Yeah I could do that but... I don't want to create new bitmaps, the main usage right now is combining entities.
Have a look at the following scenario for example: http://superku.de/entCombine.jpg
I wrote a code to automatically place thousands of leaf entities around the base mesh (as I couldn't get it to look right in Blender after some time). I actually have a video of that from an earlier version: https://i.gyazo.com/aa7ec68b29ba24c413bc58459aa7f7f5.mp4
Another scenario was where I had a bunch of coconuts covering the floor, which I replaced with the click of a button (or 2) by just one entity instead.

Having to input the texture files is a little bothersome to me but oh well.
Btw. I'd probably compare the buffers directly instead of using pixel instructions, *should* work if you grab the right BMAP member.