This maze is generated by random traversal and then flooded with color. Hue encodes Manhattan distance from the starting cell. (This is not an optimal visual encoding, but it suffices and is pretty.)
Color is useful to visually compare the structure of mazes; without color, the black and white alternating cells are too noisy to offer any pre-attentive comparisons. Compare a maze generated by random traversal to randomized depth-first traversal, Wilson’s algorithm and Prim’s algorithm.
See this color flood applied directly to the pixel grid.