Electrical computers and digital processing systems: support – Multiple computer communication using cryptography – Particular communication authentication technique
Reexamination Certificate
1999-07-28
2004-08-31
Hua, Ly V. (Department: 2135)
Electrical computers and digital processing systems: support
Multiple computer communication using cryptography
Particular communication authentication technique
C713S171000, C380S200000, C380S054000, C382S100000
Reexamination Certificate
active
06785814
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an information embedding method and apparatus for embedding information in original data such as image data by using a deep layer encryption method or the like and to a supplementary information reading method and apparatus for obtaining supplementary information related to a the original data based on the embedded information, and also to a computer-readable recording medium storing a program to cause a computer to execute the above methods.
The present invention also relates to an image processing method and apparatus, and more specifically, to a method and apparatus for processing the original data wherein the supplementary information related to the data has been embedded by using deep layer encryption.
2. Description of the Related Art
Various kinds of information such as image, audio, and movie data have been digitized, and data in various file formats exist, depending on a recording medium to store the data or on application software to use the data. For example, as formats for image data used on the Internet, JPEG, GIF, and FlashPix proposed by Eastman Kodak Co. have been known, and image data in a format suitable for the content of an image are exchanged. Following installation of infrastructure of such open networks, the chances of processing or using data via various kinds of recording media and applications have been growing. For example, the chances of repeatedly processing image data by using different applications or saving image data in various formats have been growing.
For this reason, it has been very useful to add information to data, in prospect of more complex and general usage of the data in an open network environment. For example, when image data obtained by a digital camera or the like are converted to output data such as a hard copy, ways in which the image data are manipulated are different depending on a photographed scene. In a case like this, if light source information of the photographed scene, such as color fog, under-exposure, over-exposure and the like, is known, appropriate image processing can be carried out on the image data, depending on the light source information. Furthermore, by adding a keyword to original data, various useful effects are expected, such as capability of a search for the original data after database compilation. Meanwhile, for print data used in the field of printing, information regarding process management such as an instruction of trimming or correction of an image and information as to which page the image belongs to is added to image data for publishing, and process management can be carried out by compiling the management information into a database.
How to add the supplementary information to original data is an issue to be considered. In reality, supplementary information is attached to an original data file as a file separate from the original data file, or written in a header of the original data file. However, in the former case, if various kinds of processing are carried out on the image data by various kinds of applications, or if format conversion is carried out, correspondence between the original data and the supplementary information may not be maintained. In the latter case, the supplementary information in the header cannot be read in some cases depending on application software, or the information written in the header may be lost as a result of carrying out format conversion after reading the data. In other words, the file header has a basic part and an extension part, and the supplementary information is included in the extension part which may be lost or altered by repeated writing or reading.
Meanwhile, various methods for embedding authentication information or copyright information in original data by using deep layer encryption have been proposed (see Japanese Unexamined Patent Publication Nos. 8(1996)-289159, 10(1998)-108180, 9(1997)-214636, for example). According to these methods, when the original data are image data for example, by embedding authentication information and copyright information in a redundant portion of the data, the information embedded in the data can be read and displayed by using an apparatus and software for reading the information, although the embedded information cannot be confirmed by simply reproducing the image data. This kind of deep layer encryption is described in detail in various references (for example, see K. Matsui, “Digital Watermark”, O Plus E No. 213, 1997).
As methods for this kind of deep layer encryption, methods of various types such as a pixel space utilizing type, a quantization error utilizing type, and a frequency range utilizing type have been known. The pixel space utilizing type takes out a plane of 3×3 pixels around a target pixel for example, and supplementary information is embedded in the surrounding 8 bits. The quantization error utilizing type pays attention to a quantization error which occurs in a process of compressing image data. Quantization output is regulated into even numbers and odd numbers by using 0 and 1 of a bit series of the supplementary information and the supplementary information is embedded in the image data as apparent quantization noise. “Video Steganography” (in Japanese) by K. Matsui published from Morikita Shuppan in 1993 has the details of the quantization error utilizing type. The frequency range utilizing type is a method of embedding supplementary information in a frequency range of an image area to which the human visual system is comparatively insensitive. For example, since a high frequency component in an image is the range wherein the human visual system is comparatively insensitive, supplementary information can be embedded by decomposing image data into a plurality of frequency bands so that the information can be embedded in the high frequency band and by reconstructing the image data thereafter. As a characteristic of the human visual system, sensitivity to color difference and to chroma information is generally lower than to luminance information. Therefore, a range wherein invisible recording is possible exists in a difference between the luminance and the color difference or between the luminance and the chroma information. Consequently, the supplementary information can be embedded in this range.
In addition to these methods, methods of embedding supplementary information in a bit plane having a low S/N ratio as an image by concealing the information in noise redundancy, or in redundancy of an information change in a pixel block (space) of a predetermined range, or in a quantization error occurring in the case of degeneracy of data amount due to coding for data compression, can be used, for example.
An information embedding method using information conversion redundancy of a pixel block in a density pattern for representing tones in a binary image will be explained next.
A density pattern method is a method of representing multi-valued tones by a binary bit map.
FIG. 16
is a diagram showing the case of representing tones by an area change of a unit, using 4 binary pixels as one unit. The number of tones Leq which can be represented by the specific number of bits L and n×n pixels can be expressed as follows:
Leq
=(
L
−1)
n
2
+1 (1)
Therefore, for the case shown in
FIG. 16
, 5 tones can be expressed. As is obvious from
FIG. 16
, as a pattern of showing one quantization level (the same tone), several patterns exist depending on which of the 4 pixels has a bit representing black. For example, there is only one pattern for the quantization levels
0
and
4
. However, the quantization levels
1
and
3
have 4 patterns each and the quantization level
2
has 6 patterns. In other words, since the number of patterns is determined by a combination arrangement of m black pixels and (n
2
−m) white pixels out of n
2
pixel arrangements, there are n
2
Cm patterns for one tone. By using these redundant pixel arrangement patterns for the same quantization level, other
Ito Wataru
Usami Yoshinori
Yoda Akira
Fuji Photo Film Co., LTD
Hua Ly V.
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