Nonogram Generator

How nonogram clues describe a picture

Every clue is an ordered list of the lengths of consecutive filled runs. Row clues are read from left to right; column clues are read from top to bottom. Two runs in the same line must have at least one empty cell between them. Empty cells before the first run and after the last run are allowed. A line with no filled cells is shown as 0.

The order matters. The patterns ■■·■· and ■·■■· have clues 2 1 and 1 2, so they are different puzzle lines.

Worked 5×5 example

Suppose the picture contains these rows:

· ■ ■ · ·
■ ■ ■ ■ ·
■ ■ ■ ■ ·
· ■ ■ · ·
· · ■ · ·

Its row clues are 2 / 4 / 4 / 2 / 1. Reading down the same picture, the column clues are 2 / 4 / 5 / 2 / 0. The fifth column receives a 0 because it contains no filled cells.

Why uniqueness has to be checked

The picture you draw is always one valid answer to its own clues, but it may not be the only answer. Different black-and-white grids can produce exactly the same row and column run lengths. Nonogram construction research treats a single solution as a separate quality requirement, not an automatic consequence of converting a picture into clues.

This generator reports one of three outcomes:

• Unique: the verifier completed its search and found exactly one solution.
• Multiple: it found at least two different grids that satisfy the same clues.
• Unverified: the capped search did not finish, so the tool makes no uniqueness claim.

A unique solution also does not guarantee an elegant human solve. A puzzle can have one mathematical answer yet require trial-and-error or deductions beyond the techniques a beginner knows.

Design and printing tips

• Start with a bold silhouette. Isolated pixels and visual noise create long strings of 1 clues that are harder to read.
• Use a 5×5 or 10×10 grid for a first puzzle. Move up to 15×15 or 25×25 when the subject genuinely needs more detail.
• Treat empty and fully filled lines as easy footholds. Too many can make the puzzle trivial.
• Check the printed clue size before distributing a worksheet. The grid, numbers, and cell boundaries should remain clear in grayscale.
• Keep the solution on a separate page when sharing the puzzle.

The clue rules above follow the standard black-and-white Pic-a-Pix format described by Conceptis. For the distinction between an image, its clues, and unique reconstruction, see Batenburg and colleagues on constructing nonograms of varying difficulty and Henstra’s work on image-based construction and multiple solutions.