Show postscript point versus Anglo-Saxon point

Question

I am doing a practical job comparing the postscript point (1/72) with the Anglo-Saxon point (1/72.27). I need help to be able to show the difference in size in a character (it is indistinct of which). The idea is to show the difference not with a rule, but with two overlapping characters (one on top of the other). Thanks for the help

Not that it answers your question, but the issue of 1/72 vs. 1/72.27 came up in this answer: https://tex.stackexchange.com/questions/161297/is-there-such-a-thing-as-a-mathrule-rounded-endcaps/161309#161309. I was calling it \mystery@factor before Dan figured out what it was. — Steven B. Segletes, Sep 19 '19 at 14:36

score 1 · Answer 1 · answered Sep 19 '19 at 13:49

The visual difference is small:

\documentclass[landscape]{article}

\usepackage{graphicx}
\usepackage{calc}

\newlength\charheight

\begin{document}
\settoheight\charheight{\Huge X}
\setlength\charheight{\charheight*\ratio{72.27pt}{72pt}}

pt$\rightarrow$\scalebox{10}{\Huge X\resizebox{!}{\charheight}{X}}$\leftarrow$bp
\end{document}

Paul Gaborit · Answer 2 · 2019-09-19T15:19:44.017

1

Here is a solution (the difference is very small...).

\documentclass[tikz,margin=0mm]{standalone}
\usepackage{lmodern}
\begin{document}
\begin{tikzpicture}[inner sep=0]
  \begin{scope}[blend group=difference]
    \node[font=\fontsize{52pt}{52pt}\selectfont]{A};
    \node[font=\fontsize{52bp}{52bp}\selectfont,text=white]{A};
  \end{scope}
\end{tikzpicture}
\end{document}

Here is a south west anchored variant:

\documentclass[tikz,margin=0mm]{standalone}
\usepackage{lmodern}
\begin{document}
\begin{tikzpicture}[inner sep=0]
  \begin{scope}[blend group=difference]
    \node[anchor=south west,font=\fontsize{52pt}{52pt}\selectfont]{A};
    \node[anchor=south west,font=\fontsize{52bp}{52bp}\selectfont,text=white]{A};
  \end{scope}
\end{tikzpicture}
\end{document}

edited Sep 19 '19 at 15:19

answered Sep 19 '19 at 13:52

Paul Gaborit

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Thanks Paul, your example is what I need, but the characters should not be centered, but anchored at a point equivalent to 0 of an x and y coordinate, to correctly dimension the difference. Is it possible with is code? – Alberto Moyano Sep 19 '19 at 14:37
@ImagoMundi You can add the anchor=south east key to each node... – Paul Gaborit Sep 19 '19 at 15:03
Thanks Paul, it's exactly what I was looking for. My practical work is based on showing that this small difference added to 800,000 characters (for example a 320-page book) plus the efficiency of the TeX engine in typographical calculations, make a big difference. – Alberto Moyano Sep 19 '19 at 23:23

egreg · Answer 3 · 2019-09-19T16:09:58.700

If I compile

\font\PT=ptmr at 1000pt
\font\BP=ptmr at 1000bp

\setbox0=\hbox{\PT A}\showthe\ht0
\setbox0=\hbox{\BP A}\showthe\ht0

\bye

I get on the console

> 673.00034pt.
l.4 \setbox0=\hbox{\PT A}\showthe\ht0

? 
> 675.52408pt.
l.5 \setbox0=\hbox{\BP A}\showthe\ht0

?

which means that the difference in height is about 2.5pt, less than one 1mm. At 100pt/100bp, the difference is less than 0.1mm.

You're not going to see any difference at standard sizes (and TeX doesn't load fonts at different sizes if the gap is very small).

Here's the picture I get by printing a black 1000bp A under a red 1000pt A, at 2400% (just the top).

At 100% magnification on a Retina display,

Show postscript point versus Anglo-Saxon point

3 Answers3