py3.6 tk圖片縮放

import io  
#python -m pip install  pillow  （pillow是3版本之後的包PIL是2版本的）
from PIL import Image, ImageTk  
import tkinter as tk  
 
def resize(w, h, w_box, h_box, pil_image):  
  ''' 
  resize a pil_image object so it will fit into 
  a box of size w_box times h_box, but retain aspect ratio 
  對一個pil_image對象進行縮放，讓它在一個矩形框內，還能保持比例 
  '''  
  f1 = 1.0*w_box/w # 1.0 forces float division in Python2  
  f2 = 1.0*h_box/h  
  factor = min([f1, f2])  
  #print(f1, f2, factor) # test  
  # use best down-sizing filter  
  width = int(w*factor)  
  height = int(h*factor)  
  return pil_image.resize((width, height), Image.ANTIALIAS)  
  
 
root = tk.Tk()  
# size of image display box you want  
#期望圖像顯示的大小  
w_box = 400  
h_box = 200  
 
  
# open as a PIL image object  
#以一個PIL圖像對象打開  
pil_image = Image.open(r'S.png')  
  
# get the size of the image  
#獲取圖像的原始大小  
w, h = pil_image.size  
  
# resize the image so it retains its aspect ration  
# but fits into the specified display box  
#縮放圖像讓它保持比例，同時限制在一個矩形框範圍內  
pil_image_resized = resize(w, h, w_box, h_box, pil_image)  
  
  
# convert PIL image object to Tkinter PhotoImage object  
# 把PIL圖像對象轉變爲Tkinter的PhotoImage對象  
tk_image = ImageTk.PhotoImage(pil_image_resized)  
  
# put the image on a widget the size of the specified display box  
# Label: 這個小工具，就是個顯示框，小窗口，把圖像大小顯示到指定的顯示框   
label = tk.Label(root, image=tk_image, width=w_box, height=h_box)  
#padx,pady是圖像與窗口邊緣的距離   
label.pack(padx=5, pady=5)  
root.mainloop()