Department of Image Processing

We propose a novel method for the refinement of Maximally Stable Extremal Region (MSER) boundaries to sub-pixel precision by taking into account the intensity function in the 2 x2 neighborhood of the contour points. The proposed method improves the repeatability and precision of Local Affine Frames (LAFs) constructed on extremal regions. Additionally, we propose a novel method for detection of local curvature
extrema on the refined contour.

Experimental evaluation on publicly available datasets shows that matching with the modified LAFs leads to a higher number of correspondences and a higher inlier ratio in more than 80% of the test image pairs. Since the processing time of the contour refinement is negligible, there is no reason not to include the algorithms as a standard part of the MSER detector and LAF constructions.