Summary: | antialiasing can cause spurious lines at joined edges | ||
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Product: | Ghostscript | Reporter: | arnaud01 <arnaud.desitter> |
Component: | Documentation | Assignee: | Ralph Giles <ralph.giles> |
Status: | NOTIFIED FIXED | ||
Severity: | normal | CC: | dolfi |
Priority: | P2 | ||
Version: | 8.13 | ||
Hardware: | PC | ||
OS: | Linux | ||
Customer: | Word Size: | --- |
Description
arnaud01
2004-10-08 07:47:29 UTC
I confirm that this problem exists in all versions tested from 6.61 to the current CVS. The problem appears to be related to anti-aliasing logic. This is what happens when you antialias on a tight gap. The background can bleed through. Please add a note in the documentation. I took me a while to trace the problem to antialising. This problem should probably be documented in Issues.htm or somewhere else appropriate in the documentation. Issues isn't really a good place for this I think, since it's not really a bug. I'll add a note next to GraphicsAlphaBits. Note that ImageMagick uses ghostscript as postscript generator and set by default -dGraphicsAlphaBits=4 in a fairly well hidden config file which is not user modifiable (that is without root access). From http://www.cs.wisc.edu/~ghost/doc/cvs/Use.htm#Rendering_parameters, <quote> -dTextAlphaBits=n -dGraphicsAlphaBits=n These options control the use of subsample antialiasing. Their use is highly recommended for producing high quality rasterizations. The subsampling box size n should be 4 for optimum output, but smaller values can be used for faster rendering. Antialiasing is enabled separately for text and graphics content. Allowed values are 1, 2 or 4. </quote> Please mention that -dGraphicsAlphaBits=n may produce undesirable results and may not consequently be "highly recommended". Regards, It's still highly recommended, it's just that one occasionally encounters files that depend on a particular rendering behavior. In any case, I've added a warning to the documentation. *** Bug 687789 has been marked as a duplicate of this bug. *** |