Extract Rectangle From Contour OpenCV

Question

after making some edge and corner detection and then find contours i have this output.

how i can crop this image and return only this rectangle using openCV

EDIT:

i tried cvBoundingRect and then setimageROI but the output image still having some background but i want the rectangle only

Thank You.

Answer 1

i hope you need the rectangle area you selected.

For this you need to make another grayscale image, let us call it 'mask'. Then draw the rectangle contour obtained on it and fill it with white (255,255,255). You will obtain an image like this ( all images hand-edited in paint program):

Now just have an bitwise_and operation on both the images. You will get result as this:

**NB:**Now if it is not the one you wanted, instead you wanted this kind of selection, You can find information about it in this SOF question (thanks to karl philip for the link) .