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);
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
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.
Type: Buffer|ArrayBuffer|File
Example running in the browser reading a File (ArrayBuffer):
import exifer from 'exifer';
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);
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';
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 }});
Type: object
default: {}
Hash-map with additonal exif tags.
OBS: Find list of exif tags here
Type: object
default: {}
Hash-map with additonal IPTC tags.
OBS: Find list of IPTC tags here
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:
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}`}
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
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