[NTG-pdftex] Time for Type3 bitmap fonts to cause a warning?

Markus Kuhn Markus.Kuhn at cl.cam.ac.uk
Tue Mar 28 13:50:10 CEST 2017

Type3 bitmap fonts look much worse on most output devices than
properly-hinted Type1 fonts.

Type3 fonts also can cause problems with PDF interpreters in
printers, which sometimes no longer implement all aspects of
the Type3 language correctly.

Type3 fonts were once a hack that seems no longer widely used
outside the TeX community, and therefore are now less
well tested and supported by device manufacturers.

Type3 bitmap fonts seem an anachronism from the 1980s, when it
was customary to output DVI files using Metafont-generated
device-specific bitmaps, and when there were only a small
number of standard output resolutions in use.

Today, I find that in nearly all cases where I encounter
pdftex-generated documents with Type3 bitmap fonts, these
were actually selected by an inexperienced author by accident,
(often as a result of copying a line such as
\usepackage[T1]{fontenc} without understanding its
font-selection implications).

Suggestion: it would be useful to actively discourage in
pdftex the use of Type3 fonts.

This could be done in steps, e.g.:

- initially just output a warning that prominently
   lists any Type3 fonts used in the PDF produced
   (plus add an "I know what I do and really want Type3"
   command-line override option to suppress that warning)

- later turn that warning into an error, such that Type3
   fonts can now only be included into PDFs using the
   "I know what I do and really want Type3" command-line
   option, to make sure they only appear in PDFs as a
   deliberate choice by an experienced author.

[The idea is similar to how HTTPS browsers like Chrome or
Firefox gradually added warnings to phase out outdated

If Type3 fonts generated a clear warning, this would make it
much easier for the authors of document-submission guidelines
to tell PDF authors what they need to avoid. At the moment,
such guidelines have to rely on more complex instructions to
check font types with e.g.

   pdffonts file.pdf | grep 'Type 3'


Markus Kuhn, Computer Laboratory, University of Cambridge
http://www.cl.cam.ac.uk/~mgk25/ || CB3 0FD, Great Britain

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