Abstract: An encrypting device generates an encrypted image by converting an image of a specified region in an input image with an encryption key, by embedding information obtained by encrypting the encryption key with a public key pairing with the private key of a destination, and by performing pixel value conversion. Then, the encrypted image is transmitted to the destination as a printed matter or via a network. A decrypting device converts the encrypted image in the form of print data or electronic data into an image, and inputs it. Next, the decrypting device extracts a decryption key (the encryption key) from the image of the encryption region by executing a process reverse to that of the encrypting device for the encryption region of the converted encrypted image. Then, the decrypting device decrypts the original image of the encrypted region by using the decryption key, and restores the entire encrypted image.

Abstract: An encrypting device encrypts original document data by use of a password of an addressee, thereby generating encrypted document data. A decryption authority changing device, of which operating authority is held by the addressee, generates authority changing information M structured by encrypting the password of the addressee with a password of a proxy, and notifies a decrypting device of the information, of which the operating authority is held by the proxy. The decrypting device decrypts the password of the addressee by employing the password of the proxy, and decrypts the encrypted document data by use of the decrypted password of the addressee.

Abstract: An image encryption apparatus encrypts a digital image by specifying a partial region from the digital image, converting the selected partial region into a processing image based on an encryption key, and specifying a position of the partial region by regularly converting a pixel value of the processing image.

Abstract: In order to encrypt a part of an input image in such a manner that the encrypted part can be located for decryption, means for regularly converting pixel values in the area to be encrypted and generating a pattern unique to the pixel value conversion in order to encrypt the area to be encrypted; means for setting a specified positioning marker for locating an encryption position at two or more of the four corners of the area to be encrypted; and means for setting one or more checking marks for verifying appropriateness of a decrypted image in the encrypted area before the decryption are included.

Abstract: An image processing apparatus sections an image to be processed into a plurality of blocks, rearranges the blocks into positions specified by an encryption key that uniquely specifies the positions of the blocks in the image, determines a computing method used to convert pixel values of pixels that form a minimum area included in each of the blocks after the blocks are rearranged based on the pixel values of predetermined pixels that do not belong to the minimum area, and converts the pixel values based on the computing method.

Abstract: In an image encryption apparatus, each of pixel-value inverse-converters applies pixel-value inverse-conversion on an input image in each of previously-encrypted areas. An image combiner superimposes images with inversely-converted pixels in the previously-encrypted areas to the input image to obtain a ready-to-encrypt image. An image encryptor scrambles blocks in the ready-to-encrypt image. A pixel-value converter applies pixel-value conversion on each of scrambled blocks to obtain a multiply-encrypted image. In an image decryption apparatus, a pixel-value inverse-converter applies pixel-value inverse-conversion on each scrambled block in the multiply-encrypted image to obtain a dot-erased image. An image decryptor inversely scrambles the scrambled blocks in the dot-erased image to obtain a decrypted image. Each of pixel-value converters applies pixel-value conversion on the decrypted image in each of previously-encrypted areas.

Abstract: In an image encryption apparatus for visually encrypting an input image, an encryption area selector selects an encryption area within an input image including an area to be encrypted. An image converter divides the encryption area into a plurality of blocks. The image converter divides each block of the encryption area into a plurality of sub-blocks. An image converter performs an image conversion including rotation and mirror-reverse in accordance with an encryption key on the image in each sub-block. The image converter scrambles the image on a block-by-block basis in accordance with the encryption key. A pixel value converter converts a pixel value of a minimal area in a block so that a position of the block may be detected.

Abstract: A display processor displays on a display screen an encrypted image accepted by an image data acceptor. An encrypted region acquirer extracts encrypted regions contained on the encrypted image. A target region selector or an authorized target region selector selects decryption target regions from among encrypted regions contained in the encrypted image. A decryption order determiner determines a decryption order of the decryption target regions. The display processor displays on the display screen a prompt for inputting a decryption key (or a password) used for decryption of the encrypted image in each of the decryption target regions in accordance with the decryption order. A decryption key acceptor accepts the decryption key input by a decryption user. An image decryptor performs a decryption process on the encrypted image in the decryption target regions in accordance with the decryption order. A decrypted image of each decryption target region is output.

Abstract: In an image encryption apparatus, an input processor inputs data of an input image. An encryptor encrypts a part or whole of the data of the input image. A marker generator generates data of a marker indicating an encrypted area. An image saver saves data of a marker-covered image covered with the marker. A marker sticker sticks the marker. An output processor outputs an encrypted image. In an image decryption apparatus, an input processor inputs data of an input image. A marker detector detects a marker and identifies an encrypted area. A decryptor decrypts data in the encrypted area. An image restorer restores data in an area covered with the marker by sticking data of a marker-covered image. An output processor outputs data of a decrypted image.

Abstract: A prediction error generating unit generates a predictive vector from the motion vectors of a plurality of adjacent blocks, and obtains a difference from a target vector. A plurality of variable-length coding units respectively encode the output of the prediction error generating unit with different encoding methods. A determining unit estimates the accuracy of the predictive vector generated by the prediction error generating unit based on the degrees of non-uniformity of the motion vectors of the plurality of adjacent blocks. A selecting unit selects one of the encoding results obtained by the plurality of variable-length coding units.

Abstract: When a decrypting apparatus receives an encrypted image, the apparatus detects the state of the encrypted image and determines whether the encrypted image is an image passed through only a digital medium or an analog medium, according to the state of the encrypted image. When the encrypted image is determined to be the image passed through only the digital medium, the decrypting apparatus switches to perform a digital decryption process and, when the encrypted image is determined to be the image passed through the analog medium, the decrypting apparatus switches to perform an analog decryption process.

Abstract: Area data indicating an encryption area of image data and level data indicating an authority level for the encryption area are received. Upon being triggered by an input password, an encryption key is generated for each received authority level. Check data to be detected in verifying whether or not the encrypted image data in the encryption area is appropriately decrypted through decryption is implanted in the encryption area. Image encryption is performed on the encryption area where the check data is implanted, by using the encryption key corresponding to the authority level designated for the encryption area. In decryption, all decryption keys corresponding to all authority levels lower than or equal to the set authority level are used to decrypt each encryption area and determines whether or not an appropriate decryption has been performed on the basis of the result of the detection of the check data.

Abstract: A plurality of background texture patterns each of which includes a region not having a dot and having a feature different from those of the other background texture patterns, are combined, and information is embedded in a background region of a document image. Then, a mathematical-morphology-based conversion is performed on the document image, and thereby a feature of a region not having a dot in each of the background texture patterns is extracted in order to identify the embedded information.

Abstract: A high-definition magnified image is obtained by simple computation. A magnified image is obtained by obtaining a deteriorated image on the basis of an input original image, determining enhancement filters used for individual small areas of the original image using the deteriorated image at least, performing a filtering process by applying the filters thus determined to the individual small areas to achieve enhancement, and interpolating the image for magnification.

Abstract: When decrypting an image of a part of a document that is encrypted and therefore illegible, a user uses a decryption apparatus 15 to read the document as an electronic image and also to receive a user authentication by accessing a key management server 11. Then, the user transmits a management number obtained from the image to the key management server 11 from the decryption apparatus 15. The key management server 11 extracts position information of the portion of the document that is encrypted and a decryption key for decrypting this portion from a key management database 13 and transmits the decryption key to the decryption apparatus 15. The decryption apparatus 15 processes the electronic image by using the position information and decryption key received from the key management server 11 so as to decrypt the encrypted part so that it is legible.

Abstract: Provided is a digital watermarking technology for embedding digital watermark information in text data thereby to generate a digitally watermarked image. The technology includes a digital watermarking program, a digital watermarking device and a digital watermarking method, in which digital watermark information can be embedded in document in such a way as not to be easily detected visually and be stably detected even after being printed out, copied or scanned by detecting the features of a character as data to be digitally watermarked, such as the direction and thickness of a line composing the character as the features thereof and embedding the digital watermark information in the character on the basis of the detected features.

Abstract: A block where basic units of a background pattern are arranged two-dimensionally is formed so as to stably read buried information from a printed background pattern. Binary or multivalued number is assigned to the block to express information. When a binary number (bit) is assigned to a block made up of background patterns in double size, error correction can be made if an error occurs only in one background pattern while reading the block. In each background pattern, a diagonal lacking its center part is drawn, and isolated dots are placed along the other diagonal. With this, while ensuring the stability of reading the buried information after the read by a scanner, the uniformness of appearance of the printed object can be ensured.

Abstract: An embedding area in which a background pattern can be embedded from the color document image is extracted. At least one of a color and a shape of a background pattern appropriate for the embedding area is determined depending on an area color of the embedding area. A background pattern image is generated by embedding watermark information in the embedding area using the determined background pattern.

Abstract: A figure pattern expressing information to be embedded, or a position of an area in which the information to be embedded exists, is embedded in an area other than the background of image data, thereby generating image data embedded with a watermark. Then, the figure pattern is detected from the generated image data embedded with the watermark, and embedded information expressed by the detected figure pattern or embedded information existing in an area at a position expressed by the detected figure pattern is detected.

Abstract: A prediction error generating unit generates a predictive vector from the motion vectors of a plurality of adjacent blocks, and obtains a difference from a target vector. A plurality of variable-length coding units respectively encode the output of the prediction error generating unit with different encoding methods. A determining unit estimates the accuracy of the predictive vector generated by the prediction error generating unit based on the degrees of non-uniformity of the motion vectors of the plurality of adjacent blocks. A selecting unit selects one of the encoding results obtained by the plurality of variable-length coding units.