system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How does a Chameleons colour change work and how does it activate it? Also, is there any colours it struggles with and can it change into colours beyond our visible spectrum?
gpt
Chameleons aren't the masters of color and camouflage - for that you need to go to the octopus, the cuttlefish and the squid.

Chameleon are mostly greens or browns and shift to lighter and darker colors. Some do have red or yellow markings as well and they have UV markings as well. When they get angry or threatened then their color changing goes into overdrive and they go very dark. 

But Chameleons are born with particular markings / pattern and they can't change those - their color changing is restricted to lightening or darkening their existing pattern.