An extra cone may not necessarily allow you extra colour resolution. For example it might mean that there is less over all resolution (cones might not fit toge

An extra cone may not necessarily allow you extra colour resolution. For example it might mean that there is less over all resolution (cones might not fit together properly) also the brain might not be using them, as there is no need. (optical nerve atrophy happens when you have a squint. This means that if the squint is not corrected at a young age the nerve will decay to the point where significant resolution is lost in that eye.) You have to be aware of a skill to really take advantage of it. I work in the VFX industry, which means I can see orthogonal light sources a mile off (two clips shot at different locations could mean that objects are lit from subtly different angles.) Most people don't notice, as its not something they'd ever have to look for in real life. As for colour, I wasn't that great (I have top 10% visual accuracy, or resolution) I took a hue matching test and came out just below average. After 6 years in VFX I'm top 1% Seeing subtle changes in colour require a surprisingly large amount of practice.