$img->read( data => $temp, type => 'pnm');


##</code><code>##

my $finger = 0;  # or wherever the data starts
while ($finger < length $temp) {
    substr( $temp, $finger, 3) =
        pack 'C3',
            reverse unpack 'C3', substr $temp, $finger, 3;
    $finger += 3;
}