Cannot install Gimp 64 bit

I am trying to install Gimp on a 64 bit PC with Ubuntu 14.10. I have added the dedicated PPA

ppa:otto-kesselgulasch/gimp

but I am not able to install Gimp due to its reliance on a lot of 32 bit libraries (nor was I able without the PPA).

For instance it depends on libgegl, which does not seem to be in the repositories, according to Synaptic. I can find the debugging symbols libgegl-0.2-0-dbg:i386, but if I try to install those (not that they would help, just to see), I find that they depend on a lot of i386 stuff, and this in turn would force me to remove a lot of important 64 bit libraries, such as libblas3 or liblapack3, on which numpy depends. Same happens with other dependencies such as libbabl.

So, while there seems to be a 64 bit version of Gimp, it seems to rely on 32 bit libraries which are not installable in my system, and often do not appear into Synaptic at all.

What is the way to install Gimp?

EDIT As request, I post the terminal output

andrea@lafcadio:~$ LC_ALL=C sudo apt-get install gimp
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
 gimp : Depends: libbabl-0.1-0 (>= 0.1.10) but it is not installable
        Depends: libgegl-0.2-0 (>= 0.2.0) but it is not installable
        Depends: libwebkitgtk-1.0-0 (>= 1.3.10) but it is not installable
E: Unable to correct problems, you have held broken packages.