PNG and Perl (file uploads)

I have a strange problem. When I use my CGI module to handle PNG uploads it corrupts them somehow. the file is the same size but wont open or view in the browser. I haven't had a change to diff them yet so I am not sure what's getting changed but it's rather annoying. JPG or GIF upload just fine not problems. It must be something about the PNG format. Oh well I'll figure it out later I guess. If any of you perl folks out there have had a similar problem and fixed it please let me know.