Fig. 1. Comparison of CLE between KCF and the proposed algorithms based on four videos. (a) BlurBody; (b) couple; (c) deer; (d) soccer

Fig. 2. Comparison of APCE and its threshold, and APCE gradient and its threshold (take the couple video as an example). (a) APCE curve of the proposed algorithm; (b) DifAPCE curve of the proposed algorithm; (c) APCE curve of the proposed algorithm (without the judgment of gradient threshold); (d) two frame changes corresponding to the label ring 4 in Fig. 2(b)

Fig. 3. Comparison of tracking performance with and without gradient threshold judgment. (a) Without gradient threshold; (b) with gradient threshold

Fig. 4. Qualitative tracking comparison of KCF (top) and proposed algorithms (bottom). (a) BlurBody; (b) couple; (c) soccer; (d) deer

Table 1. Comparison of accuracy and speed between KCF and the proposed algorithm (threshold value is 20 pixel)

Table 2. Comparison of tracking precision with and without gradient threshold judgment