(10) | ||

(11) |

The threshold can be constant, linear-decreasing (Abma and Kabir, 2006) and exponential-decreasing (Gao et al., 2010). However, all of these defining criterion are based on a prior knowledge about the data and is often not easy to choose. Instead, a processing-convenient percentile-thresholding strategy can be selected to overcome this inconvenience (Wang et al., 2008). is selected as the th largest absolute value among all values in the transformed domain, where the predefined percentile threshold such that . Here, returns percentile of the values in .

2020-02-28