python代码计算图像的分辨率

def jpeg_res(filename):
   """"This function prints the resolution of the jpeg image file passed into it"""

   # open image for reading in binary mode
   with open(filename,'rb') as img_file:

       # height of image (in 2 bytes) is at 164th position
       img_file.seek(163)

       # read the 2 bytes
       a = img_file.read(2)

       # calculate height
       height = (a[0] << 8) + a[1]

       # next 2 bytes is width
       a = img_file.read(2)

       # calculate width
       width = (a[0] << 8) + a[1]

   print("The resolution of the image is",width,"x",height)

jpeg_res("dca.jpg")

The resolution of the image is 21799 x 21333