hola, i'd highly recommend that you check out

http://mah.everybody.org/hacks/perl/getcomics.txt,

(core by Mark Hershberger, adapted by J.Stoffel)

a spritely wee script which downloads images intelligently; it is almost directly applicable to your problem of finding new images.

the business end of how it determines newness is in the following snippet, which could pretty much directly be copied & pasted to achieve what you want. rc is the request obtained from a lwp::useragent

# Get the MD5 fingerprint of the file.
open(IMAGE, "<$imagedir/$imagename") || die "Can't open $imagedir/$ima
+gename\n";
$context = new MD5;
$context->MD5::reset();
$context->MD5::add(<IMAGE>);
$filehash = $context->hexdigest();
close(IMAGE);
            
# Get the MD5 fingerprint of the new picture
open(TEMP, ">/tmp/getcomics.$$") || die "Can't open tempfile\n";
print TEMP $rc->content();
close(TEMP);
        
open(TEMP, "</tmp/getcomics.$$") || die "Can't open tempfile\n";
$context->MD5::reset();
$context->MD5::add(<TEMP>);
$newhash = $context->hexdigest();
close(TEMP);
unlink "/tmp/getcomics.$$";
        
# See if the old info is different from the new.
if( $newhash ne $filehash ) {
# strut your funky stuff *here*
}
[download]

hope that helps,

...wufnik

-- in the world of the mules there are no rules --