JP2010200018A - Encoder, decoder, image forming apparatus, image reader, encoding method, decoding method, program, and recording medium thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase the amount of information to be recorded as a code image without enlarging the size of the code image to be printed in an image processor for encoding information to be recorded and generating the code image which indicates the information to be recorded. <P>SOLUTION: An encoder includes: a color code table 33 for defining the code image as a color code image constituted of data with a plurality of color components, and associating the respective color components with mutually different bit strings to be expressed by binary data; an encoding part 36 for converting the bit strings of the information to be recorded into the data of the respective color components, based on the color code table 33, dividing the converted data by each prescribed amount of data, and generating a plurality of color code images; a decoding order-setting part 38 for setting decoding order information which indicates the decoding order of the respective color codes when the color code images are decoded; and a watermark information embedding-processing part 41 for embedding the decoding order information in the color code image as watermark information. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an encoding device that generates a code image obtained by encoding recording target information, an image forming device including the encoding device, and a decoding device that decodes a code image formed by the encoding device. is there.

  2. Description of the Related Art Conventionally, a technique for converting information to be added into a two-dimensional code is known as a method for encoding various information and adding it to a printed material. As the two-dimensional code, a stack type two-dimensional code such as PDF417 (registered trademark) or a matrix type two-dimensional code such as QR code (registered trademark) is known.

  In these technologies, for example, a homepage URL (Uniform Resource Locator) is converted into a two-dimensional code and added to a printed matter, and the two-dimensional code is read and decoded by an imaging unit provided in a mobile phone. It is used by a method such as accessing the homepage based on the URL.

  However, the conventional two-dimensional code has a problem that the amount of information that can be written is small. For example, in the case of the QR code, in the standard version 40 (177 × 177), the number of characters that can be accommodated is “Kanji / Kana”, which is 1817 characters at maximum.

  Therefore, Non-Patent Document 1 proposes a color dot code as a new code with a large amount of information that can be written. In this technology, for example, binary data 00 is associated with each color code of K (black), 01 is C (cyan), 10 is M (magenta), and 11 is Y (yellow), and a document, audio, or the like A color code string representing the binary data using the above color code is generated. That is, in the conventional two-dimensional code, the information amount of one cell is 1 bit in black and white, whereas the color dot code can write the information amount of 4 values in 2 bits. Then, an image created with color dots corresponding to this color code string is added to a printed matter or the like as a color dot code.

JP 2002-094805 A (published March 29, 2002)

Kenichi Ueda, “Color Dot Code System”, Proc. Of the 206th meeting of the Institute of Image Electronics Engineers of Japan, Vol. 03-05 (2003), p. 53-69 (release date: December 26, 2003) Ikuo Noda, Jun Shio, Hirotaka Chiba, “Printing Steganography Technology”, FUJITSU May 2005 (VOL. 57, NO. 3), p. 320-324

However, in the technique of Non-Patent Document 1, by using a color dot code, the amount of information that can be written is increased compared to the case of using a conventional two-dimensional code such as a QR code, but information that can be recorded per 1 cm ^2. The amount is about 1000 bytes, which is insufficient to record information having a relatively large data size such as image data (for example, image data of an A4 size document).

  Therefore, when the amount of information to be encoded is large, it is conceivable to increase the number of dots without changing the size of the two-dimensional code to be printed, that is, increase the number of dots per unit area. However, in that case, when the resolution of the imaging means for imaging the two-dimensional code formed on the printed material is not sufficient, that is, the entire two-dimensional code is imaged with a resolution that can identify each dot in the two-dimensional code. If this is not possible, there is a problem that the original information cannot be properly restored. In particular, when the imaging means is provided in a mobile phone or the like, the resolution is often relatively low, and the original information cannot be properly restored if the size of the two-dimensional code is too large.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide an image processing apparatus that encodes recording target information and generates a code image of the recording target information. The purpose is to increase the amount of information that can be recorded as a code image without increasing the size (number of dots).

  In order to solve the above problems, an encoding device according to the present invention is an encoding device that encodes recording target information to generate a code image indicating the recording target information, and the code image includes a plurality of color components. A color code image composed of data of the above-described data, and a bit string in which each color component is expressed by binary data, and the bit string of the recording target information is assigned to each color based on a correspondence relationship previously associated with a different bit string for each color component. An encoding unit that converts the data into component data and divides the converted data into predetermined data amounts to generate a plurality of color code images, and the decoding order of the color codes when decoding the color code images. And an embedding processing unit that embeds the decoding order information shown in the color code image as watermark information.

  In addition, the encoding method of the present invention is an encoding method for generating a code image indicating the recording target information by encoding the recording target information in order to solve the above-described problem. A color code image composed of color component data, and a bit string in which each color component is expressed by binary data, and is a bit string of recording target information based on a correspondence relationship previously associated with a different bit string for each color component Are converted into the data of each color component, the converted data is divided into predetermined data amounts to generate a plurality of color code images, and the decoding order of each color code when decoding each color code image Embedded in the color code image as watermark information.

  According to the above encoding apparatus and encoding method, each color component constituting a color code image is a bit string expressed by binary data and is associated with a different bit string for each color component in advance, and the correspondence relationship Based on the above, the bit string of the recording target information is converted into the data of each color component. The converted data is divided into predetermined data amounts to generate a plurality of color code images. Also, decoding order information indicating the decoding order of each color code when decoding each color code image is embedded in the color code image as watermark information. Thereby, the amount of information that can be recorded as a code image can be increased without increasing the number of dots per unit area of each code image to be printed. In addition, when decoding each of these code images, the original recording target information is appropriately restored by decoding and combining the codes in the order based on the decoding order information embedded as watermark information in the code image. can do.

  The embedding processing unit may be configured to embed authentication information for performing authentication as to whether or not to permit decoding of the color code image as watermark information in the color code image.

  According to said structure, the user who can decode a color code image using the said authentication information is restrict | limited, and security can be improved.

  In addition, a compression unit that compresses the data of the recording target image is provided, and the encoding unit generates a color code image by converting a bit string of the recording target information after the compression processing into data of each color component. It is good also as composition to do.

  According to said structure, the data amount which can be recorded on a color code image can further be increased by producing | generating a color code image based on the recording object information after a compression process.

  In addition, a configuration may include a random number generation unit that outputs a random number corresponding to the number of color code images, and a decoding order setting unit that sets the decoding order information based on a random number output from the random number generation unit. Good.

  According to said structure, the decoding order of these each color code at the time of decoding each said color code image can be set at random.

  Further, the image processing apparatus includes an arrangement setting unit that sets an arrangement position of each color code image when printing each color code image on a recording material, and the decoding order setting unit includes each of the decoding order setting units generated by the encoding unit. A configuration in which the order of the color code images is rearranged based on the random number output from the random number generation unit, and the arrangement setting unit sequentially arranges the color code images rearranged by the decoding order setting unit at predetermined arrangement positions. It is good.

  According to the above configuration, since the arrangement position of each color code image can be set at random, it is possible to prevent the recording target information from being restored against the intention of the code creator and to improve security. it can.

  The recording target image may be image data. According to the above configuration, even image data having a relatively large data size compared to text data or the like can be converted into a code image.

  A decoding apparatus according to the present invention is a decoding apparatus that decodes each color code image generated by any one of the above-described encoding apparatuses, and that extracts a watermark information embedded in the color code image. And a decoding unit that decodes the color code images in an order based on the decoding order information included in the watermark information.

  The decoding method of the present invention is a decoding method for decoding each color code image generated by the above encoding method, and a watermark information extracting step for extracting watermark information embedded in the color code image; And a decoding step of decoding the color code images in the order based on the decoding order information included in the watermark information.

  According to the above configuration, the original recording target information can be appropriately restored by decoding each color code image in the order based on the decoding order information embedded as watermark information in the color code image.

  The decoding device of the present invention is a decoding device that decodes each color code image generated by the above encoding device that embeds authentication information in a color code image as watermark information, and is embedded in the color code image. A watermark information extraction unit that extracts the watermark information, an authentication unit that performs an authentication process to determine whether or not to permit decoding based on the authentication information included in the watermark information, and a decoding order information included in the watermark information A decoding unit that decodes each color code image in order, and the decoding unit may decode each color code image only when the authentication unit determines to permit decoding.

  According to said structure, by performing the authentication process of whether to permit decoding, the user who can decode a color code image can be restrict | limited and security can be improved. In addition, by decoding each color code image in the order based on the decoding order information embedded as watermark information in the color code image, the original recording target information can be restored appropriately.

  The decoding device of the present invention is a decoding device that decodes each color code image generated by the encoding device including a compression unit that compresses a recording target image, and is embedded in the color code image. A watermark information extracting unit for extracting the watermark information, a decoding unit for decoding the color code images in an order based on the decoding order information included in the watermark information, and the colors decoded by the decoding unit. It is good also as a structure provided with the decompression | decompression part which performs the decompression | decompression process of the compression process currently performed to the code image.

  According to the above configuration, the original recording target information can be appropriately restored by decoding each color code image in the order based on the decoding order information embedded as watermark information in the color code image. Further, by generating a color code image based on the recording target information after the compression processing, it is possible to further increase the amount of data that can be recorded in the color code image and to appropriately restore the recording target image.

  An image forming apparatus according to the present invention includes any one of the encoding devices described above and an image output device that prints each color code image generated by the encoding device on a recording material. .

  According to the above configuration, the amount of information that can be recorded as a code image can be increased without increasing the number of dots per unit area of each code image to be printed.

  An image reading apparatus according to the present invention includes an image input device that reads a document image formed on a recording material to acquire image data of the document image, and one of the decoding devices described above, and is included in the document image. A plurality of color code images are decoded by the decoding device.

  According to the above configuration, the plurality of color code images included in the document image are decoded in the order based on the decoding order information embedded as watermark information in the color code image, so that the original recording target information is appropriately Can be restored.

  The encoding device may be realized by a computer. In that case, a program that causes the encoding device to be realized by the computer by causing the computer to operate as each unit, and a computer-readable program that records the program. Recording media are also included in the scope of the present invention.

  Similarly, the decoding device may be realized by a computer. In that case, a program that causes the decoding device to be realized by the computer by causing the computer to operate as each unit, and a computer-readable recording that records the program Media are also included in the scope of the present invention.

  The encoding device according to the present invention is a bit string in which each color component is represented by binary data, and the bit string of the recording target information is assigned to the bit component of each color component based on a correspondence relationship previously associated with a different bit string for each color component. An encoding unit that converts the data into data and divides the converted data into predetermined data amounts to generate a plurality of color code images; and a decoding that indicates a decoding order of the color codes when the color code images are decoded. And an embedding processing unit that embeds the order information as watermark information in the color code image.

  In the encoding method of the present invention, the bit sequence of the recording target information is converted to each color based on a correspondence relationship in which each color component is represented by binary data and is previously associated with a different bit sequence for each color component. Converting the data into component data, dividing the converted data into predetermined data amounts to generate a plurality of color code images, and decoding indicating the decoding order of the color codes when decoding the color code images And embedding the sequence information as watermark information in the color code image.

  Therefore, the amount of information that can be recorded as a code image can be increased without increasing the size of each printed code image. In addition, when decoding each of these code images, the original recording target information is appropriately restored by decoding and combining the codes in the order based on the decoding order information embedded as watermark information in the code image. can do.

It is a block diagram which shows schematic structure of the color coding process part with which the image processing apparatus concerning one Embodiment of this invention is equipped. 1 is a block diagram illustrating a schematic configuration of an image processing apparatus according to an embodiment of the present invention. It is explanatory drawing which shows the structure of the color code table used in the color coding process part shown in FIG. It is explanatory drawing which shows an example of the arrangement | positioning method of the color code image on a recording material. It is explanatory drawing which shows the other example of the arrangement | positioning method of the color code image on a recording material. It is explanatory drawing which shows an example of the decoding order information of a color code image. It is a flowchart which shows the flow of a process in the color coding process part shown in FIG. It is a block diagram which shows schematic structure of the color code decoding part with which the image processing apparatus concerning one Embodiment of this invention is provided. It is a flowchart which shows the flow of a process in the color code decoding part shown in FIG.

  An embodiment of the present invention will be described. In the present embodiment, an example in which the present invention is applied to a digital color multifunction peripheral having a copier function, a printer function, a facsimile transmission / reception function, and a scan to e-mail function will be mainly described.

(1) Overall Configuration of Digital Color Multifunction Device FIG. 2 is a block diagram showing a schematic configuration of the digital color multifunction device 1 according to the present embodiment. As shown in FIG. 1, the digital color multifunction peripheral 1 includes an image input device 2, an image processing device (encoding device, decoding device) 3, an image output device 4, a communication device 5, and an operation panel 6.

  The image input device 2 reads an image of a document and generates image data. For example, a scanner unit (not shown) provided with a device that converts optical information such as a CCD (Charge Coupled Device) into an electrical signal. It is configured. In the present embodiment, the image input device 2 outputs the reflected light image from the document to the image processing device 3 as RGB (R: red, G: green, B: blue) analog signals.

  The image processing apparatus 3 includes an A / D conversion unit (analog / digital conversion unit) 11, a shading correction unit 12, an input tone correction unit 13, a color code decoding unit 14, a region separation processing unit 15, a color correction unit 16, and a black color. A generation under color removal unit 17, a spatial filter processing unit 18, an output tone correction unit 19, a tone reproduction processing unit 20, and a color coding processing unit 21 are provided.

  The image processing apparatus 3 outputs CMYK image data obtained by performing various image processes on the image data input from the image input apparatus 2 to the image output apparatus 4.

  The A / D converter 11 converts the RGB analog signal input from the image input device 2 into a digital signal. The shading correction unit 12 performs processing for removing various distortions generated in the illumination system, the imaging system, and the imaging system of the image input apparatus 2 on the RGB digital signals sent from the A / D conversion unit 11. The input tone correction unit 13 performs processing (input γ correction processing) for adjusting the color balance of the RGB signal (RGB reflectance signal) from which various distortions have been removed by the shading correction unit 12.

  The color code decoding unit (decoding device) 14 decodes each color code included in the color code image when a color code image (color dot code, code image) is printed on the document. When the color code image is not printed on the original, the process of the color code decoding unit 14 is “through”, and the color code decoding unit 14 directly inputs the image data input from the input tone correction unit 13 to the region separation processing unit 15. Output. The decrypted information may be displayed on the operation panel 6 or a display unit of an external device that is communicably connected to the digital color multifunction peripheral 1, may be printed on a recording material, and stored in a predetermined storage location. May be. Details of the color code decoding unit 14 will be described later.

  The region separation processing unit 15 separates each pixel of the input image expressed by the RGB signals into a plurality of regions such as a character region, a halftone dot region, and a photographic region (photographic paper photographic region). Then, based on the separation result, the region separation processing unit 15 generates a region identification signal indicating which region each pixel of the input image belongs to, a black generation and under color removal unit 17, a spatial filter processing unit 18, a tone reproduction The signal is output to the processing unit 20 and the color coding processing unit 21 and the signal input from the color code decoding unit 14 is output to the subsequent color correction unit 16 as it is.

  The color coding processing unit (encoding device) 21 includes (1) color coding of image data (processing for generating a color code image), (2) user authentication information, color code image management information (for example, Watermark information about the order of each color code image when there are a plurality of color code images) and the type of signal to be color coded (for example, whether it is RGB format data or CMYK format data) And (3) embedding watermark information in a color code image. The watermark information is information embedded in the original image data so that it is not visible to humans (or difficult to view) when printed on a recording material. Details of the color coding processing unit 21 will be described later.

  The color correction unit 16 generates a CMY (C: cyan, M: magenta, Y: yellow) signal which is a complementary color of the RGB signal, and in order to faithfully reproduce the color, a CMY color material including an unnecessary absorption component is generated. Processing to remove color turbidity based on spectral characteristics is performed.

  The black generation and under color removal unit 17 generates black (K) signals from the CMY three-color signals after color correction, and generates a new CMY signal by subtracting a portion where the original CMY signals overlap. Thus, the CMY three-color signal is converted into a CMYK four-color signal.

  The spatial filter processing unit 18 performs spatial filter processing using a digital filter on the image data of the CMYK signal input from the black generation and under color removal unit 17 based on the region identification signal, thereby correcting the spatial frequency characteristics. Reduces blurring and graininess of output image.

  The output tone correction unit 19 performs output tone correction processing (output γ correction processing) for converting a signal such as a density signal into a halftone dot area ratio that is a characteristic value of the image output device 4.

  Similar to the spatial filter processing unit 18, the gradation reproduction processing unit 20 performs predetermined processing on the image data of the CMYK signal based on the region identification signal, and finally simulates the gradation of the image. Gradation reproduction processing (error diffusion processing, dither processing, etc.) is performed so as to be able to be reproduced in an automatic manner.

  The image data subjected to the above-described processes is temporarily stored in a memory (not shown), read at a predetermined timing, and output to the image output device 4.

  The image output device 4 outputs an image corresponding to input image data onto a recording material (for example, paper). The configuration of the image output apparatus 4 is not particularly limited, and for example, an image forming apparatus using an electrophotographic system or an inkjet system can be used. The above processing is controlled by a main control unit (CPU (Central Processing Unit)) not shown.

  The communication device 5 includes, for example, a modem or a network card, and is connected to another network (for example, a personal computer, a server device, a display device, another digital multifunction device, a network card, a LAN cable, or the like). Data communication with a facsimile machine or the like).

  When the image data is transmitted, the communication device 5 performs a transmission procedure with the other party and secures a transmittable state. The image data compressed in a predetermined format (image data read by a scanner or the like) Is read from a memory (not shown), subjected to necessary processing such as changing the compression format, and sequentially transmitted to the other party via the communication line.

  Further, when receiving the image data, the communication device 5 performs a communication procedure, receives the image data transmitted from the other party, and inputs it to the image processing device 3. The received image data is output by the image output device 4 after being subjected to predetermined processing by the image processing device 3. The received image data may be stored in a memory (not shown), and the image processing apparatus 3 may read the data as necessary to perform the predetermined processing.

  Further, when receiving the facsimile, the communication device 5 receives the image data transmitted from the other party while performing the communication procedure, and inputs it to the image processing device. The image processing apparatus 3 performs a decompression process on the received image data by a compression / decompression processing unit (not shown), and performs a process such as a rotation process and a resolution conversion on the decompressed image data as necessary. Output gradation correction and gradation reproduction processing, and output to the image output device 4.

  The operation panel 6 includes, for example, a display unit such as a liquid crystal display and setting buttons (none of which are shown), and displays information corresponding to instructions from the main control unit of the digital color multifunction peripheral 1 on the display unit. At the same time, information input from the user via the setting button is transmitted to the main control unit. The user can input various types of information such as a processing mode for the input image data, the number of printed sheets, a sheet size, a transmission destination address, a color dot code group size, and a color dot code group arrangement method via the operation panel 6. .

  The main control unit is composed of, for example, a CPU, and controls the operation of each unit of the digital color multifunction peripheral 1 based on programs and various data stored in a ROM (not shown), information input from the operation panel 6, and the like. .

(2) Details of Color Coding Processing Unit 21 FIG. 1 is a block diagram showing the configuration of the color coding processing unit 21. As shown in this figure, the color coding processing unit 21 includes a control unit 31, a compression unit 32, a color code table 33, a memory 34, an arrangement setting unit 35, an encoding unit 36, a capacity determination unit 37, and a decoding order setting unit. 38, a random number generation unit 39, a watermark information creation unit 40, and a watermark information embedding processing unit (embedding processing unit) 41.

  The control unit 31 includes, for example, a CPU and controls the operation of each unit of the color coding processing unit 21 based on programs and various data stored in a ROM (not shown), information input from the operation panel 6, and the like. . The control unit 31 may be provided in a main control unit (not shown) of the digital color multifunction peripheral 1, and is provided separately from the main control unit and performs processing in cooperation with the main control unit. You may do it.

  Specifically, in the present embodiment, the user is set to execute color coding via an external device (for example, a personal computer) that is communicably connected to the operation panel 6 or the digital color multifunction peripheral 1. When the selected processing mode is selected, the control unit 31 controls each unit of the color coding processing unit 21 to perform color coding processing of recording target information (image data in the present embodiment). The main control unit of the digital color multifunction peripheral 1 displays a mode selection screen on the display unit of the operation panel 6, and the user selects a desired mode from among the displayed modes using an operation key or the like. In addition, when the user selects a mode via the external device, a mode selection screen is displayed on the display unit of the external device, and the user selects an input means such as a mouse or a keyboard from the displayed modes. Use to select the desired mode.

  When any one of filing, e-mail transmission, and facsimile transmission is selected, the control unit 31 color-codes the RGB signal output from the region separation processing unit 15 and includes the generated color code. A color code image (code image), which is image data, is output to the color correction unit 16.

  On the other hand, when performing the copying (printing) mode, the user selects whether the RGB signal is color-coded or the CMYK signal is color-coded via the operation panel 6 or an external device. In the copying (printing) mode, it may be set in advance whether the RGB signal is color-coded or the CMYK signal is color-coded.

  When the RGB signal is color-coded, the control unit 31 outputs an RGB color code image obtained by color-coding the RGB signal output from the region separation processing unit 15 to the color correction unit 16 and outputs the CMYK signal. When color coding is performed, a CMYK color code image obtained by color coding the CMYK signal output from the black generation and under color removal unit 17 is output to the spatial filter processing unit 18. In the present embodiment, a case where CMYK signals are color-coded will be mainly described. Note that information indicating which signal of the RGB signal or the CMYK signal is color-coded is embedded in the color code as watermark information described later.

  When color coding processing is performed, all or part of image data (RGB signals output from the region separation processing unit 15 or CMYK signals output from the black generation and under color removal unit 17) as recording target information is stored in memory. It may be stored once (not shown), and the stored data may be read as appropriate to perform color coding processing. For example, when image data is compressed by JPEG, image data for 8 lines or more may be stored in a memory and read out as appropriate.

  The compression unit 32 performs compression processing of image data (recording target information) to be color coded. The compression process is not essential and may be omitted.

The compression processing method is not particularly limited, but in the present embodiment, a method of separating image data into a foreground layer representing characters / line drawings and a background layer representing other than characters / line drawings is used. Specifically, the following processes (a) to (e) are performed.
(A) A pixel determined to be a character region in the region separation processing unit 15 is binarized and a character pixel is extracted.
(B) The character pixel data extracted in (a) is converted into data expressed in a predetermined number of colors. For example, the foreground pixel color (character pixel color) is indexed using the method described in Patent Document 1. This is a method of expressing all foreground pixels (character pixels) with a limited number of colors when generating the foreground layer. Specifically, for each foreground pixel, it is determined whether or not the foreground pixel color is already registered in the foreground index color code table, and if it is determined that it is registered, the closest color in the foreground index color code table Assign an index value with If it is determined that the foreground pixel color is not registered in the foreground index color code table, a new index value is assigned and registered in the foreground index color code table. The foreground image is indexed by repeating the above processing.
(C) The background layer is generated by removing the foreground pixel data from the input image data. At this time, in order to improve the compression ratio of the background layer, background pixels that are not foreground pixels around the foreground pixels are referred to, and the foreground pixel portion in the background layer is filled using the average value of the background pixels. In addition, for the foreground pixels, for pixels in which there are no background pixels that are not foreground pixels in the vicinity, the filling process is performed using the result of the above-described filling process for the foreground pixels in the vicinity.
(D) A binary image of each index is output using the index value of each pixel in the foreground layer and the coordinate information of each pixel.
(E) The foreground layer (text region (character / line drawing region)) is compressed using a reversible compression method such as MMR (Modified Modified Reed) or MR (Modified Reed) method, and the background layer (photo region (dot region) The non-text area (such as the continuous tone area) is compressed using an irreversible compression method such as JPEG.

  The color code table 33 is a table showing the correspondence between the color code of each color component in the image data and the bit string of binary data assigned to each component. For example, in the case of CMYK image data, as shown in FIG. 3, for CMYK colors (color codes), 00 for K (black), 01 for C (cyan), and M (magenta). 10, 11 is associated with Y (yellow). That is, each color component in the image data is associated with a 2-byte bit string of binary data. When RGB signals are used, a binary data bit string is assigned to RGB color codes.

  The memory 34 is for temporarily storing various data used for the color coding process.

The encoding unit 36 converts the image data into a color code with reference to the color code table 33, and generates a color code image that is an image including the converted color code. For example, in the case of image data compressed by JPEG, the encoding unit 36 converts the data into YCrCb signals and performs sampling processing, spatial frequency conversion processing, quantization processing, and Huffman encoding processing (recording target information). Is converted into a color code, and a color code image including the converted color code is generated. The size (capacity) of the color code image is set in advance, and when the data size of the converted color code is larger than the size that can be recorded in one color code image, that is, the converted color code is one color code. If the image does not fit in the image, the converted color code is divided into a plurality of color code images. For example, when the size of one color code image is 1 cm ² , the data size of the color code that can be recorded in one color code image is set within a range of 0.8 to 1.5 kilobytes. The size of the color code image may be arbitrarily set by the user via the operation panel 6 or an external device. When an external device is used, a setting screen related to color coding processing may be displayed on the display unit and set using an input unit such as a mouse or a keyboard.

  The arrangement setting unit 35 determines an arrangement position of each color code image when the color code image is printed on a printed matter. For example, as shown in FIG. 4, the header portion and the footer portion may be separately arranged, may be arranged only in the header portion, or may be arranged only in the footer portion. Further, as shown in FIG. 5, only the color code image may be printed without printing the image data (original image data) other than the color code image. Further, image data other than the color code image may be printed on the front surface of the printed material, and the color code image may be printed on the back surface of the printed material. Further, the layout of the color code image may be set by the user via the operation panel 6 or an external device.

  In this embodiment, the arrangement method of the color code image is set in advance and stored in the memory 34, and the arrangement setting unit 35 arranges the arrangement by the above arrangement method stored in the memory 34 and the decoding order setting unit 38 described later. The arrangement information of each color code image is generated based on the order of the replaced color code images. For example, when there are four color code images, the first color code image is the upper left of the recording material, the second color code image is the upper right of the recording material, the third color code image is the lower left of the recording material, and the fourth Color code images (1) to (4) generated by the encoding unit 36 in the order of (1) to (4) are set so that the color code images are respectively arranged on the lower right of the recording material. ) Are rearranged in the order of (3), (1), (2), (4) by the decoding order setting unit 38 to be described later, the color code image (3) is displayed on the upper left and the color code image (1). Are arranged at the upper right, the color code image (2) is arranged at the lower left, and the color code image (4) is arranged at the lower right.

  Further, in the present embodiment, the processing unit to which each color code image is input from the color coding processing unit 21 (when the CMYK signal is color coded, the spatial filter processing unit 18, when the RGB signal is color coded) The color correction unit 16) integrates each color code image into the original image data based on the arrangement information, and after performing predetermined processing in the processing unit after the processing unit, the original image data and each color code image Are output from the image processing apparatus 3 to the image output apparatus 4.

  The decoding order setting unit 38 rearranges the order of the color code images generated by the encoding unit 36 into an order corresponding to the random numbers generated by the random number generation unit 39. The random number generator 39 generates a random number corresponding to the number of color code images. The rearrangement may be performed after the generation of all the color code images for the image data to be subjected to the color coding process, and the order of the color code images every time the generation of one color code image is completed. May be set.

  Note that the decoding order setting unit 38 generates decoding order information in which each color code image is associated with the order in which each color code image is decoded.

  For example, as shown in FIG. 6, the order of decoding the color code images and the decoding code indicating the decoding order are stored in the memory 34 in association with each other in advance, and the decoding order setting unit 38 sets the set decoding A decoding code corresponding to the order is read from the memory 34 and used as decoding order information. When setting the order of decoding each color code image, an index (for example, indexes (1) to (4) as shown in FIG. 4) for identifying each color code image is assigned to each color code image. It may be set using coordinate information (for example, coordinate values as shown in FIG. 5) indicating the arrangement position of each color code image. FIG. 6 shows an example of the decoding code when there are four color code images. However, the present invention is not limited to this, and if the number of color code images is different, a corresponding decoding code should be prepared. That's fine.

  The watermark information creation unit 40 generates watermark information to be embedded in the color code image. The watermark information includes authentication information (for example, a password) for authenticating whether or not to permit decoding of the color code image, decoding order information of each color code image when decoding the color code image, and The type information of the signal to be color coded (for example, whether it is RGB format data or CMYK format data) is included. The authentication information may be set by the user via the operation panel 6 or an external device as necessary.

  The watermark information embedding processing unit 41 embeds the watermark information generated by the watermark information creating unit 40 in each color code image. In other words, the watermark information is included in the color code image so that the watermark information is not visually recognized (or difficult to view) even if a human sees the printed matter on which the color code image is printed. In the present embodiment, the same watermark information is embedded in each color code image. Thereby, even when reading is started from any color code image, authentication information, decoding information, and type information can be detected based on watermark information embedded in the color code image. Decoding processing for each color code image can be performed efficiently and smoothly.

  The method for embedding watermark information is not particularly limited, and various conventionally known methods can be used, for example. In this embodiment, the method described in Non-Patent Document 2 is used. Specifically, the color code image is divided into blocks of a predetermined size (for example, blocks composed of 7 × 7 pixels), and the total value of yellow density in the central portion (for example, a block composed of 3 × 3 pixels) of each block is calculated. calculate. Then, the density of the central portion between adjacent blocks on the left and right is compared, and it is defined as “0” if the left side is dark and “1” if the right side is dark. Also, the watermark information is converted into a bit string, the bit string of the watermark information is compared with the value defined as above, and if the two do not match, the density relationship between the adjacent blocks in the color code image is inverted. Thus, the gradation levels of both blocks are changed. Specifically, the yellow value in the central portion of the dark block is reduced by about 10, for example. The value to be subtracted is preferably set to a level at which no erroneous determination occurs when reading using various image samples in advance. The color code image in which watermark information is embedded is different from the color code image before embedding, but if the size of the central part of the block is 0.8 mm or less, the difference before and after embedding is almost recognized by human eyes. Not.

  FIG. 7 is a flowchart showing the flow of processing in the color coding processing unit 21.

  First, the control unit 31 controls the compression unit 32 to perform compression processing of image data (recording target information) to be color-coded (S1).

  Next, the control unit 31 controls the encoding unit 36 to convert (encode) the compressed image data into a color code (S2). At this time, the control unit 31 controls the capacity determination unit 37 to detect the data size of the color code converted by the encoding unit 36, and the data size corresponds to the capacity that can be stored in one color code image. It is determined whether or not the set value is equal to or greater than a predetermined value (S3).

  When it is determined that the value is less than the predetermined value, the control unit 31 determines whether or not image data to be encoded remains, that is, whether or not unconverted image data remains (S4). If the converted image data remains, the process returns to S2 and the encoding process for the unconverted image data is continued.

  On the other hand, if it is determined in S3 that the value is equal to or greater than the predetermined value, or if it is determined in S4 that no unconverted image data remains, the control unit 31 causes the encoding unit 36 to generate a color code including the converted color code An image is generated and stored in the memory 34 (S5).

  If encoding of all image data is completed before the converted color code data size reaches a predetermined value, the control unit 31 has already encoded, for example, until the color code data size reaches a predetermined value. Insignificant data generated by data or random numbers is converted into a color code and added. Even when meaningless data is added in this way, at the time of decoding, the end portion of the document image data can be determined using the end code (for example, EOI in the case of JPEG) used in the data compression method. . When converting the recording target information into a color code image without compression, the end of the recording target information can be determined by embedding the size (for example, the number of bytes) of the recording target information in the color code image as watermark information.

  Thereafter, the control unit 31 determines whether or not the processing of S1 to S5 has been completed for all the image data that is the target of the color coding processing (S6). If it is determined that the processing has not ended, the process returns to S2 to continue the processing on the unprocessed image data. On the other hand, when determining that the processing has been completed, the control unit 31 causes the decoding order setting unit 38 to generate decoding order information (S7).

  Next, the control unit 31 acquires authentication information (password or the like) input from the user via the operation panel 6 or the like (S8). Then, the control unit 31 controls the watermark information creation unit 40 to perform authentication information, decoding order information, and signal type information for color coding (for example, whether the data is RGB format data or CMYK format data). Is generated (S9). Thereafter, the control unit 31 controls the watermark information embedding processing unit 41 to embed watermark information in the color code image (S10).

  Next, the control unit 31 controls the arrangement setting unit 35 to set the position for printing the color code image, that is, the arrangement position of each color code image on the recording material to be printed (S11).

  Then, the control unit 31 outputs the color code image in which the watermark information is embedded and the arrangement position information indicating the arrangement position of each color code image to the color correction unit 16 when the document image data is an RGB signal, If the document image data is a CMYK signal, it is output to the spatial filter processing unit 18. Accordingly, the main control unit of the digital color multifunction peripheral 1 integrates the color code image in which the watermark information is embedded into print target data (for example, text (document) data) other than the color code image based on the arrangement position information. Then, a predetermined process is performed, and finally, the gradation reproduction processing unit 20 outputs the image to the image output device 4 (S12), and the process ends. The color coding processing unit 21 may perform integration processing of the color code image and print target data other than the color code image.

  In the present embodiment, the case where output image data obtained by integrating a color code image and print target data other than the color code image is output from the image processing device 3 to the image output device (image data output processing device) 3 has been described. However, it is not limited to this. For example, the output image data may be output to the communication device (image data output processing device) 5 and transmitted to the external device via the communication device 5. Further, the output image data may be recorded on various recording media connected to the digital color multifunction peripheral 1. Examples of the recording medium include a tape system such as a magnetic tape and a cassette tape, a magnetic disk such as a floppy (registered trademark) disk / hard disk, and an optical disk such as a CD-ROM / MO / MD / DVD / CD-R. A disk system, a card system such as an IC card (including a memory card) / optical card, or a semiconductor memory system such as a mask ROM / EPROM / EEPROM / flash ROM can be used.

(3) Details of Color Code Decoding Unit 14 FIG. 8 is a block diagram showing a configuration of the color code decoding unit 14. As shown in this figure, the color code decoding unit 14 includes a control unit 51, a color code table 52, an authentication unit 53, a memory 54, a decompression unit 55, a decoding unit 58, a watermark information extraction unit 56, and a decoding order determination unit. 57.

  The control unit 51 includes, for example, a CPU, and controls the operation of each unit of the color code decoding unit 14 based on a program stored in a ROM (not shown), various data, information input from the operation panel 6, and the like. The control unit 51 may be provided in a main control unit (not shown) of the digital color multifunction peripheral 1, and is provided separately from the main control unit and performs processing in cooperation with the main control unit. You may do it.

  The color code table 52 is a table showing the correspondence between each color component in the image data and the color code value assigned to each component, and is a table having the same data as the color code table 33. One table may be shared as the color code table 52 and the color code table 33.

  The watermark information extraction unit 56 extracts watermark information embedded in the color code image.

  The authentication unit 53 displays a message for prompting input of authentication information (for example, a password) on the operation panel 6 or a display unit of the external device, and displays the authentication information input by the user and the authentication information embedded in the watermark information. In comparison, authentication processing is performed to determine whether or not to permit decoding of the color code image. When the authentication is successful, the color code image decoding process is performed. When the authentication is unsuccessful, the color code image decoding process is not performed.

  When the authentication process is successful, a screen that prompts input of the processing content for the color code image decoded by the control unit 51 may be displayed on the operation panel 6 or the display unit of the external device, or the authentication process may be performed. Before performing the process, the control unit 51 displays a screen for prompting input of the processing contents for the decoded color code image on the operation panel 6 or the display unit of the external device, accepts an instruction from the user, and performs an authentication process as necessary. It may be.

  The memory 54 is for temporarily storing various data used in the color code decoding unit 14 and appropriately reading out as necessary.

  The decoding order determination unit 57 determines the decoding order of each color code image included in the document image based on the decoding order information (order code) included in the watermark information extracted by the watermark information extraction unit 56.

  The decoding unit 58 decodes each color code image included in the document image data based on the decoding order determined by the decoding order determination unit 57 and the color code table 52.

  The decompression unit 55 performs decompression processing when the data obtained by the decoding unit 58 decoding the color code image is subjected to compression processing.

  FIG. 9 is a flowchart showing the flow of processing in the color code decoding unit 14.

  When image data including a color code image is input from the input tone correction unit 13, the control unit 51 causes the watermark information extraction unit 56 to extract a watermark image embedded in the color code image (S21).

  Next, the control unit 51 displays a screen prompting the user to input authentication information on the operation panel 6 or the display unit of the external device, and receives the authentication information input from the user (S22). Then, the authentication information input from the user is compared with the authentication information included in the watermark information, and it is determined whether or not the authentication is successful (S23).

  When the authentication fails, the control unit 51 determines whether or not the number of authentication failures has reached a predetermined number (S24), and when the predetermined number has been reached, ends the process without performing the decryption process. On the other hand, if the predetermined number of times has not been reached, the process returns to S22 to accept re-input of authentication information.

  When the authentication process is successful in S23, the control unit 51 causes the decoding order determination unit 57 to determine the decoding order of each color code image and rearranges the image data of each color code image based on the decoding order (S25, S26). ).

  Then, the control unit 51 causes the decoding unit 58 to decode the image data of the color code images rearranged as described above (S27), and causes the decompression unit 55 to decompress the decoded color code image (S28). Then, the decompressed color code image is output to the region separation processing unit 15 (S29), and the process is terminated.

  The color code image output to the region separation processing unit 15 is output by the color correction unit 16, the black generation and under color removal unit 17, the spatial filter processing unit 18, the output gradation correction unit 19, and the gradation reproduction processing unit 20. After being subjected to predetermined processing, it is output to the image output device 4 and printed on the recording material. Alternatively, the color code image subjected to the above predetermined processing may be output to the communication device 5 and transmitted to an external device, or may be recorded on various recording media.

  As described above, the image processing apparatus 3 according to the present embodiment uses the color code table 33 in which each color component in the image data is associated with different bit strings expressed by binary data, and is the target of color coding processing. An encoding unit 36 that converts a bit string of image data (recording target information) into data of each color component based on the color code table 33 and divides the converted data into predetermined data amounts to generate a plurality of color code images. A decoding order setting unit 38 for setting decoding order information indicating the decoding order of each color code when decoding each color code image, and watermark information embedding for embedding the decoding order information as watermark information in the color code image And a processing unit 41.

  As a result, the amount of information that can be recorded as a color code image can be increased without increasing the size (number of dots) of each color code image to be printed. In addition, when decoding each of these code images, the original recording target information is appropriately restored by decoding and combining the codes in the order based on the decoding order information embedded as watermark information in the code image. can do.

  In the present embodiment, the configuration in which image data is converted into a color code image and formed on a recording material has been described. However, information to be converted into a color code image (recording target image) is not limited to image data. For example, data such as documents and voices may be used.

  In the present embodiment, the configuration in which the image processing device 3 includes the color code decoding unit (decoding device) 14 and the color coding processing unit (encoding device) 21 has been described. It is good also as a structure provided only with either. Alternatively, a color code decoding unit 14 may be provided in an electronic device such as a mobile phone provided with an imaging unit, and the color code image captured by the imaging unit may be decoded.

  In the above embodiment, each unit (each block) provided in the digital color multifunction peripheral 1 and the image processing apparatus 3 may be realized by software using a processor such as a CPU. In this case, the digital color multifunction peripheral 1 and the image processing apparatus 3 include a CPU that executes instructions of a control program for realizing each function, a ROM (read only memory) that stores the program, and a RAM (random access) that expands the program. memory), a storage device (recording medium) such as a memory for storing the program and various data. The object of the present invention is to read the program code (execution format program, intermediate code program, source program) of the control program for the digital color multifunction peripheral 1 and the image processing apparatus 3 which are software for realizing the above-described functions. The recording medium recorded in (1) is supplied to the digital color multifunction peripheral 1 and the image processing apparatus 3, and the computer (or CPU or MPU) reads out and executes the program code recorded in the recording medium.

  Examples of the recording medium include a tape system such as a magnetic tape and a cassette tape, a magnetic disk such as a floppy (registered trademark) disk / hard disk, and an optical disk such as a CD-ROM / MO / MD / DVD / CD-R. Card system such as IC card, IC card (including memory card) / optical card, or semiconductor memory system such as mask ROM / EPROM / EEPROM / flash ROM.

  Further, the digital color multifunction peripheral 1 and the image processing apparatus 3 may be configured to be connectable to a communication network, and the program code may be supplied via the communication network. The communication network is not particularly limited. For example, the Internet, intranet, extranet, LAN, ISDN, VAN, CATV communication network, virtual private network, telephone line network, mobile communication network, satellite communication. A net or the like is available. Also, the transmission medium constituting the communication network is not particularly limited. For example, even in the case of wired such as IEEE 1394, USB, power line carrier, cable TV line, telephone line, ADSL line, etc., infrared rays such as IrDA and remote control, Bluetooth ( (Registered trademark), 802.11 wireless, HDR, mobile phone network, satellite line, terrestrial digital network, and the like can also be used. The present invention can also be realized in the form of a computer data signal embedded in a carrier wave, in which the program code is embodied by electronic transmission.

  The blocks of the digital color multifunction peripheral 1 and the image processing apparatus 3 are not limited to those realized using software, but may be constituted by hardware logic, and hardware that performs a part of the processing. Hardware and arithmetic means for executing software for performing control of the hardware and remaining processing may be combined.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope shown in the claims. That is, embodiments obtained by combining technical means appropriately modified within the scope of the claims are also included in the technical scope of the present invention.

  The present invention can be applied to an encoding apparatus that generates a code image obtained by encoding recording target information, an image forming apparatus that includes the encoding apparatus, and a decoding apparatus that decodes a code image formed by the encoding apparatus. .

1 Digital color MFP (image forming device, image reading device)
2 Image input device 3 Image processing device (encoding device, decoding device)
4 image output device 5 communication device 6 operation panel 14 color code decoding unit (decoding device)
21 Color coding processing unit (encoding device)
31, 51 Control unit 32 Compression unit 33, 52 Color code table 35 Arrangement setting unit 36 Encoding unit 37 Capacity determination unit 38 Decoding order setting unit 39 Random number generation unit 40 Watermark information creation unit 41 Watermark information embedding processing unit (embedding process) Part)
53 Authentication Unit 55 Decompression Unit 56 Watermark Information Extraction Unit 57 Decoding Order Determination Unit 58 Decoding Unit

Claims (16)

An encoding device that encodes recording target information and generates a code image indicating the recording target information,
The code image is a color code image composed of data of a plurality of color components,
A bit string in which each color component is expressed by binary data, and a bit string of recording target information is converted into data of each color component based on a correspondence relationship previously associated with a bit string different for each color component, and converted data An encoding unit that generates a plurality of color code images by dividing a predetermined data amount;
An encoding apparatus, comprising: an embedding processing unit that embeds decoding order information indicating the decoding order of each color code when decoding each color code image as watermark information in the color code image.   2. The encoding according to claim 1, wherein the embedding processing unit embeds authentication information for performing authentication as to whether or not to permit decoding of the color code image as watermark information in the color code image. apparatus. A compression unit for compressing the image to be recorded;
The encoding apparatus according to claim 1, wherein the encoding unit converts the bit string of the recording target information after the compression processing into data of each color component to generate each color code image. A random number generator for outputting a random number corresponding to the number of the color code images;
The encoding apparatus according to claim 1, further comprising: a decoding order setting unit that sets the decoding order information based on a random number output from the random number generation unit. An arrangement setting unit for setting an arrangement position of each color code image when printing each color code image on a recording material;
The decoding order setting unit rearranges the order of each color code image generated by the encoding unit based on a random number output from the random number generation unit,
The encoding apparatus according to claim 4, wherein the arrangement setting unit sequentially arranges the color code images rearranged by the decoding order setting unit at a predetermined arrangement position.   6. The encoding apparatus according to claim 1, wherein the recording target image is image data. A decoding device for decoding each color code image generated by the encoding device according to any one of claims 1 to 6,
A watermark information extraction unit for extracting watermark information embedded in the color code image;
A decoding apparatus comprising: a decoding unit configured to decode the color code images in an order based on decoding order information included in the watermark information. A decoding device for decoding each color code image generated by the encoding device according to claim 2,
A watermark information extraction unit for extracting watermark information embedded in the color code image;
An authentication unit that performs an authentication process as to whether or not to permit decoding based on authentication information included in the watermark information;
A decoding unit that decodes each color code image in an order based on the decoding order information included in the watermark information,
The decoding apparatus, wherein the decoding unit decodes each color code image only when the authentication unit determines to permit decoding. A decoding device for decoding each color code image generated by the encoding device according to claim 3,
A watermark information extraction unit for extracting watermark information embedded in the color code image;
A decoding unit that decodes each color code image in an order based on decoding order information included in the watermark information;
A decoding device, comprising: a decompression unit that performs decompression processing of compression processing applied to each color code image decoded by the decoding unit. The encoding device according to any one of claims 1 to 6,
An image forming apparatus comprising: an image output device that prints each color code image generated by the encoding device on a recording material. An image input device that reads a document image formed on a recording material and acquires image data of the document image;
A decoding device according to claims 7 to 9,
An image reading apparatus, wherein a plurality of color code images included in the original image are decoded by the decoding apparatus. An encoding method for encoding recording target information to generate a code image indicating the recording target information,
The code image is a color code image composed of data of a plurality of color components,
A bit string in which each color component is expressed by binary data, and a bit string of recording target information is converted into data of each color component based on a correspondence relationship previously associated with a bit string different for each color component, and converted data Generating a plurality of color code images by dividing a predetermined data amount;
And a step of embedding decoding order information indicating the decoding order of each color code when decoding each color code image as watermark information in the color code image. A decoding method for decoding each color code image generated by the encoding method according to claim 12,
A watermark information extraction step of extracting watermark information embedded in the color code image;
And a decoding step of decoding the color code images in an order based on decoding order information included in the watermark information.   A program for operating the encoding apparatus according to any one of claims 1 to 6, wherein the program causes a computer to function as each unit.   A program for operating the decoding device according to any one of claims 7 to 9, wherein the program causes a computer to function as each unit.   The computer-readable recording medium which recorded the program of Claim 14 or 15.

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