用python对比两张图片的不同

from PIL import Image
from PIL import ImageChops 

def compare_images(path_one, path_two, diff_save_location):
    """
    比较图片，如果有不同则生成展示不同的图片
 
    @参数一: path_one: 第一张图片的路径
    @参数二: path_two: 第二张图片的路径
    @参数三: diff_save_location: 不同图的保存路径
    """
    image_one = Image.open(path_one)
    image_two = Image.open(path_two)
    try: 
        diff = ImageChops.difference(image_one, image_two)
 

        if diff.getbbox() is None:
        # 图片间没有任何不同则直接退出
            print("【+】We are the same!")
        else:
            diff.save(diff_save_location)
    except ValueError as e:
        text = ("表示图片大小和box对应的宽度不一致，参考API说明：Pastes another image into this image."
                "The box argument is either a 2-tuple giving the upper left corner, a 4-tuple defining the left, upper, "
                "right, and lower pixel coordinate, or None (same as (0, 0)). If a 4-tuple is given, the size of the pasted "
                "image must match the size of the region.使用2纬的box避免上述问题")
        print("【{0}】{1}".format(e,text))

 
if __name__ == '__main__':
    compare_images('1.png',
                   '2.png',
                   '我们不一样.png')

执行结果：

第二种方法：

from PIL import Image
import math
import operator
from functools import reduce


def image_contrast(img1, img2):

    image1 = Image.open(img1)
    image2 = Image.open(img2)

    h1 = image1.histogram()
    h2 = image2.histogram()

    result = math.sqrt(reduce(operator.add,  list(map(lambda a,b: (a-b)**2, h1, h2)))/len(h1) )
    return result

if __name__ == '__main__':
    img1 = "./1.png"  # 指定图片路径
    img2 = "./2.png"
    result = image_contrast(img1,img2)
    print(result)

如果两张图片完全相等，则返回结果为浮点类型“0.0”，如果不相同则返回结果值越大。

同样用上面两张图片，执行结果为38，还是比较小的：

这样就可以在自动化测试用例中调用该方法来断言执行结果。

关于Pillow库的详细文档：

http://pillow.readthedocs.org/en/latest/index.html