Generate and then save an image

I just wrote this code to generate an image

<?php

$canvas =开发者_开发百科 imagecreatetruecolor(800, 350);

$pink = imagecolorallocate($canvas, 255, 105, 180);
$white = imagecolorallocate($canvas, 255, 255, 255);
$green = imagecolorallocate($canvas, 132, 135, 28);

imagefill($canvas, 0, 0, $white); // BACKGROUND

function drawlinebox($x1, $y1, $x2, $y2, $height, $color){
    global $canvas;
    imagesetthickness ( $canvas, 1 );
    for ($i=1; $i < $height; $i++){
        imageline( $canvas, $x1, $y1, $x2, $y2, $color );
        $y1++; $y2++;
    }
}

drawlinebox(20, 20, 780, 300, 30, $green);

drawlinebox(20, 300, 780, 20, 30, $pink);

// Output and free from memory
header('Content-Type: image/png');

imagepng($canvas, NULL, 9);

imagedestroy($canvas);

?>

but I also want this image to saved automatically on the server. Think of it as a cron job. Which creates images, then saves the image on the sever for later use and inserts the saved image location in the DB.

As stated in the manual, imagepng()'s second parameter is $filename which allows you to store the result in a file.