{
  "patent_number": "US 6567533",
  "country": "US",
  "title": "How Digital Images Hide Invisible Markers to Track Rotation and Scaling",
  "original_title": "Method and apparatus for discerning image distortion by reference to encoded marker signals",
  "summary": "A method for hiding invisible patterns in digital images that allow computers to detect if an image has been rotated or resized, even if the original version is missing.",
  "what_it_does": "This patent describes a way to embed invisible 'orientation markers' into a digital image. These markers are essentially a specific pattern of energy peaks that appear when the image is analyzed using a mathematical process called a Fourier transform. Because these peaks follow a predictable geometric pattern, a computer can compare the distorted version of an image against the known original pattern to calculate exactly how much it has been rotated or scaled. This allows software to automatically 'undo' these distortions to recover hidden data, such as a copyright watermark, without needing the original, unedited file.",
  "what_it_does_not_cover": [
    "Does not cover visible watermarks like logos or text overlays.",
    "Does not cover methods that require the original, unedited image to calculate distortion.",
    "Does not cover distortion types other than rotation and scaling, such as perspective warping or cropping.",
    "Does not cover non-digital image formats or physical analog prints."
  ],
  "filed": "2000-04-27",
  "granted": "2003-05-20",
  "expires": null,
  "status": "active",
  "holder": "Digimarc Corp",
  "holder_url": "https://patentbrief.org/company/digimarc-corp",
  "inventors": [
    {
      "name": "Geoffrey B. Rhoads",
      "url": "https://patentbrief.org/inventor/geoffrey-b-rhoads"
    }
  ],
  "times_cited": 136,
  "tags": [
    "software",
    "consumer_electronics",
    "ai_ml"
  ],
  "abstract": "To permit scaling or rotation of an image to be discerned—even if the original image is not available—certain marker signals are steganographically encoded in the image. In one particular implementation, encoding is effected by adding an overlay signal to the image. The overlay signal—when represented in the spatial frequency domain—includes a pattern of spots. If the image is scaled or rotated, this pattern changes in known ways. By examining the change in this pattern, the distortion (i.e., scale/rotation) of the image can be inferred. This technology finds particular application in conjunction with watermarking systems, permitting recovery of watermark data from images that have been scaled or rotated subsequent to watermarking.",
  "url": "https://patentbrief.org/patent/us/6567533/playstation-2-emotion-engine",
  "markdown_url": "https://patentbrief.org/patent/us/6567533/playstation-2-emotion-engine/md",
  "google_patents_url": "https://patents.google.com/patent/US6567533",
  "relatedPatents": []
}