如下程序：
import tkinter as tk
from tkinter import *
from PIL import Image,ImageTk
class pic(Canvas):
     i=0
     j=0
     n=0
     def __init__(self,fr,i,j):
         Canvas.__init__(self,fr)
         self.i=i
         self.j=j
frame=tk.Tk()
img0=Image.open("0.jpg")
im0=ImageTk.PhotoImage(img0)
b1=pic(frame,0,0)
b1.create_image(300,200,image=im0)
b1.pack()
frame.mainloop()
怎么控制图片的大小？