I love a good puzzle game, and this was a lot of fun! I think I was trying to look for pictures in the nonograms after stage 2 due to thinking you were going for a picture of a breast on it.
The music was quite catchy, and you got a good base for something more here!
Other than aligning the columns and rows with the puzzle tiles a bit better, and putting a grid on it to see the individual boxes, the only thing I can think of is maybe have the grid dissolve to show the image underneath? The images were a fun reward for solving the puzzle, but having them float down felt a little disjointed from the nonogram itself.