async-image-hash

async-image-hash

A wrapper around block-hash to easily hash a local or remote file with Node.

Supports JPG, PNG and WebP

Install

npm i -S image-hash

Use

const { imageHash }= require('image-hash');

// remote file simple
imageHash('https://ichef-1.bbci.co.uk/news/660/cpsprodpb/7F76/production/_95703623_mediaitem95703620.jpg', 16, true, (error, data) => {
  if (error) throw error;
  console.log(data);
  // 0773063f063f36070e070a070f378e7f1f000fff0fff020103f00ffb0f810ff0
});

// remote file with requestjs config object
const config = {
  uri: 'https://ichef-1.bbci.co.uk/news/660/cpsprodpb/7F76/production/_95703623_mediaitem95703620.jpg'
};

imageHash(config, 16, true, (error, data) => {
  if (error) throw error;
  console.log(data);
  // 0773063f063f36070e070a070f378e7f1f000fff0fff020103f00ffb0f810ff0
});

//local file
imageHash('./_95695590_tv039055678.jpg', 16, true, (error, data) => {
  if (error) throw error;
  console.log(data);
  // 0773063f063f36070e070a070f378e7f1f000fff0fff020103f00ffb0f810ff0
});

//Buffer
const fBuffer = fs.readFileSync(__dirname + '/example/_95695591_tv039055678.jpeg');
imageHash({
  ext: 'image/jpeg',
  data: fBuffer
}, 16, true, (error, data) => {
  if(error) throw error;
  console.log(data);
  // 0773063f063f36070e070a070f378e7f1f000fff0fff020103f00ffb0f810ff0
});

//Buffer, without ext arg
const fBuffer = fs.readFileSync(__dirname + '/example/_95695591_tv039055678.jpeg');
imageHash({
  data: fBuffer
}, 16, true, (error, data) => {
  if(error) throw error;
  console.log(data);
  // 0773063f063f36070e070a070f378e7f1f000fff0fff020103f00ffb0f810ff0
});

API

// name
imageHash(location, bits, precise, callback);

// types
imageHash(string|object, int, bool, function);

SETTINGS

Image hash will log out warnings if environment variable VERBOSE is set to true.

Image-Hash Arguments

Argument	Type	Description	Mandatory	Example
location	object or string	A RequestJS Object, Buffer object (See input types below for more details), or String with a valid url or file location	Yes	see above
bits	int	The number of bits in a row. The more bits, the more unique the hash.	Yes	8
precise	bool	Whether a precision algorithm is used. true Precise but slower, non-overlapping blocks. false Quick and crude, non-overlapping blocks. Method 2 is recommended as a good tradeoff between speed and good matches on any image size. The quick ones are only advisable when the image width and height are an even multiple of the number of blocks used.	Yes	true
callback	function	A function with error and data arguments - see below

Location Object Types

// Url Request Object
interface UrlRequestObject {
  encoding?: string | null,
  url: string | null,
};

// Buffer Object
interface BufferObject {
  ext?: string, // mime type of buffered file
  data: Buffer,
  name?: string // file name for buffered file
};

Callback Arguments

Argument	Type	Description
error	Error Object or null	If a run time error is detected this will be an Error Object, otherwise null
data	string or null	If there is no run time error, this be will be your hashed result, otherwise null

Development

I have made this with Typescript, ESLint, Jest, Babel and VSCode. All config files and global binaries are included. For developers using VS Code, make sure you have ESLint extension installed.

Testing

npm test

Credit

The hard bit of this comes with thanks from commonsmachinery for blockhash-js

License

Distributed under an MIT license