convert color image to grayscale
convert color image to greyscale
color to b&w
color to black and white
color to grayscale
use strict;
use warnings;
use GD;
my $in_file = qw[foo.png];
my $ni_file = $in_file.".ni.png";
my $image = GD::Image->new($in_file);
my $i = 0;
my $t = $image->colorsTotal();
while($i < $t) {
my( @c ) = $image->rgb( $i );
my $g = ( $c[0] + $c[1] + $c[2] ) / 3; # Color::Calc::grey
$image->colorDeallocate($i);
$image->colorAllocate( $g, $g, $g );
$i++;
}
write_file( $ni_file, $image->png );
sub write_file {
my $i = shift;
open DISPLAY, ">$i" or die "can't clobber $i $!";
binmode DISPLAY;
print DISPLAY @_;
close DISPLAY;
}
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