my %SEEN;
my $key;

open( FH, '<', "image.raw" ) or die $!;
binmode(FH);

my $startpos = 10; # skip header
seek(FH, $startpos, 0);

$/ = \42; # set record size

while( <FH> ) {
    $key = join("", unpack 'H42', $_ );
    $SEEN{$key}++;
    # not sure how to calculate stop
}

for my $key (keys %SEEN){
        print "key $key seen $SEEN{$key} times\n";
}
# Add method to go from hex key to numeric rgb values if you want