Download Ghostscript from the following site:
https://sourceforge.net/project/showfiles.php?group_id=1897&package_id=108733
http://www.cs.wisc.edu/~ghost/doc/GPL/gpl850.htm

The package downloaded was : ghostscript-8.50-gpl.tar.gz

Copy it in /usr/local/src

gunzip ghostscript-8.50-gpl.tar.gz
tar -xvf ghostscript-8.50-gpl.tar

cd ghostscript-8.50-gpl
./configure [--prefix=/usr/bin]
make 
and then it may be installed in the default location (/usr/local/bin) with: 
make install 
The installation directory can be changed to any other directory of choice by adding --prefix=path to the configure invocation in the first step. 

Upto this much everything was fine and installation was done without any major errors. Only warnings were there. 

I needed an utility to convert a html file to a pdf from a web page. I was successfully able to convert the html file to ps using the program html2ps. But ps2pdf was failing with the error message : Error: /invalidfont in findfont.
I checked for the dependencies and found that on my server the following rpms 
libjpeg-6b-33
libpng
zlib-1.2.1.2-1
zlib-devel-1.2.1.2-1 
were already installed. These dependencies were available from the page : http://www.cs.wisc.edu/~ghost/doc/AFPL/8.00/Make.htm

I put the error message in Google and found one page that helped me. The page was : http://asterfax.sourceforge.net/FAQ.html
Excerpts from the site:
Q. Ghostscript Error: invalidfont in findfont
A. Ghostscript's fonts has not been configured properly.
Ghostscript has not been configured properly and cannot find the required font files or the fonts where not installed correctly on your system. 

Solution
Ghostscript has not been configured properly and cannot find the required font files or the fonts where not installed correctly on your system. 

Start by reviewing the ghostscript installation notes and consider re-installing ghostscript.

if that doesn't work the following may help.

Check that you should find the following fonts on your system.  (the directory name may vary on your system). 

Times-Roman /usr/local/share/ghostscript/fonts/n021003l.pfb
Times-Italic /usr/local/share/ghostscript/fonts/n021023l.pfb
.........................

Ghostscript uses the following environment variables to locate the font files: 
GS_FONTPATH and GS_LIB. 

I found that in my server the pfb files were available in the sub-directory : /usr/share/fonts/default/Type1

Therefore, I created the two environment variables in my .bash_profile and it started working.