Comparison between QSL and CA interfaces. The left panel shows a map of Q and CA interfaces in an extended area around the flux rope. Colored lines represent the interface of the flux rope and the CA with the designated color. The black lines represent the interfaces between other CAs except the flux rope. The middle panel shows the histograms of Q values at the CA interfaces and those over the full domain in the left panel. The right panel shows histograms of the maximum Q within an epsilon-neighborhood of each pixel at the CA interface. Two ϵ values have been tested.