Stick to Perl, use the underlying C routines, and the hash capabilities of perl (unless you run out of memory)
Once you binary read a pixel and have 48 bits of data, it can be unpacked to a large integer.
However, for speed, you should not use 3 times a 16 bit value, then shift them together, but use quad values, which only are available if your perl is 64 bit. Check Pack/Unpack Tutorial (aka How the System Stores Data)
But still, in perl, it would be better to unpack to hex strings, which are much shorter (thus faster), and use those as keys in a hash counter, like so: 

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

[download]

In reply to Re: Perl Hashes in C? by FreeBeerReekingMonk
in thread Perl Hashes in C? by BrianP

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