to detect the sudoku

To get SuDoKu from an image I think we can
1. Get the largest contour of the image.
2. Get the largest bounding rectangle within the contour.
3. Compute the grid corners.

Start by locating the project notebook and the image-processing entry point, then review how the input image is currently handled. Implement and verify the three stated stages—largest contour, bounding rectangle, and grid corners—using representative Sudoku images; done means the grid corners are reliably detected.

Written by the indexing model from the issue text.