title: How to enforce constraints on some of the pixels in a QR code?
body: <p><a href="https://i.stack.imgur.com/YLy3V.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/YLy3V.png" alt="enter image description here" /></a></p>
  <p>A QR code is basically a boolean vector, displayed as pixels on a small image.<br />
  It encodes some data, that can later be decoded using a pre-known protocol.</p>
  <p>Apart from the (3/4) corners, used to align the camera to the size of each pixel of the actual code data, and its orientation, I was wondering if the rest of the data can, in theory be engineered with constraints, while still maintaining meaning?</p>
  <p>Could I enforce some constraints for making &quot;nice looking&quot;, and still meaningful QR codes? possibly with larger-than-necessary resolution?</p>
  <hr />
  <p><em>This is not opinion-based</em></p>
  <p><strong>I am asking if and how I could create a QR encoder with extra constraints and that takes in arbitrary data, such that a standard QR decoder would still be able to decode the data</strong></p>
  <p>For example, to always force some of the pixels to be black.</p>