Something I learned recently and which this article sort of hints at - look at the three drafts of Under The Wave Off Kanagawa. The composition is different, but also the colours are much more muted. In the first draft, the only colours highlighted are the people in the corner; in the second, the cliffs. The third draft finally colours the wave, but it's a sedate grey-blue. It's not until the fourth draft that everybody recognizes that we get this brilliant dark blue wave rising up over the the boat, dwarfing the mountain in the background.

And that's because when Hokusai sat down to print that fourth draft, people had recently started exporting prussian blue dye to Japan; prior to that point, he just straight up didn't have access to that striking blue colour that dominates the print.