Home > Archive > PostScript > August 2007 > transfer function ignored in OS X Preview.app ?
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| Author |
transfer function ignored in OS X Preview.app ?
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| François Robert 2007-08-28, 7:11 pm |
| Dear NG
It seems that Mac OS X embedded version of Distiller (used by
Preview.app) does not honor the transfer function. I tried the following
:
%!PS
100 100 scale
8 8 8 [8 0 0 -8 0 8]
<FFEEDDCCBBAA99887766554433221100>
image
0 1.5 translate
0 setgray
0 0 1 1 rectfill
[ currenttransfer /exec cvx
1 /exch cvx /sub cvx
] cvx bind dup == settransfer
currenttransfer ==
1.5 -1.5 translate
8 8 8 [8 0 0 -8 0 8]
<FFEEDDCCBBAA99887766554433221100>
image
0 1.5 translate
0 setgray
0 0 1 1 rectfill
showpage
%%EOF
With Distiller 7 and Ghostscript 8.54, it looks as expected (the
right-hand image and patch are the negative of the left-hand ones).
With Preview.app 3.0.6 (build 409) from OS X 10.4.6, the left-hand and
the right-hand drawing are identical, even though there is an inverting
transfer function in force.
Is there some parameter to set somewhere for Preview.app to honor the
transfer function ? Or is this simply a bug ?
________________________________________
________________
François Robert
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| François Robert 2007-08-28, 7:11 pm |
| In article <moc.xeta-79EBA3.20093828082007@powernews.iol.it>,
François Robert <moc.xeta@trebor.siocnarf> wrote:
> Is there some parameter to set somewhere for Preview.app to honor the
> transfer function ? Or is this simply a bug ?
FWIW, I found that PSNormalizer.framework has a PS startup file located
in :
/System/Library/PrivateFrameworks/PSNormalizer.framework/Versions/A/Resou
rces/startupNORM.ps.
At the end of this file, one finds :
<</AutoPositionEPSFiles true /AutoRotatePages /All >> setdistillerparams
Based on the Acrobat Distiller Parameters documentation
(http://partners.adobe.com/public/de.../pdf/pdf_creati
on_apis_and_specs/DistillerParameters.pdf), I changed that to :
<<
/AutoPositionEPSFiles true
/AutoRotatePages /All
/TransferFunctionInfo /Apply[color=darkred]
and that fixed the issue. However, the default value (/Preserve) for
/TransferFunctionInfo is apparently either not honored or PDF transfer
functions are not understood by the PDF viewer component of Preview.app.
________________________________________
________________
François Robert
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