exif

Read and modify EXIF data in Browsers and Node.

• Install
• Example
  • Read EXIF data
  • Remove EXIF data
• Browsers
  • Reading from a File Input
  • Reading from a URL
• Node.js
  • Reading and Writing Files
  • Working with Buffers
• API
  • Tag Constants
  • Helpers
• CLI
  • Show available commands
  • Strip EXIF data
  • Print EXIF summary as JSON
• Modues

Install

npm i -S @substrate-system/exif

Example

Read EXIF data

import { load } from '@substrate-system/exif'
import { getSummary } from '@substrate-system/exif/summary'

const exif = await load(data)  // Uint8Array of image data

const info = getSummary(exif)

// => {
//   make,
//   model,
//   software,
//   artist,
//   copyright,
//   ...
// }

Remove EXIF data

Just remove all the exif data from an image.

import { stripExif } from '@substrate-system/exif/remove'

const stripped = stripExif(jpeg)

Browsers

Import from the browser-specific entry point for utilities like loadFromBlob and loadFromUrl.

import * as exif from '@substrate-system/exif/browser'

// Or use named imports
import {
  loadFromBlob,
  loadFromUrl,
  ImageIFD,
  ExifIFD
} from '@substrate-system/exif/browser'

Reading from a File Input

Read and update EXIF metadata in a browser.

<input type="file" id="file-input" />

import * as exif from '@substrate-system/exif/browser'

const input = document.getElementById('file-input')
input.addEventListener('change', async (ev) => {
  const file = ev.target.files[0]
  
  // Load EXIF data directly from the File object
  const exifData = await exif.loadFromBlob(file)
  console.log('Camera Make:', exifData['0th'][exif.ImageIFD.Make])
  
  // Modify EXIF data
  exifData['0th'][exif.ImageIFD.Make] = "My Custom Camera"
  
  // Create a new Blob with modified EXIF
  const newBlob = await exif.insertIntoBlob(exif.dumpToBlob(exifData), file)
  
  // Create a download link
  const url = URL.createObjectURL(newBlob)
  console.log('Modified image URL:', url)
})

Reading from a URL

import * as exif from '@substrate-system/exif/browser'

async function logExifFromUrl(url) {
  const exifData = await exif.loadFromUrl(url)
  console.log(exifData)
}

Node.js

Import from the node-specific entry point for filesystem and Buffer helpers.

import * as exif from '@substrate-system/exif/node'

// Or use named imports
import {
  modifyFile,
  loadFromFile,
  ExifIFD,
  GPSIFD
} from '@substrate-system/exif/node'

Reading and Writing Files

The modifyFile helper makes it easy to read, update, and save in one go.

import * as exif from '@substrate-system/exif/node'
import * as ExifIFD from '@substrate-system/exif/tags/exif-ifd'
import * as GPSIFD from '@substrate-system/exif/tags/gps-ifd'

const inputPath = './photo.jpg'
const outputPath = './parsed-photo.jpg'

// Read, modify, and save
exif.modifyFile(inputPath, outputPath, (exifData) => {
  // Add a UserComment
  exifData.Exif[ExifIFD.UserComment] = "Edited with @substrate-system/exif"
  
  // Update GPS Altitude (Rational type: [numerator, denominator])
  exifData.GPS[GPSIFD.GPSAltitude] = [100, 1] 
  
  return exifData
})

Working with Buffers

import * as fs from 'node:fs'
import * as exif from '@substrate-system/exif/node'

const buffer = fs.readFileSync('./photo.jpg')

// Load from Buffer
const exifData = exif.loadFromBuffer(buffer)

// Dump to Buffer
const exifBuffer = exif.dumpToBuffer(exifData)

// Insert into original image buffer
const newImageBuffer = exif.insertIntoBuffer(exifBuffer, buffer)

API

Available as named exports from all entry points.

• load(data: Uint8Array): Exif Parse EXIF data from a JPEG binary array.
• dump(exifData: Exif): Uint8Array Convert an EXIF object into a binary array ready for insertion.
• insert(exifBinary: Uint8Array, jpegData: Uint8Array): Uint8Array Insert an EXIF binary block into a JPEG binary array.

Tag Constants

EXIF tag constants are available as named exports:

• ImageIFD - Image (0th IFD) tags
• ExifIFD - Exif sub-IFD tags
• GPSIFD - GPS sub-IFD tags
• InteropIFD - Interoperability tags

Example:

import {
  load,
  ImageIFD,
  GPSIFD
} from '@substrate-system/exif'
import * as ExifIFD from '@substrate-system/exif/tags/exif-ifd'
import * as ImageIFD from '@substrate-system/exif/tags/image-ifd'

const exifData = load(jpegBytes)
const cameraMake = exifData['0th'][ImageIFD.Make]
const userComment = exifData.Exif[ExifIFD.UserComment]
const altitude = exifData.GPS[GPSIFD.GPSAltitude]

Helpers

Browser

@substrate-system/exif/browser

• loadFromBlob(blob: Blob): Promise<Exif>
• loadFromUrl(url: string): Promise<Exif>
• dumpToBlob(exifData: Exif): Blob
• insertIntoBlob(exifBlob: Blob, jpegBlob: Blob): Promise<Blob>
• removeFromBlob(blob: Blob): Promise<Blob> - Strip EXIF from JPEG, PNG, or WebP

Node JS

@substrate-system/exif/node

• loadFromFile(path: string): Exif
• loadFromBuffer(buffer: Buffer): Exif
• dumpToBuffer(exifData: Exif): Buffer
• insertIntoBuffer(exifBuffer: Buffer, jpegBuffer: Buffer): Buffer
• removeFromBuffer(buffer: Buffer): Buffer - Strip EXIF from JPEG, PNG, or WebP
• modifyFile(input: string, output: string, callback: (data: Exif) => Exif): void

GPS Helper

The GPSHelper export provides utilities for GPS coordinate conversion:

import { GPSHelper } from '@substrate-system/exif'

// Convert decimal degrees to DMS rational format for EXIF
const dmsRational = GPSHelper.degToDmsRational(37.7749)
// Returns: [[37, 1], [46, 1], [2964, 100]]

// Convert DMS rational format back to decimal degrees
const decimal = GPSHelper.dmsRationalToDeg([[37, 1], [46, 1], [2964, 100]], 'N')
// Returns: 37.7749

CLI

This exposes a command line interface.

Show available commands

exif --help

Strip EXIF data

exif strip photo.jpg
exif strip photo.jpg -o photo-clean.jpg

Print EXIF summary as JSON

exif print photo.jpg

Modues

This library uses named exports. You can import what you need:

// Named imports
import {
  load,
  dump,
  insert,
  remove,
  ImageIFD,
  ExifIFD,
  GPSIFD
} from '@substrate-system/exif'

// Or import everything as a namespace
import * as exif from '@substrate-system/exif'