Example of the spectral subtraction method with UVES spectra in the Hα (upper panel) and Hβ (lower panel) regions for an active star in γ Vel. The target spectrum is represented by a solid black line, while the best-fitting reference spectrum of a low-activity star artificially broadened at the vsini of the target is overplotted with a thin red line. In both panels, the difference spectrum (blue line) is displayed as shifted upward by 1.3 for clarity. The residual Hα and Hβ profiles integrated over wavelength (hatched green areas) provide the net equivalent widths (EW_Hα and EW_Hβ). The narrow absorption features visible in the upper panel are telluric water-vapor lines.