Synthetic images computed with HDUST (upper panels) and their respective radial brightness profile curves (lower panels), at 870 μm, 3.26 mm, and 2 cm. In all cases, the maximum disk emission was normalized to unity. Overplotted to the images are the contours of same flux, at log (I/I_MAX) = −0.2, −1.5, −2.5, and −3.5 (which correspond to 63%, 3%, 0.3%, and 0.003% of the disk maximum brightness, respectively). The transition between the optically thick region (pseudophotosphere) and the diffuse part of the disk is indicated by a vertical dotted line over the plots, as estimated from the extrapolation of the distinct brightness profile regions (gray dashed curves).