The method from four years ago no longer works:
$ sudo aptitude install gimp
The following NEW packages will be installed:
gimp{b} gimp-data{a} libbabl-0.0-0{a} libgegl-0.0-0{ab} libgimp2.0{a} liblcms1{a} libmng2{a}
libopenexr6{ab} libtiff4{a}
0 packages upgraded, 9 newly installed, 0 to remove and 17 not upgraded.
Need to get 11,0 MB of archives. After unpacking 56,2 MB will be used.
The following packages have unmet dependencies:
libgegl-0.0-0 : Depends: libpng12-0 (>= 1.2.13-4) which is a virtual package and is not provided by any available package
gimp : Depends: python-gtk2 (>= 2.8.0) which is a virtual package and is not provided by any available package
Depends: libpng12-0 (>= 1.2.13-4) which is a virtual package and is not provided by any available package
Depends: libwebkitgtk-1.0-0 (>= 1.3.10) which is a virtual package and is not provided by any available package
libopenexr6 : Depends: libilmbase12 (>= 2.2.0) which is a virtual package and is not provided by any available package
The following actions will resolve these dependencies:
Keep the following packages at their current version:
gimp [Not Installed]
libgegl-0.0-0 [Not Installed]
libopenexr6 [Not Installed]
Leave the following dependencies unresolved:
gimp-data recommends gimp
So how do you install Gimp2.6 now?
$ cat /etc/upstream-release/lsb-release
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=20.04
DISTRIB_CODENAME=focal
DISTRIB_DESCRIPTION="Ubuntu Focal Fossa"
