gistfile1.txt

#!/usr/bin/perl
use strict;
use warnings;
use autodie;
use Image::Magick;
use IO::File;
use Scalar::Util 'isdual';
use feature 'say';

my $fh = IO::File->new(shift @ARGV, "r+");
my $img = Image::Magick->new( magick => 'bmp' );
my $data = $fh;

# $data is a filehandle.
if ( ref $data ) {
    warn "file based\n";
    my $error = $img->Read( file => \*$data );
    say $error, " :: ", $error + 0;
    say isdual($error) ? "is dual var" : "is not dual var";
    my $set = $img->set( magick => 'png' );
    say "set: $set";
    open my $out, '>result.png';
    my $wrote = $img->Write( file => $out );
    say "wrote: ", $wrote + 0;
}
else {
    warn "string based\n";
    my $result = $img->BlobToImage($data);
    say $result;
    $img->set( magick => 'png' );
    $data = $img->ImageToBlob();
    say length($data);
}