An Interactive Image Rectification Method Using Quadrangle Hypothesis

In this paper, we propose an interactive image rectification method for general planar objects. Our method has two interactive techniques that allow a user to choose the target region of interest. First, with a user-stroke based cropping. Second, with a box based cropping. Our method can be applied to non-rectangular objects. The idea is based on use of horizontal and vertical lines with the target object. We assume that such lines can be richly detected. Practically, at least two horizontal lines and two vertical lines must be observed. Our method has the following procedures: First, detect primitive line segments, and then select horizontal and vertical line segments using baselines. Next, make a quadrangle hypothesis as a combination of 4 line segments. And then, evaluate whether re-projected line segments will be horizontal (vertical) or not. The quadrangle hypothesis with max goodness is the final solution. In our experiments, we showed promising cropping results for several images. And we demonstrated real-time marker-less tracking using the rectified reference image.