&sysread_uint48($RGB, \@rgbz);  # Store RGB in uint64, RGBZ array
&RADIX_SORT(\@rgbz);  # Sort by digits!
$std=$rgbz[0];  # Make first uint64 the STanDard 
$unique=1;      # First one is Always Unique!
for($ii=1; $ii < $num_pix; $ii++)  {
	next  if($rgbz[$ii] == $std);  # Same Old value as last time!
	$unique++;                    # New value, Increment Unique
	$std=$rgbz[$ii];              # Make new THIS the STD
}
printf("%d distinct values\n", $unique);

##</code><code>##

 I:\exp\raw>cdrc pf-2015.0531-249465.pprgb.7360x4912.raw
CDRC: 27645898 distinct RGBs = 76.471% in 0.946 sec

I:\exp\raw>cdrc pf-2015.0531-249465.pprgb.7360x4912.raw -d
CDRC: Read 216.913920MB, 36.2MP in 73 msec->2964 MB/s, CPU@3.421GHz
CDRC: 36.152320M MemCpy in 67 msec
RS: R_Sort-> 775 ms, C_Unique-> 32 ms, total-> 808 ms
CDRC: 27645898 distinct RGBs = 76.471% in 0.950 sec 
##</code><code>##

Running C:\bin\bb2.pl   Sun Dec 13 16:30:19 2015
Unique colors=27.645898M =  76.471%  <<< EXACT!

SE: Sum of Event Times = 6.789 min, now-init = 6.78937 min
ETime=239.024 ms =  0.059%, 1 Hits, Event 'PerlMagic Read Raw File'
ETime=  6.785 min = 99.941%, 1 Hits, Event 'Quantize'
99.94% -> Quantize
 0.06% -> PerlMagic Read Raw File
Elapsed C:\bin\bb2.pl time = 6.789 min


# Here is the hash way implemented by ImageMagick Bone-Nary[*]:
Running C:\bin\bb.pl   Sun Dec 13 15:19:29 2015;  
Conv convert.exe -size 7360x4912 -depth 16 \
RGB:i:/exp/raw/pf-2015.0531-249465.pprgb.7360x4912.raw \
-unique-colors \
i:/exp/raw/pf-2015.0531-249465.pprgb.7360x4912.raw.tif ->
        size=165875652
Elapsed C:\bin\bb.pl time = 6.936 min

I:\exp\raw>mult 165875652 /27645898
6.0000    <<  Very close agreement on Unique Count

I:\exp\raw>mult 6.936 60 /0.946
439.915433


##</code><code>##

# =============================================================
sub unique_colors_perl()  {
use Image::Magick;  # 
my($debug, $raw, $xres, $yres, $xysize, $unique, $xysize, %e2at);
	$debug=0;
	%e2at = ();
	$raw='i:/exp/raw/pf-2015.0531-249465.pprgb.7360x4912.raw';
	&time_event('init', \%e2at, $debug*0);  # Initialize timing 
	&time_event('PerlMagic Read Raw File', \%e2at, $debug*0);
	($xres, $yres)=&fname_to_xyres($raw, $debug);
	$xysize=$xres . "x$yres";  # 7360x4912
	# Create a new rgb48 with just the right size
	$im=Image::Magick->new(size=>"$xysize", type=>'TrueColor',\
depth=>16);  
	$err=$im->Read(filename=>"RGB:$raw");  warn $err  if $err;
	&time_event('Quantize', \%e2at, $debug*0);
	($unique) = $im->Get('colors');
	printf("Unique colors=%.6fM = %6.3f%%\n",
		$unique/1E6, $unique/(7360*4912));
	&time_event('term', \%e2at, $debug*0);  # Finalize timing 
	&show_event(\%e2at, $debug*0);  # Event timing
}  # End Unique_Colors_Perl().

NOTE: Bone-Nary: Special build for BoneHeads who can't \
 make their own! :)