How to Convert PNG to JPG with compression in PHP?

pngtojpg.php

<?php

$filePath = dirname(__FILE__).'/hq.png';

$image = imagecreatefrompng($filePath);
$bg = imagecreatetruecolor(imagesx($image), imagesy($image));
imagefill($bg, 0, 0, imagecolorallocate($bg, 255, 255, 255));
imagealphablending($bg, TRUE);
imagecopy($bg, $image, 0, 0, 0, 0, imagesx($image), imagesy($image));
imagedestroy($image);
$quality = 50; // 0 = low / smaller file, 100 = better / bigger file 
imagejpeg($bg, $filePath . ".jpg", $quality);
imagedestroy($bg);