What are the conditions suitable for optimum colour vision?

Answer 1

You need natural lighting (or a source that reproduces natural lighing) where the entire spectrum is present; somewhere around 380 nm up to 780 nm.

Artifical light could be absent some of these wavelengths; if they are not included in the spectra of that light, they cannot be included in the observable light; you would not see the true color of whatever it is you are trying to observe.

Answer 2

You need enough light. The eye is composed of cones which see the colors .these cones demand enough light especially for red