Driving RGB panel with Kendryte K210

I was playing with 64x32 RGB panel using Maix Bit and other K210 and all works great.
I can easily drive many panels - at least 4. My question is - for experiments with color scale - I am looking for some nice algorithms to generate rainbow or similar animated effects.
With fast pwm on MCU we can achieve insane number of colors - several bits (8+) per channel
Thanks for any suggestions :wink: