[EMBOSS] "Invalid XY graph value 'png' "

[ajb at ebi.ac.uk]

You mentioned linux but not what distribution. So, using Fedora as
an example, make sure you have the following RPMs installed.

    gd, gd-devel, libpng, libpng-devel

and then configure and compile emboss again. That will give you PNG
support. If you're using a debian-style distribution those packages
will have basenames like gd2 and libpng12.

HTH

Alan Bleasby
EBI