export bitmap:
Simple as piece of cake, I think you know what it mean.

Import with existing:
The system will compare between every pixels and palettes(those colors you can pick in editor) to make your bitmaps fit to the old palettes, when your bitmap is too different to the older one, this will cause a mess.

Import and recreate:
The system will produce new palettes(maximum colors is hard coded, transparent also count) for you automatically, if this button cause the quality being bad, that shows your bitmap is too complicated, and you should simplify it, that is another problem.

Export all:
When you want to modify lots of bitmap and they uses the same palettes(e.g. Jyotyu), you can use this, system will produce a big bitmap, the same column the same palettes, the same vow the same bitmap.

Import all:
When you want to import lots of bitmap and they uses the same palettes(e.g. Jyotyu), you can use this, the system will import all them at the same time, remember to sort the bitmaps in the same sort you exported, or they will mix together!