JP2003304386A - Electronic watermark information detecting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a means of increasing cases wherein insert information is correctly detected through information detection processing from image data into which the information is inserted through electronic watermark information insertion processing. <P>SOLUTION: Image data 101 are inputted and the watermark information inserted image data 103 are outputted through electronic watermark information insert image processing 102. The data become image data 105 to be examined about whether information is inserted as a watermark as it is or through image compression, image alteration 104, etc. After the examined image data 105 are preprocessed 106 using a direction-dependent smoothing filter, detected information 108 is outputted through the electronic watermark information detection processing 107. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital watermark information detecting technique for detecting insertion information from an image in which digital watermark information in which various information is embedded in image data is inserted.

[0002]

2. Description of the Related Art Copyright, sales date, sales destination,
The digital watermark insertion processing technology for inserting various kinds of information such as the sales source and the digital watermark technology including the digital watermark detection processing for detecting the insertion information from the image data in which the information is inserted are described in, for example, the following documents. .

Reference (1): Isao Echizen, etc; “Gen
eral Quality Maintenance Module for Motion Picture
Watermarking ”, Vol.45, No.4, pp.1150-1158 (1999). In the above literature (1), 4.3 Generality on page 1156.
(1) Still-picture An example in which information is embedded in a WM system (Standard system) and 40 bits of information is included in a basic unit of 2 * 2 pixels. The information is such that the brightness of the image is increased or decreased with 2 * 2 pixels as one unit, and quasi-random noise is added to the image as a whole.

In the present invention, the information inserting process and the information detecting process of the digital watermark described in the above-mentioned document (1) can be used as they are.

[0005]

In the above prior art, when the insertion information is detected by the information detection processing from the image in which the information is inserted by the digital watermark information insertion processing, there is a change in luminance depending on the form such as the edge portion of the image. In some cases, the inserted information cannot be read correctly because it cannot be distinguished from the brightness change due to the watermark insertion information.

[0006]

According to the present invention, it is possible to accurately detect the information by reflecting the influence of the brightness change depending on the form of the image to a small extent and creating a preprocessed image in which the ratio of the brightness change due to the watermark insertion information is large. Provide the technology to increase the case.

The present invention uses a direction-dependent smoothing filter as a pre-process of the information detection process when detecting information from an image in which digital watermark information is inserted.

That is, the following processing is performed as preprocessing. Image data to be inspected for checking whether information is inserted is used as input image data, and smoothed image data is created by smoothing this input image data with a direction-dependent smoothing filter, and the input image data and the smoothing process are performed. A process of using difference image data of the obtained image data as output image data is referred to as preprocessing. The direction-dependent smoothing filter is described in the following document (2).
It is described in.

Reference (2): Kunihiko Kido, et al., “Image quality improvement of MRI images using direction-dependent filter”, IEICE Transactions (D-II), vol.J79-D-II, no.8. , Pp.1347-135
3 (1996).

In the above-mentioned document (2), the minimum change direction in which the change in brightness is the smallest is found around each point of the image, and the data is smoothed only from the data in a predetermined pixel in the minimum change direction. The smoothing method is a weighted average depending on the deviation of the luminance value of the data in the direction of minimum change. When the change is large, the degree of smoothing decreases and the degree of referring to the original image increases.

By using the direction-dependent smoothing filter as described above, it is possible to obtain a smoothed image in which unevenness is reduced while leaving the image form. By taking the difference between the original image and the smoothed image, unevenness that does not depend much on the image form can be obtained as the difference image. The unevenness of the difference image is often due to the information inserted into the image by the digital watermark insertion processing, and if this difference image is used as the input image of the digital watermark information detection processing, correct information can be detected in many cases.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION In the present embodiment, there are digital watermark information insertion image processing for inserting desired information into image data and digital watermark information detection image processing for detecting insertion information from image data in which information is inserted. In the digital watermark image processing system, the image data to be inspected for inspecting whether information is inserted is preprocessed by using a direction-dependent smoothing filter. In the preprocessing, which is a feature of this embodiment, image data obtained by smoothing the image to be inspected is created, difference image data between the image data to be inspected and the smoothed image data is created, and this difference image data is used as the above information. This is the input image data for the detected image processing.

The electronic watermark inserting process and the information detecting process can be realized by creating and executing a program having the function on a computer. It can also be realized by creating hardware having a function equivalent to this. Similarly, the preprocessing of this embodiment can be realized as a program on a computer or as hardware.

The above program may be installed from another device via a storage medium or a communication medium.

The preprocessing of this embodiment can be independent software or hardware as preprocessing, or can be incorporated in the information detection processing.

The image data handled here may be image data captured by a digital camera, image data acquired by a scanner or the like, or video image captured by a video camera. For video images, for example, 30 per second
The images are taken in time series, one image per
Focusing on one sheet, it can be handled in the same manner as normal plane image data.

In the following, in section (1), the overall configuration of this embodiment will be described, and in section (2), the procedure of preprocessing, which is a feature of this embodiment, will be described. (1) Overall Configuration FIG. 1 is a diagram showing a first overall configuration of this embodiment.

Watermark information insertion image data 103 is output by digital watermark information insertion image processing 102 in which desired data is inserted using image data 101 as input data. The watermark information-inserted image data 103, as it is, or after being subjected to image compression, image tampering 104, etc., becomes the inspected image data 105 that is inspected whether the information is inserted as a watermark. The inspection image data 105 is subjected to preprocessing 106 using a direction-dependent smoothing filter, and then detection information 108 is output by the digital watermark information detection processing 107.

FIG. 2 shows a conventional overall structure. Comparing FIG. 1 and FIG. 2, the present embodiment is characterized in that it has a pre-processing 106 using a direction-dependent smoothing filter, and otherwise the conventional configuration can be used as it is.

FIG. 3 shows a second overall structure of this embodiment. The digital watermark information detection processing 307 integrated with the digital watermark information detection processing 107 is combined with the digital pre-processing 106 using the direction-dependent smoothing filter, which is a feature of this embodiment.
It shows the case of having as a configuration. In this case as well, the feature is that the preprocessing 106 using the direction-dependent smoothing filter is similarly provided. (2) Pre-Processing Procedure The processing procedure of the pre-processing 106 using the direction-dependent smoothing filter, which is a feature of this embodiment, will be described below using the numbers in FIG. 5 as step numbers. Step 501: Input inspected image data for inspecting whether information is inserted. Step 502: For each pixel of the image, a change in luminance value in each line direction is obtained centering on the pixel of interest. The line direction in the case of 3 * 3 pixels centered on the pixel of interest of the image is shown in FIG.
In FIG. 4, the line direction from the pixel 401 to the pixel 405 with respect to the pixel 400, the line direction from the pixel 402 to the pixel 406, the pixel 403
4 directions from the pixel 407 to the pixel 407 and the line direction from the pixel 404 to the pixel 408 are illustrated. The respective brightness changes in the above four directions are obtained. For example, for each pixel in each direction, the sum of the absolute values of the differences between the surrounding pixels and the central pixel 400 can be used as the luminance change. In this case, in the line direction from the pixel 401 to the pixel 405, the pixel 401
And the absolute value of the difference between the central pixel 400 and the absolute value of the difference between the pixel 405 and the central pixel 400 are the luminance change in the line direction from the pixel 401 to the pixel 405. Step 503: For each pixel of the image, obtain the minimum change direction with the smallest change in luminance. Step 504: For each pixel of the image, only the data in the direction of the minimum change of each pixel is referred to and smoothing processing is performed to create a smoothed image. For example, when the minimum change direction of the center pixel 400 is the line direction from the pixel 401 to the pixel 405, the process of obtaining the average value of the center pixel 400, the pixel 401, and the pixel 405 can be the smoothing process. There are various smoothing methods such as weighting. For example, there is a method described in the reference (2) in the above section. Step 505: Output the smoothed image.

The processing procedure of the direction-dependent smoothing filter is a processing procedure in which the direction-dependent direction-dependent smoothing filter is applied once, but the processing procedure performed twice is the same as the direction of this embodiment. It can also be used as the dependent filter use preprocessing 106. In the experiment, the one that uses the process of applying the direction-dependent smoothing filter twice, which refers to the data in the 3 * 3 pixel with the pixel of interest of the input image data as the center, has a great effect as the pre-process for correctly detecting the information.

[0022]

According to the present invention, the insertion information can be detected more correctly by the information detection processing from the image data in which the information is inserted.

[Brief description of drawings]

FIG. 1 is a diagram showing a first configuration example.

FIG. 2 is an overall configuration diagram of a conventional art.

FIG. 3 is a diagram showing a second configuration example.

FIG. 4 is a diagram showing pixels and directions of 3 * 3 pixels.

FIG. 5 is a diagram showing a processing procedure of a direction-dependent smoothing filter.

[Explanation of symbols]

101: image data, 102: digital watermark information insertion image processing,
103: Watermark information inserted image data, 105: Image data to be inspected, 106: Pre-processing using direction dependent smoothing filter, 1
07: Digital watermark information detection processing, 108: Detection information.

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Claims (2)

[Claims] 1. A digital watermark image processing system having digital watermark information insertion image processing for inserting desired information into image data and digital watermark information detection image processing for detecting existing information from image data into which existing information has been inserted. , Creates image data that is smoothed by the direction-dependent smoothing filter for the image data to be inspected to check whether information is inserted, and creates difference image data between the image data to be inspected and the smoothed image data. A method for detecting digital watermark information, characterized in that pre-processing is performed by using already-existing image data as input image data for the information detection image processing. 2. The direction-dependent smoothing filter according to claim 1, wherein a pixel of interest in the input image data is used as a center.
* 3 A digital watermark information detecting method characterized by using a process of applying a direction-dependent smoothing filter that refers to data in pixels twice.