Beginner guide: solve a puzzle from a photo
By the end of this page you will have photographed a Sudoku, checked that Sudoku Solver read it correctly, and seen the solution.
Before you start
- Sudoku Solver installed. See Install.
- A printed Sudoku (a newspaper, a puzzle book or a screen) or a photo of one.
Find your way around
There is one screen, titled Sudoku Solver. From top to bottom:
- Clear board (the bin icon at the top right) empties the whole grid.
- The board: 9 by 9 cells. Tap a cell to select it.
- The number pad: the digits 1 to 9 and a backspace key that empties the selected cell.
- Camera, Upload and Solve along the bottom.
Take the photo
Tap Camera. Your phone's camera app opens.
To use a photo you already have, tap Upload instead and pick it.
Hold the phone straight above the puzzle, so the grid looks square rather than slanted, and take the photo in good light.
Confirm the photo in the camera app.
Crop to the grid
The Crop to the grid screen opens: Drag the corners so the frame covers exactly the 9×9 grid.
Drag the corners of the frame to the outer corners of the Sudoku grid. Leave out the title, the page number and any other puzzles.
Tap Use this crop.
The crop does not have to be perfect: Sudoku Solver finds the grid's lines inside the frame. While it works, it shows Reading the puzzle….
Check the digits
When reading finishes, the digits it found fill the board, and a message says how many, for example Read 27 digits — check the grid, then tap Solve.
Compare the board with your puzzle, cell by cell:
If a digit is wrong, tap the cell and tap the right digit on the number pad.
If a digit is missing, tap the empty cell and tap the digit.
If a cell should be empty, tap it and tap the backspace key.
A digit shown in red clashes with another one in the same row, column or 3×3 box. Usually one of the two was misread.
Solve it
Tap Solve. The empty cells fill in and the button changes to Solved.
| On the board | Meaning |
|---|---|
| Bold dark digit | A clue: from the photo, or one you typed. |
| Coloured digit | Filled in by the solver. |
| Red digit | Clashes with another digit in its row, column or box. |
If you change a cell after solving, Sudoku Solver keeps your clues, clears the solver's answers and lets you solve again.
What you learned
- How to photograph and crop a puzzle.
- How to check and correct the digits Sudoku Solver read.
- How to read the solved board.