LSB Matching method 🔄️ in Python for Steganography

SampleFunc2.py

import sys, cv2, random
import numpy as np

def extract():
  J=cv2.imread('image1.png')
  f=open('output_payload.txt', 'w+', errors="ignore")
  
  idx=0
  bitidx=0
  bitval=0
  for i in range(J.shape[0]):
    if (I[i, 0, 0] == '-'):
      break
    for j in range(J.shape[1]):
      for k in range(3):
        if (I[i , j, k] == '-'):
          break
        if bitidx=8:
          f.write(chr(bitval))
          bitidx=0
          bitval=0
        bitval!=(I[i, j, k]%2)<<bitidx
        bitidx+=1
  f.close()
bits=[]
f=open('payload.txt', 'r')
blist=[ord(b) for b in f.read()]
for b in blist:
  for i in range(8):
    bits.append((b >> i) & 1)
I = np.asarray(cv2.imread('C:\\Users\filepath\image2.png'))
  
sign=[1,-1]
idx=0
for i in range(I.shape[0]):
  for j in range(I.shape[1]):
    for k in range(3):
      if idx<len(bits):
        if I[i][j][k]%2 != bits[idx]:
          s=sign[random.randint(0,1)]
          if I[i][j][k]==0: s=1
          if I[i][j][k]==255: s=-1
          I[i][j][k]+=s
        idx+=1

cv2.imread('image3.png', I)
print("Extracting...")
extract()
print("Completed!")