How to save progressive JPEG with GD Library?

PHP imageinterlace() funtion turns the interlace bit on or off.

If the interlace bit is set and the image is used as a JPEG image, the image is created as a progressive JPEG.

<?php

// Create an image instance

$im = imagecreatefromjpeg('test.jpg');

// Enable interlancing

imageinterlace($im, true);

// Save the interlaced image

imagegif($im, './progressive.jpg');

imagedestroy($im);

?>