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I installed the latest version of Darktable from the Ubuntu PPA from their homepage (1.6.8). When I import RAW ges from a folder they all seem to have a lot of noise.

I opened the exact same images in other programs (DigiKam and Corel Aftershot) and there, these images did not have as much noise. In comparison, it seemed also that Darkroom turned up the brightness or exposure as the images there seemed a lot brighter.

I looked over all the settings and none of them were turned on. Also, this is still the standard installation (I did not change anything after installing).

Also using the lens correction for my camera (Lumix LX7) makes the images even more bright and produces more noise.

Does anyone have a tip on how to remove this? I would really like to use Darkroom instead of Corel Aftershot or Digikam, as it seems to have all the features I want and it looks more stable than Aftershot.

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  • \$\begingroup\$ Are you sure that no filters are applied? Look into the History stack in darktable view. Usually some things get applied on import. \$\endgroup\$
    – ziggystar
    Commented Aug 25, 2015 at 7:16
  • \$\begingroup\$ Nope that is not it. There are some operations done upon import, but when I click on "original" the noise is still there. \$\endgroup\$
    – Martin
    Commented Aug 25, 2015 at 15:23
  • \$\begingroup\$ A correction: This only seems to happen to raw images. The jpegs from the camera are fine! \$\endgroup\$
    – Martin
    Commented Aug 25, 2015 at 15:42

2 Answers 2

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Michael is right. More precisely:

The RAW image contains two images: the embedded JPEG preview, which has your camera's processing applied including noise reduction, and the RAW data. When you open your image with an image viewer, you usually see the JPEG preview. In darktable, by default, you will see the JPEG preview in lighttable mode before you start editing the image. In darkroom mode, you will see the result of darktable processing the image, which by default does not do noise reduction. After editing in darkroom mode, the thumbnails in lighttable mode are computed by processing the RAW image.

Activating "denoise (profiled)" is the simplest way to reduce noise. Basically, you trust darkable to apply the right amount of denoising based on your camera and ISO setting (if your camera is supported). There are many other ways to denoise a picture in darktable. Read the manual about the correction group for details.

You can make the denoise module a preset if you want darktable to automatically apply it to all images you open.

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  • 2
    \$\begingroup\$ It seems that you are correct. In lighttable-mode the pictures look fine, but when I take them to darkroom mode they don't. I tried various things like the mentioned profiled denoise, but I can't make the raw pictures look as nice as the JPEG ones. I guess I just have to keep taking JPEG pictures then! The noise in the RAWs is very colorful and bright. When I apply a denoise operation the picture seems to loose a lot of detail. \$\endgroup\$
    – Martin
    Commented Aug 27, 2015 at 15:07
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    \$\begingroup\$ Don't hope that shooting RAW will magically give you better images. The in-camera JPEG are the result of a lot of processing, accumulated years of work from your camera manufacturer (even though it's done on a limited resource device). It does take some time before your own RAW processing really gets better that SOOC JPEG. OTOH, once you've tasted the freedom you get with RAW images and darktable, you don't look back ;-). \$\endgroup\$
    – Matthieu Moy
    Commented Aug 27, 2015 at 15:33
  • \$\begingroup\$ I found a video explaining a lot about noise reduction in raw pictures, which helped me a lot: youtube.com/watch?v=4nBzAeM0tpI \$\endgroup\$
    – Martin
    Commented Aug 28, 2015 at 6:35
  • \$\begingroup\$ +1: more generally, the videos by Robert Hutton are really great. Each single video he did is a must-see. There are cool french videos too (Carafife). See darktable.org/resources/#screencasts for details. \$\endgroup\$
    – Matthieu Moy
    Commented Aug 28, 2015 at 11:53
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Any time you view a "raw" image, you aren't really viewing the raw image. You are either viewing a preview image created by the camera and embedded in the raw file at the time the photo was captured or you are viewing a conversion of the raw image made for display on your monitor by the application at the time you open the image file.

My intuition is that in your case Darktable is giving you a less processed view of the original data and that the other two are already performing some noise reduction and "auto enhancement" to the raw data before sending the image to your graphics adapter for view on your screen. Or they may just be showing the jpeg preview generated in-camera. In which case the in-camera noise reduction, contrast, WB, etc. settings were applied at the time the jpeg was created.

Lens correction will brighten the corners of an image to counteract the natural drop off of brightness that every lens does, to one degree or another, as you move from the center to the edges and corners of the frame. Any time you amplify the signal for a particular area of a photo you also amplify the noise included in that area.

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