The method I use was taught to me by a guy who grew up in the Middle East where Pomegranates are available pretty much all year round. It was also featured on Martha Stewart.
Get a bowl of water. Score the skin so that you can pull it apart into two halves.
Take a wooden spoon ( or anything with a broad flat surface) Holding one half of the Pom with fingers spread apart over the bowl, start giving it firm thwacks and the seeds will begin falling out into the bowl of water.
You do get some pith but it’s minimal. Keep whacking away at each half until all the red seeds are in the water. The pith floats on top of the water making it easy to separate from the seeds in the bottom of the bowl.
It takes longer to describe than it does to do it. The whole thing takes about 10 seconds.
YouTube has clips showing how to do this.