請問老師：程式第５～８，圖片尺寸部份是否應該修正為

thumb($filename,"image_50/".$filename,50,50,true);
thumb($filename,"image_220/".$filename,220,220,true);
thumb($filename,"image_350/".$filename,350,350,true);
thumb($filename,"image_800/".$filename,800,800,true);

老師的思路太流暢了，我有時候會卡卡，呵呵～