A bi-modal dimming mirror includes a display and a switchable mirror configured to vary in transmissivity in response to a dimming control signal, which includes one or more of an LCD voltage, a rotator control signal, and/or a polarizer control signal. The bi-modal dimming mirror includes a visible segment overlying the display panel and a sample segment for calibrating the transmissivity or the reflectivity of the switchable mirror. A light source projects a light beam through the sample segment, which is measured by a light sensor. A liquid crystal cell changes polarization of light passing therethrough in response to application of an LCD voltage. In some embodiments, an active absorptive polarizer varies in absorption of polarized light in response to a polarizer control signal. An active polarization rotator varies rotation of polarized light in response to a rotator control signal.