pdqhash-node

A minimal Node.js wrapper around the Cargo crate pdqhash, which is a pure Rust implementation of Meta's PDQ algorithm.

Prerequisites

• Rust programming language

Install

yarn add pdqhash-node

Usage

import { readFileSync } from 'fs';
import { pdqhash, pdqhashBuffer } from 'pdqhash-node';

const buf = readFileSync('image.jpg');
var hashHex = pdqhash(buf); // string | null
// or
var hashBuf = pdqhashBuffer(buf); // Buffer | null
console.log(hashHex);

API

• pdqhash(input: Buffer): string | null
  • Hex string PDQ hash. Returns null if hashing fails.
• pdqhashBuffer(input: Buffer): Buffer | null
  • Raw PDQ hash bytes as a Buffer. Returns null if hashing fails.
• pdqhashWithQuality(input: Buffer): { hash: string; quality: number } | null
  • Hex string PDQ hash plus the quality score. Returns null if hashing fails.
• hammingDistance(a: Buffer, b: Buffer): number
  • Computes Hamming distance between two PDQ hash Buffers.

Examples

Compute hash in hex and Buffer:

import { readFileSync } from 'fs';
import { pdqhash, pdqhashBuffer } from 'pdqhash-node';

const buf = readFileSync('image.jpg');
console.log(pdqhash(buf)); // hex string
console.log(pdqhashBuffer(buf)?.toString('hex')); // same hash from Buffer

Get hash with quality:

import { readFileSync } from 'fs';
import { pdqhashWithQuality } from 'pdqhash-node';

const buf = readFileSync('image.jpg');
const result = pdqhashWithQuality(buf);
if (result) {
	console.log(result.hash, result.quality);
}

Compute Hamming distance:

import { readFileSync } from 'fs';
import { pdqhashBuffer, hammingDistance } from 'pdqhash-node';

const a = pdqhashBuffer(readFileSync('image1.jpg'));
const b = pdqhashBuffer(readFileSync('image2.jpg'));
if (a && b) {
	console.log(hammingDistance(a, b));
}