🚀 go-pugleaf

In article <3273@medusa.informatik.uni-erlangen.de> eckert@medusa.informatik.uni-erlangen.de (Toerless Eckert) writes:
eckert> - Conclusion: if you need to render images on low resolution (300dpi)
eckert> printers with more spatial resolution than the standard dot function
eckert> of postscript, use ordered dither. It can be done simply by
eckert> redefining the spot function and the transfer function.

After some private discussions with other netlanders about this, I
don't think that you can redefine the spot and transfer functions to
achieve this. It turns out that in *at least* one implementation of
postscript, the spot function is called during the execution of the
setscreen operator (AND NOT during the display of grey levels), and
the transfer function is called during the execution of the setgrey
operator. 

I admit that I have not tested when the transfer function is called
for images -- but I would expect it to be called once for each SOURCE
point. 

All this is consistent with reducing the amount of work that the
interpreter has to do (i.e. goes faster). 

Of course, all this may be wrong, and I'd be only too pleased to be
contradicted by a piece of postscript posted to the net!

--
Philip Gladstone      
Development Lab Europe 
Data General, Cambridge
England.  +44 223-67600