Re: Spurious lines between joined filled rectangles and antialiasing

[Ethan A M. <merritt@u.washington.edu>]

On Thursday 11 August 2005 01:21 am, Petr Mikulik wrote:
> Does somebody knows whether this directive
>
>  	 << ... /Interpolate false ... >>
>
> would help? 

As I understand it, this is an optional dictionary value that is
passed on to the interpreter (printer, or in this case ghostscript).
So any effect it has will vary depending on the output device.
Newer versions of ghostscript claim to process this value, but I have
not found any explicit statement of exactly what they do with it. 

> (And how/where to use it? Inside some gsave/grestore?)

I think you would have to load it into a dictionary during the prolog.
So far as I know, dictionary values are unaffected by gsave/grestore.

It is disappointing that this is all so poorly documented. The closest
I can find is from the notes to ghostscript version 6, which is quite
out of date. And even so it's not very helpful:

  The image operator honors the Interpolate flag in the image dictionary
  only for ImageType 1 and 3 images, only if the combined transformation
  (ImageMatrix + CTM) doesn't involve rotation, skewing, or X-reflection,
  and only for certain scalings and color spaces; imagemask doesn't
  honor Interpolate at all.




-- 
Ethan A Merritt
Biomolecular Structure Center
University of Washington, Seattle 98195-7742