The current development version of Gimp 2.9.x has support for 16 and 32 bit image files. I couldn’t find packages to install on Debian Jessie so I set out to build from source. Here are the steps I followed:
mkdir -p ~/src/gimp
cd ~/src/gimp
git clone https://github.com/json-c/json-c.git
cd json-c/
./autogen.sh
make -j 4
sudo make install
cd ..
git clone https://github.com/mypaint/libmypaint.git
cd libmypaint/
scons prefix=/usr/local
sudo scons prefix=/usr/local install
cd ..
git clone git://git.gnome.org/babl
git clone git://git.gnome.org/gegl
git clone git://git.gnome.org/gimp
cd babl
./autogen.sh
make
sudo make install
cd ../gegl
./autogen.sh –without-libavformat –disable-docs
make
sudo make install
cd ../gimp
./autogen.sh
make
sudo make install
LD_LIBRARY_PATH=/usr/local/lib /usr/local/gimp-2.9
It took a little while, and there were a few missteps along the way, but SUCCESS!
For bonus points, build and install the resynthesizer plugin too.
cd ~/src/gimp
git clone https://github.com/bootchk/resynthesizer.git
cd resynthesizer
./autogen.sh
./configure
make
sudo make install
Many thanks to the developers!