Data processing apparatus and data recording media

Details Data processing apparatus and data recording media Data processing apparatus and data recording media

1999-10-08

2003-03-04

Hsu, Alpus H. (Department: 2662)

Multiplex communications

Pathfinding or routing

Switching a message which includes an address header

C370S469000, C382S100000, C713S176000, C725S087000, C725S098000

Reexamination Certificate

active

06529506

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to data processing apparatuses and data recording media and, more particularly, to a process of embedding a watermark (information to be embedded) in digital data such as audio data obtained by electronic distribution or from recording media, by using a specific watermarking method such as a watermarking method employed for versatile data reproduction apparatuses.
BACKGROUND OF THE INVENTION
In recent years, with the progress of digitization of video data and audio data, the facility of forming a perfect copy of original digital data has become a great problem.
As a countermeasure against such problem, a watermarking technique has been employed. The watermarking technique is described in detail in Japanese Published Patent Applications Nos. Hei.9-191394 and Hei.9-191395.
The watermarking technique is not a direct method for preventing original digital data to be reproduced, such as video data or audio data, from being copied, but a method for restricting copying of the original digital data by embedding copyright information relating to the copyright for the digital data, in the digital data.
For example, by embedding, as a watermark, copyright information indicating the name of the copyright holder (information source) in digital data such as video data and audio data, the copyright information (watermark) is copied when the digital data is copied. Therefore, when the copyright holder has found digital data (video data or audio data) formed by illegal copying, the copyright holder can prove the illegality by using the copyright information embedded in the digital data.
Hereinafter, the watermarking technique will be described with reference to FIG.
18
.
FIGS.
18
(
a
) and
18
(
b
) are diagrams for explaining, as an example of a watermarking technique for video, a process of embedding information relating to the copyright holder of digital video data (relevant information Dwmi) in digital video data to be supplied from the distribution end to the user (supply digital data). Hereinafter, this relevant information is called “watermark” or “embedded information”.
To simplify the description, as shown in FIG.
18
(
a
), it is assumed that an image F is a gray-scale still picture, and its size is vertical 50 pixels×horizontal 50 pixels. Further, each of pixels P constituting the image F takes an integral value within a range from 0 to 99, as a luminance level (pixel value) indicating its brightness.
In the watermark embedding process, initially, the image F is divided into a plurality of blocks B each comprising a predetermined number of pixels (vertical 10 pixels×horizontal 10 pixels). That is, the original still picture F is divided into 25 blocks (vertical 5 blocks×horizontal 5 blocks) as shown in FIG.
18
(
b
). At this time, the pixel values constituting image data corresponding to each block (sub-imaqe) B are represented as the values of the respective components of a matrix of 10 rows×10 columns.
Next, this matrix is subjected to DCT (Discrete Cosine Transform) to obtain a transformed matrix of 10 rows×10 columns. The numerical values arranged at the lower-right portion of the transformed matrix are values which represent the high-frequency components of the image data corresponding to the original image.
By the way, it is known that the human sense of sight is less responsive to change of high-frequency components of image data than to change of low-frequency components thereof. In other words, even if the original image is subjected to image processing for changing the values of the high-frequency components to slightly different values, it is very difficult for the human sense of sight to recognize the difference between the processed image (reconstructed image) and the original image. The reconstructed image is, to be specific, an image corresponding to image data reconstructed from an inversely-transformed matrix which is obtained by subjecting the transformed matrix to inverse DCT.
The watermarking technique for video utilizes the above-described characteristics of human sight, and it is able to embed information in the image data corresponding to the original image, by controlling the high-frequency components of the original image, without making the viewer sense the degradation of the image quality.
Although the watermarking technique for video has been described above, there is a watermarking technique for audio. Further, there is a watermarking technique which is able to extract or remove information from video data or audio data in which the information is embedded.
Moreover, according to the watermarking technique, when digital data recorded in a digital recording medium is copied to another digital recording medium, information embedded in the digital data can be copied as well. Further, when the digital data recorded in the digital recording medium is once converted to analog data by a DA converter and then recorded in an analog recording medium, the embedded information can be held in the analog data recorded in the analog recording medium.
Hereinafter, a description will be given of the watermarking technique for audio.
FIG. 19
is a diagram conceptually illustrating an information embedding process and an information extracting process for digital audio data.
With reference to
FIG. 19
, signature data (information to be embedded) is embedded in digital audio data recorded as an audio data file ODau (signature data embedding process Pad), and then the digital audio data in which the signature data is embedded is recorded as a signature-data-embedded audio data file SDau.
The signature data Dwmx embedded in the digital audio data is extracted in accordance with the digital audio data which is recorded as the audio data file ODau and the digital audio data which is recorded as the signature-data-embedded audio data file SDau (signature data extraction process Pex).
FIG. 20
is a flowchart of the information embedding process.
Initially, digital audio data is subjected to blocking (step S
1
). This process is to divide the digital audio data into a plurality of data groups (blocks) each comprising a predetermined number of sampling data, for convenience in the subsequent process.
Next, each block is subjected to the Fourier transform (step S
2
). The arithmetic operation for the Fourier transform will be later described in detail.
Thereafter, the following data transform is carried out as the watermark (information to be embedded) embedding process.
The watermark is composed of multiple bits of digital data (signature data), and each bit of the signature data corresponds to each block.
Initially, it is confirmed that the value of each bit as a component of a block string (bit string) of the signature data is “0” or “1” (step S
3
). A block corresponding to a bit of “0” is not subjected to the watermark embedding process. A block corresponding to a bit of “1” is subjected to the watermark embedding process, wherein an imaginary part and a real part of a function which has been obtained by subjecting the audio data corresponding to this block to the Fourier transform (hereinafter, referred to as a Fourier transformed function), are replaced with each other, and the real part is multiplied with −1 (step S
4
). This process is performed for each block.
Then, the Fourier transformed function corresponding to each block is subjected to the inverse Fourier transform (step S
5
). Thereby, audio data of each block is restored. The inverse Fourier transform will be later described in more detail.
Through the above-described processes, information to which a normal human ear does not respond is embedded in the audio data.
Hereinafter, the respective processes of the watermarking technique will be described in more detail.
Initially, the Fourier transform and the inverse Fourier transform will be briefly described. The Fourier transform employed in the process of embedding a watermark (information to be embedded) is called “discrete Fourier transform” which is defined as follows.

Affiliated with

Also associated with

Rating

Data processing apparatus and data recording media does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Data processing apparatus and data recording media, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Data processing apparatus and data recording media will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3037266