About preserving the transparency when resizing PNGs this was the only thing that worked for me:
<?php imagealphablending($new_watermark, false);
$color = imagecolortransparent($new_watermark, imagecolorallocatealpha($new_watermark, 0, 0, 0, 127));
imagefill($new_watermark, 0, 0, $color);
imagesavealpha($new_watermark, true);
imagecopyresampled($new_watermark, $watermark, 0, 0, 0, 0, $new_watermark_width, $new_watermark_height, imagesx($watermark),imagesy($watermark));
?>
Tried without success:
<?php imagealphablending($new_watermark, false);
$color = imagecolortransparent($new_watermark, imagecolorallocate($new_watermark, 0, 0, 0));
imagefill($new_watermark, 0, 0, $color);
imagesavealpha($new_watermark, true);
imagecopyresampled($new_watermark, $watermark, 0, 0, 0, 0, $new_watermark_width, $new_watermark_height, imagesx($watermark),imagesy($watermark));
?>
hope it helps someone.
