Create a png alpha image from base 64 data - Stackoverflow snippet (http://stackoverflow.com/questions/9771986/fabric-js-canvas-todataurl-sent-to-php-by-ajax)

createPNGAlphaImageFromBase64.php

<?php
$urlUploadImages = '../uploads/img/';
$nameImage = $_POST['nameImage'];
$data = base64_decode($_POST['strBase64']);
$img = imagecreatefromstring($data);
$width = imagesx($img);
$height = imagesy($img);
$image = imagecreatetruecolor($width, $height);
imagealphablending($image, true);
$alpha_image = imagecolorallocatealpha($image, 0, 0, 0, 127); 
imagefill($image, 0, 0, $alpha_image); 
imagecopyresampled($image, $img, 0, 0, 0, 0, $width, $height, $width, $height); 
imagealphablending($image, false); 
imagesavealpha($image, true);
header('Content-type: image/png'); 
imagepng($image, $urlUploadImage.$nameImage, 0);
imagedestroy($img);
?>