i made one with maximum error correction but the reality is with these codes they are not designed to be mangled pictures those little marker squares are alignment points and the bits are redundantly encoded with reed solomon encoding and the particular way they used to do this precludes wiping out more than the central 1/9th of the image

it would be possible to devise other ways to make it look prettier, for example you can blur and then round the edges of the shapes so it's a bit more pretty but that is the limitations of the encoding

definitely you can't make the edges round, and you can't leave out the margin around the square... that is how the algorithm finds the shape it needs to straighten into a square and aligns where all the bits are placed