The rendering effect of Koreader on KPW2 seems different from that of KPW1. In KPW1, the rendering effect is good while in KPW2, 2 or 3 pages partial refresh after one full screen fresh, there remains a lot of e-ink in the screen. As can be seen from the figures attached, in KPW1, the blank region (upper part) is as white as expected, but in KPW2 the blank region (below part) seems contain a lot of "boundary" ink of the characters from previous pages. Such phenomenon is more obvious for the screen regions which is changing from text to images.

One of the developer told me that it may be because the default waveform setting is incorrect. He suggested changing line 26 in frontend/ui/uimanager.lua into:

default_waveform_mode = 8; -- REAGL waveform

However, such change disables the full refresh. Could any developer who owns a KPW2 help to solve this problem?