Illustration of the calculation of the spectral contrast on the average spectrum of red (D-type) Jupiter Trojans (Martin & Emery 2023). Top: Removal of a linear continuum that is tangent to the maxima before (11.2 μm) and after (18 μm) the band. Bottom: The depth of the band was computed after the continuum removal using a polynomial fit (blue) to determine the minimum in emissivity. The contrast is illustrated by the arrow (black).