[gs-bugs] [Bug 698817] - Ghostscript - ColorConversionStrategy=Gray breaks image with smask

[b***@artifex.com]

http://bugs.ghostscript.com/show_bug.cgi?id=698817

Bug ID: 698817
Summary: ColorConversionStrategy=Gray breaks image with smask
Product: Ghostscript
Version: 9.22
Hardware: PC
OS: FreeBSD
Status: UNCONFIRMED
Severity: normal
Priority: P4
Component: PDF Writer
Assignee: ***@artifex.com
Reporter: ***@ci.com.au
QA Contact: gs-***@ghostscript.com
Word Size: ---

Created attachment 14534
--> http://bugs.ghostscript.com/attachment.cgi?id=14534&action=edit
input pdf prior to greyscale conversion

Starting with the attached input pdf, if I run
"gs -dNOPAUSE -dBATCH -sDEVICE=pdfwrite -sColorConversionStrategy=Gray -o
out.pdf input.pdf", the resulting out.pdf doesn't view correctly in acrobat.
Acrobat reports the very helpful "An error exists on this page ...". Xpdf and
various linux viewers seem to have no problem. When I extract the images with
the "pdfimages" tool (xpdf family) although the images are extracted I get
"Syntax Error: Matte entry should have 1 components but has 3". No such error
happens prior to greyscale conversion.

[b***@artifex.com]

http://bugs.ghostscript.com/show_bug.cgi?id=698817

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

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

--- Comment #1 from Ken Sharp <***@artifex.com> ---
Its not as simplas as an image with an SMask, we have plenty of examples of
those, its an image with an SMask where the SMask has a /Matte entry. This is
an optional and rarely used entry. Its even more rare to find one which has any
useful effect (this one doesn't).

So this commit :

http://git.ghostscript.com/?p=ghostpdl.git;a=commit;h=1143a7aba79e6316ccfb5fc2b0943dcd7a64a48f

drops the unusable entry when the image colour space (and therefore the Matte
colour space) isn't the same as the target colour space. This resolves the
problem for me.