why pswrite device converts cmyk to rgb ?

[victorp]

Hi,
I am new to ghostscript, but I feel either its a bug or I am doing something wrong....

I am trying the following:

gswin32c -q -sColourModel#CMYK -dNOPAUSE -dSAFER -dBATCH -dDEVICEWIDTHPOINTS#899 -dDEVICEHEIGHTPOINTS#1270 -sOutputFile#merged.ps -dLanguageLevel#2 -sDEVICE#pswrite 2.ps 317x448.ps

The resulting merged.ps is NOT CMYK !!!!!!

Both 317x448.ps and 2.ps are CMYK postscript files.
I know that they are cmyk bcs after converting them to PDF with ps2pdf (see below) and making output preview in acrobat i can turn on/off C,M,Y,K correctly.

ps2pdf -dProcessColorModel#/DeviceCMYK -dDEVICEWIDTHPOINTS#899 -dDEVICEHEIGHTPOINTS#1270 -dCompatibilityLevel#1.3 -dPDFSETTINGS#/prepress 2.ps 2.pdf

But if i convert the resulting merged.ps into pdf, in acrobat output preview shows incorrect color separations = not cmyk.
2.ps
317x448.ps
merged.ps
Is it a bug or am i making something wrong?

Gs 8.64 (win)

Also, a question: is there a way to overlay one postscript page into another?
Like watermarks, or background?
I need to put color bars (317x448.ps) over 2.ps
I am merging 2 separate .ps files into one file and putting them one over another with pstops.
Is this possible to do it with ghostscript? Or are there other better solutions?

Am 01.09.09, 22:52 -0700 schrieb victorp:
> gswin32c -q -sColourModel#CMYK -dNOPAUSE -dSAFER -dBATCH
> -dDEVICEWIDTHPOINTS#899 -dDEVICEHEIGHTPOINTS#1270 -sOutputFile#merged.ps
> -dLanguageLevel#2 -sDEVICE#pswrite 2.ps 317x448.ps

'#' is a comment character on the posix shell. So I wonder whether
arguments are so different on a windows machine. Are you shure to need to
use '#' or better just '='?

kind regards
Kai-Uwe Behrmann
--
developing for colour management
www.behrmann.name + www.oyranos.org

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[Ken Sharp]

At 22:52 01/09/2009 -0700, victorp wrote:


>I am trying the following:
>
>gswin32c -q -sColourModel#CMYK -dNOPAUSE -dSAFER -dBATCH
>-dDEVICEWIDTHPOINTS#899 -dDEVICEHEIGHTPOINTS#1270 -sOutputFile#merged.ps
>-dLanguageLevel#2 -sDEVICE#pswrite 2.ps 317x448.ps

I believe ColourModel is incorrect, to start with. The correct switch is
ProcessColorModel, note the US spelling.

Secondly you should not use pswrite but should use ps2write instead, unless
you absolutely require DSC compliant output. pswrite is barely maintained
and we hope to replace it completely with ps2write in the long term.


>The resulting merged.ps is NOT CMYK !!!!!!

[snip]

Sorry, but I only believe the contents of the files, I am not convinced by
converting to a different format using a different device and displaying in
Acrobat.


>Is it a bug or am i making something wrong?

Well the switch appears to be incorrect, but more than that is impossible
to tell from the information. If you truly believe this is a bug then
please open a bug report for it. Don't forget to attach specimen files to
work on.


>Also, a question: is there a way to overlay one postscript page into
>another?

Yes, several. Firstly you can redefine the 'showpage' operator to do
nothing. Run the first job, then run the second job, then execute the
original showpage operator. Note that this will *NOT* work for files
containing multiple pages.

You can also use the BeginPage/EndPage procedures which have more
flexibility and are intended for page level control, but these only work
with level 2 or better interpreters.


>Like watermarks, or background?
>I need to put color bars (317x448.ps) over 2.ps
>I am merging 2 separate .ps files into one file and putting them one over
>another with pstops.
>Is this possible to do it with ghostscript? Or are there other better
>solutions?

There are many potential solutions, which is better depends on your
criteria, for example you could load the files into Illustrator and add
crop/register/colour marks there. You could convert to PDF and do likewise
in Acrobat. You could invest in an expensive heavyweight application like
OneVision's Asura product.

There are almost certainly other possibilities.

             Ken
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[Ken Sharp]

At 08:39 02/09/2009 +0200, Kai-Uwe Behrmann wrote:


>>gswin32c -q -sColourModel#CMYK -dNOPAUSE -dSAFER -dBATCH
>>-dDEVICEWIDTHPOINTS#899 -dDEVICEHEIGHTPOINTS#1270 -sOutputFile#merged.ps
>>-dLanguageLevel#2 -sDEVICE#pswrite 2.ps 317x448.ps
>
>'#' is a comment character on the posix shell. So I wonder whether
>arguments are so different on a windows machine. Are you shure to need to
>use '#' or better just '='?

Both will work, # is used in places where '=' is inappropriate, see
gs/doc/use.htm, section 9.3 'MS Windows':

"When passing options to ghostcript through a batch file wrapper such as
ps2pdf.bat you need to substitute '#' for '=' as the separator between
options and their arguments."

In fact this is no longer true for modern versions of the Windows command
shell, which are perfectly happy with '=' in the batch file, but the
capability is still present, should this be required.


             Ken
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