I've been writing a program using imagemagick which makes animated tiled background gifs of lots of objects falling (originally to make a snow effect but it could be anything). I'd like to have them all rendered in different random opacities over the background to get a layered effect, but I can't get the opacity function to work in Image->composite.

I've reproduced the error in the following code (adapted from an earlier reply i found on a similar subject.) 

#!/usr/bin/perl -w

use strict;
use Image::Magick;

# Simulate background picture... :)
my $image1 = Image::Magick->new;
$image1->Set(size=>'100x100');
$image1->ReadImage('xc:orange');

# Textbackground image
my $image2 = Image::Magick->new;
$image2->ReadImage('testopaq.png');

# Make composite image of background and a 50 % transparent image.
$image1->Composite(compose=>'over', image=>$image2, x=>0, y=>0, 
         opacity=>50
  );

$image1->Display;

[download]

testopaq.png is a black stripe and a white stripe on a transparent background.

with opacity=0 or not stated, it does the normal 'over' overlay, with transparent areas untouched, but with opacity >0, testopaq.png is overlaid with a black background and no effect on opacity. The transparent areas of testopaq.png end up black.

when i use the 'dissolve' option instead of 'over', nothing happens at all, for any value of opacity.

using ImageMagick 5.5.5 and perl 5.6.1

In reply to Image compositing with opacity not working in perlmagick by skullcap23

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