[gs-bugs] [Bug 698766] - Ghostscript - Incorrect CMYK color after rendering

[b***@artifex.com]

http://bugs.ghostscript.com/show_bug.cgi?id=698766

Bug ID: 698766
Summary: Incorrect CMYK color after rendering
Product: Ghostscript
Version: unspecified
Hardware: PC
OS: Linux
Status: UNCONFIRMED
Severity: normal
Priority: P4
Component: Color Management
Assignee: ***@artifex.com
Reporter: ***@mail.ru
QA Contact: gs-***@ghostscript.com
Word Size: ---

Created attachment 14474
--> http://bugs.ghostscript.com/attachment.cgi?id=14474&action=edit
files before and after GS conversion

I have PDF with correct CMYK color if file test.pdf (for example 0%,0%,0%,40%).
After executing

gs -dNOPAUSE -dNOCACHE -sDEVICE=pdfwrite -dNoOutputFonts
-sOutputFile=test_outline.pdf ./test.pdf

it becomes 0%,0%,0%,39.99% in test_outline.pdf.

[b***@artifex.com]

http://bugs.ghostscript.com/show_bug.cgi?id=698766

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

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

--- Comment #1 from Ken Sharp <***@artifex.com> ---
(In reply to Mike from comment #0)

Created attachment 14474 [details]
files before and after GS conversion
I have PDF with correct CMYK color if file test.pdf (for example 0%,0%,0%,40%).

Where, precisely do you see the colour difference ? This is not a simple file
and there are *many* colour definitions within it.

After executing
gs -dNOPAUSE -dNOCACHE -sDEVICE=pdfwrite -dNoOutputFonts
-sOutputFile=test_outline.pdf ./test.pdf
it becomes 0%,0%,0%,39.99% in test_outline.pdf.

That's as close as you are going to get, its a rounding error caused by the
fact that colours are specified as real numbers. It seems unlikely that a
difference of 0.01% would be visible, or indeed result in a different real gray
value when converted to an 8 bit integer.

Please read:

https://www.ghostscript.com/doc/9.22/VectorDevices.htm#Overview

[b***@artifex.com]

http://bugs.ghostscript.com/show_bug.cgi?id=698766

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

What |Removed |Added
----------------------------------------------------------------------------
Assignee|***@artifex.com |***@artifex.com
Component|Color Management |PDF Writer