First check whether it is on your machine - I already had it
$ locate */libpng12.so.0
If it is already installed on your machine, then change the "LD_LIBRARY_PATH" line in the shell script to
Or the path where libpng12.so.0 is located, if different.
If you don't have libpng12.so.0 installed, you can use Yum to find a package providiing it
# yum provides */libpng12.so.0
2:libpng-compat-1.5.10-1.fc17.i686 : Temporary backwards-compatibility copy of old libpng
Repo : fedora
Filename : /usr/lib/libpng12.so.
You can then install the package indicated
# yum install libpng-compat