terkelg / Exifer

A lightweight exif image meta-data decipher
Exifer is a small module that read JPEG/TIFF meta-data.

Exif tags/fields are used to encode additional information into images taken by digital still cameras. The exif meta information is organized into different Image File Directories (IFD's) within the image. It contains useful information like image rotation, GPS coordinates, times stamps. ISO, etc.

Features

• 📦 Lightweight: Small with zero Dependencies
• 🔍 Extract Exif, GPS, XMP and IPTC
• 📷 Files: Support both JPEG, DNG and TIFF files
• 📚 Add-ons: Extra tags and parsers available
• ♻️ Isomorphic: Works in node.js and the browser

This module exposes three module definitions:

• ES Module: dist/exifer.mjs
• UMD: dist/exifer.umd.js
• CommonJS: dist/exifer.js

Install

$ npm install exifer

The script can also be directly included from unpkg.com:

<script src="https://unpkg.com/exifer"></script>

Usage

import exifer from 'exifer';
import fs from 'fs';

const buffer = fs.readFileSync('photo.jpg');
const tags = await exifer(buffer);
// {
//   Make: 'Apple',
//   Model: 'iPhone X',
//   Orientation: 6,
//   Software: '12.4',
//   ModifyDate: '2019:08:25 15:07:02',
//   ... and so on
// }

OBS: Exifer only reads a few tags by default. You can add your own or use add-on modules to read and parse additional tags.

API

exifer(input, [opts])

Returns: object <Promise>

Takes a JPEG, DNG or JIFF image as input and returns an object with extracted meta-data. A Promise is returned that resolves to an hash-map of tag/value pairs.

Exifer only reads the most essential tags out of the box – which should cover 99% of all use cases.

To read or parse more tags chekcout opts.tags.

input

Type: Buffer|ArrayBuffer|File

Example running in the browser reading a File (ArrayBuffer):

import exifer from 'exifer';

/**
 * Assume 'input' is the value coming from an input field:
 * <input type="file" accept="image/*" id="input" >
 */

const input = document.getElementById('#input').files[0];
const tags = await exifer(input);

Example running in node.js reading a JPEG Buffer:

import exifer from 'exifer';
import fs from 'fs';

const buffer = fs.readFileSync('photo.jpg');
const tags = await exifer(buffer);

It's recomended to only feed Exifer some of the image buffer when dealing with very large files. The first 500kb should be enough in most cases:

import exifer from 'exifer';
import fs from 'fs';

const full = fs.readFileSync('photo.jpg');
const slice = full.buffer.slice(0, 0.5 * 1024 * 1024);
const tags = await exifer(slice);

opts.tags

Type: object

Exifer does not extract more than the most essential tags.

You can extract additional tags, or overwrite the default tags, if you want to read more tags than what's provided by default or wamt custom parsers. You can do this by passing tag objects to either tags.exif, tags.gps and/or tags.iptc.

The key for additional IFD image tags is the IFD field code in hexadecimal notation. The value is a tag object with at least a name property.

Here's an example where Exifer is instructed to read two additional gps tags. They are passed as tag objects to tags.gps:

import exifer from 'exifer';
import fs from 'fs';

// try to read more GPS tags and parse timestamp
const gps = {
  0x0001: {name: 'GPSLatitudeRef'},
  0x0007: {name: 'GPSTimeStamp', parse: x => {
    return new Date(Date.UTC(1970, 0, 1, x[0], x[1], x[2]));
  }}
}

const buffer = fs.readFileSync('photo.jpg');
const parsed = await exifer(buffer, {tags: { gps }});
// {
//    ...
//    GPSLatitudeRef: 'N',
//    GPSTimeStamp: 1970-01-01T19:06:58.000Z
//    ...
// }

opts.tags.exif

Type: object
default: {}

Hash-map with additonal exif tags.

OBS: Find list of exif tags here

opts.tags.iptc

Type: object
default: {}

Hash-map with additonal IPTC tags.

OBS: Find list of IPTC tags here

opts.tags.gps

Type: object
default: {}

Hash-map with additonal GPS tags.

OBS: Find list of exif tags here

Add-ons

If you want to read all tags the following exifer add-on packages have you covered:

• @exifer/exif: Read and parse all Exif tags
• @exifer/gps: Read and parse all GPS tags
• @exifer/iptc: Read and parse all IPTC tags

To read and parse all exif and tiff tags using add-ons, you simply import and pass them to the corresponding tags option:

import exifer from 'exifer';
import iptc from '@exifer/iptc';
import exif from '@exifer/exif';
import fs from 'fs';

const buffer = fs.readFileSync('photo.jpg');
const parsed = await exifer(buffer, {tags: { exif, iptc }});

options.skipexif

Type: boolean
Default: false

Skip exif tags.

options.skipiptc

Type: boolean
Default: false

Skip IPTC tags.

options.skipxmp

Type: boolean
Default: false

Skip XMP tags.

Tag

Type: Object

Exifer only comes with a few built-in tags. None of the default tag objects have parsers associated with them.

Example with a rather useless parser:

{name: 'ModifyDate', raw: false, parse: x => `date is ${x}`}

tag.name

Type: String

Required tag name. This is used as the key in the returned result object from exifer.

OBS: name is the only required porperty.

tag.raw

Type: Boolean
Default: false

By default all tags are interpreted as ASCII strings. Set raw to true to get the raw tag value.

tag.parse

Type: Function

Custom parser function. Use this to transform tag values. Input is a ASCII string unless raw is true.

The returned output is used in the final result object returned by exifer.

Credit

Inspired by exif-orientation and ExifReader.

License

MIT © Terkel Gjervig