How to recognize rectangles in this image?

Question

I have a image with horizontal and vertical lines. In fact, this image is the BBC website converted to horizontal and vertical lines. My problem is that I want to be able to

Answer 1

Assuming it's a reasonably noise free image (not a video of a screen) then one of the simple floodfill algorithms should work. You might need to run a dilate/erode on the image to close up the gaps.

The normal way to find lines is a Hough transform ( then find lines at right angles) Opencv is the easiest way.

Take a look at this question OpenCV Object Detection - Center Point