GD - resizování průhledného GIFu

if(isset($_GET['name']))
{
    $way = dirname(__FILE__) . "/photos/" . $_GET['name'];
    if(file_exists($way))
    {
        $imgInfo = getimagesize($way);
        
        switch($imgInfo[2])
        {
            case(1):
                $main = imagecreatefromgif($way);
                break;
            
            case(2):
                $main = imagecreatefromjpeg($way);
                break;
            
            case(3):
                $main = imagecreatefrompng($way);
                break;
            
            default:
                header('Location: ' . dirname(__FILE__) . "/photos/galaxije.jpg");
                exit();
                break;
        }
        
        if(!isset($_GET['w']))
        {
            list($width, $height) = $imgInfo;
        
            /*image resize*/
            $originalWidth = $width;
            $originalHeight = $height;
            $ratio = $width / $height;
            $height = 112;
            $width = $height * $ratio;
        
            if($width > 150)
            {
            $ratio = $height / $width;
            $width = 150;
            $height = $width * $ratio;
            }
        
            $newImg = imagecreatetruecolor($width, $height);
            
            /*saved alpha in image*/
            if(($imgInfo[2] == 1) || ($imgInfo[2] == 3))
            {
                imagealphablending($newImg, false);
                imagesavealpha($newImg, true);
                
                $transparent = imagecolorallocatealpha($newImg, 255, 255, 255, 127);
                imagefilledrectangle($newImg, 0, 0, $width, $height, $transparent);
            }
            
            imagecopyresampled($newImg, $main, 0, 0, 0, 0, $width, $height, $originalWidth, $originalHeight);
            
            /*image output*/
            header('Content-type: ' . $imgInfo['mime']);
            switch($imgInfo[2])
            {
                case(1): imagegif($newImg, ""); break;
                case(2): imagejpeg($newImg, "", 100); break;
                case(3): imagepng($newImg, "", 9); break;
                
                default:
                    trigger_error('resizování obrázku se nezdařilo', E_USER_WARNING);
                    break;
            }
        
            imagedestroy($main);
            imagedestroy($newImg);
        }
        else
        {
            
            $watermark = imagecreatefromgif(dirname(__FILE__) . "/thumbs/watermark.gif");
            list($width, $height) = getimagesize(dirname(__FILE__) . "/thumbs/watermark.gif");
            list($mainWidth, $mainHeight) = getimagesize($way);
            
            $x = ($mainWidth / 2) - ($width / 2);
            $y = ($mainHeight / 2) - ($height / 2);
            
            if(($imgInfo[2] == 1) || ($imgInfo[2] == 3))
            {
                imagealphablending($main, false);
                imagesavealpha($main, true);
            }
            
            imagecopymerge($main, $watermark, $x, $y, 0, 0, $width, $height, 30);
            
            header('Content-type: ' . $imgInfo['mime']);
            switch($imgInfo[2])
            {
                case(1): imagegif($main, ""); break;
                case(2): imagejpeg($main, "", 100); break;
                case(3): imagepng($main, "", 9); break;
                
                default:
                    trigger_error('resizování obrázku se nezdařilo', E_USER_WARNING);
                    break;
            }
            
            imagedestroy($main);
            imagedestroy($logo);
        }
    }
    else
    {
        echo "error- file is not exist";
    }
}
else
{
    echo "error - undefined get";
}