I made an ISO image from Mac OS X Snow Leopard Installation DVD using PowerISO on Windows machine. The ISO file size is 7.6GB, but when I mount the ISO using PowerISO, what I can see is only the files for Windows (900+MB). How can I convert it back to Mac format ISO?
That's pretty normal to see only the files for windows, when you are mounting the ISO image on a windows!
Even if you have inserted a MAC OS Installation DVD (physical) into tray and openned it in a windows machine, you would have seen only the Windows files and not the MAC files.
Have you tried looking at the contents of the DVD from the cmd prompt under Windows? I suspect the explorer is hiding the Mac contents.
In the same vein, put the DVD in a Mac and examine it there for the Mac files.