We review developments in transparent data embedding and watermarking for audio, image, and video. Data-embedding and watermarking algorithms embed text, binary streams, audio, image, or video in a host audio, image, or video signal. The embedded data are perceptually inaudible or invisible to maintain the quality of the source data. The embedded data can add features to the host multimedia signal, e.g., multilingual soundtracks in a movie, or provide copyright protection. We discuss the reliability of data-embedding procedures and their ability to deliver new services such as viewing a movie in a given rated version from a single multicast stream. We also discuss the issues and problems associated with copy and copyright protection and assess the viability of current watermarking algorithms as a means for protecting copyrighted data.

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Multimedia data-embedding and watermarking technologies

A method and system for embedding signatures within visual images in both digital representation and print or film. A signature is inseparably embedded within the visible image, the signature persisting through image transforms that include resizing as well as conversion to print or film and back to digital form. Signature points are selected from among the pixels of an original image. The pixel values of the signature points and surrounding pixels are adjusted by an amount detectable by a digital scanner. The adjusted signature points form a digital signature which is stored for future identification of subject images derived from the image. In one embodiment, a signature is embedded within an image by locating relative extrema in the continuous space of pixel values and selecting the signature points from among the extrema. Preferably, the signature is redundantly embedded in the image such that any of the redundant representations can be used to identify the signature. Identification of a subject image includes ensuring that the subject image is normalized with respect to the original image or the signed image. Preferably, the normalized subject image is compared with the stored digital signature.

Method and system for digital image signatures

A system for printing security documents which have copy detection or tamper resistance in plural colors with a single pass electronic printer printing an integrated image controlled by an image generation system which electronically generates a safety background image pattern with first and second interposed color patterns which is electronically merged with alphanumeric information and a protected signature into an integrated electronic image for the printer. The single pass printer preferably has an imaging surface upon which two latent images thereof are interposed, developed with two differently colored developer materials, and simultaneously transferred to the substrate in a single pass. The color patterns are preferably oppositely varying density patterns of electronically generated pixel dot images with varying spaces therebetween. Preferably a portion of the alphanumeric information is formed by a special secure font, such as a low density shadow copy. The validating signature also preferably has two intermixed color halftone patterns with halftone density gradients varying across the signature in opposite directions, but differently from the background. Also electronically superimposed in the safety background pattern may be substantially invisible latent image pixel patterns which becomes visible when copied, and/or are machine readable even in copies.

System for electronically printing plural-color tamper-resistant documents

Non-continuous reflective holograms or diffraction gratings are provided in various forms for authenticating documents and things, and for decorative and product packaging applications. In one specific authentication application, such a hologram or diffraction grating is firmly attached to a surface that contains visual information desired to be protected from alteration. Examples of such information include written personal data and photograph on a passport, driver's license, identity card and the like. The reflective discontinuous hologram is formed in a pattern that both permits viewing the protected information through it and the viewing of an authenticating image or other light pattern reconstructed from it in reflection. In another specific authentication application, a non-transparent structure of two side-by-side non-continuous holograms or diffraction patterns, each reconstructing a separate image or other light pattern, increases the difficulty of counterfeiting the structure.

Non-continuous holograms, methods of making them and articles incorporating them

Two or more digital watermarks, with different characteristics, are embedded in a document. The characteristics are chosen so that the watermarks will be affected in different manners if the document is subsequently copied or reproduced. The detection process or mechanism reads two or more of the watermarks and compares their characteristics. While wear and handling may change the characteristics of the digital watermarks in a document, the relationship between the characteristics of the multiple digital watermarks in a document will nevertheless give an indication as to whether a document is an original or a copy of an original. Document wear can be independently assessed and used as an aid in interpreting the detected watermark characteristics.

Methods and systems using multiple watermarks

Disclosed is a protected document such as a negotiable instrument, a title instrument, indentification document or other documents which should be kept secure from illegal copying by color copiers. The method of making the document comprising preprinting a "VOID" or other warning or cancellation phrase pattern in half tone or multitone on the document and camouflaging this pattern is also disclosed.

Protected document and method of making same

Disclosed is a protected document such as a negotiable instrument, a title instrument, identification document or other documents which should be kept secure from illegal copying by color copiers The method of making the document comprising preprinting a "VOID" or other warning or cancellation phrase pattern in half tone or multitone on the document and camouflaging this pattern is also disclosed The document bears a watermark which adds to the security of the system

William H. Mowry

Papers

Protected document and method of making same

Protected document bearing watermark and method of making