Examples of computed S/N using the inverse of 1.48 times a rolling MAD in YARARA river diagram maps (labeled as ’extracted’) and compared with the theoretical S∕N_cont value if only photon-noise limited. In the case of a star photon-noise limited with S/N_cont ~ 200, both methods produce similar values (green and red curves). For a spectrum flat-field limited as for HD 128621 observations (blue and orange curves), the S∕N_cont is saturated to the S∕N_cont of the flat-field raw frames (black dashed line).