# node-image-hash [![npm version](https://badge.fury.io/js/node-image-hash.png)](https://badge.fury.io/js/node-image-hash)
Perceptual image hash for node.js

## Installation

```
npm install node-image-hash
```

## Basic usage

```javascript
const imageHash = require('node-image-hash');

imageHash
  .hash('buffer/or/path/to/file/', 8, 'hex')
  .then((hash) => {
    console.log(hash.hash); // '83c3d381c38985a5'
    console.log(hash.type); // 'blockhash8'
  });
```

## API

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

Returns: ES6 `Promise`, resolved returns hash string in specified format and length (e.g. `83c3d381c38985a5`)

Parameters:

* `filepath` - path to the image, or `Buffer`
* `bits` (optional) - hash length [default: `64`]
* `format` (optional) - output format [default: `hex`] (Available: `hex`, `latin1`, `base64`, `binary`)


##### `.syncHash(filepath[, bits][, format])`

By default, `.hash` generates new node.js processes to calculate the hash.
.syncHash will calculate the `hash` in the same node.js process (About 2.3x times slower, depending on your CPU)

##### `.close()`
Close all underlying workers. If you use the asynchronous hashing algorithm,
you need to call this at the end of your program to close all currently open
workers. Otherwise, your program may keep running until manually interrupted.