I made a photo of 2 sheets of paper with a phone camera, each of them cropped at the:
- (x1, y1) top left corner of top QR code
- (x2, y2) bottom right corner of bottom QR code
I hoped that the x, y coordinate of checkboxes would be nearly the same. In fact it's not, because of the angle of the camera, skewness, etc.
Question: How to have a better deskewing by using 8 corners:
- the 4 corners of top QR code (detected automatically by this method): (x1, y1), ..., (x4, y4)
- the 4 corners of bottom QR code: (x5, y5), ..., (x8, y8)