совершенно верно выше уже привели пример
rpiccan, wpiccan
Test which image formats can be read/written
$im = PDL->rpic('PDL.jpg') if PDL->rpiccan('JPEG');
@wformats = PDL->wpiccan();
finds out if PDL::IO::Pic can read/write certain image formats. When called without arguments returns a list of supported formats. When called with an argument returns true if format is supported on your computer (requires appropriate filters in your path), false otherwise.