Why do RAW files look noisier than JPEGs, and what noise reduction options work in open-source editors?
Asked 2/24/2020
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I’m editing high-ISO images (around ISO 1600–2500) in darktable and finding the RAW files look much noisier than the camera JPEGs. I’ve tried darktable’s noise-reduction tools and also looked at RawTherapee, but I’m unsure whether I’m missing a better open-source approach.
Why does the RAW file appear noisier than the JPEG from the camera? And within open-source RAW editors, what should I try to get better noise reduction results?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
6y ago
2 Answers
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Why my RAW is noisier than Jpeg?
Because the JPEG created by your camera included the noise reduction contained in the camera's raw processing engine. When you work with the raw file in another application, none of the in-camera processing used to create the JPEG is used by your external raw processing application. It uses its own noise reduction algorithms based on the settings you have selected within that application.
If your camera's manufacturer has their own raw processing application, using it may include noise reduction very similar to the camera's internal JPEG engine.
The reason your image is so noisy to begin with is because it was exposed very dark, so there's not much signal (light) to overcome the noise. Thus you have a low signal-to-noise ratio.
Originally by user15871. Source · Licensed CC BY-SA 4.0
user15871
6y ago
0
Generated from our catalog & community — verify before relying on it.
RAW files often look noisier than camera JPEGs because the JPEG already has the camera’s built-in processing applied, including noise reduction. A RAW editor like darktable or RawTherapee does not use that in-camera JPEG processing; it applies its own algorithms based on your settings.
The bigger issue in your example is likely exposure: if the image was captured quite dark, the signal-to-noise ratio is low, so noise becomes much more visible when you brighten it later.
In open-source software, both darktable and RawTherapee can reduce noise, but results depend on settings and viewing scale. In RawTherapee, noise reduction is best judged at 1:1 zoom, and it offers both global presets (for example, more conservative vs. more aggressive reduction) and wavelet-based controls that let you target noise at different detail scales. Those wavelet tools can be especially useful for reducing fine-grain noise while preserving larger detail.
If your camera maker provides its own RAW software, it may give results closer to the in-camera JPEG look.
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