Cone density, out from the centre of gaze
Drawn at its defaults, in where in the eye, and which eye. It takes no options at all, so every essay calling it gets this exact drawing.
Called by 2 essays
the blast radius of changing it
Colour stops at the edge of sight
Cone density falls twenty-one-fold between the centre of gaze and ten degrees out, and the three channels give out at three different rates — so a colour difference in the periphery does not merely shrink, it turns. At the exact point of fixation there are no short-wavelength cones at all.
Difference and uniformityA difference has no place
A colour difference formula answers a question about two patches somebody is looking straight at. Move the same pair ten degrees into the periphery and a third of it is left — and it has turned twenty-four degrees of hue, because the three channels give out at three different rates.