[tex-live] TeX and recent ghostscript changes

[Nelson H. F. Beebe]

There is a round of release candidates in progress for ghostscript: I
installed version 9.21 here on 5-Sep-2017, and since then 9.22rc1
appeared on 13-Sep-2017.  There are discussions of this on the
developers list (archives at

	http://ghostscript.com/pipermail/gs-devel/

), but one message today in particular caught my eye, and may be
useful information for the TeX Live team:

>> ...
>> To: ken.sharp at artifex.com
>> From: Masamichi Hosoda <trueroad at trueroad.jp>
>> Subject: Re: [gs-devel] Ghostscript/GhostPDL 9.22 Release Candidate 1
>> 
>> >> > Please give them a try on your system if you're interested in helping
>> >> > test the release-in-progress. Your feedback is appreciated.
>> >>
>> >>It seems that `-dPDFDontUseFontObjectNum` option does not work.
>> > 
>> > It has been removed, as documented in History9.htm:
>> > 
>> > 2017-08-02 13:41:59 +0100
>> > Ken Sharp <ken.sharp at artifex.com>
>> > ca1ec9b486ddba3f921355fd1d775f27f4871356
>> > 
>> >     PDF interpreter - remove the PDFDontUseObjectNum switch
>> > 
>> >     This was implemented to allow us to restore the default behaviour if
>> >     it caused problems. No real problems reported, so lets get rid of
>> >     (yet another) of our many, many command line switches.
>> > 
>> > 
>> >>`-dPDFDontUseFontObjectNum` is useful to unify duplicate fonts.
>> >>So I would like to use `-dPDFDontUseFontObjectNum`.
>> > 
>> > The fonts can't realistically be described as duplicates, if they have
>> > different object numbers. Or if they are then the original PDF file
>> > (this only works with PDF input) was poorly constructed. Using this
>> > option isn't really sensible, it was only ever present in case the
>> > Font numbering usage went awry. Consider creating the original PDF
>> > files more efficiently instead.
>> > 
>> > I'll discuss it with the other developers but I am not inclined to
>> > restore this. Obviously if you feel its important you can revert the
>> > change locally.
>> 
>> When you create a PDF document using something like a TeX system
>> you may include many small PDF files in the main PDF file.
>> It is common for each of the small PDF files to use the same fonts.
>> 
>> If the small PDF files contain embedded full font sets,
>> the TeX system includes all of them in the main PDF.
>> The main PDF contains duplicates of the same full sets of fonts.
>> Therefore, `PDFDontUseFontObjectNum` can remove the duplicates.
>> This may considerably reduce the main PDF-file's size.
>> 
>> There is a tool for using this method of removing duplicate fonts.
>> https://www.ctan.org/pkg/extractpdfmark
>> https://packages.debian.org/stretch/extractpdfmark
>> http://packages.ubuntu.com/zesty/extractpdfmark
>> 
>> LilyPond has option `--bigpdfs` for unifying duplicate fonts in this method.
>> http://lilypond.org/doc/v2.19/Documentation/usage/command_002dline-usage#basic-command-line-options-for-lilypond
>> ...

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- Nelson H. F. Beebe                    Tel: +1 801 581 5254                  -
- University of Utah                    FAX: +1 801 581 4148                  -
- Department of Mathematics, 110 LCB    Internet e-mail: beebe at math.utah.edu  -
- 155 S 1400 E RM 233                       beebe at acm.org  beebe at computer.org -
- Salt Lake City, UT 84112-0090, USA    URL: http://www.math.utah.edu/~beebe/ -
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