可以在python中更改PixelAccess的大小吗？

我在没有使用PIL的crop（）函数的情况下裁剪了一个像素（只是为了好玩），但我找不到减小PixelAccess大小的方法

我可以更改所需部分的颜色，但我不能仅获得所需部分

谁能指导我如何从图像中获取所需的部分

from PIL import Image

i = Image.open('astro.bmp')
pixels = i.load()
width, height = i.size

all_pixels = []
print(type(pixels))

#image resolution is 1024 x 768
for x in range(width) :
    for y in range(height) :
        ap = pixels[x, y]
        all_pixels.append(ap)

center_x = 40
center_y = 40
crop_width = 180
crop_height = 180


#for cropping
for x in range(crop_width) :
    center_y = 40
    for y in range(crop_height) :
        pixels[center_x, center_y] = all_pixels[768 * center_x + center_y]
        center_y += 1
    center_x += 1

center_x = 40
# to change color of the required region
for x in range(crop_width) :
    center_y = 40
    for y in range(crop_height) :
        pixels[center_x, center_y] = 253
        center_y += 1
    center_x += 1

i.save('out.bmp')

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添加一些您试图让他人帮助您的代码：）PS-欢迎使用SO！谢谢@garfbradaz，我已经添加了全部代码。