The Kuwahara filter is an edge preserving noise filter. It splits an area into 4 overlapping regions and picks the average of the region that has the smallest variance.
Before:
After applying a Kuwahara Filter of Size 5:
Before:
After applying a Kuwahara Filter of Size 5:
Before:
After applying a Kuwahara Filter of Size 5:
Before:
After applying a Kuwahara Filter of Size 5:
Before:
After applying a Kuwahara Filter of Size 5: