TikZ: nodes with text, scale = or \large, \Large, \Huge?

Question

If one needs to slightly increase the size of the text in a TikZ node. What are the pros and cons of using scale= in the style options instead of changing the font size with the usual LaTeX\TeX macros: \Huge, \Large and \large ?

Answer 1

Scaling affects all the glyph strokes and this can be not very pleasant (some strokes will be unnecessarily and excessively thick); changing the font size using the font switches or \fontsize produce more harmonious results.

Compare the results in the following simple experiment; the upper line uses \fontsize; the lower line uses scale:

\documentclass[border=3pt]{standalone}
\usepackage{tikz}
\usepackage{fix-cm}

\begin{document}

\begin{tikzpicture}
\begin{scope}[scale=12,transform shape]
\node (A) {1234AQMI};
\end{scope}
\node[font=\fontsize{120}{144}\selectfont] at (0,4) (B) {1234AQMI};
\end{tikzpicture}

\end{document}

Of course, for a small scaling factor the difference can be almost imperceptible, but I'd use the font switches for better results unless, of course, one is specifically after the effect produced by scaling.

Addressing this same situation, D. Knuth mentions on the fourth bend sign on page 16 of the TeXbook:

What's the difference between cmr5 at 10pt and the normal 10-point font, cmr10? Plenty; a well-designed font will be drawn differently at different point sizes, and the letters will often have different relative heights and widths, in order to enhance readability[...]

It is usually best to scale fonts only slightly with respect to their design size, unless the final product is going to be photographically reduced after TeX has finished with it, or unless you are trying for an unusual effect.