Ghosting

This only appears in FAST mode, after calling refresh(). The following is an example of a display from the Pyboard driver in normal mode: no ghosting visible.

This shows the outcome of clock.py on the Pyboard, and raspberry_pi_clock.py on the Pi. In both cases partial updates are used and ghosting is apparent. It demonstrates that the Pyboard driver is no worse in this repect than the RePaper reference driver. The two images are from a single photographic exposure of two displays mounted side by side, so the improved contrast of the Pyboard image was genuine. However it may simply be a consequence of manufacturing tolerances.

Ghosting can be always be cleared by issuing show() or exchange().

To some degree ghosting can be reduced by design: unlike the official Pi demos, my clock demos aim to show it at its worst. A prettier clock would result if the second hand and digits were eliminated and exchange() issued every few minutes.