Figure 3

The plane for the feature point { x - max( a, b ), x - min( a, b )}. All feature points are located within the trapezoid region composed of six triangular regions. Regions 1 and 2 correspond to x = 1 in Fig. 2B. Regions 3 to 6 correspond to b = 1 in Fig. 2C. The yellow line represents a + b = 1 for SF in Eq. (5). The green line represents a + 1 = 2x for CF in Eq. (6). The solid red line represents x = a, x ≤ 0.5 for NF in Eq. (7). Each feature point can be classified as SF, CF, or NF fate by its distance to the three lines.