Finding "Missing" objects in image using openCV

Question

Please have a look at the following 2 images

Image 1

Image 2

In image 1, you can see there is a Mat on wall, and in image2 the mat is missing. Now, I am going to insert the Image1 as the first image and Image2 as the second and going to find what is missing. Then, I need to draw a rectangle above the missing object.

In my program, I will check for this in each and every our.

I can't think about something else than "image difference" which is "absDiff()" method. But I am using this technique for motion detection in the same application, so I am not sure whether the same technique will suit for "Finding Missing objects" (because in that case, how this is going to be different from motion detection" ?

Any ideas about how i can find the missing objects like this?

Answer 1

You could try something like looking for points of interest on both images and then look at the areas where are points that were not matched between pictures.