[zdimension]

About 90 millions rods vs 6 millions cones. Sometimes I'm surprised we can even see detail at all. Though it certainly helps that they're not uniformly distributed; most cones are in the macula, around the middle of the back of the eye. Still, it's not a lot.

[woleium]

And within the macula, the red and green are generally towards the centre and the blue are generally towards the edge. This helps prevent the red shift problem photographs with high contrast changes sometimes get.

[valleyer]

This is the basis of chroma subsampling (like the common 4:2:0, 2 chroma samples for every 8 luma samples) in encoded video.