The showpicture program will allow a user on a properly-equipped workstation to view a picture using the xloadimage(1) program. It is intended to be called from mailcap files, typically by the metamail(1) program.
By default, the program used to display pictures under X11 is "xloadimage -view -quiet -geometry +1+1". This can be overridden either by the environment variable X_VIEWER or by the -viewer command line option.