The customer reports and I've verified that the attached PDF file is not read correctly with Ghostscript. The customer reported this using 8.54, but 8.57 and head (r8085) produce the same results. The command line I used for testing: bin/gs -sDEVICE=ppmraw -sOutputFile=test.ppm ./trans.pdf I've attached a screenshot comparing Acrobat 1.5 output to Ghostscript.
Created attachment 3088 [details] trans.pdf
Created attachment 3089 [details] screenshot.png
Note that with a later rev than 8.57 (rev 8075) I see: Error: /rangecheck in --.discardtransparencygroup--
Interestingly I do not see the rangecheck message: % ~/artifex/ghostscript/trunk/gs/bin/gs -sOutputFile=test.ppm -sDEVICE=ppmraw trans.pdf GPL Ghostscript SVN PRE-RELEASE 8.60 (2007-05-12) Copyright (C) 2007 Artifex Software, Inc. All rights reserved. This software comes with NO WARRANTY: see the file PUBLIC for details. Processing pages 1 through 1. Page 1 >>showpage, press <return> to continue<< GS>quit %
My results are as shown in screenshot.png. That is, job completes, but gs produces bad output.
Created attachment 3100 [details] transillus.pdf
It appears this is not a color compositing problem so much as a problem in the PDF interpreter. When I take the original PDF (trans.pdf) and open it in Illustrator CS2, make a single minor change to the PDF (move a cliprect a few pixels) and save the PDF as a new PDF, this new PDF renders properly. Please see the attachment transillus.pdf, which is the PDF that renders correctly. This indicates that gs can handle the tranparecy operations, but something about the structure of the original PDF is not being dealt with correctly. It it were truly a compositing problem, the structural change in transillus.pdf would not circumvent that problem.
Tim, we request a better analysis here, we really can't conclude much from comment #7.
There is a problem with the PDF interpretation when graphic states contain a softmask dictionary. What happens is the softmask is never composited as it never becomes part of a transparency group. Since compositing only takes place when a group is "popped", the interpreter needs to recognize transparency groups that are part of a graphics state. Currently the PDF interpreter only recognizes groups that are part of a form group or imagemasks. The reason transillus.pdf works correctly is that the file was restructured by Illustrator in such as way that the SMask become part of a form group. This is a duplicate of bug #688601 *** This bug has been marked as a duplicate of 688601 ***
Changing customer bugs that have been resolved more than a year ago to closed.