python利用PIL实现对图片截图

在对图像处理时，我们有时候需要对图片某区域进行截图，话不多说，直接上代码：

from PIL import Image
import sys

#先将 input image 填充为正方形
def fill_image(image):
    width, height = image.size
    #选取长和宽中较大值作为新图片的
    new_image_length = width if width > height else height
    #生成新图片[白底]
    new_image = Image.new(image.mode, (new_image_length, new_image_length), color='white') 
    #将之前的图粘贴在新图上，居中
    if width > height:#(x,y)二元组表示粘贴上图相对下图的起始位置,是个坐标点。
        new_image.paste(image, (0, int((new_image_length - height) / 2)))
    else:
        new_image.paste(image, (int((new_image_length - width) / 2),0))
    return new_image

def cut_image(image):
    width, height = image.size
    item_width = int(width / 3)
    box_list = []
    for i in range(0,3):
        for j in range(0,3):
            print((i*item_width,j*item_width,(i+1)*item_width,(j+1)*item_width))
            box = (j*item_width,i*item_width,(j+1)*item_width,(i+1)*item_width)
            box_list.append(box)
    image_list = [image.crop(box) for box in box_list]
    return image_list

#保存
def save_images(image_list):
    index = 1
    for image in image_list:
        image.save(str(index) + '.png', 'PNG')
        index += 1

if __name__ == '__main__':
    file_path = "app.png"  #图片保存的地址
    image = Image.open(file_path)
    #image.show()
    image_new = fill_image(image)
    image_list = cut_image(image_new)
    save_images(image_list)