BrianP

I downloaded the file, but it was in '.jpg' format and not a raw file. I used it in the following script, and then I copied it until the file size was larger than 217MB. The result of the 2 runs are below. I may be wrong but I don't think you need to convert to an integer and then use pack. The result will be the same as the raw 6 bytes ( 48 bits ) for the pixel. 

    use strict;
    use warnings;

    my %Image = (); keys %Image = 4096 * 128;
    my $rdamt = 4096 * 6;
    my $buffer;
#   my $file = '249465.pprgb-srgb.absv.4000.cs.jpg';     #    Original
+ File downloaded
    my $file = '249465.pprgb-srgb.absv.4000.cs.jpg2';    #    New File
+ multiple copies
    my $compraw = -s $file; my $pixels = int ( $compraw / 6 );
    open ( my $in, "<", "./$file") or die "$!\n";
    while( 1 )
    {
        my $size = sysread( $in, $buffer, $rdamt );    #    No bufferi
+ng
        if ( $size == 0 ) { last; }
        while( $buffer )
        {    if ( length( $buffer ) < 6 ) { last; }    #    Throw away
+ odd number of pixels
            my $key = substr( $buffer, 0, 6, '' );
            $Image{$key}++;
        }
    }
    close $in;
    my $uniq = keys %Image;
    my $factor = sprintf("%.2f", $uniq / $pixels );

    print "Found $uniq colors in $pixels pixels $factor\%\n";
__END__

[download]

This is the results of run1, almost all unique pixels. About 1 second. 

> time pyrperl uniqcolors.plx
Found 153601 colors in 153606 pixels 1.00% ( File size:  921,638 )
real    0m0.098s
user    0m0.092s
sys     0m0.008s

[download]

This is using the larger file. We got some more uniques since the '.jpg' file was not a multiple of 6 bytes. About 15-16 seconds. 

> time pyrperl uniqcolors.plx
Found 460775 colors in 41473710 pixels 0.01% ( File size:  248,842,260
+ )
real    0m15.015s
user    0m14.937s
sys     0m0.080s

[download]

Try it on your real data and let us know if it helps.

Regards...Ed

"Well done is better than well said." - Benjamin Franklin

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

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