[gentium] Display Bug in Overleaf and Acrobat

[pavel.farar at centrum.cz]

Hi,

after some problems, I installed a virtual machine with Linux and the last
available Acrobat Reader for Linux (version 9.5.5, 32 bit, from 2013) and it
shows the artifacts in the PDF document.

Because I had several versions of TeX Live installed and some changes, I
deleted all the TeX stuff and started with vanilla TeX Live 2022 DVD.

This contains the old version of Gentium fonts, where there was no overlapping
in the fonts. I processed the same source file, that is used in the Overleaf
project:

\documentclass{article}
\usepackage{gentium}

\begin{document}
\huge\bfseries Hello, World!
\end{document}

I created files with these old version of Gentium fonts (both Type 1 and
TrueType):

hello-old-type1.pdf
hello-old-truetype.pdf

and they show no artifacts (as expected).

Then I updated the whole TeX Live. This gives the new version of the fonts.

I created the file hello-new-type1.pdf with these new version of the fonts and
Acrobat Reader shows the artifacts.

Then I tried to use also the TrueType version of the fonts, but pdflatex
couldn't process them. Here is info about pdftex version and the error:

This is pdfTeX, Version 3.141592653-2.6-1.40.24 (TeX Live 2022) (preloaded format=pdflatex)
 restricted \write18 enabled.
entering extended mode

...

!pdfTeX error: pdflatex (file /usr/local/texlive/2022/texmf-dist/fonts/truetype
/public/gentium-tug/GentiumPlus-Regular.ttf): unknown version of OS/2 table (00
04)
 ==> Fatal error occurred, no output PDF file produced!

I stopped trying the TrueType version of the fonts.

Then I took the Type 1 font (just the bold version) and removed the
overlapping in FontForge for letters H, e and d. I regenerated the font and
replaced just the one corresponding *.pfb file in the installed TeX Live. Then
I created a file hello-new-type1-corrected.pdf and it doesn't show (at least
to me) any artifacts.

All the *.pdf files are attached and I will see if they will be accessible
also on the mailing list.


Can you (especially Tom) confirm, that you can view the last pdf without any
artifacts? And please use the current version of Acrobat Reader. That should
be easy for you, but it would take much more time to me.

There is also the new problem with pdftex and the TrueType fonts. Can someone
confirm this?

I know about the github site for the fonts, but I didn't report the problem.
I think that we should do as much work and research as possible ourselves.

I think that Victor composes the glyphs from several parts to achieve
consistency or for some other good reason (and he knows about fonts more that
me). It doesn't look to me like an error but like an intention. I haven't
checked if overlapping or self-intersection is acceptable these days.

If document created with luatex + TrueType fonts looks OK in Acrobat Reader (I
haven't tried it), than there are several solutions:

1) Change the Type 1 fonts (more work for us; less work for Victor)

2) Change the TrueType fonts (more work for Victor; easy for us)

3) Change pdftex

4) Change Acrobat Reader (report problem; probably the least probable to
   succeed).


Victor might prefer something else that we.

I can use old Acrobat Reader with some pain, but I can't see the problems in
the browser (older Firefox 68 in the virtual machine doesn't render the PDF
for the Overleaf project; however it can download the resulting pdf).

Pavel
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