https://www.syfy.com/syfy-wire/another-brain-frying-optical-illusion-what-color-are-these-spheres

https://mymodernmet.com/color-constancy-optical-illusion/

https://tumblestoneblog.wordpress.com/2021/06/15/the-colour-purple-twenty-stones-for-mrs-purple-part-one/colour-illusion-1/