Variable message coding protocols for encoding auxiliary data in media signals

• US 20030033530A1
• Filed: 07/10/2002
• Published: 02/13/2003
• Est. Priority Date: 05/16/1996
• Status: Active Grant

• Current Assignee: Digimarc Corporation
• Original Assignee: Digimarc Corporation
• Inventors: Sharma, Ravi K., Rhoads, Geoffrey B., Bradley, Brett A.
• Granted Patent: US 7,412,072 B2
• Time in Patent Office: Days
• US Class Current: 713/176
• CPC Class Codes: G06T 1/0021 Image watermarking
• CPC Class Codes: G06T 1/005 Robust watermarking, e.g. average attack or collusion attack resistant
• CPC Class Codes: G06T 2201/0051 Embedding of the watermark in the spatial domain
• CPC Class Codes: G06T 2201/0052 Embedding of the watermark in the frequency domain
• CPC Class Codes: G06T 2201/0061 Embedding of the watermark in each block of the image, e.g. segmented watermarking
• CPC Class Codes: G06T 2201/0065 Extraction of an embedded watermark; Reliable detection
• CPC Class Codes: G06T 2201/0601 whereby calibration information is embedded in the watermark, e.g. a grid, a scale, a list of transformations
• CPC Class Codes: G06V 30/40 Document-oriented image-based pattern recognition
• CPC Class Codes: H04N 1/00005 relating to image data
• CPC Class Codes: H04N 1/00037 Detecting, i.e. determining the occurrence of a predetermined state H04N1/00031 takes precedence
• CPC Class Codes: H04N 1/00079 remotely
• CPC Class Codes: H04N 1/00127 Connection or combination of a still picture apparatus with another apparatus, e.g. for storage, processing or transmission of still picture signals or of information associated with a still picture
• CPC Class Codes: H04N 1/32122 in a separate device, e.g. in a memory or on a display separate from image data
• CPC Class Codes: H04N 1/32144 embedded in the image data, i.e. enclosed or integrated in the image, e.g. watermark, super-imposed logo or stamp
• CPC Class Codes: H04N 1/32352 Controlling detectability or arrangements to facilitate detection or retrieval of the embedded information, e.g. using markers for decoding, detection or retrieval operations H04N1/32149 and subgroups take precedence
• CPC Class Codes: H04N 21/23892 involving embedding information at multiplex stream level, e.g. embedding a watermark at packet level
• CPC Class Codes: H04N 21/8358 involving watermark protecting executable software by watermarking G06F21/16; image watermarking in general G06T1/0021; watermarks inserted in still images for transmission purposes H04N1/32144; inserting watermarks during video coding H04N19/467
• CPC Class Codes: H04N 2201/3205 of identification information, e.g. name or ID code H04N2201/3209 takes precedence
• CPC Class Codes: H04N 2201/3207 of an address
• CPC Class Codes: H04N 2201/3225 of data relating to an image, a page or a document
• CPC Class Codes: H04N 2201/3226 : of identification information or the like, e.g. ID code, index, title, part of an image, reduced-size image
• CPC Class Codes: H04N 2201/3233 : of authentication information, e.g. digital signature, watermark
• CPC Class Codes: H04N 2201/327 : which are undetectable to the naked eye, e.g. embedded codes
• CPC Class Codes: H04N 2201/3271 : Printing or stamping
• CPC Class Codes: H04N 2201/3274 : Storage or retrieval of prestored additional information
• CPC Class Codes: H04N 2201/328 : Processing of the additional information

Abstract

Variable message coding protocols enable greater flexibility in encoding auxiliary data in media signals. One such protocol employs a version identifier that indicates the type of coding used to process an auxiliary data message before it is embedded in a host media signal. This version identifier specifies the type of error robustness coding applied to a variable message. The error robustness coding may be varied to alter the message payload capacity for different versions of auxiliary data embedding and reading systems. Another protocol uses control symbols to specify the format and variable length of the variable message.

Claims

1. A message protocol method comprising:

forming a fixed message protocol portion having a fixed length and identifying a version of a variable protocol portion;

forming the variable message protocol portion having variable error robustness message coding format, wherein the version indicates the error robustness coding format of the variable protocol portion; and

embedding message symbols of the fixed and variable message protocol portions into a host media signal such that the message is substantially imperceptible in the host media signal.

2. The method of claim 1 wherein the error robustness coding format includes error correction coding.

3. The method of claim 2 wherein the error robustness coding format includes repetition coding of an error correction coded message.

4. The method of claim 3 wherein the repetition coding repeats certain error correction coded symbols differently than other error correction coded symbols.

5. The method of claim 1 wherein the fixed message portion includes fixed message symbols along with one or more variable symbols indicating the version of the variable protocol portion.

6. The method of claim 1 wherein the version indicates one or more parameters of the error robustness message coding format.

7. The method of claim 6 wherein the one or more parameters include a parameter of an error correction coding method.

8. The method of claim 6 wherein the version indicates a number of symbols in the variable protocol portion before the symbols are error robustness coded.

9. The method of claim 6 wherein the one or more parameters include a repetition indicator specifying a number of repetitions of a message in the variable protocol portion.

10. A computer readable medium on which is stored instructions for performing the method of claim 1.

11. A method of decoding a digital watermark having fixed and variable protocol message portions, the method comprising:

extracting a hidden message code embedded in a host media signal by evaluating the host media signal to compute the hidden message code having the fixed and variable message protocol portions;

performing error robustness decoding of the fixed protocol portion of the extracted message code to produce one or more message symbols representing a version identifier;

interpreting the version identifier to ascertain a version of variable protocol used to embed the variable protocol portion; and

applying an error robustness decoding method of the version to decode message symbols of the variable message protocol portion.

12. The method of claim 11 wherein the error robustness decoding method includes error correction decoding specified by the version.

13. The method of claim 11 wherein the error robustness decoding includes a particular format of repetition coding specified by the version.

14. A message protocol method for steganographically encoding a variable message into a media signal, the method comprising:

forming a control message portion including at least one symbol that identifies the format of the variable message;

forming a variable message according to the format, wherein the format indicates a variable length of the variable message portion; and

producing a media signal with the variable message steganographically encoded in the media signal such that the variable message is not discernable by a human but is readable by an automated reader.

15. The method of claim 14 wherein the format indicates how the variable message is repeated within the media signal.

16. The method of claim 15 wherein the format indicates how the variable message is repeated within a block of the media signal, wherein the block has a fixed size.

17. The method of claim 16 wherein the variable message is encoded into the fixed size blocks, which are tiled across the media signal.

18. The method of claim 14 wherein the media signal comprises an image.

19. The method of claim 14 wherein the variable message carries information related to the media signal in which it is encoded.

20. A computer readable medium on which is stored instructions for performing the method of claim 14.