├── test ├── lena_gray_256.png └── index.js ├── index.js ├── README.md ├── package.json ├── LICENSE └── .gitignore /test/lena_gray_256.png: -------------------------------------------------------------------------------- https://raw.githubusercontent.com/Abdelaziz18003/ndarray-entropy/master/test/lena_gray_256.png -------------------------------------------------------------------------------- /test/index.js: -------------------------------------------------------------------------------- 1 | const test = require('tape'); 2 | const ndarray = require('ndarray'); 3 | const entropy = require('../index'); 4 | 5 | const ndarray1 = ndarray([1, 2, 3, 4]); 6 | 7 | test('Basic tests', (t) => { 8 | t.equal(typeof entropy(ndarray1), 'number', 'entropy should return a number'); 9 | t.equal(entropy(ndarray1), 2, 'entropy of [1, 2, 3, 4] should equal 2'); 10 | t.end(); 11 | }); 12 | -------------------------------------------------------------------------------- /index.js: -------------------------------------------------------------------------------- 1 | 'use strict'; 2 | 3 | const imhist = require('ndarray-imhist'); 4 | 5 | const defaultOptions = { 6 | channel: 0 7 | } 8 | 9 | function entropy (ndarray, options) { 10 | options = Object.assign({}, defaultOptions, options); 11 | let [, y] = imhist(ndarray, {...options, plot: false}); 12 | 13 | let ySum = sum(y); 14 | let s = 0; 15 | for (let i = 0; i < y.length; i++) { 16 | y[i] = y[i] / ySum; 17 | 18 | if (y[i] === 0) { 19 | continue; 20 | } 21 | 22 | s += y[i] * Math.log2(y[i]); 23 | } 24 | return -s; 25 | } 26 | 27 | function sum (array) { 28 | return array.reduce((a, b) => { 29 | return a + b; 30 | }) 31 | } 32 | 33 | module.exports = entropy; 34 | -------------------------------------------------------------------------------- /README.md: -------------------------------------------------------------------------------- 1 | # ndarray-entropy 2 | 3 | Calculate the entropy of an intensity image, inspired by Matlab "entropy" function. 4 | 5 | ## Usage 6 | 7 | ### Syntax 8 | 9 | ```js 10 | entropy(img [,options]); 11 | ``` 12 | 13 | ### Options 14 | 15 | Option | required | default | description 16 | ------- | -------- | ------- | ----------- 17 | channel | no | 0 | Select the RGB channel to calculate the entropy for. `0` for the red channel, `1` for the green and `2` for the blue one. If `img` is a 2D array, this option has no effect. 18 | 19 | ## Example 20 | 21 | ```js 22 | const getPixels = require('get-pixels'); 23 | const entropy = require('ndarray-entropy'); 24 | 25 | getPixels('nature.png', (err, img) => { 26 | if (!err && img) { 27 | console.log(entropy(img)); 28 | // > 7.140717410116984 29 | } 30 | }) 31 | ``` 32 | -------------------------------------------------------------------------------- /package.json: -------------------------------------------------------------------------------- 1 | { 2 | "name": "ndarray-entropy", 3 | "version": "0.5.0", 4 | "description": "Calculate the entropy of an intensity image, inspired by Matlab \"entropy\" function.", 5 | "main": "index.js", 6 | "dependencies": { 7 | "ndarray-imhist": "^0.5.0" 8 | }, 9 | "devDependencies": { 10 | "get-pixels": "^3.3.2", 11 | "ndarray": "^1.0.18", 12 | "tap-spec": "^5.0.0", 13 | "tape": "^4.11.0" 14 | }, 15 | "scripts": { 16 | "test": "node test/index.js | tap-spec" 17 | }, 18 | "repository": { 19 | "type": "git", 20 | "url": "git+https://github.com/Abdelaziz18003/ndarray-entropy.git" 21 | }, 22 | "keywords": [], 23 | "author": "Abdelaziz Mokhnache", 24 | "license": "MIT", 25 | "bugs": { 26 | "url": "https://github.com/Abdelaziz18003/ndarray-entropy/issues" 27 | }, 28 | "homepage": "https://github.com/Abdelaziz18003/ndarray-entropy#readme" 29 | } 30 | -------------------------------------------------------------------------------- /LICENSE: -------------------------------------------------------------------------------- 1 | MIT License 2 | 3 | Copyright (c) 2019 Abdelaziz Mokhnache 4 | 5 | Permission is hereby granted, free of charge, to any person obtaining a copy 6 | of this software and associated documentation files (the "Software"), to deal 7 | in the Software without restriction, including without limitation the rights 8 | to use, copy, modify, merge, publish, distribute, sublicense, and/or sell 9 | copies of the Software, and to permit persons to whom the Software is 10 | furnished to do so, subject to the following conditions: 11 | 12 | The above copyright notice and this permission notice shall be included in all 13 | copies or substantial portions of the Software. 14 | 15 | THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 16 | IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 17 | FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 18 | AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 19 | LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 20 | OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE 21 | SOFTWARE. 22 | -------------------------------------------------------------------------------- /.gitignore: -------------------------------------------------------------------------------- 1 | # Logs 2 | logs 3 | *.log 4 | npm-debug.log* 5 | yarn-debug.log* 6 | yarn-error.log* 7 | 8 | # Runtime data 9 | pids 10 | *.pid 11 | *.seed 12 | *.pid.lock 13 | 14 | # Directory for instrumented libs generated by jscoverage/JSCover 15 | lib-cov 16 | 17 | # Coverage directory used by tools like istanbul 18 | coverage 19 | 20 | # nyc test coverage 21 | .nyc_output 22 | 23 | # Grunt intermediate storage (http://gruntjs.com/creating-plugins#storing-task-files) 24 | .grunt 25 | 26 | # Bower dependency directory (https://bower.io/) 27 | bower_components 28 | 29 | # node-waf configuration 30 | .lock-wscript 31 | 32 | # Compiled binary addons (https://nodejs.org/api/addons.html) 33 | build/Release 34 | 35 | # Dependency directories 36 | node_modules/ 37 | jspm_packages/ 38 | 39 | # TypeScript v1 declaration files 40 | typings/ 41 | 42 | # Optional npm cache directory 43 | .npm 44 | 45 | # Optional eslint cache 46 | .eslintcache 47 | 48 | # Optional REPL history 49 | .node_repl_history 50 | 51 | # Output of 'npm pack' 52 | *.tgz 53 | 54 | # Yarn Integrity file 55 | .yarn-integrity 56 | 57 | # dotenv environment variables file 58 | .env 59 | 60 | # next.js build output 61 | .next 62 | --------------------------------------------------------------------------------