I have a large PDF with mostly vector and a bit of pixel graphics. It is in two colours only (the pixels are either one colour or the other, no dithering). I want to create a new PDF of a segment of the larger PDF (bottom left corner), where vector is maximally preserved, and where one colour is replaced by 100% transparency.

I was wondering if that is doable by using LMTX instead of trying to do this with some GUI app.