Horizontal: different groups
Vertical: group size (darker: smaller)
An exploration of flag similaritiesHow to read the colors: countries with similar flags are painted the same color. The bigger the group is, the brighter the group color. Countries with unique flags are black. There's a great discussion on Quora about flag similarity. Here, an algorithm was used for grouping images together. There are several metrics of comparison: color (all red flags), shape (how are they partitioned into colors), symbols (stars in particular region), etc. I used a hybrid metric that tries to consider colors and shapes of individual flags, and grouped countries with similar flags together. For more technologically inclined, here's a description of technique used to group them together.