An Effective Rotational Invariant Key-point Detector for Image Matching

Traditional detectors e.g. Harris, SIFT, SFOP... are known inflexible in different contexts as they solely target corners, blobs, junctions or other specific human-designed structures. To account for this inflexibility and additionally their unreliability under non-uniform lighting change, recently, a Sparse Coding based Key-point detector (SCK) relying on no human-designed structures and invariant to non-uniform illumination change was proposed. Yet, geometric transformations such as rotation are not considered in SCK. Thus, a novel Rotational Invariant SCK called RI-SCK is proposed in this paper. To make SCK rotational invariant, an effective use of multiple rotated versions of the original dictionary in the sparse coding step of SCK is proposed. A novel strength measure is also introduced for comparison of key-points across image pyramid levels if scale invariance is required. Experimental results on three public datasets have confirmed that significant gains in repeatability and matching score could be achieved by the proposed detector.