[MiKTeX] forcing PS to grayscale

[Armin R. <xa...@bi...>]

I have a problem that in some black-and-white pictures I 
included as eps, the gray tones take on funny pink and green 
tones when printed on a color printer.

Is there a way to force eps to be printed in grayscale - maybe 
as an option to graphicx includegraphics, or on the post script 
level (and possibly an easy way to call that function from 
LaTeX)?

Alternatively, is there a simple-minded conversion program that 
can stip the color out of a jpeg file?  (My figures are 
generated with jpeg2ps.  I meant to have told PhotoShop to turn 
the pictures to gray scale before I saved them, but obviously I 
was misundersood. :-)

Sorry the question is only very remotely related to MikTeX.  
Thanks for any advice none the less.

Armin