use strict;
use warnings;

use GD;
use Imager;

# doesn't fail on non-existent file?... 
#my $image = GD::Image->newFromPng("rudddy.png") || die("cant on loading file\n");

my $image = GD::Image->newFromPng("ruddy.png") || die("cant on loading file\n");
$image->trueColor(1);
my ($max_X, $max_Y)=$image->getBounds();
my $maxColors = $image->colorsTotal;

my $X0 = int($max_X / 3);
my $Y0 = int($max_Y / 3);

for (my $x = $X0; $x < $X0+5; $x++) {
   for (my $y = $Y0; $y < $Y0+5; $y++) {

#for (my $x = 0; $x < $max_X; $x++) {
#   for (my $y = 0; $y < $max_Y; $y++) {

      printf(" PIXEL: X=%03d Y=%03d\n", $x, $y);

      my $org_colour = $image->getPixel($x, $y);
      my @rgb = $image->rgb($org_colour);

      printf("BEFORE: colour idx=%5d R=%3d, G=%3d, B=%3d\n", $org_colour, @rgb);
		
#      Update_Saturation(\@rgb, \my @new_rgb);  # REAL transformation

      @rgb[1] = 0;  # ### TESTING ### transformation
      my @new_rgb = @rgb; 

#      my $new_colour = $image->colorAllocate(@new_rgb);   # Generates error; result = -1
      my $new_colour = $image->colorClosest(@new_rgb);     # Non-accurate colours
      $image->setPixel($x, $y, $new_colour);

      printf(" AFTER: colour idx=%5d R=%3d, G=%3d, B=%3d\n\n", $new_colour, @new_rgb);
		
   } # end: another row (y)
} # end: another column (x)

open(my $fh, ">", "new.png") || die("cant on output file\n");
binmode $fh;
print $fh $image->png;

exit(0);

# -------------------------------------
#  Update_Saturation - Reduce saturation of a pixel
#  Uses Globals: 
# -------------------------------------

sub Update_Saturation
{
   my ($in_arr_ref, $out_arr_ref) = @_;

   my $colour = Imager::Color->new(@$in_arr_ref);
   my @hsv = $colour->hsv();
	
	my ($h, $s, $v) = @hsv;

   $s = 0.7 * $s;

   my $new_colour = Imager::Color->new(hue => $h, saturation => $s, value => $v);	
   my ($red, $green, $blue, $alpha) = $new_colour->rgba();
	
	@$out_arr_ref = ($red, $green, $blue);

   return(1);

} # end Update_Saturation