GIMP installed via FlatPak asks me to install DarkTable, but I've already installed it. (not via Flatpak). How can I get GIMP to find it?

Question

I'm running Ubuntu 18.04 MATE and recently downloaded GIMP 2.10 as a Flatpak. I also have Darktable loaded (not a Flatpak) as I work with RAW format photos. I want to be able to post process RAW images using GIMP as well as Darktable, but when I try to load a RAW image into GIMP I receive a dialogue that asks me to install Darktable. I'm assuming I need to have Darktable in my path, if that is what is needed I just don't know how to do that. Any comments and guidance will be appreciated.

This is my current $PATH:-

/home/-/bin:/home/-/.local/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin

Answer 1

Installing Gimp plug-ins isn't a matter of PATH contents. To add plugins to Gimp you put the executable (a file-* in it can load/save files) in specific directories:

• /usr/share/gimp/2.0/plugins (for "regular" installs, not flatpak ones)
• the plugins directory in your Gimp user profile

The equivalents for flatpak installs would be:

• /var/lib/flatpak/app/org.gimp.GIMP/current/[...]/files/lib/gimp/2.0/plug-ins/
• .var/app/org.gimp.GIMP/config/GIMP/2.10/plug-ins

But the problem with flatpack-ed Gimp is that it has its own runtime, so using executables not compiled for the flatpak environment isn't guaranteed to run smoothly.

IMHO, flatpak is just a stopgap measure for people stuck on 16.04, since you are on 18.04 you should add the Gimp PPA to your software sources and do regular installs from that.

Answer 2

Note that the original question asked for how to change PATH before it was edited. The questions aren't supposed to be edited in fundamental ways that make correct answers incorrect.

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I'm not sure how to fix the problem with GIMP, but modifying the PATH for all users is easy enough. You just create a few files in /etc/profile.d and restart:

1. Open a terminal by pressing Ctrl+Alt+T.
2. Check whether Darktable starts when you try running it (it might already be in the PATH). If so, stop. If not, continue.
3. Run sudo nano /etc/profile.d/darktable.sh

4. Add a line, replacing the path below with the proper path:

   export PATH=$PATH:/path/to/darktable/bin
   

5. Press Ctrl+O to save.

6. Press Enter to accept the given filename.
7. Press Ctrl+X to exit nano.
8. Run sudo nano /etc/profile.d/darktable.csh

9. Add a line, replacing the path below with the proper path:

   setenv PATH ${PATH}:/path/to/darktable/bin
   

10. Press Ctrl+O to save.

11. Press Enter to accept the given filename.
12. Press Ctrl+X to exit nano.
13. Close the terminal window.
14. Restart your system.

Answer 3

Any supported version of GIMP can open raw images with gimp-dcraw from the default Ubuntu repositories. The gimp-dcraw plug-in integrates with GIMP apt packages only, it does not integrate with either GIMP snap packages or GIMP flatpak packages. Therefore if you're a stickler for GIMP version 2.10, you'll have to wait for two weeks until Ubuntu 18.10 which has this version of GIMP in the repos is released.

To install gimp-dcraw open the terminal and type:

sudo apt install gimp-dcraw  

The proof that this plug-in works is shown in this screenshot.

^{off color raw image in GIMP + gimp-dcraw in Ubuntu 18.04}

The problem with this method is that the colors of the raw image look off color and not like colors in the original image. The water in the image is supposed to be blue, not off color. You can see the original image at this answer. The solution is to stay with Darktable. I tried opening raw images in GIMP, Krita, and Darktable and only Darktable has an acceptable level of color accuracy for raw images by default.