Seam: Before/After Compare

Seam photographs a place before you leave it, and again when you come back. Then it shows you what is different. TAKING THE SECOND PHOTOGRAPH The second photograph is taken through the first. Seam holds the baseline on screen as a ghost and locks the camera to the settings the baseline used — the same exposure, the same white balance, the same focus, the same lens and zoom. Line the ghost up and shoot. Matching those settings is the point. Without it, a room that merely got darker reads as a room that changed. READING THE PAIR Four instruments. All of them run on your iPhone. None of them needs an account, a key or a network. Wipe — drag the seam across the frame to bring one photograph over the other. Hold — press anywhere to see the other frame whole, release to come back. Blink — alternate the two at a fixed interval. The eye is very good at this. Difference — wash the frame amber wherever the two photographs genuinely disagree. The difference map is deliberately conservative. Seam first re-aligns the two frames for translation, rotation, scale and perspective, then discards anything a small camera movement could explain, and anything a change of light could explain. It compares only the part both photographs actually cover, and it shows you the noise floor it measured rather than hiding it. What survives all of that is what the two frames really disagree about. WHAT SEAM DOES NOT DO Seam does not tell you what a change means, and it will never advise you about your safety. It reports what it can measure and leaves every conclusion to you. AN OPTIONAL READING If you want the pair described in words, Seam can send the two photographs to an AI provider you choose — OpenAI, Anthropic or Moonshot — using your own API key. It is off until you set it up. It names the recipient before it sends anything, and it strips all metadata from both photographs first. The name you gave the place is not sent. No location is sent. Everything else in Seam works without it. PRIVACY Your photographs live on your iPhone. If you leave iCloud mirroring on they are also copied to your own private iCloud database, which belongs to your Apple account and not to us. Nowhere else. There is no Seam account and no Seam server. Seam contains no analytics, no crash reporting, no advertising and no third-party code of any kind. We receive nothing about you or your photographs. Locations, comparison results and any depth measurements are never uploaded by Seam and never mirrored to iCloud. If you ask Seam to name a trap after where you are, that one coordinate goes to Apple's geocoder to be turned into a street address, and is discarded.