Unpack() does the reverse of pack(): it takes a string representing a structure and
expands it out into a list value, returning the array value. (In scalar context, it
returns merely the first value produced.) The TEMPLATE has the same format as in the 
pack() function. (...)
##</code><code>##

open(IMG,"foo.gif");
foreach (<IMG>) {
    # something wrong here I suppose
    @hex = unpack("H*",$_);
    foreach $b (@hex) {  # this array on has one item
        print "$b ";     # which gets printed here
    }                    # shouldn't it be a list?
    print "\n";
}
close(IMG);