import bpy
import os

# Change to the directory where the .blend file is
blenddir = bpy.path.abspath("//")
os.chdir(blenddir)

import PIL
from PIL import Image

imgbasename = 'Channel_'


for i in range(445,455):
    imname = 'Channel_'+str(i)+'.png'
    img = Image.open(imname)
    area = (1,1,4322,2162)
    img = img.crop(area)
    img.save(imname)