This package makes it possible to read out simple or verbose meta information from image files.
It can be used in browser and Node.js environment.
Once installed, three classes become available for use, JPGMetadata, PNGMetadata, GIFMetadata. These are for reading out metadata from JPG, PNG and GIF files respectively. These classes take a String in ISO-8859-1 encoding or a data URI as an input. If the input is a data URI, it has to be specified.
Decompile a String in ISO-8859-1 encoding:
let jmd = new JPGMetadata('file-as-string....');Or decompile a data URI:
let jmd = new JPGMetadata('data:image/jpeg;base64,...', 'dataURI');Print meta information in console:
console.log( jmd.getMetadata() );E.g. this will print out the following information:
{ image_width: 1022,
image_height: 654,
colorspace: 'YCbCr',
colordepth: 24,
quality: 94,
comments:
[ { name: 'APP0', index: 0, size: 14 },
{ name: 'APP1', index: 0, size: 110 },
{ name: 'APP2', index: 0, size: 3158 } ],
filesize: 272195,
data_size: 268304,
raw_data_size: 2005164,
compression: 86.62 }Other methods are:
-
getStructure(type = 'minimal'): Returns information about the file structure by putting all chunks and sizes in an array.typecan beminimalorverbose. -
getChunks(): Returns an object where all chunks and information from the file are collected.
This function reads out an URL to a JPG file as text via XMLHttpRequest and uses that information to print out the structure, chunks and meta information of the file.
{
let xhr = new XMLHttpRequest();
xhr.open('GET', 'https://your-website.com/your-image.jpg', true);
// Response is a plain text with ISO-8859-1 encoding
xhr.responseType = 'text';
xhr.overrideMimeType('text/plain; charset=ISO-8859-1');
xhr.onload = function (e) {
let jmd = new JPGMetadata(this.response);
console.log(jmd.getStructure());
console.log(jmd.getChunks());
console.log(jmd.getMetadata());
};
xhr.send();
}Reminder, that CORS must be enabled on the server the file is read from.
This library can be installed directly in an HTML document or in a Node.js package.
Create a script tag in the document <head>, where you include the JS file from the dist folder.
<script src="/image_metadata.js" type="text/javascript"></script>The minified version image_metadata.min.js can be used, if desired.
Install this library to your package.
npm install git+https://github.com/smcgit/Image-Metadata.git --save
Include the classes from the image-metadata package in your code.
const JPGMetadata = require('image-metadata').JPGMetadata;
const PNGMetadata = require('image-metadata').PNGMetadata;
const GIFMetadata = require('image-metadata').GIFMetadata;This package might only work for common files. There are some special cases, where the script might break.
Thanks to the JavaScript community!