Understanding color difference in LAB vs sRGB using "@thi.ng/color"

color-difference.js

import { distCIEDE2000 } from "@thi.ng/color";
import distance from 'euclidean-distance';

const difference = (color1, color2) => {
  return distCIEDE2000()(
    '#' + (color1.red).toString(16) + (color1.green).toString(16) + (color1.blue).toString(16),
    '#' + (color2.red).toString(16) + (color2.green).toString(16) + (color2.blue).toString(16),
  )
}

console.log('lab difference')
console.log('black to white', distCIEDE2000()(
  '#000000',
  '#ffffff',
))

console.log('two blue hex', distCIEDE2000()(
  '#4287f5',
  '#429bf5',
))

console.log('two blue rgb', difference({
  red: 66,
  green: 135,
  blue: 245,
}, {
  red: 66,
  green: 155,
  blue: 245,
}))

console.log('rgb difference')
console.log('black to white', distance([0,0,0], [255,255,255])/4.41672956)
console.log('two blues', distance([66,135,245], [66,155,245])/4.41672956)

console.log('rgba difference')
console.log('black to white', distance([0,0,0,255], [255,255,255,255])/4.41672956)
console.log('two blues', distance([66,135,245,255], [66,155,245,125])/4.41672956)

output.sh

▶ node test.js
lab difference
black to white 99.99999999999999
two blue hex 6.9116634623669375
two blue rgb 6.9116634623669375
rgb difference
black to white 99.99999998416558
two blues 4.52823740469181
rgba difference
black to white 99.99999998416558
two blues 29.779832021152558