Designing real-time multimedia applications on mobile devices

This paper explores the challenge of real-time image search and registration on mobile devices. We propose using the histogram of oriented gradients (HOG) features for characterizing image regions, and propose an algorithm based on the entropy of HOG to select "good" regions for image matching and registration. We also propose a novel implementation of a dual-mode mobile system based on a hybrid tracking and visual matching algorithm. We apply the algorithms to several mobile applications, including image matching for mobile visual search and panorama on mobile phones. The effectiveness of our approach is demonstrated on a large dataset.