Mean and standard deviation on the N_H values from ¹³CO (1–0) (top) and C¹⁸O (1–0) (bottom) implemented during the Monte-Carlo process for the three layers of the Orion B cloud, namely the low-velocity layer (left), the intermediate-velocity layer (middle), and the main-velocity layer (right) rebuilt by ROHSA. Isolated pixels and pixels with a signal-to-noise ratio lower than 3 are blanked.