A clustering-based color model and integral images for fast object tracking

The paper presents a clustering-based color model and develops a fast algorithm for object tracking. The color model is built upon K-means clustering, by which the color space of the object can be partitioned adaptively and the histogram bins can be determined accordingly. In addition, in each bin the multi-channel gray level is modelled as Gaussian distribution. Defined in this way the color model can describe accurately the color distribution with very little bins. To evaluate similarity between the reference model and the candidate model, a similarity measure based on Bhattacharrya distance is introduced and its simplified form is derived under assumption that in each bin distribution of gray level in different channel is independent of each other. Motivated by the paper of Viola and Jones, the Integral Images for computation of histogram, mean and variance are proposed, with which the similarity measure can be evaluated at negligible computational cost. Thus, exhaustive search is made efficiently for object localization which guarantees the global maximum be achieved. Comparisons with the well-known mean shift algorithm demonstrate that the proposed algorithm has better performance while having the same (or less) computational cost.