Table 3: Comparison with the state of art.

Chaisorn et al. 2003 [7]Misra et al. 2010 [8]Goyal et al. 2009 [9]Ma et al. 2009 [10]Our methodOur method + channel

Recall0.7490.540.4970.5810.8780.893
Precision0.8020.640.7500.7390.7670.767
F10.7750.580.6000.6510.8190.825