JP2000050193A - Method and device for generating digital image and storage medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To generate a digital image with high reliability and sufficient proofing ability. SOLUTION: A radio wave from a global positioning system(GPS) satellite 20 is received by a GPS receiving means 11 in the vicinity of a place where digital image data is generated, information S to indicate a position of a place of reception on the earth and/or time obtained based on the received radio wave is ciphered to a ciphered sentence (s) which is digitally signed by a generating means 13 for ciphered sentence with digital signature. The ciphered sentence (s) is embedded in image data D as in depth additional information which is impossible to be visually recognized when it is provided for image reproduction by an electronic watermark embedding means 14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for generating a digital image, and more particularly, to a method for generating a digital image having a high evidential ability and having information indicating a generation place and time of an image in a state in which it is difficult to falsify. And a method and apparatus for performing the method.

[0002] The present invention also relates to a storage medium storing software for executing the above-described digital image generation method.

[0003]

2. Description of the Related Art Generally, an image such as a photograph taken by a camera is often employed as evidence for some event. Not only photographs but also images generated by computer graphics or the like may be employed as evidence for claiming the copyright of the image itself.
When an image is employed as evidence in this way, it is always necessary to obtain reliable information indicating the generation time and location of the image (photographing time and location in the case of a photograph).

Many conventional cameras have a function of imprinting the date and time of photographing by a built-in clock on a photographing screen. If this function is used, it is possible to respond to a request for presenting an image generation time. is there.

A device for recording information indicating an image generation location together with an image has also been proposed. One example of such a device is disclosed in JP-A-5-224290.
An S (Global Positioning System) camera is used. The GPS-based camera receives radio waves from GPS satellites, obtains the position and time on the earth of the receiving location based on the received radio waves, and stores information on these positions and times on the recording medium of the camera, that is, a film or the like. It is to be recorded in.

The above-mentioned GPS information can be recorded optically on a film, or in a digital camera or the like, can be electronically recorded on a memory card or a floppy disk together with digital image data. In a so-called APS (Advanced Photo System) camera or the like, it is also possible to record on a magnetic recording layer of a film.

[0007]

However, in the case of a camera in which the date and time of shooting by the built-in clock are printed in the shooting screen, the shooting time can be easily forged by changing the built-in clock. Is not high enough.

In the case where GPS information is optically recorded on a film, there is a problem that the image quality is impaired because the information is printed in a photographic image. The same applies to the case where the shooting date and time are imprinted on the shooting screen.

In the case where the information of the camera built-in clock or the GPS information is electronically recorded on a memory card or the like, or in the case where it is recorded on a magnetic recording layer of a film, the problem that the image quality is deteriorated can be avoided. However, on the other hand, data by this type of recording method can be easily rewritten,
There is a problem of poor evidence capacity.

[0010] As a method of removing or falsifying related information from image data and attaching the image data to the image data, for example, as shown in Japanese Patent Application Laid-Open No. 9-191394,
A technique for embedding deep additional information called “digital watermark” is known. The deep additional information is embedded in a format that cannot be recognized by a normal human sense when the data in which it is embedded is used for its intended purpose. That is, for example, the deep additional information embedded in the image data includes, for example, a signal component corresponding to an extremely high spatial frequency so that the content indicated by the deep additional information is not visually recognized when the image data is used for image reproduction. Embedded.

It is conceivable to apply this digital watermarking technique to attach the GPS information and the like to the image data. However, it is also possible to insert a fake electronic watermark. Is not high enough.

The present invention has been made in view of the above circumstances, and has as its object to provide a method capable of generating a digital image having high reliability and sufficient evidential ability.

Another object of the present invention is to provide an apparatus for implementing such a digital image generation method.

[0014]

A digital image generating method according to the present invention receives a radio wave from a GPS satellite in the vicinity of a place where digital image data is being generated, and obtains a reception location obtained based on the received radio wave. After encrypting information indicating the position and / or time on the earth into a digitally signed ciphertext, the ciphertext is digitally watermarked, that is, visually recognizable when used for image reproduction. It is characterized by being embedded in the image data as deep additional information.

On the other hand, a digital image generating apparatus according to the present invention comprises means for generating digital image data, means for receiving a radio wave from a GPS satellite in the vicinity of the data generating means, and a receiving area obtained by the receiving means. Means for encrypting the information indicating the position and / or time on the earth into a digitally signed ciphertext, and using the ciphertext as deep additional information that is not visually recognizable when used for image reproduction. Means for embedding in image data.

The present invention also provides a storage medium storing software for executing the above-described digital image generation method.

The digital signature is, for example, “Comp
uter Today, 1998, 7, pp. 4-9, the signer encrypts data with a private key (signing key), and the signature verifier encrypts data with a public key (signature verifier). The system restores the encrypted data, and the signer is authenticated when the data can be encrypted.

[0018]

According to the digital image generation method of the present invention, since the GPS information is encrypted into a digitally signed cipher text, it is extremely difficult or practically impossible to falsify the GPS information. In addition, since the obtained encrypted text is digitally watermarked and embedded in the image data, it is extremely difficult or practically impossible to completely replace the GPS information. As described above, according to the method of the present invention, it is possible to obtain a digital image having highly reliable GPS information and highly evidential ability.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a digital image generating apparatus according to an embodiment of the present invention.

As shown in the figure, the digital image generating apparatus includes a digital image data generating means 10, a GPS receiving means 11 for receiving a radio wave from a GPS satellite 20, and a secret key (signature key) used in a digital signature. Secret key data holding means 12 for holding data, and information S indicating the position and time on the earth of the receiving location obtained by the receiving means 11
Is inputted, and a digital watermark embedding means 14 for receiving the cipher text s formed by the digital signature-added encryption generating means 13 is provided. The output of the digital watermark embedding unit 14 is output to a digital image output unit 15 such as a printer or a memory card.
To be entered.

The digital image generating apparatus of the present embodiment is, for example, a digital camera. The digital image data generating means 10 includes at least an image sensor such as a lens and a CCD, and an A / D converter for digitizing the output of the image sensor. It consists of a container and the like.

When photographing is performed using this digital camera, the digital image data generating means 10 outputs digital image data D carrying a photographed image. This digital image data D is transferred to the digital watermark embedding means 14.

The GPS receiving means 11 is installed in the camera body or attached to the camera body with an attachment so that the GPS receiving means 11 is not distant from the camera. The GPS receiving means 11 receives positioning radio waves emitted by a plurality of GPS satellites 20 orbiting the earth, obtains the position and time of the receiving place on the earth based on the received radio waves, and Or GP indicating time
The S information S is input to the digital signature-added encryption generating means 13.

The secret key data holding means 12 is, for example, a ROM (read only memory) built in the camera body.
, A camera manufacturer, a camera model, or a camera manufacturing number. The secret key data set for each is stored and held.

The digital signature-added encryption generating means 13 receives the data K relating to the secret key from the secret key data holding means 12 and uses this secret key as a signature key to convert the GPS information S into a digitally signed cipher text s. Encrypt. This cipher text s is transferred to the digital watermark embedding means 14.

The digital watermark embedding means 14 uses the cipher text s
Is embedded in the digital image data D as a digital watermark, that is, deep additional information that cannot be visually recognized when used for image reproduction.

When receiving the digital image data Ds in which the ciphertext s is embedded, the digital image output means 15 converts the image carried by the image data Ds, that is, the photographed image of the digital camera, into a medium such as a memory card as a file. Record or output in hard copy or other form. In this hard copy output image, the cipher text s embedded in the digital image data D as a digital watermark is invisible.

As described above, the digital image data Ds to be used for reproducing the photographic image is accompanied by the GPS information indicating the GPS radio wave receiving location, that is, the position on the earth of the photographing point, and the photographing time. Therefore, this photographic image can be adopted as evidence of various events related to the subject.

Since the GPS information is encrypted in the digitally signed ciphertext s, it is extremely difficult or practically impossible to falsify the GPS information. In addition, since the obtained encrypted text s is digitally watermarked and embedded in the digital image data D, it is extremely difficult or practically impossible to completely replace the GPS information. Therefore, the proof ability of the photographic image is extremely high.

The embodiment applied to the digital camera has been described above. However, the present invention is not limited to such a digital camera, and can be applied to, for example, a case where an image is generated by computer graphics.
And it has the same effect.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a digital image generation apparatus according to an embodiment of the present invention.

[Explanation of symbols]

 10 Digital image data generating means 11 GPS receiving means 12 Private key data holding means 13 Encryption means with digital signature 14 Digital watermark embedding means 15 Digital image output means 20 GPS satellite

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Claims (4)

[Claims] 1. A radio wave from a GPS satellite is received in the vicinity of a place where digital image data is generated, and information indicating the position and / or time of the receiving place on the earth obtained based on the received radio wave is obtained. A digital image generation method, comprising: encrypting a digitally signed ciphertext; and embedding the ciphertext in the image data as deep additional information that cannot be visually perceived when used for image reproduction. 2. A storage medium storing software for executing the digital image generation method according to claim 1. Means for generating digital image data; means for receiving radio waves from GPS satellites in the vicinity of the data generating means; and the position and / or location of the receiving place on the earth obtained by the receiving means. Means for encrypting information indicating a time into a digitally signed cipher text; and means for embedding the cipher text in the image data as deep additional information that is visually unrecognizable when provided for image reproduction. A digital image generation device characterized by the above-mentioned. 4. The digital camera according to claim 3, wherein said means for generating digital image data comprises a digital camera, and said camera stores a secret key for performing said encryption. Digital image generation device.