how to reduce the size of a postscript file?

[DING at OCELOT.RUTGERS.EDU]

Dear Colleagues,

One of postdoctor in our lab has a question.  She wants to reduce
 the Ramachandran plots produced using PROCHECK to a smaller size
which can be fit into her thesis.  Does anyone know any tools or
programs which have this kind of function.

Any suggestions will be greatly appreciated.


Thanks in advance!


Jianping