Transform domain watermarking of image signals

• US 20050036657A1
• Filed: 09/28/2004
• Published: 02/17/2005
• Est. Priority Date: 08/26/1997
• Status: Active Grant

• Current Assignee: Digimarc Corporation
• Original Assignee: Digimarc Corporation
• Inventors: Rodriguez, Anthony, Davidson, Clay, Rhoads, Geoffrey B.
• Granted Patent: US 7,139,408 B2
• Time in Patent Office: Days
• US Class Current: 382/100
• CPC Class Codes: G06T 1/0035 Output size adaptive watermarking
• CPC Class Codes: G06T 1/0064 Geometric transfor invariant watermarking, e.g. affine transform invariant
• 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 2201/0053 Embedding of the watermark in the coding stream, possibly without decoding; Embedding of the watermark in the compressed domain
• CPC Class Codes: G06T 2201/0061 Embedding of the watermark in each block of the image, e.g. segmented watermarking
• CPC Class Codes: G06V 30/40 Document-oriented image-based pattern recognition
• CPC Class Codes: G10L 19/018 Audio watermarking, i.e. embedding inaudible data in the audio signal
• CPC Class Codes: G11B 20/00884 involving a watermark, i.e. a barely perceptible transformation of the original data which can nevertheless be recognised by an algorithm
• CPC Class Codes: G11B 2020/10537 Audio or video recording
• 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 1/32122 in a separate device, e.g. in a memory or on a display separate from image data
• CPC Class Codes: H04N 1/32154 Transform domain methods H04N1/32309 takes precedence
• CPC Class Codes: H04N 1/32165 using cosine transforms
• CPC Class Codes: H04N 1/32187 with selective or adaptive application of the additional information, e.g. in selected frequency coefficients
• CPC Class Codes: H04N 1/32277 Compression
• 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 19/48 : using compressed domain processing techniques other than decoding, e.g. modification of transform coefficients, variable length coding [VLC] data or run-length data motion estimation in a transform domain H04N19/547; processing of decoded motion vectors H04N19/513
• CPC Class Codes: H04N 19/60 : using transform coding
• CPC Class Codes: H04N 19/61 : in combination with predictive coding
• CPC Class Codes: H04N 2005/91335 : the copy protection signal being a watermark
• 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 2201/3233 : 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 5/913 : for scrambling ; for copy protection

Abstract

The invention provides methods and related systems for embedding and detecting watermarks in images, such as JPEG or MPEG formatted images as well as other types of image signals. One method receives transform coefficients of the image, and changes the value of selected coefficients to embed watermark data in the coefficients. The changing of the coefficients is controlled such that it both embeds the data and forms an orientation signal that facilitates determination of rotation or scale of the image. Another aspect of the invention is a variation of embedding a watermark in an image. This method receives message bits to be embedded in the image, receives transform coefficients of the image, and maps the message bits to selected transform coefficients. The method changes the value of selected coefficients to embed data in the coefficients. The characteristics of the image are used to control the change of transform coefficients to embed the watermark, and a bit rate control is used to modify the change of transform coefficients to embed the watermark according to a bit rate limit.

Claims

1. A method of embedding a watermark in an image comprising:

receiving transform coefficients of the image;

changing the value of selected coefficients to embed multi-bit message data in the coefficients, the changing including controlling the changing of the coefficients such that the changing embeds the data and forms an orientation signal that facilitates determination of rotation or scale of the image.

2. The method of claim 1 wherein the transform coefficients comprise Discrete Cosine Transform coefficients.

3. The method of claim 1 wherein the transform coefficients are extracted from compressed image blocks.

4. The method of claim 1 wherein the data comprises message bits, and a message bit is mapped to selected transform coefficients.

5. The method of claim 4 wherein the change of the selected transform coefficients to embed the watermark is modified by a characteristic of the image.

6. The method of claim 4 wherein the change of the selected transform coefficients to the embed the watermark is modified to control bit rate of the image according to a bit rate limit.

7. The method of claim 1 wherein the orientation signal is formed by embedding message bits according to an embedding rule.

8. The method of claim 1 wherein the transform coefficients form part of a video.

9. A method of embedding a watermark in an image comprising:

receiving message bits to be embedded in the image;

receiving transform coefficients of the image;

mapping the message bits to selected transform coefficients;

changing the value of selected coefficients to embed data in the coefficients;

wherein characteristics of the image are used to control the change of transform coefficients to embed the watermark, and a bit rate control is used to modify the change of transform coefficients to embed the watermark according to a bit rate limit.

10. The method of claim 9 wherein each of the message bits are mapped to selected transform coefficients.

11. The method of claim 10 wherein the image comprises at least part of an MPEG video.