Font-sizes in figures and subfigures

Question

Assume the following example of two images inside a figure environment

The left image uses font-size 10 and is not scaled. Therefore, the numbers on the axes are of the same size as the Main caption. On the other hand, the right image uses 10pt font-size but has an image-size which would fit over the whole page. Therefore, it is scaled by 0.5. I have two concerns:

• A graphic which ranges over the whole width of the page should maybe use the same font-size which is used in the text. Otherwise numbers maybe look like they are lost.

• For subfigures having a width of approx .45\textwidth the font-size 10pt feels too big. It should be smaller like the caption of the subfigure. The scaled left subfigure has too small numbers IMHO.

Question: Is there a general rule for the font-sizes to use in figures and subfigures? Is it ok to scale the images or should I always create my pdf/eps graphics having the correct final size (and therefore exact font-sizes which match small, footnotesize, scriptsize..)

Additional notes:

I didn't came here unprepared. The first thing I did was skimming through some of my Knuth books. There I noticed, that he uses many different font-sizes in images (at least in the Fascicles of TAOCP), but it always looks kind of coherent.

I thought since there are enough guidelines for good typographic style, there are guidelines for images, diagrams and graphics in books too.

Answer 1

If you want to be perfect, you use in all your graphics the same font (for example libertine) and font size (for example 12 pt) used in your document. So the best would be to prepare all graphics in a way, that they can included in your document without changing, scaling, etc. That has the advantage you can build all your images with the same resolution (for example 600 dpi).

If that is not possible, use the same kind of font (for example with or without serifes) and the same font size (I mean not the number here, I mean that it looks as tall/small as the other font).

If you have to change the fontsize, be not too small (everything, legend and numbers, must be readable!) and do not use a greater font size in your images.

For example with a fontsize of 12 pt in your document I would use as lower fontsize in the graphics 10 pt or 11 pt, not smaller.

If you have to scale your images prepare them (that could mean some trial and error runs ;-)) that they have an optimal font size for legend and numbers in the printed document.