Ratio between the Hα line profiles observed in the spectrum of image D and the spectrum of image B, corrected for the macro-magnification ratio. The continua that compose the spectra of images B and D were previously subtracted. This ratio is a proxy for the effect of microlensing on the Hα line profile in D. At a given wavelength, a ratio higher than unity corresponds to the micro-magnification of the BLR emission. Conversely, a lower ratio indicates a micro-de-magnification. The spectra were smoothed with a fifteen-pixel-wide median filter for clarity.