Color Scale for specific colors (like blue and pink, for Synthwave or Retrowave)

[ktaherig]

When I installed GIMP, I used Flatpak, yes. I didn't use sudo apt, because that tends to install older versions. I'm on Ubuntu 18.04. When I ran gimp --verbose, it returned:

Command 'gimp' not found, but can be installed with:

sudo snap install gimp # version 2.10.8, or
sudo apt install gimp

See 'snap info gimp' for additional versions.

even though I definitely have GIMP installed. I'll try that, and see what happens.