For example, a black four followed by a red two could mean four black boxes, some empty spaces, and two red boxes, or it could simply mean four black boxes followed immediately by two red ones.

Two differently colored numbers may or may not have a space in between them. If colored, the number clues are also colored to indicate the color of the squares. These puzzles are often black and white-describing a binary image-but they can also be colored. For example, a clue of '4 8 3' would mean there are sets of four, eight, and three filled squares, in that order, with at least one blank square between successive sets.

In this puzzle type, the numbers are a form of discrete tomography that measures how many unbroken lines of filled-in squares there are in any given row or column.

Nonograms, also known as Hanjie, Paint by Numbers, Picross, Griddlers, and Pic-a-Pix, and by various other names, are picture logic puzzles in which cells in a grid must be colored or left blank according to numbers at the side of the grid to reveal a hidden pixel art-like picture. A completed nonogram of the letter 'W' from the Wikipedia logo

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