Red-White-Red Bands
3 flags that get mixed up with each other. The two hardest are Austria and Latvia — 69.4 apart, where two copies of one picture score 0.
Every pair, measured
Nearest first. 0 is the same picture; the number is the worst single tile, out of 255.
What they have in common
They were not all measured as the same shape, so what they share is colour and habit rather than construction.