https://github.com/tj/palette
Node.js image color palette extraction with node-canvas
https://github.com/tj/palette
Last synced: 9 months ago
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Node.js image color palette extraction with node-canvas
- Host: GitHub
- URL: https://github.com/tj/palette
- Owner: tj
- Created: 2011-12-18T14:07:09.000Z (about 14 years ago)
- Default Branch: master
- Last Pushed: 2016-09-24T20:28:34.000Z (over 9 years ago)
- Last Synced: 2025-04-13T11:09:36.852Z (9 months ago)
- Language: JavaScript
- Homepage:
- Size: 196 KB
- Stars: 291
- Watchers: 7
- Forks: 24
- Open Issues: 6
-
Metadata Files:
- Readme: Readme.md
- Changelog: History.md
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README
# Palette
Image color palette extraction with node-canvas for [node.js](http://nodejs.org)
## Installation
```
$ npm install palette
```
*Note:* Palette's dependency, [node-canvas](https://github.com/Automattic/node-canvas), requires that Cairo be installed. Please see the [installation guide](https://github.com/Automattic/node-canvas#installation) for node-canvas for further details.
## API
Palette's public API consists of a single function, the one returned by `require()`. This function accepts the `canvas` you wish to compute a color palette for, and an optional number of samples defaulting to `5`.
The following example is taken from the `./test` script, showing you how you may re-draw the palette onto the original canvas, however it is of course possible to save these values in a database etc.
```js
var colors = palette(canvas, 10);
colors.forEach(function(color){
var r = color[0]
, g = color[1]
, b = color[2]
, val = r << 16 | g << 8 | b
, str = '#' + val.toString(16);
ctx.fillStyle = str;
ctx.fillRect(x += 31, canvas.height - 40, 30, 30);
});
```
## Running the examples
```
$ ./test examples/cat.jpg && open /tmp/out.png
```
## Full example
This is the contents of `./test`. The means of loading the image data and drawing it to the Canvas is up to you, they could be from a database, the file system, fetched from the web, however here we simply use `img.src = path`.
```js
#!/usr/bin/env node
var palette = require('./')
, fs = require('fs')
, Canvas = require('canvas')
, Image = Canvas.Image
, canvas = new Canvas
, ctx = canvas.getContext('2d')
, path = process.argv[2]
, out = '/tmp/out.png';
if (!path) {
console.error('Usage: test ');
process.exit(1);
}
var img = new Image;
img.onload = function(){
canvas.width = img.width;
canvas.height = img.height + 50;
ctx.fillStyle = 'white';
ctx.fillRect(0, 0, canvas.width, canvas.height);
ctx.drawImage(img, 0, 0);
paintPalette();
save();
};
img.src = path;
function paintPalette() {
var x = 0;
var colors = palette(canvas);
colors.forEach(function(color){
var r = color[0]
, g = color[1]
, b = color[2]
, val = r << 16 | g << 8 | b
, str = '#' + val.toString(16);
ctx.fillStyle = str;
ctx.fillRect(x += 31, canvas.height - 40, 30, 30);
});
}
function save() {
fs.writeFile(out, canvas.toBuffer(), function(err){
if (err) throw err;
console.log('saved %s', out);
});
}
```
## Booyah
## License
(The MIT License)
Copyright (c) 2011 TJ Holowaychuk <tj@vision-media.ca>
Permission is hereby granted, free of charge, to any person obtaining
a copy of this software and associated documentation files (the
'Software'), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so, subject to
the following conditions:
The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.