python＋OpenCVでのエラー(上げなおし)

前提・実現したいこと

http://kamonohashiperry.com/archives/699
上記のページの「以下は、類似度計算の実行用コードとなります。」
以降のプログラムを実行した際、
以下のようなエラーが起こりました。
原因はなんでしょうか？ご教示お願いします。

発生している問題・エラーメッセージ

Traceback (most recent call last):
File "C:\Users\Owner\compare.py", line 2, in <module>
from skimage.measure import structural_similarity as ssim
ImportError: cannot import name structural_similarity

該当のソースコード

＃import the necessary packages
from skimage.measure import structural_similarity as ssim
import matplotlib.pyplot as plt
import numpy as np
import cv2
%matplotlib inline

def mse(imageA, imageB):
    ＃the 'Mean Squared Error' between the two images is the
    ＃sum of the squared difference between the two images;
    ＃NOTE: the two images must have the same dimension
    err = np.sum((imageA.astype("float") - imageB.astype("float")) ** 2)
    err /= float(imageA.shape[0] * imageA.shape[1])
    
    ＃return the MSE, the lower the error, the more "similar"
    ＃the two images are
    return err
 
def compare_images(imageA, imageB, title):
    ＃compute the mean squared error and structural similarity
    ＃index for the images
    m = mse(imageA, imageB)
    s = ssim(imageA, imageB)
 
    ＃setup the figure
    fig = plt.figure(title)
    plt.suptitle("MSE: %.2f, SSIM: %.2f" % (m, s))
 
    ＃show first image
    ax = fig.add_subplot(1, 2, 1)
    plt.imshow(imageA, cmap = plt.cm.gray)
    plt.axis("off")
 
    ＃show the second image
    ax = fig.add_subplot(1, 2, 2)
    plt.imshow(imageB, cmap = plt.cm.gray)
    plt.axis("off")
 
    ＃show the images
    plt.show()

＃load the images -- the original, the original + contrast,
＃and the original + photoshop
original = cv2.imread("resize/re_pic006.jpg")
contrast = cv2.imread("resize/re_pic005.jpg")
shopped = cv2.imread("resize/re_pic003.jpg")
    
＃convert the images to grayscale
original = cv2.cvtColor(original, cv2.COLOR_BGR2GRAY)
contrast = cv2.cvtColor(contrast, cv2.COLOR_BGR2GRAY)
shopped = cv2.cvtColor(shopped, cv2.COLOR_BGR2GRAY)

＃initialize the figure
fig = plt.figure("Images")
images = ("Original", original), ("Contrast", contrast), ("Photoshopped", shopped)
 
＃loop over the images
for (i, (name, image)) in enumerate(images):
    ＃show the image
    ax = fig.add_subplot(1, 3, i + 1)
    ax.set_title(name)
    plt.imshow(image, cmap = plt.cm.gray)
    plt.axis("off")
 
＃show the figure
plt.show()
 
＃compare the images
compare_images(original, original, "Original vs. Original")
compare_images(original, contrast, "Original vs. Contrast")
compare_images(original, shopped, "Original vs. Photoshopped")