[gs-bugs] [Bug 698713] - Ghostscript - Regression: -dGraphicsAlphaBits=4 causes horizontal lines in path fill

[b***@artifex.com]

http://bugs.ghostscript.com/show_bug.cgi?id=698713

Bug ID: 698713
Summary: Regression: -dGraphicsAlphaBits=4 causes horizontal
lines in path fill
Product: Ghostscript
Version: 9.22
Hardware: Macintosh
OS: MacOS X
Status: UNCONFIRMED
Severity: normal
Priority: P4
Component: Regression
Assignee: ghostpdl-***@artifex.com
Reporter: ***@mavericklabel.com
QA Contact: gs-***@ghostscript.com
Word Size: ---

Created attachment 14429
--> http://bugs.ghostscript.com/attachment.cgi?id=14429&action=edit
The source file

The attached PS file produces horizontal lines in 9.22 that are not present
when rasterized in 9.21. The command used is:

/opt/local/bin/gs -sOutputFile=output92X.png -sDEVICE=png48 -dTextAlphaBits=4
-dGraphicsAlphaBits=4 -q -dBATCH -dNOPAUSE -r170 -f outputPS2.ps

[b***@artifex.com]

http://bugs.ghostscript.com/show_bug.cgi?id=698713

--- Comment #1 from Eric <***@mavericklabel.com> ---
Created attachment 14430
--> http://bugs.ghostscript.com/attachment.cgi?id=14430&action=edit
The 9.21 output

[b***@artifex.com]

http://bugs.ghostscript.com/show_bug.cgi?id=698713

--- Comment #2 from Eric <***@mavericklabel.com> ---
Created attachment 14431
--> http://bugs.ghostscript.com/attachment.cgi?id=14431&action=edit
The 9.22 output

[b***@artifex.com]

http://bugs.ghostscript.com/show_bug.cgi?id=698713

Chris Liddell (chrisl) <***@artifex.com> changed:

What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |RESOLVED
CC| |***@artifex.com
Resolution|--- |DUPLICATE

--- Comment #3 from Chris Liddell (chrisl) <***@artifex.com> ---
Almost certainly this issue:

https://bugs.ghostscript.com/show_bug.cgi?id=698672

*** This bug has been marked as a duplicate of bug 698672 ***

[b***@artifex.com]

http://bugs.ghostscript.com/show_bug.cgi?id=698713

Ken Sharp <***@artifex.com> changed:

What |Removed |Added
----------------------------------------------------------------------------
Resolution|DUPLICATE |---
Assignee|ghostpdl-***@artifex.com |***@artifex.com
Status|RESOLVED |UNCONFIRMED

--- Comment #4 from Ken Sharp <***@artifex.com> ---
This appears to be yet another weird interaction of GraphicsAlphaBits and the
news scan converter.

You can restore the old behaviour by setting -dSCANCONVERTERTYPE=0

For ease of use debugging on Windows, the png16m device exhibits the same
behaviour, as do other devices such as tiff24nc.

[b***@artifex.com]

http://bugs.ghostscript.com/show_bug.cgi?id=698713

--- Comment #5 from Ken Sharp <***@artifex.com> ---
(In reply to Chris Liddell (chrisl) from comment #3)
I don't think so, its still exhibits with HEAD for me.....

[b***@artifex.com]

http://bugs.ghostscript.com/show_bug.cgi?id=698713

--- Comment #6 from Eric <***@mavericklabel.com> ---
Thanks for locating the (potential) duplicate bug. Of note, the search engine
cannot find the duplicate when searching for "GraphicsAlphaBits", which is why
I didn't find it in my initial search.

[b***@artifex.com]

http://bugs.ghostscript.com/show_bug.cgi?id=698713

--- Comment #7 from Chris Liddell (chrisl) <***@artifex.com> ---
(In reply to Eric from comment #6)

Post by b***@artifex.com
Thanks for locating the (potential) duplicate bug. Of note, the search
engine cannot find the duplicate when searching for "GraphicsAlphaBits",
which is why I didn't find it in my initial search.

Yeh, sorry, as Ken says, it still shows in the current code, so it's not the
same problem - I must have mis-typed the command line when I tried it.

[b***@artifex.com]

http://bugs.ghostscript.com/show_bug.cgi?id=698713

Robin Watts <***@artifex.com> changed:

What |Removed |Added
----------------------------------------------------------------------------
Resolution|--- |FIXED
Status|UNCONFIRMED |RESOLVED

--- Comment #8 from Robin Watts <***@artifex.com> ---
Fixed with: commit 1626f36c9b6ae68abad7818be7cfb2a95f4ecffe
Author: Robin Watts <***@artifex.com>
Date: Thu Nov 2 17:54:57 2017 +0000

Bug 698713: Further graphicsAlphaBits + new scan converter fix.

Previous I ensured that when using graphicsAlphaBits, the new scan
converter would restrict its output rectangles/traps to fit
within y % max_fill_band pixels at a time as required.

I forgot that the base 'y' value taken for this was not necessarily
aligned to a max_fill_band multiple. Fixed here.

Thanks for the report.