PIL/pillow:无法使用putpixel（）更改像素值

Question

我在试着跑：

from PIL import Image
import os
os.chdir('C:\\.....FOLDER.....')
catIm = Image.open('zophie.png')

width, height = catIm.size
quartersizedIm = catIm.resize((int(width / 4), int(height / 4)))

for x in range(0,102,1):
    for y in range(0,136,1):
        quartersizedIm.putpixel((x,y),(0,0,255,255))
            quartersizedIm.putpixel((x,y))=quartersizedIm.putpixel((x,y))+100

无法将像素更改为固定值，获得错误：

cant assign to function call