How can I reduce high-ISO noise in a dark photo without softening the subject?
Asked 1/17/2014
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2 answers
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I have a photo taken at very high ISO that I still like, but the dark background shows lots of bright speckled noise. I tried duplicating the layer, applying Gaussian blur, and masking the foreground so only the background was softened. It helped a little, but the result still isn’t very clean and the edges around the subject don’t look great. What’s a better way to reduce this kind of noise while keeping the main subject sharp?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
12y ago
2 Answers
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Masking the foreground and denoising the background is a good technique when the background is out of focus.
You would get a slightly better result using a dedicated noise removal plugin (noiseninja or neatimage, or one of the inbuilt Photoshop tools). Gaussian blur is a bit of a blunt instrument, whilst it's good at removing pure random noise it is not as good at removing banding, which is visible in this image. It's also bad at preserving hard edges. An edge aware noise filter would let you mask much closer to the edges of your in-focus subject without risk of blurring it, which in turn would avoid the halo of grain you have around the bottle.
Blending a little (25% or 33%) of the original noisy background back in helps the result look less fake, whilst still allowing a low overall noise level.
Finally when you have a noisy image, save using the highest quality option if using JPEG (or use PNG). JPEG's attempt to compress noise often looks worse than the noise itself!
Originally by user1375. Source · Licensed CC BY-SA 4.0
user1375
12y ago
0
Generated from our catalog & community — verify before relying on it.
Yes—masking the subject and denoising only the out-of-focus background is a solid approach. The main issue is that Gaussian blur is a crude tool: it removes random speckle, but it also softens edges and doesn’t handle patterned noise or banding very well.
A better option is to use a dedicated noise-reduction tool or an edge-aware noise filter, such as built-in Photoshop noise reduction or a specialist plugin. These are designed to smooth noise while preserving edges, so you can mask closer to the subject without creating a blurry halo.
A good workflow is:
- Select or mask the foreground subject.
- Apply noise reduction only to the background.
- Refine the mask so the transition around the subject looks natural.
- Blend a small amount of the original noisy background back in (around 25–33%) so it doesn’t look overly plastic or fake.
You likely won’t remove all noise perfectly, but targeted background denoising with an edge-aware tool will usually look better than Gaussian blur alone.
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