Bug 485498 - pdfwrite with -dProcessColorModel#/DeviceGray does not gray vector images colored in RGB
pdfwrite with -dProcessColorModel#/DeviceGray does not gray vector images col...
Product: Ghostscript
Classification: Unclassified
Component: PDF Writer
All All
: P2 normal
Assigned To: L. Peter Deutsch
Bug traffic
Depends on:
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Reported: 2001-11-25 21:37 PST by Alex Cherepanov
Modified: 2014-02-17 04:37 PST (History)
1 user (show)

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Description Alex Cherepanov 2001-11-25 21:37:20 PST
Originally reported by: alexcher@users.sourceforge.net
pdfwrite doesn't convert images to grayscale in
DeviceGray color model. Vector objects are converted to

From time to time users ask how to convert PS or PDF to
grayscale. GS might be the answer.

OTOH some users prefer to preserve original color spaces.
Probably GS needs an option.
Comment 1 L. Peter Deutsch 2001-11-26 17:21:38 PST
Comment originally by lpd@users.sourceforge.net
Logged In: YES 

We think the normal mode of pdfwrite should be exactly the
same as Acrobat Distiller, namely, to preserve all the
original color spaces (except if the user asks for device
color spaces to be converted to device independent). From
this point of view, the fact that pdfwrite converts vectors
and text to a single, user-defined color space
(Gray/RGB/CMYK) is a bug -- unfortunately, one that has been
architecturally very inconvenient to fix.

pdfwrite might also choose to offer an option for converting
all colors, including those in images and shadings, to a
user-defined color space; however, this would be a
substantial amount of work to implement, and would be of
limited utility.
Comment 2 Jack Moffitt 2002-03-06 10:04:11 PST
Comment originally by jackiem@users.sourceforge.net
Logged In: YES 

Perhaps putting this in issues.htm is appropriate and
closing the bug?
Comment 3 L. Peter Deutsch 2002-04-09 15:46:42 PDT
Comment originally by lpd@users.sourceforge.net
Logged In: YES 

I've changed the documentation of the ProcessColorModel
parameter in doc/Ps2pdf.htm to state even more explicitly
that this parameter does not affect images.  (This was
documented before, but not at the place where this parameter
was defined.)

I'll also add an entry to Issues.htm.
Comment 4 Karel Horák 2007-04-22 16:04:01 PDT
The following options 
-dPDFSETTINGS#/prepress -dProcessColorModel#/DeviceGray
to pdfwrite leave RGB color of vector image unchanged in GS8.54 and 8.56,
but work fine with GS7.05