Opencv with Python error

edit

I am trying to change background over the webcam feed. Here's the main section of the code -

import numpy as np
import cv2

rows = 1280
cols = 720

cap = cv2.VideoCapture(0) #use external cam
ret = cap.set(3,rows)
ret = cap.set(4,cols)

img_back = cv2.imread('C:/Users/sys/Downloads/images/green.jpg') 
background = img_back[0:cols, 0:rows ]

thresh = 170
blur = 3
final = ""
display=1
kernel = np.ones((5,5),np.uint8)

# create window
cv2.namedWindow("chroma", cv2.WND_PROP_FULLSCREEN)

while(True):
# Capture frame-by-frame
ret, frame = cap.read()

frame = cv2.flip(frame,1,frame)

lab_image = cv2.cvtColor(frame, cv2.COLOR_BGR2LAB)
l_channel,chan_a,chan_b = cv2.split(lab_image)

b_channel = cv2.bitwise_not(chan_b)
a_channel = cv2.add(chan_a,b_channel)
a_channel = cv2.bitwise_not(a_channel)
a_channel_inv = cv2.bitwise_not(a_channel)


# create mask

im_bw = cv2.threshold(a_channel_inv, thresh, 255, cv2.THRESH_BINARY)[1]
im_bw = cv2.GaussianBlur(im_bw,(blur,blur),0)


im_bw = cv2.morphologyEx(im_bw, cv2.MORPH_OPEN, kernel)
ret ,im_bw = cv2.threshold(im_bw,thresh,255,cv2.THRESH_BINARY)

im_bw_inv = cv2.bitwise_not(im_bw)
im_bw_inv = cv2.GaussianBlur(im_bw_inv,(1,1),0)
im_bw_inv = cv2.morphologyEx(im_bw_inv, cv2.MORPH_CLOSE, kernel)

roi = cv2.bitwise_and(background,background,mask = im_bw_inv)
im = cv2.bitwise_and(frame,frame,mask = im_bw)

# add mask
dst = cv2.add(roi,im)

# Display the resulting frame

k = cv2.waitKey(33)
if k == 27: #ESC
    break
if k == ord("+"):
    thresh+=1
if k == ord("-"):
    thresh-=1

if k == ord("."):
    blur*=3
if k == ord(","):
    if blur > 1:
        blur/=3


if k == ord("1"):
    display = 1
if k == ord("2"):
    display = 2
if k == ord("3"):
    display = 3
if k == ord("4"):
    display = 4
if k == ord("5"):
    display = 5
if k == ord("6"):
    display = 6
if k == ord("7"):
    display = 7
if k == ord("8"):
    display = 8

if (display == 1):
    final = dst
if (display == 2):
    final = im
if (display == 3):
    final = roi
if (display == 4):
    final = im_bw
if (display == 5):
    final = im_bw_inv
if (display == 6):
    final = chan_a
if (display == 7):
    final = chan_b
if (display == 8):
    final = l_channel

#display image
cv2.putText(dst,"Thresh (+/-): " + str(thresh), (20,40), cv2.FONT_HERSHEY_SIMPLEX,0.5, 0)
cv2.putText(dst,"Blur (./,): " + str(blur), (20,60), cv2.FONT_HERSHEY_SIMPLEX,0.5, 0)
cv2.imshow('chroma', final)

# When everything done, release the capture
cap.release()
cv2.destroyAllWindows()

I get the following error while trying to run the program and I have no idea how to fix this -

error: C:\projects\opencv-python\opencv\modules\core\src\arithm.cpp:241: error: (-215) (mtype == CV_8U || mtype == CV_8S) && _mask.sameSize(*psrc1) in function cv::binary_op