It was a remnant of brailleimg heritage.

Good when placing different data series together, for an uniform graph size.

Values above the max get hard capped.

"provide" is a regular verb, and there's no convention to ignore this, like
"boxen".

No point in allowing exceeding it if the output is not redirected --
a line-wrapped graph is too mangled to be readable.  Anything that would
allow viewing it right also kills isatty(1).

No option to override -- forcing redirection is as simple as piping through
cat.

Currently uses a dumb RGB average.  What color space does, say, GIMP, use
for thresholding?