如何使用tkinter滑块更改PIL图像的对比度而不进行设置？

from tkinter import *
from PIL import Image, ImageEnhance, ImageTk

root = Tk()
root.title("调整图像对比度")
root.geometry("400x400")

image = Image.open("path_to_image.jpg")  # 替换为实际图像的路径
image_tk = ImageTk.PhotoImage(image)

def change_contrast(contrast):
    enhanced_image = ImageEnhance.Contrast(image).enhance(contrast)
    image_tk = ImageTk.PhotoImage(enhanced_image)
    label.config(image=image_tk)
    label.image = image_tk

contrast_scale = Scale(root, from_=0, to=2, resolution=0.1, orient=HORIZONTAL, command=change_contrast)
contrast_scale.set(1.0)
contrast_scale.pack()

label = Label(root, image=image_tk)
label.pack()

root.mainloop()