My problem is I do not know how to access vector <vector <Point>> contour (this is 2D like matrix on OpenCV)
I want to do this. If Mat element does not consists in contours area I want to suppress that matrix elements. In order to do this I need to know contours element too.
If my situation was so urgent, I would ask my question more carefully.
If I try hard to understand your question, you basically want to consider a contour in pixel level. In order to do that, you should draw the contour into a blank matrix with drawContour. And then compare two matrices or match a pixel in that matrix in case you want pixel by pixel.