This is a different method than using error correction that allows for more usable area (see details in other threads.)
It still leaves 7% of the ECC intact so you can further modify the code after it is generated. I had to modify a few pixels still to embed another QR code inside a QR code (and have both scan!)
Kinda crazy that up to 30% of a QR code can be inaccurate, and it will still work.