{"tool":"image-diff","description":"Two PNGs in, delta out. Pixel diff with threshold, percentage changed, bounding boxes, visual diff.","usage":{"GET":"/?a=URL&b=URL&threshold=25&output=json|image|overlay","POST":"{ \"a\": \"url_or_base64\", \"b\": \"url_or_base64\", \"threshold\": 25, \"output\": \"json|image|overlay\" }"},"options":{"a":"First image (URL or base64)","b":"Second image (URL or base64)","threshold":"Per-channel difference threshold 0-255 (default: 25)","output":"json (default) | image (diff PNG) | overlay (composite PNG)"},"pairs_with":"https://screenshot.b-9f2.workers.dev — take two screenshots at different times, diff them"}