Method and apparatus for superposing a digital watermark and method and apparatus for detecting a digital watermark

• US 20020015509A1
• Filed: 04/09/2001
• Published: 02/07/2002
• Est. Priority Date: 09/17/1997
• Status: Active Grant

• Current Assignee: Kazumi Sugaya, Takeshi Nakamura, Yoshiaki Moriyama
• Original Assignee: Kazumi Sugaya, Takeshi Nakamura, Yoshiaki Moriyama
• Inventors: Nakamura, Takeshi, Moriyama, Yoshiaki, Sugaya, Kazumi
• Granted Patent: US 6,389,152 B2
• Time in Patent Office: Days
• US Class Current: 382/100
• CPC Class Codes: G06T 1/0064 Geometric transfor invariant watermarking, e.g. affine transform invariant
• CPC Class Codes: G06T 1/0071 using multiple or alternating watermarks
• 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: H04N 1/32149 Methods relating to embedding, encoding, decoding, detection or retrieval operations
• CPC Class Codes: H04N 1/32165 using cosine transforms
• CPC Class Codes: H04N 1/32203 Spatial or amplitude domain methods H04N1/32309 takes precedence
• CPC Class Codes: H04N 1/32208 involving changing the magnitude of selected pixels, e.g. overlay of information or super-imposition H04N1/32219, H04N1/32224 take precedence
• 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 19/467 characterised by the embedded information being invisible, e.g. watermarking
• CPC Class Codes: H04N 19/60 using transform coding
• 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 2201/3233 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

Abstract

An apparatus for superposing a digital watermark for superposing digital watermark information on an information data signal bearing original information superposes digital watermark information on an information data signal bearing original information, for each unit block consisting of a group of pieces of information data. This apparatus is provided with an auxiliary embedding circuit 10 for embedding second digital watermark information in the information data; a blocking circuit 12 for dividing into the unit blocks the changed information data signal obtained by the auxiliary embedding circuit; and a main embedding circuit 20 for embedding first digital watermark information in the changed information data signal for each of the divided blocks. The second digital watermark information bears information for identifying the position of the divided unit block in a predetermined section of the information data signal. On the basis of the second watermark information, a detecting apparatus effects proper blocking with respect to the information data signal with the watermark embedded therein, so as to detect the first watermark information.

Claims

1. A method for superposing a digital watermark for superposing digital watermark information on an information data signal bearing original information, for each unit block consisting of a group of pieces of information data, comprising the steps of:

embedding second digital watermark information in the information data;

dividing the changed information data signal thereby obtained into the unit blocks; and

embedding the first digital watermark information in the changed information data signal for each of the divided blocks,

wherein the second digital watermark information bears information for identifying a position of the divided unit block in a predetermined section of the information data signal.

2. The method for superposing a digital watermark according to claim 1, wherein the information data signal is a video signal.

3. An apparatus for superposing a digital watermark for superposing digital watermark information on an information data signal bearing original information, for each unit block consisting of a group of pieces of information data, comprising:

auxiliary embedding means for embedding second digital watermark information in the information data;

blocking means for dividing into the unit blocks the changed information data signal obtained by said auxiliary embedding means; and

main embedding means for embedding first digital watermark information in the changed information data signal for each of the divided blocks,

wherein the second digital watermark information bears information for identifying a position of the divided unit block in a predetermined section of the information data signal.

4. The apparatus for superposing a digital watermark according to claim 3, wherein the information data signal is a video signal.

5. The apparatus for superposing a digital watermark according to claim 3 or 4, wherein the second watermark information is information of a random pattern generated on the basis of an M-sequence.

6. A method for detecting a digital watermark for detecting digital watermark information from a changed information data signal generated by superposing the digital watermark information on an information data signal, for each unit block consisting of a group of pieces of information data, comprising the steps of:

detecting second digital watermark information from the changed information data signal, and recognizing a position of a divided unit block in a predetermined section of the information data signal;

dividing the changed information data signal on the basis of the recognized position into the unit blocks; and

detecting first digital watermark information for each of the divided unit blocks from the changed information data signal.

7. The method for detecting a digital watermark according to claim 6, wherein the information data signal is a video signal.

8. An apparatus for detecting a digital watermark for detecting digital watermark information from a changed information data signal generated by superposing the digital watermark information on an information data signal, for each unit block consisting of a group of pieces of information data, comprising the steps of:

position-identifying-information detecting means for detecting second digital watermark information from the changed information data signal, and recognizing a position of a divided unit block in a predetermined section of the information data signal;

blocking means for dividing the changed information data signal on the basis of the recognized position into the unit blocks; and

information detecting means for detecting from the changed information data signal first digital watermark information for each of the unit blocks divided by said blocking means.

9. The apparatus for detecting a digital watermark according to claim 8, wherein the information data signal is a video signal.

10. The apparatus for detecting a digital watermark according to claim 9, wherein the video signal bears an image of a letter box type.

11. The apparatus for detecting a digital watermark according to claim 9, wherein the video signal bears an image of a pan scan type.

12. The apparatus for detecting a digital watermark according to any one of claims 8 to 11, wherein said position-identifying-information detecting means detects the second digital watermark information from the changed information data signal on the basis of information of a random pattern generated in accordance with an M-sequence.