OpenCV Seamless Cloning shift position after finish the process

Question

I am trying to used the seamsless cloning to blend to image together. but I notice that after using the seamsless clone function the area in the mask that I want to transfer is shift upward. So I have a question that is this a normal behaviour of the seamsless clone function or it is a bug on my implementation.

Here are the Source photo

Here are the destination photo

Here are the result photo

Answer 1

I encountered similar situation. Moreover, like @JoshuaCWebDeveloper noted, this shift disappeared when all one mask is used. Nevertheless, I got a fix for this. What I did is this. I cropped valid mask (non-zero sub-section) out using cv2.boundingRect. So my source image and mask image are reduced to a smaller size, while center is now calculated from boundingRect outputs (Since reference point is marked on destination image). This way, error got solved/shift got ridden.