It should be quite possible just to change the pallete entry for the color you want into the one you need if you want to have a little fun with pack and unpack.

I do this all the time, except I use GD (I don't use Imager).

• convert image to greyscale (color to black and white)
• http://crazyinsomniac.perlmonk.org/perl/act/

Thank you! Imager documentation leaves much to be desired, but after some tinkering I finally figured out how it worked. It does exactly what I need. Thanks again for your replies!

Cheers!
Aaron

OK. So I can now replace one colour with another. I am now trying to make the replacement colour transparent. Say I want to replace white with red; I have the following code:

my $redmap = [0 .. 255];
my $blumap = [0 .. 255];
my $grnmap = [0 .. 255];

$blumap->[255] = 0;
$grnmap->[255] = 0;

$img->map(red=>$redmap, blue=>$blumap, green=>$grnmap);
[download]

This replaces all instances of (255,255,255) with (255,0,0). Now how do I make that red transparent? I thought I would need to do:

my $redmap = [0 .. 255];
my $blumap = [0 .. 255];
my $grnmap = [0 .. 255];
my $alpha  = [0 .. 255];

$blumap->[255] = 0;
$grnmap->[255] = 0;
$alpha->[0] = 255;

$img->map(red=>$redmap, blue=>$blumap, green=>$grnmap, alpha=>$alpha);
[download]

But that doesn't do anything. I like Imager for it's flexibility, but I am really getting frustrated with the documentation. Any help would be greatly appreciated.

Cheers!
Aaron