#! perl -slw
use strict;
use GD;

my $img = GD::Image->new( $ARGV[0] ) or die $!;

my %palette;
my( $x, $y ) = $img->getBounds;
for my $yi ( 0 .. $y ) {
    ++$palette{ $img->getPixel( $_, $yi ) } for 0 .. $x;
}

for my $i ( sort{ $a <=> $b } keys %palette ) {
    printf "index:%3d (%02x:%02x:%02x) n:%d\n",
        $i, $img->rgb( $i ), $palette{ $i };
}
__END__
C:\test>imgInspect.pl v3d_usb_perf.gif
index:  0 (ff:ff:ff) n:274410
index:  1 (00:00:7f) n:4909
index:  2 (7f:7f:7f) n:80
index:  3 (00:00:ff) n:14025
index:  5 (3f:3f:3f) n:2390
index:  6 (00:ff:00) n:12507