1. Nave Weinberg & Shlomi Nissim

2. Goals Detect a “Hidato” puzzle from a “Yediot Ahronot” newspaper.
Display a digital view of the “Hidato” on an Android smart-phone.
Solve the “Hidato” and display the full solution or clues to the user.

3. Stage 1: Hidato Detection
Using adaptive threshold and morphological erosion for detecting clear contours.
Finding the biggest contour in the center of the image.

4. Stage 2: Aligning
Finding the “Hidato” four edges by dividing the max contour to four areas, computing min/max value for each local area .
Applying Projective Transformation from those edges to fixed points.

5. Stage 3: Numbers Detection
After aligning, the cells location in the table are known.
Applying normalized cross correlation with 61 number templates on each cell in order to detect the correct number, while ignoring white (empty) cells.

6. Stage 4: Solving the “Hidato”
Using a backtracking algorithm. Guess a solution by trying one of several choices. If the guess proves incorrect, the computation backtracks to the last point of guess and guesses a different choice.

7. Limitations The "Hidauto" table should be in the center of the image.
The picture orientation must be from bottom to top.

8. GUI
Example run: