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color-delta-e

A Tiny library for measuring the perceived visual difference between two colors

Defining Delta E

ΔE - (Delta E, dE) The measure of change in visual perception of two given colors.

Delta E is a metric for understanding how the human eye perceives color difference. The term delta comes from mathematics, meaning change in a variable or function. The suffix E references the German word Empfindung, which broadly means sensation.

On a typical scale, the Delta E value will range from 0 to 100.

| Delta E | Perception |
| ------- | ---------- |
|<= 1.0 | Not perceptible by human eyes. |
|1 - 2 | Perceptible through close observation. |
| 2 - 10 | Perceptible at a glance. |
| 11 - 49 | Colors are more similar than opposite |
| 100 | Colors are exact opposite |

credit to: http://zschuessler.github.io/DeltaE/learn/

Installation

``bash
npm install color-delta-e

yarn add color-delta-e

pnpm add color-delta-e
`

API




$3

takes two colors and measures the percievable difference between them and returns the deltaE value 0-100

`typescript
import { deltaE } from 'color-delta-e'

const res = deltaE(
[55,117,192],
[14,81,162],
'rgb' // need to pass the type of the values if passing a tuple
)

res // 14.143
`

you can also pass values as strings, values dont have to be the same type

`typescript
import { deltaE } from 'color-delta-e'

const res = deltaE(
'rgb(55,117,192)',
'#0e51a2', // the types will be inferred when using strings!
)

res // 14.143
`


#### Cached Results

deltaE automatically caches results, in order to save calculation of the same colors, if you need to clear this cache in order to remove a potential memory leak there are two options.

#### nocache option
`typescript
import { deltaE } from 'color-delta-e'

const res = deltaE(
[55,117,192],
[14,81,162],
'rgb',
true, //nocache option: when set to tru will not cache the result.
)

`

#### clearCache

`typescript
import { deltaE, clearCache } from 'color-delta-e'

deltaE('#BADA55', '#C0FFEE') //result cached

deltaE('#BADA55', '#C0FFEE') // cached result returned

clearCache()

deltaE('#BADA55', '#C0FFEE') // value recalculated and cached
`

$3

takes two numbers an returns a boolean indicating if the value is above the threshold default: 5


`typescript
import { isPerceivable } from 'color-delta-e'

if(isPerceivable([55,117,192],[14,81,162])){
// do stuff
}
`

$3


takes a color and will return with black or white which ever contrasts best with provided color, the return type will be in same format inputted, so and rgb string will return an rgb string, a hex string will return a hex string.


`typescript
import { contrastText } from 'color-delta-e'

const res = contrastText([0,0,0])

res // '[255,255,255]'

`




$3

takes in base options including base color to compare to, and threshold. rest arguments are a list of fallback colors to go through. selector will return the first color that has a perceptible contrast that meets the threshold provided. If no contrasting values found, will return the last fallback provided.

`typescript
import { selector } from 'color-delta-e'

const res = selector({
compare: [0, 0, 0]
},
[0, 1, 0],
[0, 2, 0],
[200, 30, 10],
[255, 255, 255]
);

res // [200, 30, 10]
`


values dont have to be the same type

`typescript
import { selector } from 'color-delta-e'

const res = selector({
compare: 'hsl(0, 0%, 0%)'
},
'rgb(0, 1, 0)',
'#002200',
[200, 30, 10],
[255, 255, 255]
);

res // [200, 30, 10]
`




$3

takes in an HTMLImageElement will sample the image and return the average(median) color in image.

only works in browser environments.

doesn't support crossOrigin images.

`typescript
import { sampleImage } from 'color-delta-e'

const myImgEl = document.querySelector('img')

const res = sampleImage(myImgEl)

res // [100, 23, 221]
``