I recently bought a Canon Powershot G7X Mark II. I am using Linux and I found darktable to be a decent photo editor. However, my RAW pictures come with a distortion which darkens the corners and displays my photos as if I had some vignette on them.

I looked at the lensfun camera list and the Mark II model is not supported yet.

Then I learned about Canon's DPP, which does have lens correction included. It does it automatically, it is already done by the time I open the photos in the DPP.

Besides the DPP only being available in Windows, I can't figure out the way to apply the lens correction on the RAW files and store them somewhere accessible from Linux.

I have saved a few of these files in TIFF format, so I could see if they're as editable as a RAW. However, when I compare the edited files in darktable (RAW vs TIFF), they're clearly different.

  • DPP is also available for Mac OS. Not that that helps you running Linux, but DPP is not "only available in Windows."
    – Michael C
    Jan 8 '19 at 10:09
  • Why not just use DPP as your raw editor? It's free and all updates are also free. Sure, it takes awhile to learn where everything is, but it does Canon color better than any other I've found.
    – Michael C
    Jan 8 '19 at 10:11
  • @MichaelC I am not against DPP but it is not available on Linux.
    – FaureHu
    Jan 8 '19 at 19:08

You cannot save images in Canon's CR2 raw format, or any other, from DPP (or any other image editing program that i know of).

Even if you could, it wouldn't change anything. The image operations are already done, the saved image is different than the original raw file because the editor has to make some arbitrary decisions when demosaicing the image appplying white balance etc. to produce the image you see. Any lens corrections are only applied then to this image. If this was saved to a raw format, all of this decisions would be baked in just as in a TIFF.

That said, if you're careful when preparing your image in DPP by keeping contrast low so that all data is kept in the image (no colours are clipped that aren't already clipped in the raw image) and export to 16 bit TIFF, you should still have more or less the same degrees of freedom when editing these TIFFs in darktable.

  • Do I specfically need to bring down the contrast in DPP or would this work by just leaving the contrast untouched?
    – FaureHu
    Jan 8 '19 at 19:10
  • you would probably have to look at this on a case by case basis. maybe you can set a useable default.
    – ths
    Jan 8 '19 at 19:12

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