masking.py

import cv2 as cv
img1 = cv.imread('input/night_sky.jpg')
img2 = cv.imread('input/moon.jpg')
img_2_shape = img2.shape
roi = img1[0:img_2_shape[0],0:img_2_shape[1]]
img2gray = cv.cvtColor(img2,cv.COLOR_BGR2GRAY)
ret, mask = cv.threshold(img2gray, 10, 255, cv.THRESH_BINARY)
mask_inv = cv.bitwise_not(mask)
# Now black-out the area of moon in ROI
img1_bg = cv.bitwise_and(roi,roi,mask = mask_inv)
print(img1.shape, mask.shape)
# Take only region of moon from moon image.
img2_fg = cv.bitwise_and(img2,img2,mask = mask)
# Put moon in ROI and modify the main image
dst = cv.add(img1_bg,img2_fg)
img1[0:img_2_shape[0], 0:img_2_shape[1]] = dst
#Create resizable windows for our display images
cv.namedWindow('img1_bg', cv.WINDOW_NORMAL)
cv.namedWindow('img2_fg', cv.WINDOW_NORMAL)
cv.namedWindow('mask', cv.WINDOW_NORMAL)
cv.namedWindow('maskinv', cv.WINDOW_NORMAL)
cv.namedWindow('res', cv.WINDOW_NORMAL)
cv.imshow('mask',mask)
cv.imshow('maskinv',mask_inv)
cv.imshow('img1_bg',img1_bg)
cv.imshow('img2_fg',img2_fg)
cv.imshow('res',img1)
if cv.waitKey(0) & 0xff == 27:
    cv.destroyAllWindows()