Top: Inclination-corrected H I foreground column density plotted against the peak flux density of the background continuum sources. Red triangles indicate absorption detections. Circles indicate non-detections against unresolved non-Hα sources, filled circles correspond to i < 70°, and open circles correspond to i ≥ 70°. Small stars indicate Hα star-forming regions, and small circles indicate resolved sources not associated with Hα. The filled circles define the ‘clean’ sample of unresolved non-Hα low-inclination sources. The horizontal line marks the Kanekar et al. (2011) threshold at 2 × 10²⁰ cm⁻². The dashed diagonal lines show the 3σ absorption detection limits for different T_s and f_CNM values. Bottom: same as top, but showing only the clean sample for clarity.