Digital BW, The Print

Bob Frost writes:

> One further point on this is that we use our B&W vision - from the rods -
> for determining detail, edges, movement, etc., and our color vision - from
> the cones - merely adds color to the details provided by the B&W vision.

All of the precise vision is provided by the cones.  Rods are largely
absence from the fovea, and they bloom readily in bright light.  People
who have only rods, for example (achromatopsia--true black-and-white
color blindness), are normally legally blind, because the vision
provided by rods is almost unusable except for very gross perception.

For fine detail and color, the cones are used.