Hi,

I tried it out of curiosity and it worked with pack and encodet64 as
well. This is ruby 1.9.2p0 on Ubuntu 10.04 64. I was able to use the
tool "base64 -d" to decode the image data properly and view in gimp, as
well undecode in PHP.

$ cat test.png | ruby -e 'puts [STDIN.read].pack "m"' | php -r 'echo
base64_decode(file_get_contents("php://stdin"));' >test2.png
$ md5sum test.png test2.png
f7fa630a147264f328e8b878ce7b39d9  test.png
f7fa630a147264f328e8b878ce7b39d9  test2.png

What version of ruby on which platform are you using?

- Markus