Each plot represents the extinction correlation from two different color excesses. The two parameters A _[4.5] /A_Ks = 0.500 (left plot) and A _[5.8] /A_Ks = 0.398 (right plot) are adjusted to obtain a one-to-one regression line (solid line). The dashed lines trace the deviation at large extinction, the corresponding slopes in these plots are 0.55 ± 0.02 and 2.52 ± 0.09, respectively.