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I shot the photo below of some brown pelicans flying over on a Nikon P950. They were against a bright sky, so the silhouette is not surprising. I imported the raw into Lightroom. I lowered the exposure -1.67, which looked right, then did highlights -100, shadows +100, whites up until something saturates which was +86, blacks down until something saturates which was +2, which is my usual process. There is a dark halo around each bird, which remains with any change to the highlight/shadow/whites/blacks sliders, though it is less noticeable around shadows -60 but back at shadows-100. It is less noticeable on the post to stackexchange than on my computer. What is going on here? The original is in Dropbox. enter image description here

Ross Millikan
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  • Are you working with a raw or JPEG file? – qrk Dec 26 '21 at 07:27
  • If you were working in jpg, I'd guess it's Active D-Lighting - see https://photo.stackexchange.com/q/93500/57929 idk for RAW. – Tetsujin Dec 26 '21 at 08:51
  • @qrk: the raw file from a Canon M6 Mark II. – Ross Millikan Dec 26 '21 at 14:47
  • Your comment to qrk makes no sense. Which is it, a .NEF from the Nikon in your question, or a .CR2 from this newly-mentioned Canon? Post the original to somewhere that won't change the data, Dropbox etc – Tetsujin Dec 26 '21 at 16:22
  • @Tetsujin: sorry, it is .NEF from the Nikon. I believe I saved it in Dropbox at https://www.dropbox.com/s/lksoq7orrrsbxp2/DSCN5700.NRW?dl=0 I tested the link and it worked for me. I tried to make it accessible to anyone with the link. – Ross Millikan Dec 26 '21 at 19:15
  • There is indeed a halo in the NEF, independent of the demosaicing algorithm, and even visible in the raw Bayer data. I cannot relate this to chromatic aberration given the "gap" between the halo and the edge, and it looks more like a sharpening halo, which makes me wonder how "raw" is the RAW. – xenoid Dec 26 '21 at 20:42

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Operations that increase contrast often produces halos at high contrast edges.

Sharpening will also produce halos at high contrast edges.

When the halos detract from your intent, it can be a sign of over-processing the image. Though it is worth keeping in mind that intent can vary. Low resolution images tend to tolerate higher degrees of sharpening and contrast than high resolution images.

(Also, there appears to be some chromatic aberration on the edges as well when I zoom in. This is a result of both the character of the lens and not applying a mitigating filter in processing).

Bob Macaroni McStevens
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