@Olga I'd suggest you remove the Debian-supplied version and instead use the Open Build Service repository; it'll get you the latest version. This is for Debian Jessie.
- Open the terminal as root and paste this code into it:
echo 'deb http://download.opensuse.org/repositories/home:/rawtherapee/Debian_8.0/ /' >> /etc/apt/sources.list.d/rawtherapee.list
apt-get install rawtherapee
- You can add the repository key to apt. Keep in mind that the owner of the key may distribute updates, packages and repositories that your system will trust (more information). To add the key, run:
wget -r http://download.opensuse.org/repositories/home:rawtherapee/Debian_8.0/Release.key
apt-key add - < Release.key
RawTherapee should now be installed and ready for use.
I pilfered these instructions from the Rawtherapee downloads page.