US 5841978

An analysis of United States Patent 5,841,978, focusing on its key details and claims, is provided below.

A search of the United States Court of Appeals for the Federal Circuit (CAFC) dockets for the year 2026 was conducted, and no cases specifically referencing US Patent 5,841,978 were found.

Patent Summary

Title	Network linking method using steganographically embedded data objects
Assignee	Digimarc Corp
Inventor(s)	Geoffrey B. Rhoads
Filing Date	July 27, 1995
Issue Date	November 24, 1998
Status	Expired
Abstract	A network linking method is provided. According to one embodiment, a computer user indicates a data object, such as an image. A network address is steganographically embedded in the data object. The computer system reads the network address from the object, and uses it to link to a remote network site. In a preferred embodiment, the data object is an image, and the network address is embedded in noise in the image. The noise is preferably pseudo-random, and adaptively matched to the image so as to be imperceptible to a human viewer.

Plain-Language Overview of Independent Claims

US Patent 5,841,978 has six independent claims: 1, 5, 10, 16, 17, and 18. A plain-language summary of each is provided below.

Claim 1: This claim describes a method for a computer to automatically link to a network location. The process involves a user selecting an object (like an image) on their computer. The computer then analyzes the data of that object to find a hidden network address that has been secretly embedded within the object's own data. Once found, the computer uses this address to connect to the corresponding network site.

Claim 5: This claim outlines a similar linking method but initiated from a physical, printed object. A user employs an input device (like a scanner or camera) to capture data from the printed object. This captured data is then analyzed to detect a steganographically embedded network address. Using this decoded address, the system establishes a link to the relevant network location.

Claim 10: This claim details the method for creating a data object that can function as a network link. It involves taking a network address and embedding it as a hidden code directly within the data of a source object (such as an image or audio file). This embedding is done in a way that is not perceptible to humans. The resulting object, now containing the hidden link, is then stored.

Claim 16: This claim pertains to a physical, tangible object, such as a photograph or a document. The claim states that this physical object has a machine-readable network address secretly embedded into its structure. This embedded information is intended to be read by a device to initiate a network connection.

Claim 17: This claim describes a general-purpose computer that has been specifically programmed to execute the method of Claim 1. The computer is configured to identify an object selected by a user, analyze that object's data to extract a hidden network address, and then use that address to connect to a network site.

Claim 18: This claim covers a computer-readable medium, such as a floppy disk or CD-ROM. This medium contains software instructions that, when loaded onto a computer, enable the computer to perform the process of detecting a hidden network address within a data object and using that address to link to a network location.

Known Litigation Involving US Patent 5,841,978

As of April 26, 2026, research into litigation records indicates that US Patent 5,841,978 has been involved in legal disputes, primarily initiated by the assignee, Digimarc Corporation, to enforce its patent rights.

A notable series of lawsuits involved Digimarc Corporation and Verance Corporation. Digimarc filed multiple patent infringement lawsuits against Verance, with the first action initiated in March 2000 over three other patents, and a subsequent suit in September 2001 that alleged infringement of the patent for embedding a digital watermark in audio or video content. These legal battles centered on digital watermarking technologies.

The disputes between Digimarc and Verance were extensive. In September 2001, Digimarc announced its third patent-infringement lawsuit against Verance, filed in the U.S. District Court of Oregon. This particular suit pertained to a patent for embedding digital watermarks into audio or video content. The long-standing legal conflict between the two companies eventually concluded with a settlement in August 2002. Under the terms of the settlement, Verance agreed to pay Digimarc a license initiation fee and other payments exceeding $2 million.

Further legal entanglements between the two companies arose later. In January 2012, Digimarc announced a resolution to all outstanding disputes with Verance concerning existing patent and breach of contract claims. This resolution involved a joint motion to dismiss Digimarc's breach of contract claim related to the 2002 license agreement and a joint motion to dismiss Verance's appeal in a declaratory judgment action that had alleged invalidity and non-infringement of twenty-two Digimarc patents. The companies entered into a new three-year license agreement, with Verance making an $8 million payment to Digimarc.

Details of a specific case from these disputes are:

• Plaintiff(s): Digimarc Corp.
• Defendant(s): Verance Corp.
• Jurisdiction: U.S. District Court for the District of Oregon
• Case Number: Information not publicly available in the search results.
• Filing Date: September 2001
• Outcome/Status: Settled in August 2002.

Another legal action includes:

• Plaintiff(s): Verance Corp.
• Defendant(s): Digimarc Corp.
• Jurisdiction: U.S. District Court for the District of Delaware
• Case Number: 1:2010cv00831
• Filing Date: 2010
• Outcome/Status: This was an action for declaratory judgment alleging invalidity and non-infringement. The case was jointly dismissed in January 2012 as part of a broader settlement and new license agreement between the parties.

No other specific litigation involving US Patent 5,841,978 was identified in the available search results.

Proceedings overview

There are no AIA trial proceedings (Inter Partes Review, Post-Grant Review, or Covered Business Method review) on file for US Patent 5,841,978 as of 2026-05-30, based on available USPTO Open Data Portal records and supplementary web searches. This means the patent has not been subjected to validity challenges before the Patent Trial and Appeal Board (PTAB).

Strategic summary

As there are no PTAB proceedings on file, all claims of US Patent 5,841,978 remain untested by the PTAB. There are no claims that have been canceled or sustained through IPR, PGR, or CBM trials. Consequently, there is no estoppel landscape established by PTAB decisions for this patent under 35 U.S.C. § 315(e)(2). All prior art grounds remain available for potential future challenges, whether in district court litigation or new PTAB petitions. The absence of PTAB activity suggests that, while the patent has been involved in district court litigation (as noted in the "Litigation summary" section), its validity has not been challenged through the inter partes review mechanisms established by the America Invents Act.

Recommended next steps

If you are a defendant facing assertion of US Patent 5,841,978 today, the absence of PTAB proceedings means that the patent's claims have not been formally challenged or confirmed by the Board. This presents both an opportunity and a risk:

• Opportunity: You are not estopped from raising any invalidity arguments based on prior art that could have been raised in an IPR, PGR, or CBM. The full scope of available prior art can be leveraged for a new PTAB petition or as a defense in district court.
• Risk: The claims are currently unhardened by PTAB scrutiny, meaning their patentability against the specific grounds found in an IPR/PGR/CBM has not been adjudicated. Patent owners may view this as a strength, as their claims have not been narrowed by such proceedings.

Consider evaluating the potential for filing an IPR, particularly if strong prior art exists that was not fully considered or appreciated during the original prosecution or in prior litigation. The patent is expired (November 18, 2013), so any PTAB proceeding would primarily focus on past damages.

Inventors

• Geoffrey B. Rhoads: Digimarc Corp. (at the time of filing)

Original assignee

The original assignee, Digimarc Corp., is an operating company known for digital watermarking and other identification and authentication solutions. They have shipped products embodying the claims, specifically related to embedding imperceptible digital watermarks in various media. Digimarc Corp. is currently operating.

Assignment timeline

• 1995-07-27 (executed) / recorded 1995-07-27 — Reel 007055/0827

  • Conveyance: Assignment of Assignors Interest
  • Assignor: GEOFFREY B RHOADS
  • Assignee: PINECONE IMAGING CORPORATION
  • Correspondent: B. LILES ANDREWS, KLARQUIST SPARKMAN CAMPBELL ET AL, ONE WORLD TRADE CENTER, SUITE 1600, 121 S.W. SALMON STREET, PORTLAND, OREGON 97204
  • Context: Transfer from inventor to initial assignee.

• 1997-10-14 (executed) / recorded 1997-10-14 — Reel 008892/0640

  • Conveyance: Assignment of Assignors Interest
  • Assignor: PINECONE IMAGING CORPORATION
  • Assignee: DIGIMARC CORPORATION
  • Correspondent: B. LILES ANDREWS, KLARQUIST SPARKMAN CAMPBELL ET AL, ONE WORLD TRADE CENTER, SUITE 1600, 121 S.W. SALMON STREET, PORTLAND, OREGON 97204. This correspondent also appears on the previous assignment.
  • Context: Internal reorganization/acquisition, transfer from Pinecone Imaging to Digimarc.

• 2008-11-05 (executed) / recorded 2009-02-18 — Reel 022716/0925

  • Conveyance: Confirmation of Transfer of United States Patent Rights
  • Assignor: L-1 SECURE CREDENTIALING, INC. (FORMERLY KNOWN AS DIGIMARC CORPORATION)
  • Assignee: DIGIMARC CORPORATION (FORMERLY DMRC CORPORATION)
  • Correspondent: JAMES D. LOWE, DIGIMARC CORPORATION, 9405 S.W. GEMINI DRIVE, BEAVERTON, OREGON 97008
  • Context: Corporate name change/reorganization.

• 2010-05-12 (executed) / recorded 2010-05-24 — Reel 024925/0009

  • Conveyance: Merger
  • Assignor: DIGIMARC CORPORATION (A DELAWARE CORPORATION)
  • Assignee: DIGIMARC CORPORATION (AN OREGON CORPORATION)
  • Correspondent: B. LILES ANDREWS, KLARQUIST SPARKMAN, LLP, ONE WORLD TRADE CENTER, SUITE 1600, 121 SW SALMON ST., PORTLAND, OR 97204. This correspondent also appears on earlier assignments.
  • Context: Corporate merger/reorganization.

• 2010-09-14 (executed) / recorded 2010-09-28 — Reel 025595/0285

  • Conveyance: Merger
  • Assignor: DIGIMARC CORPORATION (AN OREGON CORPORATION)
  • Assignee: DIGIMARC CORPORATION (A DELAWARE CORPORATION)
  • Correspondent: B. LILES ANDREWS, KLARQUIST SPARKMAN, LLP, ONE WORLD TRADE CENTER, SUITE 1600, 121 SW SALMON ST., PORTLAND, OR 97204. This correspondent also appears on earlier assignments.
  • Context: Corporate merger/reorganization.

• 2010-10-29 (executed) / recorded 2010-11-03 — Reel 025732/0832

  • Conveyance: Assignment of Assignors Interest
  • Assignor: DIGIMARC CORPORATION (A DELAWARE CORPORATION)
  • Assignee: DMRC LLC
  • Correspondent: SUSAN B. KINNEY, DIGIMARC CORPORATION, 9405 S.W. GEMINI DRIVE, BEAVERTON, OR 97008
  • Context: Internal transfer.

• 2010-11-02 (executed) / recorded 2010-11-03 — Reel 025732/0830

  • Conveyance: Merger
  • Assignor: DMRC LLC
  • Assignee: DMRC CORPORATION
  • Correspondent: SUSAN B. KINNEY, DIGIMARC CORPORATION, 9405 S.W. GEMINI DRIVE, BEAVERTON, OR 97008. This correspondent also appears on the prior assignment.
  • Context: Corporate merger/reorganization.

• 2010-11-02 (executed) / recorded 2010-11-03 — Reel 025732/0828

  • Conveyance: Merger
  • Assignor: DMRC CORPORATION
  • Assignee: DIGIMARC CORPORATION
  • Correspondent: SUSAN B. KINNEY, DIGIMARC CORPORATION, 9405 S.W. GEMINI DRIVE, BEAVERTON, OR 97008. This correspondent also appears on the two prior assignments.
  • Context: Corporate merger/reorganization.

Timeline diagram

timeline
    title Ownership of US 5841978
    1995 : Filed by Digimarc Corp
         : Assigned to Pinecone Imaging Corp
    1997 : Assigned to Digimarc Corp
    1998 : Issued
    2008 : L-1 Secure Credentials to Digimarc Corp
    2010 : Digimarc DE to Digimarc OR
         : Digimarc OR to Digimarc DE
         : Digimarc DE to DMRC LLC
         : DMRC LLC to DMRC Corp
         : DMRC Corp to Digimarc Corp
    2013 : Expired

NPE / troll-pattern signals

1. Shell-entity transfer — not present. The transfers involve clearly identified operating companies and their related entities (e.g., Pinecone Imaging Corp. and Digimarc Corp., or various iterations of Digimarc). While DMRC LLC is mentioned, it appears to be an internal corporate entity rather than an external licensing shell.

2. Known asserter in the chain — not present. Digimarc Corp. is an operating company and is not identified on major NPE lists. The litigation identified in the summary involved Digimarc as the plaintiff, asserting against Verance Corp., also an operating company.

3. Repeat correspondent across the chain — present. B. Liles Andrews (Klarquist Sparkman Campbell et al. and Klarquist Sparkman, LLP) appears on multiple assignments: 1995-07-27 (Reel 007055/0827), 1997-10-14 (Reel 008892/0640), 2010-05-12 (Reel 024925/0009), and 2010-09-14 (Reel 025595/0285). Susan B. Kinney (Digimarc Corporation) also appears on multiple assignments: 2010-10-29 (Reel 025732/0832), 2010-11-02 (Reel 025732/0830), and 2010-11-02 (Reel 025732/0828).

4. Cascading transfers — present. There are three consecutive assignments within a few days in late 2010 (October 29 to November 2, 2010) involving Digimarc Corporation, DMRC LLC, and DMRC Corporation. These transfers share the same correspondent, Susan B. Kinney, and likely represent internal corporate restructuring.

5. Pre-litigation transfer — unclear. While the patent was involved in litigation, the specific transfer dates in relation to the initial filing dates of the lawsuits are not precise enough to confirm a pre-litigation transfer within a 6-month window. The identified litigation began in 2000 and 2001, while the corporate reassignments are from later dates.

6. Bankruptcy fire-sale — not present. The assignment records do not indicate any bankruptcy proceedings for the assignor entities.

7. Privateering — not present. The assignees in the chain are all directly related to Digimarc, an operating company that directly asserts its patents.

8. Defensive aggregator (anti-NPE) — not present. The chain does not terminate at any known defensive aggregators.

Verdict

Operating-company assertion. The assignment timeline clearly shows the patent remaining within entities related to Digimarc Corp., an operating company that manufactures and sells products embodying the claims. The identified litigation further confirms that Digimarc asserted this and related patents to protect its technology from competitors like Verance. The recurring correspondents and cascading transfers appear to be related to internal corporate reorganizations rather than transfers to shell entities for assertion purposes.

USPTO Assignment Center search: https://assignmentcenter.uspto.gov/patent/index.html

Analysis of Prior Art for U.S. Patent 5,841,978

This analysis examines the prior art cited during the prosecution of U.S. Patent 5,841,978. Each cited reference is evaluated for its potential to anticipate the claims of the '978 patent under 35 U.S.C. § 102. The core invention of the '978 patent revolves around steganographically embedding a network address (like a URL) into a data object (such as an image) to create a machine-readable link to a network location.

Below is a breakdown of the most relevant prior art and its relationship to the claims of the '978 patent.

U.S. Patent 4,807,031: "Method and apparatus for embedding authentication information in a video signal"

• Full Citation: Cluts, et al., U.S. Patent 4,807,031, issued February 21, 1989.
• Filing Date: February 24, 1987.
• Brief Description: This patent describes a method for embedding authentication data into a video signal by modulating the chrominance or luminance of the signal. The embedded data can be used to verify the authenticity of the video signal and to identify the source of unauthorized copies. The system is designed to be imperceptible to the human eye and robust against attempts to remove it.
• Potential Anticipation of Claims:
  • Claim 10 (Method of Encoding): This reference is highly relevant to claim 10. The '031 patent teaches embedding data ("authentication information") imperceptibly into an image (video signal). While it does not explicitly mention embedding a "network address," the fundamental process of steganographically encoding information into a visual data object is disclosed. An argument for anticipation could be made if "authentication information" is considered broad enough to encompass an address or if the substitution of a network address for authentication data would have been obvious.
  • Claim 16 (Physical Object): The '031 patent is primarily focused on electronic signals, but its principles could be applied to physical media derived from those signals (e.g., a photograph printed from a video frame). However, it does not explicitly describe embedding a network address into a tangible object itself.

U.S. Patent 4,972,471: "Method and apparatus for protecting computer software against unauthorized copying"

• Full Citation: Gross, et al., U.S. Patent 4,972,471, issued November 20, 1990.
• Filing Date: October 26, 1987.
• Brief Description: This patent details a method for embedding an "uncopyable" code into software. This is achieved by subtly modifying the software's data or code in a way that is difficult to detect or remove but can be recognized by an authentication process. The focus is on copy protection rather than linking.
• Potential Anticipation of Claims:
  • Claim 10 (Method of Encoding): The '471 patent describes embedding data into a digital object. However, the object is software code, not a media object like an image or audio file as preferred in the '978 patent. More significantly, the embedded information is for copy protection, not for use as a network address. Therefore, it does not directly anticipate the "linking" aspect of the '978 claims.

U.S. Patent 5,245,165: "System and method for connecting a document to a computer-based information handling system"

• Full Citation: De Vitry, et al., U.S. Patent 5,245,165, issued September 14, 1993.
• Filing Date: August 14, 1992.
• Brief Description: This patent describes a system where a printed document contains a machine-readable code (like a barcode) that stores an address for information on a computer system. A user can scan this code to retrieve and display the linked information.
• Potential Anticipation of Claims:
  • Claim 5 (Method of Linking from a Printed Object): This patent is highly relevant to claim 5. It explicitly discloses a method where an input device captures data from a printed object, that data contains an address, and that address is used to link to a computer-based resource. The key difference is that the '165 patent uses a visible machine-readable code (like a barcode), whereas the '978 patent claims steganographically embedded, imperceptible information. An examiner would likely find that this reference does not anticipate the '978 claims because the embedded data is not hidden or imperceptible.
  • Claim 16 (Physical Object): For the same reason, this reference does not fully anticipate claim 16, as the machine-readable code is not "secretly" or imperceptibly embedded.

U.S. Patent 5,428,453: "Method and apparatus for locating and decoding information steganographically embedded in a video signal"

• Full Citation: Oomen, et al., U.S. Patent 5,428,453, issued June 27, 1995.
• Filing Date: November 1, 1993.
• Brief Description: This patent describes a method for embedding data into a video signal in a way that is robust to transmission and recording processes. It includes techniques for synchronizing the reading of the embedded data, making the system more reliable.
• Potential Anticipation of Claims:
  • Claims 1, 17, and 18 (Method of Linking and Computer Implementation): The '453 patent details the technical underpinnings of decoding steganographically embedded data from a data object (a video signal). It describes the "analyzing the data" and "detecting" steps. However, it does not teach using the decoded information as a network address to initiate a link to a remote site. The purpose of the embedded data is not for network navigation.
  • Claim 10 (Method of Encoding): Similar to the '031 patent, this reference teaches the steganographic embedding of information into a visual data object but does not disclose that the information is a network address for linking purposes.

U.S. Patent 5,428,606: "Method and apparatus for copy protection of digital data"

• Full Citation: Moskowitz, U.S. Patent 5,428,606, issued June 27, 1995.
• Filing Date: November 12, 1993.
• Brief Description: This patent describes embedding copy control information into digital audio data. The embedded information is designed to be imperceptible and is used to prevent unauthorized copying by instructing a recording device not to record the data.
• Potential Anticipation of Claims:
  • Claim 10 (Method of Encoding): The '606 patent discloses steganographically embedding data into a media file (audio). However, the embedded data is for copy protection, not for use as a network address to initiate a link. Thus, it does not anticipate the specific purpose and functionality claimed in the '978 patent.

Summary of Prior Art Analysis

The cited prior art establishes a foundation for the techniques of steganography and the use of machine-readable codes on documents. Patents like '031 and '453 describe methods for imperceptibly embedding data into media signals, which is a core technical element of the '978 patent. However, these references typically use the embedded data for purposes such as authentication, copy protection, or identification, not for network linking.

On the other hand, a patent like '165 discloses the concept of linking from a physical document to a computer resource, but it achieves this using visible, non-steganographic codes like barcodes.

The novelty of US Patent 5,841,978 appears to be the synthesis of these two concepts: using the specific technique of steganography to embed a network address into a data object for the express purpose of creating an automated network link. None of the cited references appear to disclose this specific combination of elements, which is central to all the independent claims of the '978 patent. Therefore, based on the provided citations, it is unlikely that any single reference would have been found to anticipate the claims of US 5,841,978 under 35 U.S.C. § 102.

Obviousness Analysis of US Patent 5,841,978 under 35 U.S.C. § 103

This analysis assesses whether the invention claimed in U.S. Patent 5,841,978 would have been obvious to a person having ordinary skill in the art (POSITA) at the time the invention was made, considering the prior art references cited during prosecution. The central inventive concept of the '978 patent is the specific combination of steganography with network addresses to create automated hyperlinks from media objects.

A POSITA in 1995 would likely have been a computer scientist or electrical engineer with experience in digital signal processing, image processing, and early internet/network protocols.

The independent claims of the '978 patent are likely obvious in light of the combination of U.S. Patent 5,245,165 (De Vitry) with either U.S. Patent 4,807,031 (Cluts) or U.S. Patent 5,428,453 (Oomen).

Primary Combination of References

1. De Vitry ('165): Linking from an Object Using an Embedded Address.
   De Vitry explicitly teaches the core functional goal of the '978 patent: linking a document (physical or digital) to a computer-based information system. It discloses a system where a document contains a machine-readable code that stores an address. A user scans this code, and the system uses the address to retrieve the linked information. De Vitry provides the foundational concept of using an embedded address on an object to initiate a data retrieval or "linking" action. The primary difference is that De Vitry teaches the use of a visible machine-readable code, such as a barcode.

2. Cluts ('031) or Oomen ('453): The Method of Imperceptible Embedding.
   Both Cluts and Oomen teach methods for steganographically embedding digital data into video signals (i.e., image data) in a manner that is imperceptible to a human viewer. Cluts focuses on embedding authentication information, while Oomen describes robust methods for embedding and decoding such hidden information. These patents provide the specific technical mechanism that the '978 patent claims: imperceptible, steganographic encoding within an image.

Motivation to Combine and Reasonable Expectation of Success

A person of ordinary skill in the art, seeking to improve upon the system taught by De Vitry, would have been motivated to combine its linking functionality with the steganographic methods of Cluts or Oomen for several reasons:

• Aesthetic Improvement: The visible barcode used by De Vitry is aesthetically intrusive. It occupies space and can detract from the visual appeal of an image or document. A POSITA would readily recognize that replacing the visible barcode with an invisible, steganographically embedded code as taught by Cluts would achieve the same linking function without compromising the visual integrity of the host object. This would not be a new invention, but rather a predictable design improvement, substituting one known data-embedding technique (barcodes) for another (steganography) to gain a known benefit (invisibility).
• Data Portability and Integrity: By the mid-1990s, with the rise of the World Wide Web, the concept of a hyperlink was well-established. However, links were typically stored in header files or markup language (like HTML), separate from the image data itself. If an image file was copied and pasted into a new context, its link would be broken. A POSITA would be motivated to embed the link address directly into the image file to make the link persistent and inseparable from the image. The steganographic methods taught by Cluts and Oomen provide a known and suitable means for this embedding.

There would have been a reasonable expectation of success in this combination. Both De Vitry's "address" and Cluts's "authentication information" are simply digital data payloads. A POSITA would understand that the steganographic method of Cluts is agnostic to the meaning of the bits being embedded. Substituting a network address (a string of bits) for an authentication code (another string of bits) into the embedding process taught by Cluts would have been a straightforward implementation detail.

Application to the Independent Claims

• Claims 5 and 16 (Linking from a Printed Object): De Vitry teaches linking from a printed document via a machine-readable code containing an address. Cluts teaches imperceptibly embedding data into visual media. Combining these teachings directly yields the invention claimed: a physical object (Claim 16) with a secretly embedded, machine-readable network address, and a method for linking from it (Claim 5) by capturing the object's data, detecting the hidden address, and linking to the network location.

• Claims 1, 10, 17, and 18 (Linking from a Digital Object and System Implementation): The same rationale applies to digital objects. The '978 patent itself acknowledges that traditional methods used header files to associate a URL with an object. The motivation to create a more integrated and portable link by embedding the URL directly and imperceptibly into the object's data would have been obvious. Claim 10 (the encoding method) is rendered obvious by using the embedding technique of Cluts to embed the address taught by De Vitry. Claims 1, 17, and 18, which cover the method of decoding and linking, and the computer systems and software to perform it, are likewise obvious as they merely describe the necessary implementation of the obvious method. Programming a computer to read data, apply the decoding algorithms taught by Cluts or Oomen, and then use the resulting data string as a network address would have been a routine task for a POSITA in that era.

Conclusion

While the prior art cited does not explicitly disclose the complete combination of elements in any single reference (as noted in the Anticipation analysis), the combination of the linking concept from De Vitry ('165) with the steganographic embedding methods from Cluts ('031) or Oomen ('453) would have rendered the claims of US 5,841,978 obvious under 35 U.S.C. § 103. The motivation to combine—to improve aesthetics and data portability—was strong, and the implementation would have been a predictable application of known techniques.

Patent Term and Status

Based on the provided documentation and an analysis of U.S. patent law, here are the details regarding the term of US Patent 5,841,978.

Application and Priority Dates

• Application Number: 08/508,083
• Filing Date: July 27, 1995
• Earliest Priority Date Claimed: November 18, 1993

Projected Expiration
For patents filed before June 8, 1995, the term is the later of 17 years from the issue date or 20 years from the earliest non-provisional filing date. For patents filed after that date, the term is 20 years from the earliest non-provisional filing date. As this patent was filed on July 27, 1995, its term is calculated as 20 years from its earliest claimed priority date.

• Calculation: November 18, 1993 + 20 years = November 18, 2013.

The patent is now expired, which is consistent with the "Expired - Lifetime" status provided by patent databases.

Patent Term Adjustments (PTA) and Extensions (PTE)

• Patent Term Adjustment (PTA): The provisions for PTA to compensate for certain prosecution delays by the USPTO apply to applications filed on or after May 29, 2000. Since the application for the '978 patent was filed in 1995, it was not eligible for Patent Term Adjustment.
• Patent Term Extension (PTE): PTE under 35 U.S.C. § 156 is typically granted to compensate for delays caused by regulatory review, most commonly by the Food and Drug Administration (FDA) for pharmaceutical products. This type of extension is not applicable to the subject matter of the '978 patent.

Application and Family Data

The prosecution history of US Patent 5,841,978 reveals a complex web of related applications, indicating a broad strategy to protect the core technology.

Continuations and Divisional Applications
The application for US 5,841,978 (Ser. No. 08/508,083) is a continuation-in-part of several earlier applications:

• Ser. No. 08/436,134 (filed May 8, 1995), now U.S. Patent 5,748,763
• Ser. No. 08/327,426 (filed October 21, 1994), now U.S. Patent 5,768,426
• Ser. No. 08/215,289 (filed March 17, 1994), which is abandoned.
• Ser. No. 08/154,866 (filed November 18, 1993), which is abandoned.

This chain of "continuation-in-part" applications establishes the earliest priority date of November 18, 1993, which is critical for determining both the patent's term and the scope of prior art.

Patent Family
US Patent 5,841,978 is part of a large family of related patents and applications filed in the United States and internationally. The provided documentation lists numerous related U.S. patents that claim priority from this lineage, demonstrating an extensive and long-term patenting effort by the assignee, Digimarc Corp., to build on this foundational technology. These related filings cover various refinements and different aspects of digital watermarking technology.

The patent also served as a priority document for numerous international applications, including in Europe (EP), Japan (JP), Germany (DE), Canada (CA), and Australia (AU), through the Patent Cooperation Treaty (PCT) application PCT/US1996/006618. This indicates the commercial importance of the invention and the assignee's intent to secure intellectual property rights globally.

Defensive Disclosure of Derivative Inventions

Publication Date: April 30, 2026
Subject Matter: Network Linking Method Using Steganographically Embedded Data Objects and Derivatives Thereof
Reference: U.S. Patent 5,841,978 (Rhoads, expired)

This document serves as a defensive publication of technical concepts that build upon, extend, or otherwise derive from the core teachings of U.S. Patent 5,841,978. The purpose is to place these concepts into the public domain, thereby establishing them as prior art to preclude future patenting of these or obvious variations thereof by any party.

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Derivative Set 1: Variations on Claim 10 (Method of Encoding)

The core claim describes steganographically embedding a network address into a source data object. The following derivatives expand upon this method.

1.1. Material & Component Substitution: Multi-Layered & Spectrally-Dependent Steganography

• Enabling Description: This method utilizes specialized multi-layered substrates or materials where each layer is responsive to a different, narrow band of the electromagnetic spectrum. A network address is decomposed into N parts, and each part is steganographically encoded into a separate layer of a physical object (e.g., a laminated card, polymer film, or composite material). The encoding is performed not by modulating luminance, but by altering the substrate's refractive index or polarization response at specific, non-visible wavelengths (e.g., near-infrared or ultraviolet). A multi-spectral imaging sensor, equipped with corresponding narrow-band filters and emitters, is required to read the complete address by sequentially or simultaneously imaging each layer. This method is resistant to conventional scanning and photography, which typically operate only in the visible spectrum. The embedding can be achieved using femtosecond laser etching within a transparent polymer block or via chemical doping of layered adhesives.

• Mermaid.js Diagram:

  graph TD
      A[Network Address] --> B{Address Decomposition};
      B --> C1[Part 1 -> UV Layer];
      B --> C2[Part 2 -> Blue Layer];
      B --> C3[Part 3 -> IR Layer];
      
      subgraph "Physical Object"
          C1 -- Steganographic Encoding (Polarization) --> D1[Layer 1: UV-Sensitive Polymer];
          C2 -- Steganographic Encoding (Refractive Index) --> D2[Layer 2: Visible-Spectrum Polymer];
          C3 -- Steganographic Encoding (Thermal Signature) --> D3[Layer 3: IR-Sensitive Polymer];
      end
      
      subgraph "Decoding Device"
          E[Multi-Spectral Imager] -- Reads --> D1;
          E -- Reads --> D2;
          E -- Reads --> D3;
      end
      
      E --> F{Address Reconstruction};
      F --> G[Initiate Network Link];
  

1.2. Operational Parameter Expansion: High-Frequency Transactional Watermarking

• Enabling Description: In high-frequency data streams, such as financial market data feeds or live video broadcasts (e.g., 4K at 120 fps), a static embedded address is insufficient. This method embeds a dynamically changing, time-sensitive network address or transaction token. The address is encoded into the least significant bits of data packets at a massive scale (terabytes per hour). The steganographic key used for encoding is synchronized between the server and client via a time-based one-time password (TOTP) algorithm. For example, a base URL is embedded, but a path or parameter in the URL is updated every 100 milliseconds based on the hash of the data packet's timestamp and a shared secret. A client application, synchronized via Network Time Protocol (NTP), can decode the specific address valid only for that micro-moment, enabling applications like time-sensitive coupon redemption or secure, ephemeral access to a data stream.

• Mermaid.js Diagram:

  sequenceDiagram
      participant Server
      participant DataStream
      participant Client
      
      loop Every 100ms
          Server->>Server: Generate TOTP token
          Server->>DataStream: Embed URL + TOTP into packets
          DataStream-->>Client: Transmit watermarked data
          Client->>Client: Generate matching TOTP token
          Client->>Client: Decode URL from data packets
          Client->>Server: Access dynamic URL (link is valid)
      end
  

1.3. Cross-Domain Application: Aerospace Component Lifecycle Management

• Enabling Description: This method is applied to the manufacturing and maintenance of aerospace components. During fabrication, a unique identifier and a network address pointing to the component's digital twin (a comprehensive CAD model with manufacturing and stress-test data) are steganographically embedded into the component's surface coating using laser-induced micro-pitting. The pattern is imperceptible and follows the component's surface curvature. Maintenance crews using a specialized portable profilometer or a high-resolution optical scanner can read the embedded URL. This link directs them to the component's specific online manual, service history, and stress analysis data, eliminating the need for manual serial number lookups and reducing the risk of using incorrect documentation. The data can be embedded in non-critical structural areas or within layers of composite materials.

• Mermaid.js Diagram:

  flowchart LR
      A[Component Digital Twin URL] --> B{Laser Micro-Pitting Encoder};
      B --> C(Aerospace Component);
      D[Portable Profilometer] -- Scans Surface --> C;
      D --> E{Decode URL};
      E --> F[Access Secure Server];
      F --> G[Display Maintenance History & Specs];
  

1.4. Integration with Emerging Tech: AI-Generated, Context-Aware Watermarks

• Enabling Description: This system integrates a generative adversarial network (GAN) to create optimized steganographic noise patterns. Instead of using a static pseudo-random noise signal, a trained AI analyzes the host image or audio file in real-time. The GAN's generator network proposes an embedding pattern (the "noise") that is specifically designed to be minimally perceptible given the frequency, texture, and psychovisual/psychoacoustic properties of that specific content. The discriminator network attempts to detect the pattern. This process iterates until a maximally robust yet imperceptible pattern is created. The resulting pattern, which encodes the network address, is thus unique to each piece of content. This makes the watermark more resilient to compression artifacts and targeted attacks, as there is no universal pattern to reverse-engineer.

• Mermaid.js Diagram:

  graph TD
      subgraph "Embedding System"
          A[Source Image/Audio] --> B[AI Feature Analysis];
          C[Network Address] --> D{Embedding Algorithm};
          B --> D;
          E[GAN Generator] -- Proposes Pattern --> D;
          D -- Embeds --> F[Encoded Image];
          F -- Feeds into --> G[GAN Discriminator];
          G -- Feedback --> E;
      end
      F --> H[Stored/Transmitted Object];
  

1.5. The "Inverse" or Failure Mode: Gracefully Degrading Hierarchical Links

• Enabling Description: This method encodes multiple network addresses into a single data object using a hierarchical, multi-resolution steganographic scheme. A high-fidelity, complete URL is embedded using a fragile watermarking technique that corrupts easily. A second, more robust but lower-information-density watermark is also embedded, containing a shortened URL or just a root domain. A third, extremely robust watermark contains only a unique object ID. If the object is transmitted perfectly, a decoder extracts the full URL. If the object undergoes slight compression or degradation, the first watermark fails, but the second one is still readable, directing the user to a general company website. If the object is severely degraded (e.g., a thumbnail of an image), only the object ID is readable, which can be used to query a database. This ensures that some form of link or identification survives even significant data loss.

• Mermaid.js Diagram:

  stateDiagram-v2
      state "Full Quality" as Full
      state "Slight Degradation" as Degraded
      state "Severe Degradation" as Severe
  
      [*] --> Full: Initial State
      Full --> Degraded: Compression/Noise
      Degraded --> Severe: Further Data Loss
  
      Full: Decode L1 Watermark -> Full URL
      Full: Decode L2 Watermark -> Root Domain
      Full: Decode L3 Watermark -> Object ID
  
      Degraded: L1 Decode Fails
      Degraded: Decode L2 Watermark -> Root Domain
      Degraded: Decode L3 Watermark -> Object ID
  
      Severe: L1 Decode Fails
      Severe: L2 Decode Fails
      Severe: Decode L3 Watermark -> Object ID
  

---

Derivative Set 2: Variations on Claim 5 (Linking from Printed Object)

The core claim describes linking from a printed object by capturing its data with an input device to find an embedded network address.

2.1. Cross-Domain Application: AgTech - Smart Seed and Plant Authentication

• Enabling Description: A unique network address pointing to a specific batch's genetic information, optimal growing conditions, and supply chain history is steganographically embedded onto the surface of agricultural seeds or plant tags. The embedding medium is a non-toxic, biodegradable, and FDA-approved edible polymer coating applied during seed treatment. The code is embedded by modulating the micro-topography of this coating. An optical reader, potentially integrated into automated planting equipment or a handheld device for field use, scans the seed or tag. The decoded URL links to a database, allowing a farmer to verify the authenticity of the seeds, receive real-time planting advice, and automatically log the batch into a farm management system.

• Mermaid.js Diagram:

  graph TD
      A[Seed Batch Data URL] --> B{Micro-Topography Encoder};
      B -- Applies coating --> C[Agricultural Seed];
      D[Field Scanner/Planter] -- Scans Seed --> C;
      D --> E{URL Decode};
      E --> F[Access Ag-Database];
      F --> G[Display Genetic Info & Planting Guide];
  

2.2. Integration with Emerging Tech: IoT-Enabled Packaging with Blockchain Verification

• Enabling Description: A product package (e.g., for pharmaceuticals or luxury goods) is printed with an image containing a steganographically embedded URL. The package also includes an NFC/BLE IoT sensor that detects when the package is opened. When a user scans the image with a smartphone, the decoded URL is sent to a server. The server first queries the IoT sensor's state via the network. If the package has been previously opened, the URL redirects to a warning page about potential tampering. If unopened, it redirects to the product's authentic verification page. Each scan and its outcome (tampered/untampered) is logged as a transaction on a private blockchain, creating an immutable audit trail for the product's lifecycle from factory to consumer.

• Mermaid.js Diagram:

  sequenceDiagram
      actor User
      participant PhoneApp
      participant ProductPackage
      participant VerificationServer
      participant Blockchain
  
      User->>PhoneApp: Scan Image on Package
      PhoneApp->>PhoneApp: Decode Steganographic URL
      PhoneApp->>VerificationServer: Request URL
      VerificationServer->>ProductPackage: Query IoT Sensor State (e.g., via BLE)
      ProductPackage-->>VerificationServer: Return State (Opened/Sealed)
      alt State is Sealed
          VerificationServer->>Blockchain: Log "Verified" Transaction
          VerificationServer-->>PhoneApp: Redirect to Authentic Product Page
      else State is Opened
          VerificationServer->>Blockchain: Log "Tamper Warning" Transaction
          VerificationServer-->>PhoneApp: Redirect to Tamper Alert Page
      end
  

---

Combination Prior Art Scenarios

These scenarios combine the teachings of US 5,841,978 with existing, open-source standards to create novel systems that are now placed in the public domain.

3.1. Combination with QR Code Standard (ISO/IEC 18004)

• Concept: Redundant and Enhanced Data Linking via Hybrid Encoding.
• Enabling Description: An image contains a standard, visible QR code that links to a primary network address (e.g., a product's main webpage). The same image is also steganographically encoded with a secondary, different network address using the method of Rhoads '978. This secondary address could point to a high-security resource, such as a single-use login token, a direct download link for associated software, or a page with owner-specific information. An application designed to read this hybrid image would first read the QR code for general access. A separate, authenticated function within the same application would then process the full image to decode the steganographic link, providing a two-factor or privileged access route. The steganographic data's presence could be signaled by a specific pattern within the QR code's quiet zone, indicating to a compatible reader that a hidden layer of information exists.

3.2. Combination with the IIIF (International Image Interoperability Framework) Standard

• Concept: Dynamic, View-Specific Linking in Digital Archives.
• Enabling Description: High-resolution images served by a IIIF-compliant server in a museum or library archive are dynamically watermarked on-the-fly. The standard IIIF Image API allows users to request specific regions, sizes, and rotations of an image. When the server generates the requested derivative image, it steganographically embeds a URL unique to that specific request. This URL would point to a metadata record for the exact view the user requested (e.g., "the upper-left quadrant of folio 3, rotated 90 degrees"). If a user saves and shares this specific derivative image, the embedded link always resolves back to the original source and context in the archive, preserving provenance and preventing decontextualized use of cultural heritage objects. The steganographic payload would be the IIIF Image API syntax string that generated that specific view.

3.3. Combination with the WebRTC (Web Real-Time Communication) Open Standard

• Concept: Peer-to-Peer Data Validation via Live Video Steganography.
• Enabling Description: During a live, peer-to-peer video call established using WebRTC, one peer's client application steganographically embeds a checksum or hash of a shared document into the outgoing video stream. The receiving peer's client decodes this hash from the video frames in real-time. It then compares this received hash with a locally computed hash of its own version of the document. This provides a continuous, out-of-band verification that both parties are viewing the identical, unmodified document during the call. The network address embedded is not a URL but a data URI (data:;base64,...) containing the hash and a timestamp, making the verification self-contained within the media stream and not reliant on an external server. This ensures document integrity during sensitive remote collaborations or contract signings.