Continuum emission toward DG Tau B at 235 GHz (1.27 mm). Left panel: original image in logarithmic color stretch. Middle panel: same image after applying unsharp masking, i.e., the subtraction from the original image of the same image smoothed by 0.1′′. Right panel: labeled version of the same image. The isophote curves at 3σ, 25σ, and 100σ (with σ= 0.034 mJy beam⁻¹) are shown together with the location of the broad ring (brown) and a putative spiral arm (gray) inferred from the unsharp masked image.