Bug 688580 - Uncolored Postscript patterns not visible with X11alpha driver
Summary: Uncolored Postscript patterns not visible with X11alpha driver
Status: RESOLVED FIXED
Alias: None
Product: Ghostscript
Classification: Unclassified
Component: Graphics Library (show other bugs)
Version: 8.53
Hardware: PC All
: P3 normal
Assignee: Michael Vrhel
URL: http://www.saunalahti.fi/shemyak/tmp/...
Keywords: bountiable
Depends on: 688933
Blocks:
  Show dependency tree
 
Reported: 2006-03-02 10:47 UTC by Konstantin Shemyak
Modified: 2011-07-07 04:06 UTC (History)
2 users (show)

See Also:
Customer:
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Attachments
Pattern is not shown with GraphicsAlphaBits > 1 (911 bytes, application/postscript)
2006-03-10 12:58 UTC, Konstantin Shemyak 		Details
pattern4.png (2.36 KB, image/png)
2009-01-07 11:25 UTC, Ralph Giles 		Details
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Description Konstantin Shemyak 2006-03-02 10:47:51 UTC 
x11alpha driver does not show "uncolored Postscript patterns" defined in chapter
4.9.2 of the "Postscript Language Reference Manual", third edition.

The Adobe's example from the manual, example 4.23, page 258, gives a rectangle
painted with uncolored pattern (stars). x11 driver shows it OK. x11alpha driver
does not show any stars.

Tested with command-line gs v.8.53 built on Linux. The offending example is put
to   http://www.saunalahti.fi/shemyak/tmp/pattern-bug.ps.
Comment 1 Dan Coby 2006-03-09 19:44:10 UTC 
Both 8.53 and SVN head silently fail (i.e. nothing displayed and no error 
messages) with this test file.

bin/gswin32c -dGraphicsAlphaBits=4 ../test_files/688580.ps -c quit
Artifex Ghostscript 8.53 (2005-10-20)
Copyright (C) 2005 artofcode LLC, Benicia, CA.  All rights reserved.
This software comes with NO WARRANTY: see the file PUBLIC for details.

This is probably a similar problem to 688588.
Comment 2 Konstantin Shemyak 2006-03-10 12:58:16 UTC 
Created attachment 2088 [details]
Pattern is not shown with GraphicsAlphaBits > 1

The file is the Adobe's example of uncolored pattern, taken from the Postscript
Language Reference Manual. GS does not show the pattern if GraphicsAlphaBits is
2 or 4. When GraphicsAlphaBits is 1, pattern is shown OK.
Comment 3 Konstantin Shemyak 2006-03-10 13:06:14 UTC 
The bug is not related to X11 driver, but to graphics library instead.
The pattern is not visible when GraphicsAlphaBits is > 1. Tested with jpeg,
bmp256, png16m and tifflzw devices. Same thing happens under MS Windows, so I
change OS to "All".
Comment 4 Ray Johnston 2009-01-07 11:04:47 UTC 
Not sure when this changed, but now the pattern _is_ displayed (r9330), but
it looks REALLY UGLY (jaggy) when GraphicsAlphaBits=2 or 4.

Tested with:

gswin32c -dGraphicsAlphaBits=2 -r100 bug_688580.ps
Comment 5 Ralph Giles 2009-01-07 11:22:47 UTC 
Confirmed with the x11alpha, x11 and pnggray devices. It's not an x11alpha
problem, but an issue with antialiasing and patterns. Specifically the bottom of
the five-point star isn't rasterized correctly.
Comment 6 Ralph Giles 2009-01-07 11:25:45 UTC 
Created attachment 4685 [details]
pattern4.png

Result of 

gs -sDEVICE=pnggray -dGraphicsAlphaBits=4 -o pattern4.png pattern-bug.ps

Showing the rendering problem. The stars look clean with -dGraphicsAlphaBits=1.
Comment 7 Ralph Giles 2009-07-30 10:28:24 UTC 
Verified with 8.70rc1. Passing to Michael.
Comment 8 Alex Cherepanov 2011-07-07 04:06:57 UTC 
The problem is confirmed in vv. 9.01 and 9.02 but it is fixed in the current development version.