Write diagnostics to stderr instead of stdout for using exempi -g in a pipe

exempi -g 'fwl:LocalCaption' test.jpg writes processing file test.jpg to stdout which mixes with the value that -g returns. The processing file ... message should either be removed or should be written to stderr or maybe exempi could have a -q quiet option to suppress all messages. I am using exempi 2.4.5 on Fedora 30 x86_64.