Nonetheless, I'd also guess that this is the contrast issue that Schussel described. It's caused by the eink-optimized framework-res.apk included in rupor's root package. The
thread Schussel has been referring to offers a solution, but it requires that you have shell access to the Reader (via adb or recovery mode) and a backup of the original system partition (or manage to extract the needed file from the restore set).