[DVIPDFMx] Filter specification in pdf:stream command

Dino Petrucci dfp.sphera at libero.it
Thu Jun 17 14:56:21 KST 2010


>dvipdfmx doesn't look at a filter entry in the stream dictionary -
>it uses flate compression for all streams unless compression is turned
>off via the "-z 0" command line option. Is it important to have a
>non-compressed metadata stream?


Thank you, Matthias, for your answer. But It's not correct to unfilter all 
streams by the command line option "-z 0". For me, only XMP metadata must be 
unfiltered, as required, for example, by PDF reference "PDF 32000-1:2008. 
Document management — Portable document format — Part 1: PDF 1.7", by Adobe 
Systems Incorporated, first edition, 2008-7-1 (p. 556):

"The contents of a metadata stream shall be the metadata represented in 
Extensible Markup Language (XML). [...] This information is visible as plain 
text to tools that are not PDF-aware only if the metadata stream is both 
unfiltered and unencrypted."

In fact:

"PDF documents are often made available on the Web or in other environments, 
where many tools routinely examine, catalogue, and classify documents. These 
tools should be able to understand the self-contained description of the 
document even if they do not understand PDF."

pdfTeX gives the possibility to use the command "\pdfcompresslevel" before 
creating a stream. And, in the article "DVI specials for PDF generation" by Jin-
Hwan Cho (TUGboat, Volume 30 [2009], No. 1), it's written:

"DVIPDFMx, therefore, provides new special commands for stream objects.
• pdf:stream @name (string) <<dict>>
constructs a stream object the source of which comes from the string object 
‘(string)’. The stream dictionary ‘<<dict>>’ is optional, and
the dictionary entry ‘/Length’ is created automatically." ==> Only the length, 
NOT THE FILTER (as specified later, instead, for "pdf:put @streamobj 
<<dict>>")!

So if DVIPDFMx's stream command doesn't allow for the filter (to choose it), 
for me it's a bug or a bad limitation.


Dino Petrucci





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