Transmissions computed using the Doppler model (upper panel) and histogram continuum models (R = 1 000 000, middle and lower panels) with relative errors for the column amounts 10¹⁹, 10²⁰, 10²¹, 10²², 10²³, and 10²⁴ molecule/cm² at T = 2000 K, P = 0 and P = 10 bar. The upper part of each panel shows the total transmission obtained from both the strong and weak lines at this temperature, while the lower part shows the relative error compared to the direct line-by-line evaluation from the 34to10 line list using the a₀ Voigt model (Barton et al. 2017). The error in regions with very low transmissions (<10^-4) are removed as the medium is optically thick.