Maze Solver from a Photo

A maze solution finder for the moment when neither the child nor the parent can solve a maze in an activity book. Take or open a photo of the maze; the walls are read and the way from start to finish is drawn over the picture as a red line. It also works for printouts and hand-drawn mazes when there is no answer page.

How to use

1. Press "Take a photo" to photograph the maze, drop a photo file, or paste a screenshot with Ctrl+V. To try it first, press "Example maze 1".
2. Check that the start and finish markers sit on the entrance and exit in the outer wall. If not, drag them, or choose "Start" or "Finish" next to "A tap on the picture moves" and tap the picture.
3. The red line is the answer. To let the child try first, press "Hide answer"; "Follow the path" shows the way slowly with a moving dot.
4. If the line goes through a wall, press "Thicker walls" or raise "Wall sensitivity". If no path is found, press "Thinner walls" or lower "Wall sensitivity". "Show detected walls" shows how the walls were read.
5. Press "Download PNG" to save the photo with the path drawn on it.

How it works

• The photo is reduced to at most 1400 px on its long side, and lines that are darker than their surroundings become walls (Sauvola local threshold). Small gaps in the printing are closed, only places at a set distance from the walls count as passage, and the shortest path is searched. If narrow passages block it, the distance is reduced and the page says so.
• Start and finish are guessed from the two largest gaps in the outer wall, so they can be wrong. Move them to match the arrows or pictures in the book.
• The photo is processed on this device only and is not uploaded. Only the wall detection settings are saved in this browser.

How to photograph a maze

Lay the activity book flat and hold the phone level, straight above the maze. A photo taken at a slight angle usually still works, but a strong angle bends the walls or makes narrow passages look closed.

Use bright light without shadows and keep the whole maze in the picture. If there are many pictures and words around it, crop the maze in your photo app before opening it.

For mazes drawn with coloured pencils or felt pens, or printed in red or blue, turn on "Coloured lines" so coloured lines are read as walls too.

Questions and answers

How to find the answer to a kids maze book without the answer page

Photograph the maze page straight from above and open it here. The way from start to finish is drawn as a red line; only move the markers if they are not on the book's entrance and exit.

Can a maze be solved from a picture

Yes. Most activity book mazes, with dark walls and passages wider than the walls, are solved. Blurred photos and mazes hidden inside a drawing, where walls and picture lines mix, can fail.

The path goes through a wall

Faint printing has left a gap in the wall. Press "Thicker walls" once or twice or raise "Wall sensitivity" to close it.

It says no path was found

First check that the markers are on the entrance and exit. Then press "Thinner walls" or lower "Wall sensitivity", and use "Show detected walls" to see where it is blocked.

I do not want to show my child the answer straight away

Press "Hide answer" and the line disappears. When a hint is needed, "Follow the path" moves a dot along the way so it appears bit by bit.