How to select keyframes using histogram based keyframe extraction?

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Python

I'm working on keyframe extraction using absolute difference of histogram. Here's the code.
Frames are extracted successfully, and the values of the difference, the variance, and the threshold appear, as well. However, selected keyframes do not appear as expected in the keyframe folder. I can't figure out what seems to be the problem.

import cv2
import os
from matplotlib import pyplot as plt
import numpy as np
import glob

cap = cv2.VideoCapture("final13.avi")
frame_list = []

try:
    if not os.path.exists('data'):
        os.makedirs('data')
except OSError:
    print("Error cant make directories")

cframe = 0
ret, frame= cap.read()

while ret:
    name = 'data/' + str(cframe) + '.jpg'
    cv2.imwrite(name,frame)
    ret, frame= cap.read()
    print('Read a new frame: ', ret)
    frame_list.append(frame)
    cframe += 1

images = {}
index = {}

for imagePath in glob.glob('data/*.jpg'):
    filename = imagePath[imagePath.rfind("/") + 1:]
                  
    image = cv2.imread(imagePath,1)
    images[filename] = cv2.cvtColor(image, cv2.COLOR_BGR2RGB)

    hist = cv2.calcHist([image],[0,1,2],None,[8,8,8],[0,256,0,256,0,256])
    hist = cv2.normalize(hist,None).flatten()
    index[filename] = hist


OPENCV_METHODS = (
    (cv2.HISTCMP_CORREL ),
    (cv2.HISTCMP_CHISQR),
    (cv2.HISTCMP_INTERSECT), 
    (cv2.HISTCMP_BHATTACHARYYA))
 

for method in OPENCV_METHODS:

    results = {}
    reverse = False
 
    if method in (cv2.HISTCMP_CORREL, cv2.HISTCMP_INTERSECT ):
        reverse = True


for (k, hist) in index.items():
        
        d = cv2.compareHist(index[k], hist, cv2.HISTCMP_INTERSECT)
        results[k] = d
        print(d)

for (k,hist) in index.items():
            mean__ = np.mean(index[k], dtype=np.float64)

for (k,hist) in index.items():
               variance = np.var(index[k], dtype=np.float64)

print("variance", variance)
standard_deviation = np.sqrt(variance)
th = mean__ + standard_deviation 
print("threshold value", th)

try:
    if not os.path.exists('keyframe'):
        os.makedirs('keyframe')
except OSError:
    print("Error cant make directories")


for (k,hist) in index.items():
        cframee = 0
        d = cv2.compareHist(index[k], hist, cv2.HISTCMP_INTERSECT)
        ret, keyframe = cap.read()
        if (d > th):
            while ret:
                namee = 'keyframe/' + str(cframee) + '.jpg'
                cv2.imwrite(namee, keyframe)
                print("Read new keyframe:", ret)
                cframee += 1

What I have tried:

I've tried changing the threshold. But I've realized that the problem is not because the if condition is not satisfied.