[gs-bugs] [Bug 689932] Halftone missing at 400 DPI

bugs.ghostscript.com-bugzilla-daemon at ghostscript.com bugs.ghostscript.com-bugzilla-daemon at ghostscript.com
Wed Jul 2 09:53:40 PDT 2008


http://bugs.ghostscript.com/show_bug.cgi?id=689932

ray.johnston at artifex.com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |DUPLICATE



------- Additional Comments From ray.johnston at artifex.com  2008-07-02 09:53 -------
The solid halftone area at 600 dpi is the incorrect behavior. The correct
display is actually the one that shows the contours.

This file does something we've seen before were the file is resolution
dependent. It fills a narrow rectangular "stripe" with a color, then
uses a Height 1 'imagemask' to paint white in the areas where it wants
to erase the "color" (in your case gray shade that is dithered) leaving
the desired area showing through. (a much better method would have been to
paint the area with the desired color using an imagemask with the opposite
polarity on the same data). 

The solid halftone happens because the width of the 'fill' operation is
wider than intended, causing the previous image line to be re-filled with
the color/gray shade.

This is a known issue that we don't know how to "fix" and stay compatible
with other Adobe products -- see bug 689364.

Note that when displaying this with Acrobat, the fills aren't actually
quite adjacent so at high zoom factors, gaps show between the image
lines.

I'll mark this new bug as a duplicate (which will close it).


*** This bug has been marked as a duplicate of 689364 ***



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