Illustration of the continuum substraction methods, close to the star (bottom row) and far from the star (top row), for the [Fe ii] 1.64 μm (left panels) and the H₂   2.12 μm line (right panels). The raw spectra are plotted in thick lines and the fitted continua in thin lines. See text for details. The analysis and discussion of H₂   2.12 μm lines will be presented in a separate paper.