nx_haar.nx

nx_haar.nx -- Haar-like rectangle features (R-FACE-1), evaluated in O(1) on the integral image (nx_integral). These are the weak-feature primitives of a Viola-Jones cascade: a feature value is (sum of "white" rects) - (sum of "black" rects), each rect summed by four integral lookups. EDGE_H : [white | black] left-right contrast (vertical edge) EDGE_V : [white / black] top-bottom contrast (horizontal edge) LINE_H : [white|black|white] a dark vertical bar between light FOUR : 2x2 checker (TL,BR)-(TR,BL) diagonal contrast Raw integer value (no per-window variance normalization yet -- that is a later rung; the cascade adds it). Pure i64 over nx_integral. genealogy_id: viola_jones_2001 + papageorgiou_haar_wavelets_1998 (record-hint) lineage_id: haar_rectangle_feature + integral_image_o1 license_tier: ORIGINAL