acknowledged) and passage upwards to the supposrt pipeline. Timelines for fixes will then be anyone's guess as it would depend on competing priorities. In this case, as the impact is only one pixel wide at the edge, I probably won't hold my breath for any quick response for a fix and just proceed to implement my own workaround, e,g, either ignore because the impact is so small that the vast majority of viewers won't notice the fringe (especially in multi-coloured images), or crop in slightly where it is noticeable (such as the monochrome test cases you provided)...
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Rikk Flohr, Official Rep

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Greetings,

We've been monitoring the discussion on this thread. Important to resolution would be to test the same file in Camera Raw and see if it exhibits the same issue as Lightroom Classic.  Have you done this? If you see it in Camera Raw it is likely an issue to report to all Photography clients. If it only happens in Lightroom Classic then we can file it with the Classic team. In any case, we would need a copy of the raw file along with detailed step-by-step instructions of how to reproduce. 
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Patrick Itten

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Thanks for answering and looking into the issue.

I have just tested in CameraRAW and the color fringe appears as well.

Step by step instruction:
  1. open raw file in LR or in CameraRAW
  2. paint over an area at the edge of the picture with the repair brush
  3. if the error does not occur, move the target or source area a little. The color border is always different.
RAW file:
For privacy reasons, I cannot send the portrait image in question. However, I can send you a scrap capture from the same session, which also shows the problem: https://we.tl/t-lXw7ucgPQB (file available for one week)
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Rikk Flohr, Official Rep

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I've logged a bug with the Camera Raw team. I have downloaded your file and attached it to the bug.  This thread will be updated when the issue is fixed. 
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Patrick Itten

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Thank you Rikk!