I just noticed, and I havn't tested it, but I'm not sure whether an ImageMagick object works with Read( -data ....), I think you may be confusing it with another Image module. You probably need BlobtoImage()

#!/usr/bin/perl
use warnings;
use strict;
use Image::Magick;

my $blob = `import jpg:-`;   
#my $blob = `import -`;  #postscript produced
#print "$blob\n";

# now $blob is in memory and you can do what you
# want with it.

my $output = Image::Magick->new(magick=>'jpg');
$output->BlobToImage( $blob );
$output->Resize(geometry=>'160x120');
$output->Write( $0.'.jpg');


# png works too
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