AJPEG (Alpha-JPEG)

PNG File size can be a hassle. This library provides transparency support to JPEG images allowing you to get lightweight images and speed up your page load.

AJPEG GULP encoder allows you to split PNG file into 2 separate files :

• a JPEG file without transparency that you can compress
• a PNG file containing the alpha channel only

The decoder loads the 2 files and fast restore the alpha channel using native html canvas composite operation.

Demo

https://mbossan.github.io/AJPEG/

Install

$ npm install --save-dev ajpeg

Graphics Magick

Make sure GraphicsMagick is installed on your system and properly set up in your PATH.

• Mac OS X (using Homebrew):

brew install graphicsmagick

• Ubuntu:

apt-get install graphicsmagick

Encoding

const gulp = require('gulp'),
    ajpeg = require('ajpeg');

gulp.task('default', function () {
    return gulp.src("src/*.png")
        .pipe(ajpeg(60))
        .pipe(gulp.dest('dist/'));
});

API

ajpeg([quality])

Type: number Default: 60

JPEG compression from 1 to 100

Decoding

Setup

Include the library

<script src="decoder/dist/ajpeg.min.js" type="application/javascript"></script>

OR

const AJPEG = require('decoder/dist/ajpeg.min');

Usage

Load into a Canvas

new AJPEG().load("assets/rp1_00000.jpg", function () {
    document.body.appendChild(this.toCanvas());
});

Load into an Image

new AJPEG().load("assets/rp1_00000.jpg", function () {
    var newImg = document.createElement('img');
    newImg.src = this.toDataURL();
    document.body.appendChild(newImg);
});

Autoload via html attribute parsing

<img alpha-src="assets/rp1_00000.jpg"/>
<script>
AJPEG.parse();
</script>

License

MIT ©