A study published in Science by Hanne H. Thoen and colleagues in January of 2014 showed that mantis shrimp are actually worse than we are when it comes to discriminating differences in color. In other words, the fact that the mantis shrimp has a greater variety of color photoreceptors does not endow the crustacean with better color vision.

https://www.jhunewsletter.com/article/2015/12/mantis-shrimp-myth-about-vision-debunked/