node-vibrant
Extract prominent colors from an image.
** NOTICE **
This project is refactored into a monorepo in version 3.2.0 (see develop branch, npm version node-vibrant@3.2.0-alpha).
We will not merge new PRs to v3.1 related to new featuresets during this time. However, bug fixes and security vulnerability fixes are still highly encouraged.
New WebWorker support in v3.0
Quantization is the most time-consuming stage in node-vibrant. In v3.0, the quantization can be run in the WebWorker to avoid freezing the UI thread.
Here's how to use this feature:
- Use WebWorker build
dist/vibrant.worker.jsordist/vibrant.worker.min.js. Or if you are re-bundling with webpack, uselib/bundle.worker.jsas entry - Use WebWorker quantizer:
let v = Vibrant.from(src) .useQuantizer(Vibrant.Quantizer.WebWorker) // Other configurations
Features
- Identical API for both node.js and browser environment
- Support browserify/webpack
- Consistent results (*See Result Consistency)
Install
$ npm install node-vibrantUsage
node.js / browserify
// ES5
var Vibrant = require('node-vibrant')
// ES6
import * as Vibrant from 'node-vibrant'
// TypeScript
import Vibrant = require('node-vibrant')
// Using builder
Vibrant.from('path/to/image').getPalette((err, palette) => console.log(palette))
// Promise
Vibrant.from('path/to/image').getPalette()
.then((palette) => console.log(palette))
// Using constructor
let v = new Vibrant('path/to/image', opts)
v.getPalette((err, palette) => console.log(palette))
// Promise
v.getPalette().then((palette) => console.log(palette))Browser
If you installed node-vibrant with npm, compiled bundles are available under node_modules/node-vibrant/dist.
Or you can download bundles from Relases.
<!-- Debug version -->
<script src="/path/to/dist/vibrant.js"></script>
<!-- Uglified version -->
<script src="/path/to/dist/vibrant.min.js"></script>
<script>
// Use `Vibrant` in script
// Vibrant is exported to global. window.Vibrant === Vibrant
Vibrant.from('path/to/image').getPalette(function(err, palette) {});
// Promise
Vibrant.from('path/to/image').getPalette().then(function(palette) {});
// Or
var v = new Vibrant('/path/to/image', opts);
// ... same as in node.js
</script>Contribution Guidelines
- Make changes
- Write test specs if necessary
- Pass tests
- Commit source files only (without compiled files)
References
Vibrant
Main class of node-vibrant.
Vibrant.from(src: ImageSource): Builder
Make a Builder for an image. Returns a Builder instance.
constructor(src: ImageSource, opts: Partial<Options>)
| Name | Description |
|---|---|
image |
Path to image file (support HTTP/HTTPs) |
opts |
Options (optional) |
ImageSource
export type ImageSource = string
| HTMLImageElement // Browser only
| Buffer // Node.js onlyOptions
export interface Options {
colorCount: number
quality: number
maxDimension: number
filters: Array<Filter>
ImageClass: ImageClass
quantizer: Quantizer
generator?: Generator
}| Field | Default | Description |
|---|---|---|
colorCount |
64 | amount of colors in initial palette from which the swatches will be generated |
quality |
5 | Scale down factor used in downsampling stage. 1 means no downsampling. If maxDimension is set, this value will not be used. |
maxDimension |
undefined |
The max size of the image's longer side used in downsampling stage. This field will override quality. |
filters |
[] |
An array of filters |
ImageClass |
Image.Node or Image.Browser |
An Image implementation class |
quantizer |
Vibrant.Quantizer.MMCQ |
A Quantizer implementation class |
generator |
Vibrant.Generator.Default |
An Generator instance |
Resolvable<T>
export type Resolvable<T> = T | Promise<T>Quantizer
export interface Quantizer {
(pixels: Pixels, opts: Options): Resolvable<Array<Swatch>>
}Generator
export interface Generator {
(swatches: Array<Swatch>, opts?: Object): Resolvable<Palette>
}Filter
Returns true if the color is to be kept.
export interface Filter {
(red: number, green: number, blue: number, alpha: number): boolean
}getPalette(cb?: Callback<Palette>): Promise<Palette>
| Name | Description |
|---|---|
cb |
(Optional) callback function. Can be omitted when using Promise. |
Callback<T>
export interface Callback<T> {
(err?: Error, result?: T): void
}getSwatches(cb?: Callback<Palette>): Promise<Palette>
Alias of getPalette.
Vibrant.Builder
Helper class for change configurations and create a Vibrant instance. Methods of a Builder instance can be chained like:
Vibrant.from(src)
.quality(1)
.clearFilters()
// ...
.getPalette()
.then((palette) => {})constructor(src: ImageSource, opts: Partial<Options>)
Arguments are the same as Vibrant.constructor.
quality(q: number): Builder
Sets opts.quality to q. Returns this Builder instance.
maxColorCount(n: number): Builder
Sets opts.colorCount to n. Returns this Builder instance.
maxDimension(d: number): Builder
Sets opts.maxDimension to d. Returns this Builder instance.
addFilter(f: Filter): Builder
Adds a filter function. Returns this Builder instance.
removeFilter(f: Filter): Builder
Removes a filter function. Returns this Builder instance.
clearFilters(): Builder
Clear all filters. Returns this Builder instance.
useImageClass(imageClass: ImageClass): Builder
Specifies which Image implementation class to use. Returns this Builder instance.
useQuantizer(quantizer: Quantizer): Builder
Specifies which Quantizer implementation class to use. Returns this Builder instance.
useGenerator(generator: Generator): Builder
Sets opts.generator to generator. Returns this Builder instance.
build(): Vibrant
Builds and returns a Vibrant instance as configured.
getPalette(cb?: Callback<Palette>): Promise<Palette>
Builds a Vibrant instance as configured and calls its getPalette method.
getSwatches(cb? Callback<Palette>): Promise<Palette>
Alias of getPalette.
Vibrant.Swatch
Represents a color swatch generated from an image's palette.
Vec3
export interface Vec3 extends Array<number> {
0: number,
1: number,
2: number
}constructor(rgb: Vec3, population: number)
Internal use.
| Name | Description |
|---|---|
rgb |
[r, g, b] |
population |
Population of the color in an image |
getHsl(): Vec3
getPopulation(): number
getRgb(): Vec3
getHex(): string
getTitleTextColor(): string
Returns an appropriate color to use for any 'title' text which is displayed over this Swatch's color.
getBodyTextColor(): string
Returns an appropriate color to use for any 'body' text which is displayed over this Swatch's color.
Vibrant.Util
Utility methods. Internal usage.
hexToRgb(hex: string): Vec3
rgbToHex(r: number, g: number, b: number): string
hslToRgb(h: number, s: number, l: number): Vec3
rgbToHsl(r: number, g: number, b: number): Vec3
xyzToRgb(x: number, y: number, z: number): Vec3
rgbToXyz(r: number, g: number, b: number): Vec3
xyzToCIELab(x: number, y: number, z: number): Vec3
rgbToCIELab(l: number, a: number, b: number): Vec3
deltaE94(lab1: number, lab2: number): number
Computes CIE delta E 1994 diff between lab1 and lab2. The 2 colors are in CIE-Lab color space. Used in tests to compare 2 colors' perceptual similarity.
rgbDiff(rgb1: Vec3, rgb2: Vec3): number
Compute CIE delta E 1994 diff between rgb1 and rgb2.
hexDiff(hex1: string, hex2: string): number
Compute CIE delta E 1994 diff between hex1 and hex2.
getColorDiffStatus(d: number): string
Gets a string to describe the meaning of the color diff. Used in tests.
| Delta E | Perception | Returns |
|---|---|---|
| <= 1.0 | Not perceptible by human eyes. | "Perfect" |
| 1 - 2 | Perceptible through close observation. | "Close" |
| 2 - 10 | Perceptible at a glance. | "Good" |
| 11 - 49 | Colors are more similar than opposite | "Similar" |
| 50 - 100 | Colors are exact opposite | Wrong |
NPM Tasks
| Task | Description |
|---|---|
build:browser |
Build browser target |
build:node |
Build node.js target |
build |
Build all targets |
clean:browser |
Clean browser build |
clean:node |
Clean node.js build |
clean |
Clean all builds |
test:browser |
Run browser specs (karma) |
test:node |
Run node.js specs (mocha) |
test |
Run all specs |
Notes
Intentional Deviation From vibrant.js
node-vibranttakes image path, not the image object as parameter for the obvious reason that node.js environment has no access to HTML DOM object.node-vibrantprovides asynchronous API since most node.js image processing library is asynchronous. And the originalvibrant.jsworkflow is asynchronous any way (though you will have to handle the image loading yourself, whilenode-vibrantdoes it for you).node-vibrantuses one singleoptsobject to hold all options for future expansions. And it feels more node.js-like.node-vibrantuses method call to initiate image processing instead of constructor so that developers can use it withPromise.
Result Consistency
The results is consistent within each user's browser instance regardelss of visible region or display size of the image, unlike the original vibrant.js implementation.
However, due to the very nature of HTML5 canvas element, image rendering is platform/machine-dependent. Thus the resulting swatches in browser environment varies and may not be the same as in node.js nor in another machine. See Canvas Fingerprinting.
The test specs use CIE delta E 1994 color difference to measure inconsistencies across platforms. It compares the generated color on node.js, Chrome, Firefox and IE11. At quality == 1 (no downsampling) and no filters, the results are rather consistent. Color diffs between browsers are mostly not perceptible by human eyes. Downsampling will cause perceptible inconsistent results across browsers due to differences in canvas implementations.