The four-fixture Google calibration showed a clean YuNet face-count split:
both zero-face text cards need 0.25 first-clean, both face fixtures clear
at 0.12 with zero cross-source spread. The adaptive arm routes face
content (face_count > 0) to the measured 0.125 rung, saving 6.4 dB PSNR
and doubling face identity cosine vs the flat 0.40 floor. The split is
Google-SynthID-specific: OpenAI's face fixture was harder than its text
fixture, so no other cohort gets an adaptive arm.
Victor Kuznetsov
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