Hello again and many thanks. I did this and it looks like libtiff6 is also installed though it doesn't show in synaptic # sudo apt-cache search libtiff libtiff-dev - Tag Image File Format library (TIFF), development files libtiff-doc - TIFF manipulation and conversion documentation libtiff5 - Tag Image File Format (TIFF) library libtiff5-dev - Tag Image File Format library (TIFF), development files (transitional package) libtiffxx5 - Tag Image File Format (TIFF) library -- C++ interface gem-plugin-tiff - Graphics Environment for Multimedia - TIFF support libtiff-opengl - TIFF manipulation and conversion tools pngtools - series of tools for PNG (Portable Network Graphics) images python3-libtiff - wrapper to the libtiff library to Python using ctypes (Python 3 version) libtiff-tools - TIFF manipulation and conversion tools libtiff6 - Tag Image File Format (TIFF) library libtiffxx6 - Tag Image File Format (TIFF) library -- C++ interface Thank you all --