Merge two pictures in PHP - php

Question

I need to combine two images in PHP. Master picture is in PNG, secondary in JPG.
First picture:
(source: grafikstudio-m.com)
Secondary picture:
(source: grafikstudio-m.com)
Test:
http://happywin.konektor.grafikstudio-m.com/imageMerge/
<?php
$dest = imagecreatefrompng('muster.png');
$src = imagecreatefromjpeg("test.jpg");
imagecolortransparent($src);
imagesavealpha($dest, false);
imagealphablending($src, true);
imagesavealpha($src, true);
imagecopymerge($dest, $src, 0, 0, 0, -100, 2000, 1300, 50);
header('Content-Type: image/png');
imagepng($dest);
imagedestroy($dest);
imagedestroy($src);
I need the pictures to be connected and with a white background

Answer 1

Create a canvas image with same size as muster.png and fill it with white color.
$muster = imagecreatefrompng('muster.png');
$canvas = imagecreatetruecolor(imagesx($muster), imagesy($muster));
$white = imagecolorallocate($canvas, 255, 255, 255);
imagefill($canvas, 0, 0, $white);
Open test.jpg and use the top-left pixel color as the transparent color.
$test = imagecreatefromjpeg('test.jpg');
imagecolortransparent($test, imagecolorallocate($test, 255, 255, 255));
Copy the 2 images to the canvas, the order is optional, notice that copy muster.png (truecolor) with imagecopy but copy test.jpg (pallete) with imagecopymerge.
imagecopy($canvas, $muster, 0, 0, 0, 0, imagesx($muster), imagesy($muster));
imagecopymerge($canvas, $test, 0, 100, 0, 0, imagesx($test), imagesy($test), 100);
header('Content-Type: image/png');
imagepng($canvas);
// ...destroy