A bit more info: if I do

my $image=Image::Magick->new(magick=>'jpg');
$image->BlobToImage($blobdata);

use Data::Dumper; print Dumper($image);
[download]

then I get

$VAR1 = bless( [], 'Image::Magick' );
[download]

so I guess it's BlobToImage() which is failing.

andy.