Nonograms, also known as Hanjie, Paint by Numbers, or Griddlers, are
picture logic puzzles in which cells in a grid have to be colored or left
blank according to numbers given at the side of the grid to reveal a
hidden picture. In this puzzle type, the numbers measure how many
unbroken lines of filled-in squares there are in any given row or column.
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 groups. These puzzles are often black and white but
can also have some colors. If they are colored, the number clues will
also be colored in order to indicate the color of the squares. Two
differently colored numbers may or may not have a space in between them.
For example, a black four followed by a red two could mean four black
spaces, some empty spaces, and two red spaces, or it could simply mean
four black spaces followed immediately by two red ones. There are no
theoretical limits on the size of a nonogram, and they are also not
restricted to square layouts.