about the icon, it is the (very) rough sketch of the last non-'artstyle test' drawing of koishi i made (daily thing no. 34)
its not very good or anything but it looked "passable" compared to anything i had made previously...
The implementation is extremely simple (it's literally one line of code.)
All it does is take a pre-processed 'map' of the image and uses the corresponding pixel value as the index into the palette.
(e.g. the color '0x06' in the map is index 6 in the palette)