🚀 go-pugleaf

    *  In article <1992Nov1.212253.16619@gandalf.UMCS.Maine.EDU>  
fishboy@gandalf.UMCS.Maine.EDU (Jon Everett) writes:
    *  >
    *  >Question:
    *  >
    *  >Can anyone provide a decent explanation of how
    *  >the 'spot function' works in halftoning?  From what I have
    *  >read in the Adobe Books, the function is supposed to take
    *  >x,y coordinates of a pixel in the halftone cellbox as arguments.
    *  >To me this is counter-intuitive. I would expect it to take a
    *  >gray value as input and return the bitmap of the cellbox.
    *  >Can anyone provide, or point me to, a fuller explanation of 
    *  >the spot function's operation and its palce in the larger 
    *  >context of halftoning?  I would like to be able to explicitly
    *  >define the order in which the pixels in a cellbox of a given
    *  >size are turned on.

Take a look at ``Adobe Accurate Screens'', by Peter Fink,
 page 63ff for information on spot functions.  

Also see chapter 13 of ``PostScript by Example'' by
Henry McGilton and Mary Campione, from Addison-Wesley,
now in all reputable bookstores near you.

	........  Henry