The red pepper is all grey, no joke (pbs.twimg.com)

It isn't all grey, it's green.

It's not red compared with the green cast?

This isn't anything even remotely interesting, this is a much better example of the brain changing the measurements of colour to fit a pattern:

https://goo.gl/images/V0d0hx

Context or explanation? What do I learn from this? Is it some display trick or are some magic sensors in my brain toggling here...