PHP压缩图片大小

图像压缩：
参数1、原图片地址（完整的图片路径）
参数2、压缩后的图片地址，也是完整的

function image_png_size_add($imgsrc,$imgdst){
        list($width,$height,$type)=getimagesize($imgsrc);
        $new_width = ($width>600?600:$width)*0.9;
        $new_height =($height>600?600:$height)*0.9;
        switch($type){
            case 1:
                break;
            case 2:
                header('Content-Type:image/jpeg');
                $image_wp=imagecreatetruecolor($new_width, $new_height);
                $image = imagecreatefromjpeg($imgsrc);
                imagecopyresampled($image_wp, $image, 0, 0, 0, 0, $new_width, $new_height, $width, $height);
                imagejpeg($image_wp, $imgdst,75);
                imagedestroy($image_wp);
                echo 232;
                break;
            case 3:
                header('Content-Type:image/png');
                $image_wp=imagecreatetruecolor($new_width, $new_height);
                $image = imagecreatefrompng($imgsrc);
                imagecopyresampled($image_wp, $image, 0, 0, 0, 0, $new_width, $new_height, $width, $height);
                imagejpeg($image_wp, $imgdst,75);
                imagedestroy($image_wp);
                break;
        }
    }