把base64l讓PHP存成實體檔案

$data = 'data:image/png;base64,AAAFBfj42Pj4';

list($type, $data) = explode(';', $data);
list(, $data)      = explode(',', $data);
$data = base64_decode($data);

file_put_contents('/tmp/image.png', $data);

資料來源
http://stackoverflow.com/questions/18230573/dataurl-to-image-for-download-in-php