DOKK / manpages / debian 12 / freetype2-demos / ftsdf.1.en
FTSDF(1) General Commands Manual FTSDF(1)

ftsdf - an SDF viewer

ftsdf pt font

ftsdf displays Signed Distance Fields (SDF) for glyphs of the given font, allowing to change various rendering and display options interactively.

The point size. Since currently the resolution is always set to 72dpi, this directly gives the ppem value (pixels per EM), too.
The font file to display.
May 2022 Freetype 2.12.1