Original Image

Local Min & Local Max

Local Max – Local Min > X

Pixel > Local Median

Detect +/- Transitions via Convolution

● Repeat for opposite transition & logical OR

Result of OR

Median Filter to close holes

Final Steps

● Repeat in orthogonal direction

● Find Indexes by fitting to line and geeting intercept

● Auto number row & columns in space

● Find points by bitwise AND

● Feed into existing algorithm to calculate perspective distortion & lens distortion.

Result