function setTransparency($new_image, $image_source)
{
        ImageAlphaBlending($new_image, false);
        ImageSaveAlpha($new_image, true);

        $transparencyIndex = imagecolortransparent($image_source);
        $transparencyColor = array('red' => 0, 'green' => 0, 'blue' => 0);
        
        if ($transparencyIndex >= 0)
            $transparencyColor = imagecolorsforindex($image_source, $transparencyIndex);   
        
        $transparencyIndex = imagecolorallocate($new_image, $transparencyColor['red'], $transparencyColor['green'], $transparencyColor['blue']);
        imagefill($new_image, 0, 0, $transparencyIndex);
//ImageAlphaBlending($new_image, true);
        imagecolortransparent($new_image, $transparencyIndex);

}

$old = imageCreateFromPng("food.png");
$w = imageSX($old);
$h = imageSY($old);
$w_new=round($w/3);
$h_new=round($h/3);

    $new=imagecreatetruecolor($w_new,$h_new);

    setTransparency($new, $old); 
    imagecopyresampled($new,$old,0,0,0,0,$w_new,$h_new,imagesx($old),imagesy($old));

header('Content-type: image/png'); 
imagePng($new);
imageDestroy($old);
imageDestroy($new);