[kepano]

I really wanted to hit 85% but the best I could do was 84.4% https://i.imgur.com/t3saf5D.jpeg

The scoring system could try to account for perceptual color differences, perhaps by ramping up the saturation of both images when calculating the differences. Since the original painting is relatively desaturated the current scoring mostly incentivizes focusing on light/dark rather than shades of color.

Lots of other great suggestions in the thread — would be fun to see a leaderboard!

[runnerup]

Doing the distance calculation in CIELAB / Oklab color space would suffice.

[johnchristopher]

What input device did you use (mouse, finger, touchpad, etc. ) ?

[kepano]

iPad + pencil