Three 640x480 synthetic PNG inputs with identical shapes and solid background RGB 255, 160 and 50. Chrome 156.0.8078.74; local production app.js SHA256 fb728a912378c8e7350a98bbbe3b656a5da1c96955411e3c3ec9e83b30dea13c; Clean Outline; A4; actual downloaded PNGs. White and gray outputs match SHA256, dark differs. No photo, competitor conversion, physical printer or generalized guarantee. See prepare.py, test.mjs and measurements.json.