Detection of local invariant features using contour

This study proposes a new method for the detection of local invariant features with contour. This method differs from traditional methods that use image intensity. Image contours can be extracted stably with changes in viewpoint, scale, illumination and other factors. The proposed algorithm first extracts the stable corner from the contour, then it fits the supporting region of the contour near the corner to an angle, and uses its bisector as the direction of the feature. Next, it searches the contour for the tangent point in the direction of the angle bisector. Finally, with the corner as the centre, and in combination with the tangent point and the feature direction, an elliptic invariant region is constructed. The feasibility of the algorithm was verified experimentally by comparing its repetition rate. Test images obtained from actual scenes include several types of transformations, such as rotation, scaling, affinity, illumination and noise. The results of the experiment show the feasibility of the proposed method for use in local invariant features detection.