I'm not sure why nworld3d at yahoo dot com's http://php.net/manual/en/function.imagecopyresized.php#69123 was downvoted--it was exactly what I was looking for to composite several alpha channel images, just like Photoshop. I needed to start with transparency and stack a few alpha images one after another on top of it. After mucking about with the built in PHP functions, I was worried that I would need to cheat by removing all the alpha and then using a transparent color in the end, but that would have looked different depending on what background I put it on top of. nworld3d at yahoo dot's comment saved me from having to go that route, and gets a +1 from me.