`+splash.bmp+` generated with:

[,sh]
----
magick montage -size 256x256 xc:magenta xc:black xc:black xc:magenta -mode Concatenate ppm:- | \
    pnmdepth 4 | \
    ppmtobmp > splash.bmp
----

Requires `+magick+` from imagemagick and `+pnmdepth+` and `+ppmtobmp+` from netpbm.