nx_presence.nx

nx_presence.nx -- person-presence detection (skin-chrominance + blob concentration). R2 of the MEDIA-STUDIO arc, and the TRUE dead-air signal: motion alone is not enough -- a moving curtain or a TV showing scenery is still "dead air" because no PERSON is onscreen. A person presents a coherent region of skin tone; empty rooms, moving non-person objects, and scattered skin-coloured noise do not. Two cheap, sovereign signals (pure integer, no learned weights): skin per-mille : fraction of pixels inside the skin-chrominance gamut. concentration : skin pixels / area of their bounding box, per-mille. A solid blob fills its own box (high); scattered skin- coloured speckle spans a huge box but fills little (low). PRESENT iff skin >= min_skin AND concentration >= min_conc. The skin gamut is the Kovac et al. 2003 uniform-daylight rule (a fixed colour-science test, documented below). The DECISION thresholds (min_skin, min_conc) are CALLER-supplied -- those are the business knobs. genealogy_id: kovac_2003_skin_segmentation + connected_region_density (attribution UNVERIFIED -- record-hint, do not cite as sourced) lineage_id: skin_chrominance_rule + bounding_box_density + threshold nx_safety_envelope: intended_use: "Flag whether a person is onscreen, for dead-air trimming and as the front-end of body/aesthetic analysis." verdict: NOT_YET_EVALUATED license_tier: ORIGINAL