Have movie posters gotten darker since the early 1900′s? That’s one of the questions the creator of this visualization wanted to answer by removing black and white, he produced this horizontal HSL chart. As Vijay himself explains: “The width of each hue represents the amount of that hue across all images for that year, and the saturation and lighting were the weighted average for all matching pixels. Since HSL has a fixed order, comparisons can be made between years visually.”
Source: Flowing Data