Colour Science & Perception
what the eye settles, and what it cannot
Generator

One colour difference, at four places in the visual field

The same pair of colours — ΔE00 21.3 at the fovea — with each of its three components divided by that channel's own threshold scaling at the stated eccentricity. What is left at 20° is 4.1, and its hue has turned by 26 degrees, because the red–green part is divided by more than the blue–yellow part. The swatches are the *predicted* colours, drawn where a reader will look straight at them; the figure states a prediction it cannot stage.
One colour difference, at four places in the visual fieldThe same pair of colours — ΔE00 21.3 at the fovea — with each of its three components divided by that channel's own threshold scaling at the stated eccentricity. What is left at 20° is 4.1, and its hue has turned by 26 degrees, because the red–green part is divided by more than the blue–yellow part. The swatches are the *predicted* colours, drawn where a reader will look straight at them; the figure states a prediction it cannot stage.0°ΔE00 21.3100% left5°ΔE00 9.947% left10°ΔE00 6.731% left20°ΔE00 4.119% lefthue turns by 26° between the centre and 20°E2 1.2/2.5/4°CIE 1931 2° observer

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 3 essays

the blast radius of changing it

What the eye does

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 uniformity

A 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.

 Where the model breaks

Nobody here has two eyes

One person's two eyes differ in macular pigment and lens density, so the same light produces two colours — a whole ΔE00 apart for an ordinary pair, seven for one replaced lens. Adaptation hides it exactly, which is why nobody notices and why nothing in colorimetry has a term for it.

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