Try to blend the Image with openCV

Question

img1 img2

img1 = cv.imread('face.png',1)
img2 = cv.imread('flower.png',1)
img2= cv.resize(img2,(642,640))
cv.imshow('img1',img1)
cv.imshow('img2',img2)
dst = cv.addWeighted(img1,0.7,img2,0.3,1)
cv.imshow('dst',dst)
cv.waitKey(0)
cv.destroyAllWindows()

Give me this

error: OpenCV(4.2.0) ../modules/core/src/arithm.cpp:666: error: (-209:Sizes of input arguments do not match) The operation is neither 'array op array' (where arrays have the same size and the same number of channels), nor 'array op scalar', nor 'scalar op array' in function 'arithm_op'

Answer 1

It should be:

img2= cv.resize(img2,(640,642))

The reason is, when you retrieve the image shape, it returns height, and width respectively.

(h, w) = img.shape[:2]

Then you resize the second image using width and height respectively.

img2 = cv.resize(img2, (w, h))

But it is best if you assert both image with the same shape, before using addWeighted, to make sure both images are the same shape.

assert img1.shape == img2.shape

Result:

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Code:

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import cv2 as cv

img1 = cv.imread('face.png', 1)
img2 = cv.imread('flower.png', 1)

(h, w) = img1.shape[:2]
img2 = cv.resize(img2, (w, h))

assert img1.shape == img2.shape

cv.imshow('img1', img1)
cv.imshow('img2', img2)

dst = cv.addWeighted(src1=img1, alpha=0.7, src2=img2, beta=0.3, gamma=1.0)

cv.imshow('dst', dst)
cv.waitKey(0)

cv.imwrite("dst.png", dst)

cv.destroyAllWindows()