有时候我们需要根据图像的大小来进行一些操作，你可以载入图片，然后查看其大小，但图片多时，这就显得低效率，这个代码允许你只查看文件头来获取图像的信息。-Sometimes we need to resize the image to carry out some operation, you can load images, and then check its size, but the picture for a long time, which seems low efficiency, t