[Dvipng] Breaks in brackets

[Kevin D. Smith]

I am running the following code in latex then using dvipng 1.9 to
generate an image. You'll see in the attached image that there are
breaks in the first four brackets. I've tried various quality levels
as well as different DPIs, but I just can't get them to go away. Do
you have any suggestions?

\documentclass{article} \renewcommand{\rmdefault }{ptm} \usepackage
{mtpro2} \makea
tletter
\@ifundefined{plasTeXimage}{\newenvironment{plasTeXimage}[1]{\vfil
\break\plasTeXre
gister\thispagestyle{empty}\def\@eqnnum{}\ignorespaces}{}}{}
\@ifundefined{plasTeXregister}{\def\plasTeXregister{\parindent=0pt
\ifhmode\hrule\e
lse\vrule\fi height 2pt depth 0pt width 2pt\hskip2pt}}{}
\begin{document}

\begin{plasTeXimage}{images/img-0001.png}
\[ \left[ \begin{array}{r} w \\ x \\ y \\ z \\ \end{array}\right] =
\left[ \begin
{array}{rrr} 1 & 1 & 1 \\ 1 & 1 & -1 \\ 1 & -1 & 1 \\ 1 & -1
& -1 \end{arr
ay}\right] \left[ \begin{array}{c} \beta _0\\ \beta _1\\ \beta _2 \end
{array}\righ
t] \]
\end{plasTeXimage}

\end{document}\endinput

[Jan-Åke Larsson]

Post by Kevin D. Smith
I am running the following code in latex then using dvipng 1.9 to
generate an image. You'll see in the attached image that there are
breaks in the first four brackets. I've tried various quality levels as
well as different DPIs, but I just can't get them to go away. Do you
have any suggestions?

The problem is that the brackets are typeset using several glyphs
(printed characters), which join together to each bracket. At the joins,
the antialiasing used is causing a light spot: the first glyph darkens
it somewhat and then the second glyph darkens it further. Whereas
typesetting both "at once" would cause the pixel to become black.

The effect is visible at screen-resolution in dvipng, but can also be
seen in xdvi and my rudimentary trials indicate that it is even worse
with the old-style dvips->gs route.

Since this is encoded into the dvi file, there is no route around it
that I can see. Turning off antialiasing isnt an option. All I can think
of is a font containing extra large brackets, or telling TeX to scale up
the existing fonts. (But that will look odd, the thickness will also
scale along with the height.)

Feel free to make suggestions, if you can cook up anything good.
/JÅ