Top left panel: total N-band spectrum observed with MIDI (black) and the transmission curves for the five filters used for the T-ReCS aperture-masking measurements. Remaining panels: the visibility amplitude V as a function of spatial frequency ν in each of the five filters. The T-ReCS measurements are shown as circles, while the MIDI measurements, averaged over each corresponding filter, are shown as triangles. The color of each data point shows the position angle (measured east of north).