Device and method for processing image data, transmitting medium, and recording medium

• US 6,341,350 B1
• Filed: 09/01/1998
• Issued: 01/22/2002
• Est. Priority Date: 09/02/1997
• Status: Expired due to Fees

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Yagasaki, Yoichi, Miyahara, Nobuyoshi
• Primary Examiner(s): Peeso, Thomas R.
• Application Number:
  US09/144,855
• Time in Patent Office: 1,239 Days
• Field of Search: 713/176, 713/178, 713/179
• US Class Current: 713/176
• CPC Class Codes: G06T 1/005 Robust watermarking, e.g. average attack or collusion attack resistant
• CPC Class Codes: G06T 2201/0065 Extraction of an embedded watermark; Reliable detection
• CPC Class Codes: H04N 19/467 characterised by the embedded information being invisible, e.g. watermarking
• 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

Abstract

A device and method for processing image data, a transmitting medium, and a recording medium are disclosed. More particularly, in image data processing by which accompanying information is embedded as a watermark into coded image data, a position in a block as a unit of coding the coded image data is detected, a blocked watermark pattern is provided, an area in which an operation relative to a first level value is performed and an area in which an operation relative to a second level value is performed are offered, and a watermark is appended to the coded image data in accordance with the blocked watermark pattern. It is thus possible to easily append a watermark that can be certainly detected.

Claims

1. An image processing device for embedding a watermark into encoded image data, comprising:

an encoder for encoding input image data into encoded image data; and

a watermarking device for embedding said watermark into the encoded image data in accordance with an accompanying information signal, said watermarking device comprising;

a decoder for partially decoding said encoded image data to locate a position within said encoded image data to embed said watermark;

a watermark image generator for setting a first watermark value and a second watermark value to predetermined values in accordance with said accompanying information signal;

a watermark pattern matching controller for selecting an area within said encoded image data starting at said position located by said decoder and corresponding to a blocked watermark pattern; and

said watermark image generator embedding said watermark by modifying each pixel of said encoded image data within the selected area by said first watermark value or said second watermark value on the basis of said blocked watermark pattern.

2. The image processing device according to claim 1, wherein said watermarking device further comprises a watermark pattern holding memory for storing a watermark pattern;

and said watermark pattern matching controller enlarges said watermark pattern into said blocked watermark pattern.

3. The image processing device according to claim 2, wherein said blocked watermark pattern has a vertical length that is an integral multiple of a minimum encoded block size.

4. The image processing device according to claim 1, wherein said encoded image data comprises fixed length blocks and said watermark is embedded in said fixed length blocks.

5. The image processing device according to claim 4, wherein said input image data is encoded into said fixed length blocks by a discrete cosine transform, and said watermark is embedded into fixed length blocks corresponding to a direct current component or a motion vector component of the encoded image data.

6. The image processing device according to claim 1, wherein said input image data is encoded using differential pulse code modulation and said watermark image generator compensates for mismatched differential values that occur when embedding said watermark.

7. The image processing device according to claim 1, wherein said watermarking device further comprises an overappendage discriminator for calculating an allowable appendage amount on the basis of said encoded image data;

and said watermark image generator sets said first watermark value and said second watermark value to appendage values on the basis of said allowable appendage amount and said accompanying information signal.

8. An image processing method of embedding a watermark into encoded image data, comprising the steps of:

encoding input image data into encoded image data; and

embedding said watermark into the encoded image data in accordance with an accompanying information signal by;

partially decoding said encoded image data to locate a position within said encoded image data to embed said watermark;

setting a first watermark value and a second watermark value to predetermined values in accordance with said accompanying information signal;

selecting an area within said encoded image data starting at said position located by said partially decoding step and corresponding to a blocked watermark pattern; and

embedding said watermark by modifying each pixel within the selected area of said encoded image data by said first watermark value or said second watermark value on the basis of said blocked watermark pattern.

9. The image processing method according to claim 8, wherein said embedding step further comprises retrieving a watermark pattern stored in a watermark pattern holding memory and enlarging said watermark pattern into said blocked watermark pattern.

10. The image processing method according to claim 9, wherein said blocked watermark pattern has a vertical length that is an integral multiple of a minimum encoded block size.

11. The image processing method according to claim 8, wherein said encoded image data comprises fixed length blocks and said watermark is embedded in said fixed length blocks.

12. The image processing method according to claim 11, wherein said input image data is encoded into said fixed length blocks by a discrete cosine transform, and said watermark is embedded into fixed length blocks corresponding to a direct current component or a motion vector component of the encoded image data.

13. The image processing method according to claim 8, wherein said input image data is encoded using differential pulse code modulation and said embedding step compensates for mismatched differential values that occur when embedding said watermark.

14. The image processing method according to claim 8, wherein said embedding step further comprises calculating an allowable appendage amount on the basis of said encoded image data;

and said watermark image generator sets said first watermark value and said second watermark value to appendage values on the basis of said allowable appendage amount and said accompanying information signal.

15. A watermark detector for detecting a watermark embedded in encoded image data, comprising:

a decoder for partially decoding said encoded image data to locate a position within said encoded image data for detecting said watermark;

an estimation value calculator for calculating an estimation value and a threshold value;

a watermark pattern matching controller for selecting an area within said encoded image data starting at said position located by said decoder and corresponding to a blocked watermark pattern; and

an estimation value comparator for adjusting said estimation value on the basis of a comparison between each pixel of said encoded image data within the selected area and said blocked watermark pattern;

comparing the adjusted estimation value with said threshold value to determine the presence of said watermark; and

outputting an accompanying information signal indicating the presence of said watermark; and

a code converter for processing said encoded image data to enable decoding of said encoded image data on the basis of said accompanying information signal.

16. The watermark detector according to claim 15, further comprising a watermark pattern holding memory for storing a watermark pattern;

and said watermark pattern matching controller enlarges said watermark pattern into said blocked watermark pattern.

17. The watermark detector according to claim 16, wherein said blocked watermark pattern has a vertical length that is an integral multiple of a minimum encoded block size.

18. The watermark detector according to claim 15, wherein said estimation value calculator calculates said estimation value on the basis of the pixel values of said encoded image data within the selected area corresponding to said blocked watermark pattern.

19. A method of detecting a watermark embedded in encoded image data, comprising the steps of:

partially decoding said encoded image data to locate a position within said encoded image data for detecting said watermark;

calculating an estimation value and a threshold value;

selecting an area within said encoded image data starting at said position located in said partially decoding step and corresponding to a blocked watermark pattern; and

adjusting said estimation value on the basis of a comparison between each pixel of said encoded image data within the selected area and said blocked watermark pattern;

comparing the adjusted estimation value with said threshold value to determine the presence of said watermark; and

outputting an accompanying information signal indicating the presence of said watermark; and

processing said encoded image data to enable decoding of said encoded image data on the basis of said accompanying information signal.

20. The method according to claim 19, further comprising the steps of retrieving a watermark pattern stored in a watermark pattern holding memory and enlarging said watermark pattern into said blocked watermark pattern.

21. The method according to claim 20, wherein said blocked watermark pattern has a vertical length that is an integral multiple of a minimum encoded block size.

22. The method according to claim 19, wherein said calculating step calculates said estimation value on the basis of the pixel values of said encoded image data within the selected area corresponding to said blocked watermark pattern.