Function to save base64 image to png with PHP

canvas-upload.php

<?php
	// requires php5
	define('UPLOAD_DIR', 'images/');
	$img = $_POST['img'];
	$img = str_replace('data:image/png;base64,', '', $img);
	$img = str_replace(' ', '+', $img);
	$data = base64_decode($img);
	$file = UPLOAD_DIR . uniqid() . '.png';
	$success = file_put_contents($file, $data);
	print $success ? $file : 'Unable to save the file.';
?>

Genial, me funcionó

`

$data = $_POST["image"];	

$rand = uniqid();

$img = $_POST['image'];
$img = str_replace('data:image/png;base64,', '', $img);
$img = str_replace(' ', '+', $img);
$data = base64_decode($img);

$file = "../firmas/" .  $rand . '.png';

$movefile = file_put_contents($file, $data);


$response = array(
	'movefile' => $movefile, 
	'rand' => $rand,
	'file' => $file
);

echo json_encode($response);

`

Thanks @fazlurr , it worked perfectly for me.