Convert 32bit PNG file to 24bit PNG file

How开发者_开发百科 to convert 32bit PNG file to 24bit PNG file using PHP.

btw I am using Codeigniter, and planning to host files at Dreamhost.

Thanks!

---

Give this a try:

exec('convert -depth 24 /path/to/old/image.png /path/to/new/image.png');

There is a PEAR package for ImageMagick, although making a system call also works if your hosting provider hasn't installed the PEAR package.