import cv2
#green screen effect
# Load two images
img1 = cv2.imread('../images/bugs.jpg')
img2 = cv2.imread('../images/logo.png')

# I want to put logo on top-left corner, So I create a ROI
rows,cols,channels = img2.shape
roi = img1[0:rows, 0:cols ]

# Now create a mask of logo and create its inverse mask also
img2gray = cv2.cvtColor(img2,cv2.COLOR_BGR2GRAY)

ret, mask = cv2.threshold(img2gray, 10, 255, cv2.THRESH_BINARY)
#threshold( src_gray, dst, threshold_value, max_BINARY_value,threshold_type );
#ret is retval for OTSU thresholding, i.e average of bimodal peaks from histogram. Default is same value we used as threshhold value

mask_inv = cv2.bitwise_not(mask)

# Now black-out the area of logo in ROI
img1_bg = cv2.bitwise_and(roi,roi,mask = mask_inv)

# Take only region of logo from logo image.
img2_fg = cv2.bitwise_and(img2,img2,mask = mask)

# Put logo in ROI and modify the main image
dst = cv2.add(img1_bg,img2_fg)
img1[0:rows, 0:cols ] = dst

cv2.imshow('img1_bg',img1_bg)
cv2.imshow('img2_fg',img2_fg)
cv2.imshow('mask',mask)
cv2.imshow('dst',dst)
cv2.imshow('result',img1)
cv2.waitKey(0)
cv2.destroyAllWindows()
