Frequently Asked Questions
Everything you need to know about PhotoNono and nonogram puzzles.
What is a nonogram?
A nonogram (also called Picross, Griddler, or Paint by Numbers) is a logic puzzle where you fill cells on a grid to reveal a hidden picture. Numbers along each row and column tell you how many consecutive cells to fill. The puzzle is solved entirely through logic—no guessing required.
How do I solve a nonogram?
Start by looking for rows or columns with large clues—these have the most overlap. Use the clue numbers to determine which cells must be filled, and mark cells you know are empty with an X. Work systematically, checking both rows and columns. Every puzzle has exactly one solution that can be found through pure logic.
What makes a good photo for a nonogram puzzle?
The best photos have high contrast between the subject and background, simple shapes, and clear silhouettes. Photos of pets, logos, simple objects, or profile shots work great. Avoid busy backgrounds or images with lots of fine detail—these are harder to recognize when converted to a grid.
What does 'uniquely solvable' mean?
A uniquely solvable puzzle has exactly one correct solution that can be found through logic alone, without any guessing. PhotoNono checks every puzzle to ensure it's uniquely solvable. If a puzzle isn't, the system will try to adjust settings automatically or suggest changes.
What grid size should I choose?
Smaller grids (10×10 to 15×15) are easier and quicker to solve—great for beginners. Larger grids (20×20 to 30×30) show more detail but take longer to solve. For photos, 15×15 or 20×20 usually offers a good balance between recognizability and challenge.
What is the threshold setting?
The threshold controls how the image is converted to black and white cells. Lower values make more cells filled (darker), higher values make fewer cells filled (lighter). Adjust it until the preview looks like a recognizable silhouette of your image.
What's the difference between Standard and Adaptive mode?
Standard mode uses a single threshold across the entire image—best for high-contrast images with even lighting. Adaptive mode adjusts the threshold locally across different areas of the image—better for photos with shadows, gradients, or uneven lighting.
Can I edit the grid manually?
Yes! After the automatic processing, you can switch to 'Edit Grid' mode to manually fill or clear cells. This is useful for fixing small imperfections or adding details. The editor shows real-time solvability checking so you know if your changes maintain a valid puzzle.
Is my image stored on your servers?
We only store a small preview image used to show the solution when someone completes the puzzle. The original full-resolution image is processed in memory and never stored. Your original photos remain private.
Can I download puzzles to solve offline?
Yes! Every puzzle can be downloaded as a PDF that's formatted for printing. The PDF includes the puzzle grid with clues, perfect for solving with pencil and paper.
How do I share a puzzle I created?
After creating a puzzle, you'll get a unique link you can share with anyone. They can solve the puzzle in their browser without creating an account. You can also optionally list your puzzle in the public gallery for everyone to discover.
Is PhotoNono free?
Yes, PhotoNono is completely free to use. You can create unlimited puzzles, solve puzzles from the gallery, and share with friends—all at no cost.
Still have questions? Ready to try it out?