Why do bright/dark halos appear around trees against the sky after raising shadows in RAW processing?
Asked 1/16/2020
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2 answers
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When editing a RAW file, I often raise shadows and reduce highlights to balance scenes like dark trees against a bright sky. On some images, this creates obvious halos along high-contrast edges: a bright halo on the dark side and a dark halo on the bright side.
I tested this with a Sony a6300 file and saw the effect in both Luminar 2018 and Darktable. The screenshots were taken directly from the editing software, and the effect becomes more visible when I push shadow recovery harder.
Is this caused by the camera or by software processing? Is it related to the same kind of artifact seen in HDR tone mapping? Can it be avoided or fixed?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
6y ago
2 Answers
1
It is a processing/software artifact and the same as what is encountered when tone mapping HDR images... that's basically what you are doing; re-mapping the tones, only w/in a single image.
Also check other contrast type settings; sharpening, clarity, etc. Those types of settings try to preserve/increase the perception of details by adding localized contrast; i.e. light next to dark/dark next to light.
Originally by user70370. Source · Licensed CC BY-SA 4.0
user70370
6y ago
0
Generated from our catalog & community — verify before relying on it.
This is most likely a software processing artifact, not a fault with your camera or lens.
What you’re seeing is typical of tone mapping or local-contrast processing around strong edges, such as dark trees against a bright sky. Raising shadows and lowering highlights is essentially a form of tone remapping, similar in principle to HDR processing, and some editors implement it more aggressively than others. Extra settings like clarity, sharpening, or other contrast-enhancement tools can make the halos worse.
So yes: it’s closely related to the kind of haloing often seen in HDR images, even if you’re working from a single RAW file.
To reduce or fix it:
- use a RAW converter with gentler shadow/highlight processing
- back off the shadows/highlights adjustment strength
- check and reduce clarity, sharpening, or local-contrast settings
- try another processor if one app produces halos and another doesn’t
Based on the shared experience, RawTherapee handled the same file without the halo, which suggests the issue is the software’s implementation rather than the hardware.
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AI6y ago
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