Important: This documentation covers Yarn 1 (Classic).
For Yarn 2+ docs and migration guide, see yarnpkg.com.

Package detail

imghash

pwlmaciejewski7.2kMIT0.0.9

Image perceptual hash calculation for node

perceptual, image, hash, phash, imgseek

readme

imghash build npm Libraries.io dependency status for GitHub repo NPM

Promise-based image perceptual hash calculation for node.

Installation

npm install imghash

:information_source: You can find the command-line interface here.

Basic usage

const imghash = require("imghash");

const hash1 = await imghash.hash("./path/to/file");
console.log(hash1);  // "f884c4d8d1193c07"

// Custom hex length and result in binary
const hash2 = await imghash.hash("./path/to/file", 4, "binary");
console.log(hash2);  // "1000100010000010"

Finding similar images

To measure similarity between images you can use Hamming distance or Levenshtein Distance.

The following example uses the latter one:

const imghash = require("imghash");
const leven = require("leven");

const hash1 = await imghash.hash("./img1");
const hash2 = await imghash.hash("./img2");

const distance = leven(hash1, hash2);
console.log(`Distance between images is: ${distance}`);
if (distance <= 12) {
  console.log("Images are similar");
} else {
  console.log("Images are NOT similar");
}

API

.hash(filepath[, bits][, format])

Returns: ES6 Promise, resolved returns hash string in specified format and length (eg. f884c4d8d1193c07)

Parameters:

  • filepath - path to the image (supported formats are png and jpeg) or Buffer
  • bits (optional) - hash length [default: 8]
  • format (optional) - output format [default: hex]
.hashRaw(data, bits)

Returns: hex hash

Parameters:

  • data - image data descriptor in form { width: [width], height: [height], data: [decoded image pixels] }
  • bits - hash length
.hexToBinary(s)

Returns: hex string, eg. f884c4d8d1193c07.

Parameters:

  • s - binary hash string eg. 1000100010000010
.binaryToHex(s)

Returns: hex string, eg. 1000100010000010.

Parameters:

  • s - hex hash string eg. f884c4d8d1193c07

Further reading

imghash takes advantage of block mean value based hashing method: