Why does the appearance of RAW files change when switching from "lighttable" to "darkroom" in Darktable?

Question

In Darktable, when extracting RAW and JPG from the camera and viewing them using lighttable mode, both look identical. Does this mean that they both contain post-processing done by the camera processor?

Then, when taking the RAW and going from lighttable to darkroom mode some properties of the picture changes significantly (the picture looks quite different). Is this because darkroom mode removes the in-camera post-processing?

Is there a way to get in darkroom, as a starting point, the RAW file just like we can see it in lighttable?

Answer 1

This is essentially the same as Why does my Lightroom preview change after loading? . The RAW file contains a JPEG preview, which reflects the camera's settings and will generally be the same as an in-camera JPEG (although usually in low quality to save space). That's what Darktable is showing you initially.

When you go to process the image, Darktable is working from the RAW itself. It's not removing in-camera processing -- it's just that that processing wasn't really there in any helpful way in the first place. (Clues to the processing may be included in the file's metadata, but usually as manufacturer-specific proprietary information.)

Darktable doesn't have access to the exact algorithms and settings used for the internal processing, so the basic answer to that part of your question is "sorry, no". Take a look at How can I reproduce the camera-internal postprocessing? for more on this.

Answer 2

The answer to all three of your sub-questions is "No."

The actual picture data from what the sensor has captured in a raw file is not affected by the in-camera processing settings. The preview JPEG file embedded in the raw image file is affected by those settings since the camera uses them to generate the preview JPEG.

When you view an image in Darktable using lighttable mode, you are viewing the JPEG preview, not a rendering of the actual raw picture data. When you go into darkroom mode then you are viewing a conversion of the raw data. This conversion is created by the program that probably doesn't even attempt to read the information from the raw file that includes what the in-camera setting were at the time. Even if it could read them, it wouldn't be able to do much with them. Unless a third party raw convertor, such as Darktable, has access to the exact algorithms used by the camera manufacturer then any rendering they do is basically a reverse-engineered educated guess. Most manufacturers make their demosaicing algorithms proprietary and either do not share them at all, or only share them with major players on the image processing software landscape such as Adobe (LR/PS/CS) and DxO Optics. And all Adobe products, to the best of my knowledge, ignore any information in a raw file that has to do with the in-camera settings. This information is, in fact, stripped away when a raw file such as a .cr2 from a Canon camera or an .nef from a Nikon camera is converted to Adobe's .dng format.