Fig. 1. Framework of proposed algorithm

Fig. 2. Flow chart of scale pre-estimation

Fig. 3. Influence of target occlusion threshold on tracking performance. (a) Average center location error; (b) average operating speed

Fig. 4. Tracking results of four occluded sequences with four algorithms. (a) Lemming; (b) walking2; (c) tiger2; (d) faceocc2

Fig. 5. Center location error of four occluded sequences with four algorithms. (a) Lemming; (b) walking2; (c) tiger2; (d) faceocc2

Fig. 6. Area error results of four scale changing sequences with four algorithms. (a) Trellis; (b) girl; (c) walking; (d) freeman1

Fig. 7. Curves of distance precision and success rate of eight algorithms. (a) Overall performance (50); (b) occlusion (29); (c) scale variation (27); (d) illumination variation (25); (e) complex background (21)

Fig. 8. Tracking results of two typical illumination variant sequences with eight algorithms. (a) Shaking; (b) soccer