The Complete Nonogram Rules

The single principle behind completing a picture from number clues.

A nonogram (also called Picross) is a logic puzzle in which you fill in the cells of a grid to complete a hidden picture. The numbers written to the left of each row and above each column are your only clues.

The numbers in a line give, in order, the lengths of the runs of consecutive filled cells in that line. When there are several numbers, the blocks are placed in that order, and there must be at least one empty cell between any two different blocks.

There is only one way to fill the grid that satisfies the clues of every row and column at the same time. Find that one solution with logic and the picture is complete. Marking cells that stay empty with an X is an important part of solving too.