Arrange five black and five white pieces in a W pattern on a 4x4 grid, as shown. The goal:  moving each piece like a chess knight (two spaces forward, one to the side in any combination), exchange the positions of the black and white pieces in the least number of moves. The end position should look like the picture but rotated 180 degrees.

Can you accomplish it in just 12 moves? A "move" is each time a piece touches down. For example, if the left piece in the top row were to move into the diagonal center row and then into the lower corner, that counts as 2 moves. Pieces may move only to unoccupied spaces.

If you can do it in less than 12 moves, we'd like to see your solution!