Greyscale display

[Kuratius]

Most e-ink screens can do some degree of greyscale if the waveform can be modified.
It seems that there have been some attempts on this for the badger, see for example
https://github.com/antirez/uc8151_micropython

It may be worth investigating if this can be integrated into the official driver in some capacity, and in particular without any risk to the display.
Even if it's only 4 levels (due to the limit of 4 waveforms per refresh cycle, due to originally being intended for B/W display), this may substantially improve image quality both with and without dithering. This should be safe from damage since you would only be driving a white->black change for less time or with less voltage (for example).

The current attempt by antirez has some quantization issues, which are not immediately visible from an image but can be seen by measuring gray levels in something like imageJ, where it becomes clear it's 4 coarse levels with minor variations in between.