JP6651864B2 - Image processing apparatus, image forming apparatus, image processing method, and image processing program - Google Patents

Description

  The present invention relates to an image processing device, an image forming device, an image processing method, and an image processing program.

  Conventionally, when printing confidential data on a paper medium in a state where it cannot be visually recognized, when printing a confidential part as an encrypted code, or when the code itself is further visually invisible, There is a case where printing is performed by embedding in a part. For example, there are two-dimensional barcodes and QR codes (registered trademark) for encrypting the data in the concealed part, and techniques such as digital watermarking are known for making the codes invisible to the user. ing.

  In addition, in order to enhance the security of confidential information, in addition to encrypting confidential information, authentication information that authenticates users and devices is also included, and decryption is performed when the authentication information of the user and the device is correct. Is also proposed (Patent Document 1).

  However, a manuscript containing an encryption code as a concealed part can be copied as it is, and many copies can be made. If a decryption method (decryption method) is known, information on the concealed part can be obtained from the copied manuscript. It is possible to get. Therefore, in a situation where a large number of originals including the confidential part can be copied, the security is reduced, and there is a problem.

  SUMMARY OF THE INVENTION It is an object of the present invention to improve security when copying a document in which a secret part is protected as an encryption code.

In order to solve the above-described problem, an image processing apparatus according to the present invention includes an encryption unit that uses a secret part of a read image as an encryption code, and an image forming the encryption code on the front and back of a medium. so that one encryption code, and, as show-through image of the encryption code image formed on one surface of the medium is removed, an image at the time of image forming the encrypted code And encrypted image generation means for generating data.

  ADVANTAGE OF THE INVENTION According to this invention, the security at the time of copying the document which protects a secret part as an encryption code can be improved.

FIG. 1 is an explanatory diagram relating to copying of a document to which a conventional encryption code is added. FIG. 2 is a block diagram illustrating an example of a hardware configuration of the image forming apparatus according to the first embodiment. FIG. 3 is a schematic block diagram illustrating a configuration for performing processing of encrypting a secret part and decrypting an encrypted code in the image processing unit. FIG. 4 is a block diagram illustrating a detailed configuration of the image processing unit. 5A is an original table (front) data of a manuscript including a confidential part, FIG. 5B is a manuscript table in which the concealment part is an encrypted code, and FIG. (D) is a diagram showing each example of show-through as seen from the surface of the encrypted code portion of the confidential portion. FIG. 6 is a diagram for explaining distribution of a document including an encryption code of a confidential portion formed by the image forming apparatus according to the first embodiment and illegal copying of the distribution. FIG. 7 is a diagram illustrating an encryption code of a secret part according to the first embodiment. FIG. 8 is a diagram illustrating the density of the image of the encryption code according to the first embodiment. FIG. 9 is a diagram illustrating the relationship between the density value of the encrypted code and the threshold value when the density threshold value for removing show-through is set to 220 in the first embodiment. FIG. 10 is a view showing a copy result when the density threshold value for show-through removal shown in FIG. 9 is set to 220. FIG. 11 is a diagram illustrating the relationship between the density value of the encrypted code and the threshold value when the density threshold value for show-through removal is set to 150 in the first embodiment. FIG. 12 is a view showing a copy result when the density threshold setting for show-through removal shown in FIG. FIG. 13 is a diagram illustrating a code value obtained by decrypting an encrypted code according to the first embodiment. FIG. 14 is a diagram illustrating the code values shown in FIG. FIG. 15 is a diagram illustrating decryption of an encrypted code (from an encrypted code to a code value) included in a document according to the first embodiment. FIG. 16 is a diagram illustrating a result of decryption of an encrypted code included in a copy document (when the density threshold setting for show-through removal is 220) according to the first embodiment. FIG. 17 is a diagram illustrating a result of decryption of an encrypted code included in a copy original (when the density threshold setting for show-through removal is 150) according to the first embodiment. FIG. 18 is a diagram illustrating the relationship between the density value of the encrypted code and the threshold value in the first embodiment when the density threshold value when the encrypted code is decrypted and converted into the code value is made variable. FIG. 19 is a flowchart illustrating a processing flow in the first embodiment when generating an encryption code for a secret part and performing printing with the encryption code added. FIG. 20 is a flowchart illustrating a processing flow when decrypting the encrypted code of the confidential part from the document in which the confidential part is encrypted in the first embodiment. FIG. 21 is a diagram illustrating a case where an image is present on the back surface portion corresponding to the confidential portion of the front surface of the original in the second embodiment. FIG. 22 is a diagram for explaining detection of a blank portion of the original shown in FIG. FIG. 23 is a flowchart illustrating a processing flow in the second embodiment when detecting a blank position on both sides as a print portion of an encrypted code and printing the encrypted code in the detected blank portion. FIG. 24 is a diagram illustrating a result of printing an image of an encryption code in a margin in the second embodiment. FIG. 25 is a diagram illustrating a case in which the encryption code is divided into a plurality of areas according to the third embodiment. FIG. 26 is a diagram illustrating an embodiment in which the threshold value of the density when the encrypted code is decrypted and converted into the code value can be changed for each region in the third embodiment. FIG. 27 is a diagram illustrating a case where the threshold value of the density when the encrypted code is decrypted and converted into the code value is not changed for each area. FIG. 28 shows a code value at the time of decoding that is equivalent to the case where the density threshold is not changed as shown in FIG. 27 when the density threshold is changed for each region as shown in FIG. 26 in the third embodiment. It is a figure explaining the case where it obtains. FIG. 29 is a diagram for explaining a case where a code value at the time of decoding is obtained when the density threshold is changed for each region as shown in FIG. 26 and the same as when the density threshold shown in FIG. 27 is not changed. is there. FIG. 30 is a diagram illustrating a case where the encrypted code shown in FIG. 29 is read from the back surface and decryption is performed in the same manner as the front (front) surface. FIG. 31 is a diagram for describing the division of the area of the encrypted code in the fourth embodiment. FIG. 32 is a diagram showing a portion to be decrypted of the encrypted code (FIG. 31) read from the front surface in the fourth embodiment. FIG. 33 is a diagram showing a portion to be decrypted of the encrypted code (FIG. 31) read from the back surface in the fourth embodiment.

  Hereinafter, an embodiment of an image processing apparatus will be described in detail with reference to the accompanying drawings.

  First, the copying of a document to which a conventional encryption code is added will be described with reference to FIG.

  In the example shown in FIG. 1, an encryption code 102 is printed on a document 101. As the encryption code 102, a two-dimensional barcode, a QR code, or the like is used. In FIG. 1, the encrypted code 102 is simply represented by five squares. The document 101 to which the confidential part including the information to be concealed (want to be concealed) is added as the encrypted code 102 by decrypting the encrypted code 102 by the decryption device and the decrypted document 104 including the concealed part 106 It is possible to get As a conventional technique, there is a technique in which security is enhanced, such as a technique that requires input of a password at the time of decryption. However, the original 101 with the confidential portion 106 added as the encryption code 102 can be copied many times by a copying machine or the like, and if the decryption (decryption) method of the encryption code 102 is known, the copied original 103 Thus, the same original 105 as the original 104 after decryption can be generated, and the confidential portion 106 can be obtained from the copied original 103. That is, according to the related art, it is possible to generate a large number of copies (103) that can decrypt the encrypted code 102 of the secret part 106.

  The embodiment described below is characterized in that when a document whose secret part is printed as an encrypted code is copied, the encrypted code part cannot be correctly decrypted. Examples of the confidential part include personal information such as a name, an address, and a personal identification number, and information that becomes confidential information with arbitrary images, photographs, characters, and the like. Also, in the following, an image forming apparatus that scans an original and reads and prints an original, such as a copier or a multifunction peripheral, will be described as an example of an image processing apparatus. However, a configuration including a personal computer, a scanner, and a printer may be used. is there.

(First embodiment)
FIG. 2 is a block diagram illustrating an example of a hardware configuration of the image forming apparatus according to the first embodiment.

  In the image forming apparatus shown in FIG. 2, a reading unit (image reading unit) 201 such as a scanner for reading a document is connected to an image processing control unit 200 including an ASIC (Application Specific Integrated Circuit) and the like. Is input. The connection between the reading unit 201 and the image processing control unit 200 is performed via the reading control unit 202 in the image processing control unit 200.

  The image processing control unit 200 is connected to a writing unit (image forming unit) 203 such as a plotter for printing out image data, and outputs image data to be printed out from the image processing control unit 200 to the writing unit 203. Done. The connection between the writing unit 203 and the image processing control unit 200 is performed via a writing control unit 204 in the image processing control unit 200.

  An image processing unit 205 in the image processing control unit 200 performs a process of adjusting the image data of the document input from the reading unit 201 via the reading control unit 202 to a designated output mode and a processing / editing process. Further, the image processing control unit 200 interfaces with a memory 207 as an auxiliary storage device that temporarily stores image data for processing such as processing and editing, and a connection with a HDD (Hard Disk Drive) 213 via a controller ASIC 212. I / F unit 206 is also provided. The I / F unit 206 also has a function of interfacing a connection with the CPU 208 for controlling the image processing control unit 200 and performing various settings. As shown in FIG. 2, the image processing control unit 200 and the HDD 213 are connected by a controller ASIC 212 connected via a data bus 211 and are accessible.

  The controller ASIC 212 has an operation unit 215 serving as an interface unit for inputting a user's operation instruction and displaying a message to the user in addition to connection with the HDD 213, and a memory serving as a temporary storage device for data processing. 216 and the network 217. Further, a CPU 214 for integrally controlling these and making various settings is connected to the controller ASIC 212.

  The setting and control of various processes for the image processing control unit 200 are performed by the CPU 208. The CPU 208 is connected to the image processing control unit 200 via the data bus 210. The CPU 208 is also connected to a memory 209 which is a temporary storage device for various processes. Note that the image processing control unit 200 can be realized using an ASIC or the like.

  FIG. 3 is a schematic block diagram illustrating a configuration for performing processing of encrypting a secret part and decrypting an encrypted code in the image processing unit 205.

  An image processing unit 205 performs predetermined image processing on input data, and an output processing unit performs predetermined image processing on image data input for image formation and generates output data. 302. The input processing unit 301 includes an input data processing unit 303 and a decoding control unit 304. The output processing unit 302 includes an output data processing unit 305 and an encryption control unit 306.

  When encryption is specified, the confidential data in the image data input to the output data processing unit 305 is passed from the output data processing unit 305 to the encryption control unit 306, where encryption is performed. The data (image data of the encryption code) encrypted by the encryption control unit 306 is passed to the output data processing unit 305 and output. On the other hand, the image data of the non-confidential part in the image data input to the output data processing unit 305 when the encryption is specified and the image data when the encryption is not specified are output from the output data processing unit 305. Are subjected to predetermined image processing, and are output from the output data processing unit 305 without passing through the encryption control unit 306.

  When decryption is specified, the encryption code in the image data input to the input data processing unit 303 is passed from the input data processing unit 303 to the decryption control unit 304 and decrypted. The image data decoded by the decoding control unit 304 is passed to the input data processing unit 303 and output. On the other hand, the image data of the part which is not the encryption code in the image data input when the decryption is specified and the image data input when the decryption is not specified After the image processing is performed, the image data is output from the input data processing unit 303 without passing through the decoding control unit 304.

  Reference numerals 416 and 417 in the figure correspond to those having the same reference numerals described later with reference to FIG. The input data processing unit 303 and the output data processing unit 305 include a scanner correction processing unit 400, an I / F unit 401, a filter unit 402, a background removal / show-through removal unit 403, and a color correction unit, which will be described later with reference to FIG. 404, a scaling unit 405, a gradation correction unit 406, a tint block synthesis unit 409, and a printer correction processing unit 410.

  FIG. 4 shows a detailed configuration of the image processing unit 205. Hereinafter, main processing and control flows of the image forming apparatus according to the present embodiment will be described with reference to FIG.

  The image data input from the reading control unit 202 is converted by the scanner correction processing unit 400 from the linear reflection data read by the reading unit 201 into linear density data. The converted image data is passed from the I / F unit 401 to the I / F unit 206 via the path 418, and the I / F unit 206 transmits the image data via the memory 207, the data bus 211, and the controller ASIC 212. The data is transferred to the HDD 213 or the memory 216 or to the memory 207, and is stored and held in these devices.

  When outputting for forming an image, the image data stored and held is read out from the HDD 213, the memory 216, or the memory 207 via the I / F unit 206 and the controller ASIC 212 under the control of the CPU 208. The read image data is transferred from the I / F unit 206 to the I / F unit 401 via the path 418.

  The image data transferred to the I / F unit 401 is processed by a filter unit 402, a background removal / show-through removal unit 403, a color correction unit 404, and a scaling unit 405 to remove background removal / show-through, color correction, and scaling. Is transferred to the gradation correction unit 406 via the path 419 via the I / F unit 206. The transferred image data is further subjected to gradation correction by the gradation correction unit 406, and is transferred from the gradation correction unit 406 to the copy-forgery-inhibited pattern synthesis unit 409 through the path denoted by reference numeral 420. The image data transferred from the tone correction unit 406 is subjected to background pattern synthesis processing by the background pattern synthesis unit 409 as necessary, and is passed to the printer correction processing unit 410. The printer correction processing unit 410 converts the image data from RGB signals to CMYK signals, performs a printer γ correction process or the like in accordance with the device characteristics of the writing unit 203, and transfers the data to the writing control unit 204. The image data is output from the writing unit 204 to the writing unit 203 and an image is formed on a medium such as printing paper. Note that the image data passed from the scaling unit 405 to the I / F unit 206 can be stored and held in the HDD 213 via the data bus 211 and the controller ASIC 212.

  Normal image formation is performed by the above-described processing and control flow.

  With continued reference to FIG. 4, a process for forming an image in which a concealed portion is encrypted and added as an encryption code from a document including a concealed portion, and an encryption code is performed from the document in which the concealed portion is added as an encryption code. The flow of processing when decoding and performing image formation will be described.

  When the user gives an instruction to encrypt the concealed part from the operation unit 215 and specifies the area of the concealed part, the CPU 214 uses the information (for example, in the document) for determining the area of the concealed part. Information for specifying the position of the secret part) is stored and held in the memory 216 or the like. When an image is formed by adding a secret part as an encryption code to form an image, the image data of the document including the secret part transferred from the reading control unit 202 to the image processing unit 205 is stored in the HDD 213 or the memory 216 as described above. Alternatively, it is stored and held in the memory 207.

  When forming an image, image data is read from the HDD 213, the memory 216, or the memory 207 in the same manner as the processing and control described above with reference to FIG. 402, a background removal / show-through removal unit 403, a color correction unit 404, and a scaling unit 405 undergo predetermined processing, and are transferred to a gradation correction unit 406 via a path 419 via an I / F unit 206. . Thereafter, the image data is transferred from the gradation correction unit 406 to the encryption unit (encryption unit) 407, and the encryption unit 407 performs encryption processing on the image data in the confidential area. If the area is not the confidential area, the encryption unit 407 only transfers the image data and does not perform encryption. Whether or not the area is the secret part is determined by the CPU 214 or the like from the information for determining the secret part area stored in the memory 216 (described above), and is notified to the encryption unit 407.

  The encryption unit 407 passes the encrypted information (encryption code) to the code generation unit (encryption image generation means) 408, and the code generation unit 408 generates an image for the front (front) surface of the encryption code. Generate data. The generated image data is passed to the tint block synthesis unit 409.

  On the other hand, if the area is not the confidential area, the processing in the encryption unit 407 and the code generation unit 408 is not performed, and the image data is passed to the tint block synthesis unit 409 as data after gradation correction by the gradation correction unit 406. . Then, the image data passed from the tone correction unit 406 to the copy-forgery-inhibited pattern synthesizing unit 409 is subjected to a copy-forgery-inhibited pattern synthesis process by the copy-forgery-inhibited pattern synthesis unit 409 as necessary, and is transferred to the printer correction processing unit 410, where After a predetermined process is performed by the correction processing unit 410, the output is output from the writing control unit 204 to the writing unit 203.

  When the image formation on the front (front) surface is completed as described above, next, the image formation on the back surface is performed. In the flow of image data in the case where the area other than the confidential area is not the confidential area, the image data (white) without data is transferred. Image data is read from the HDD 213, the memory 216, or the memory 207 in the confidential area in the same manner as described above, and the read image data passes through the I / F unit 206, passes through the path 419, and performs gradation processing. The data is transferred to the correction unit 406. Further, the image data is transferred from the gradation correction unit 406 to the encryption unit 407, and subjected to encryption processing.

  The encryption unit 407 passes the encrypted information (encryption code) to the code generation unit 408, and the code generation unit 408 generates image data for the back side of the encryption code, and performs printer correction via the tint block synthesis unit 409. The information is passed to the processing unit 410. The image data passed to the printer correction processing unit 410 is subjected to predetermined processing by the printer correction processing unit 410, and is output from the writing control unit 204 to the writing unit 203. The copy-forgery-inhibited pattern synthesis unit 409 only transfers image data here.

  By such a processing flow, an image is formed in which the encryption code is added to both sides of the document.

  With reference to FIG. 4, a case will be described in which the encrypted code is decrypted from the document to which the encrypted code of the secret part is added to form an image.

  When the reading unit 201 reads a document to which the encryption code of the secret part is added, the image data of the document transferred from the reading control unit 202 is converted from linear reflection data to linear density data by the scanner correction processing unit 400. Conversion processing is performed. The converted image data is passed to the I / F unit 401, and is further passed from the I / F unit 401 to the I / F unit 206 and the code detection unit 412.

  The code detection unit (encryption code detection unit) 412 that has received the image data from the I / F unit 401 detects the area of the encryption code and specifies its position. The position information specifying the area of the detected encrypted code is set as the area information of the encrypted code. This information is passed to the I / F unit 206 via a path indicated by reference numeral 417. The detection of the area of the encrypted code is based on information (image: mark) indicating the position. The information indicating this position is based on, for example, a finder pattern (cutout symbol) of a QR code.

  The I / F unit 206 receives the image data from the I / F unit 401 and the information from the code detection unit 412, and stores them in the HDD 213, the memory 216, or the memory 207 via the data bus 211 and the controller ASIC 212. Let it. The data stored and held here is image data and area information of the encryption code.

  When forming an image, the CPU 208 controls the CPU 208 to read the image data of the document and the area information of the encryption code from the HDD 213, the memory 216, or the memory 207, and read the read data from the I / F unit 206 to the I / F unit 206. Transfer to F section 401. The image data is further transferred from the I / F unit 401 to the filter unit 402 via a path indicated by reference numeral 411, and the area information of the encrypted code is transferred to a decoding unit (decryption unit) 413 via a path indicated by reference numeral 415.

  The image data transferred to the filter unit 402 is subjected to respective processes in order by the filter unit 402 and the background removal / show-through removal unit 403, and is passed to the color correction unit 404 and the decoding unit 413.

  The decryption unit 413 determines, based on the region information of the encrypted code, that the image data received from the background removal / show-through removal unit 403 in the path indicated by reference numeral 416 is data in the region of the encrypted code. The image data received from the background removal / show-through removal unit 403 is transferred to the decoded data generation unit 414. The decrypted data generation unit 414 decrypts the image data (encryption code) received from the decryption unit 413, and passes the decrypted image data to the color correction unit 404.

  The color correction unit 404 receives the image data from the background removal / show-through removal unit 403 and the decrypted image data from the decrypted data generation unit 414, and if it is not the area of the encryption code, the background removal / show-through removal unit The image data from 403 is selected, and in the case of the area of the encryption code, the image data after decryption from the decryption data generation unit 414 is selected and a predetermined process is performed. Here, the determination as to whether or not the area is the area of the encryption code in the color correction unit 404 is performed based on whether or not image data is input from the decryption data generation unit 414. After that, the color correction unit 404 transfers the selected image data subjected to the predetermined processing to the scaling unit 405.

  The image data transferred from the color correction unit 404 is subjected to scaling processing as necessary in the scaling unit 405, and transferred to the gradation correction unit 406 via the I / F unit 206 and the path 419. . The image data subjected to the tone correction by the tone correction unit 406 is transferred from the tone correction unit 406 to the copy-forgery-inhibited pattern synthesizing unit 409 through the path denoted by reference numeral 420. Then, the image data from the gradation correction unit 406 is subjected to background pattern synthesis processing by the background pattern synthesis unit 409 as necessary, passed to the printer correction processing unit 410, and sent from the write control unit 204 to the write unit 203. The image is output and the image is formed.

  According to the above-described processing flow, an image is formed by decrypting the encrypted code.

  In the present embodiment, when a manuscript including a confidential part is distributed only to a party who can provide information on the concealed part, the concealed part of the manuscript is encrypted in order to increase security so that the confidential part is confidential to other parties. The secret part is decrypted so that the information can be obtained, and the information cannot be obtained just by looking at the original. In addition, even if the original document of the distribution partner is copied and spread, the security code of the original including the concealed portion is enhanced by copying the encrypted code of the concealed portion in an undecryptable state. Hereinafter, generation of the image data of the encryption code of the secret part will be described.

  FIG. 5A shows an example of table (front) data of an original document including a secret part.

  As shown in FIGS. 5B and 5C, the data of the concealed portion is generated as encryption code in the front data of the front side of the document and the back side data of the back side of the document. . When the document is read from the front side, the image of the encrypted code portion printed and generated on the back side can be read as a show-through as shown in FIG. 5D. Note that the broken line in FIG. 5D indicates the position of the image on the front (front) surface and is not show-through.

  FIG. 6 shows a situation when distributing a manuscript including a confidential part and when an illegal copy is made from a distributed material. As shown in FIG. 6, it is assumed that the confidential portion 602 is printed on the original 601. The back surface is blank. Here, the back surface is blank for ease of explanation, but image data may be generated on the back surface.

  In the present embodiment, originals (603 to 605) in which images are formed using the secret part 602 as encrypted codes (606 and 607) are distributed. In FIG. 6, the encryption code is an image of an encryption code of five squares and one line, but in practice, it is a form that can handle a large amount of information such as a two-dimensional barcode and a QR code.

  In the encryption code 606 on the front (front) side, the second from the left is printed in black. In the encryption code 607 on the back side, the first and second from the left are printed in black. In addition, the encrypted code 607 on the back surface is the same as the position where the encrypted code 606 on the front (front) surface is printed when read from the front (front) surface. Therefore, the positions of black printing of the encryption code 607 on the back side are the fourth and fifth positions from the left when read from the front side. The black printing on each of the squares on the front (front) surface and the back surface is a printing state in which the density values are different.

  Originals 603 to 605 to be distributed are obtained by adding a secret part of the original 601 as an encryption code. When the distributed manuscripts 603 to 605 are illegally copied, the encryption codes of the copies 608 and 609 are such that the printing state is different from those of the manuscripts 603 to 605 to be distributed.

  For example, in the example of FIG. 6, the image 610 of the encrypted code of the copy 608 copied from the original 603 is black printed on the second side and the fifth from the left on the front side, and 611 on the back side. As shown in the figure, the first from the left is black printing. Also, the image of the encrypted code of the copy 609 copied from the original 605 has black, second, fourth, and fifth prints from the left as shown by reference numeral 612 on the front side. In the example, as shown by reference numeral 613, the first and second from the left are printed in black. In this way, when the encryption code of the secret part is copied, an image having an encryption code different from that of the distribution document is obtained.

  Here, generation and reading at the time of decryption of an encrypted code which will be in the above-described state when a document including the encrypted code is copied will be further described with reference to FIGS.

  When the encrypted code printed as shown by 606 and 607 in FIG. 6 is read from the front side, as shown in FIG. 7, the portion denoted by reference numeral 700 is black-printed, and the portions denoted by reference numerals 701 and 702 are show-through. Becomes In the portion where black printing is to be performed, printing is performed with different color densities.

For example, the density read from the front side of the encrypted code shown in FIG. 7 is, as shown in FIG.
The first (801) density value from the left is white: 255,
The second (802) density value is black: 170,
The third (803) density value is white: 255,
The fourth (804) density value is black: 230,
The fifth (805) density value is black: 150,
Becomes

  On the other hand, on the reverse side, portions indicated by reference numerals 703 and 704 in FIG. 7 are printed in black, and portions indicated by reference numeral 705 are show-through. Also, the portions indicated by reference numerals 703, 704, and 705 are the positions of the portions indicated by reference numerals 702, 701, and 700, respectively, on the surface.

The density value on the back side of the encryption code at this time is, for example,
The first density value from the left is (black: 100)
The second density value is (black: 180)
The third density value is (white: 255)
The fourth density value is (black: 220)
The fifth density value is (white: 255)
Becomes In the present embodiment, such an encrypted code is printed.

  When a document including such an encryption code is copied, reading and printing are performed with the reading density as described above.

  Some copying machines have a show-through removal function. When show-through is removed by this show-through removal function, the density value is involved in determining whether or not to perform removal. As the show-through removal function, it is determined whether to print or not to print with the density value as a threshold as one of the parameters. For example, as shown in FIG. 9, when "removal of density value 220 or more" is set for the encryption code 900 (see FIG. 9), printing of the encryption code portion on the front side of the copy is performed as shown in FIG. As shown by reference numeral 1000, the first, third, and fourth from the left are printed in white, and the others are printed in accordance with the density. In this case, the fourth (density value: 230) from the left of the encrypted code shown in FIG. 7 has been removed by the show-through removal function. On the other hand, in the printing of the encrypted code portion on the back side of the copy, the third, fourth, and fifth from the left are printed in white as indicated by reference numeral 1001 in FIG. 10, and the others are printed in accordance with the density. In this case, the fourth (density value: 220) from the left of the encrypted code shown in FIG. 7 has been removed by the show-through removal function. The larger the density value is, the whiter side.

  Also, as shown in FIG. 11, when “removing the density value of 150 or more” is set for the encrypted code 1100, the front side of the copy comes from the first from the left as indicated by reference numeral 1200 in FIG. The fourth is white printing, and the fifth is printing according to the density. In this case, in the encrypted code shown in FIG. 7, the second and fourth from the left are removed by the show-through removal function. On the other hand, as shown by reference numeral 1201 in FIG. 12, on the back side of the copy, the second to fifth from the left are printed in white, and the first is printed in accordance with the density. In this case, the second and fourth from the left of the encrypted code shown in FIG. 7 have been removed by show-through removal.

  As described above, the print density of the encrypted code differs during copying depending on the threshold value of the density value used in the show-through removal function. By using such an encryption code and performing identification based on the difference in these density values at the time of decryption, it is possible to make it impossible to decrypt the encrypted code in a copy original.

  Subsequently, the decryption of the encrypted code will be further described. In the decryption according to the present embodiment, the read result of each image block of the confidential portion image data is represented as a numerical value (code). For example, one square of the encryption code is a four-digit numerical value (see FIG. 13). As shown in FIG. 13, the first digit from the left is the print determination result (1301) on the front side of the area of the encryption code, the presence of printing is 1, the absence is 0, and the second digit is the density determination result on the front side. As (1302), if the density is equal to or higher than the threshold value, it is set to 1, if it is lower than it, it is set to 0. Also, the third digit is set as the back side print determination result (1303), with 1 with printing and 0 with no printing. The fourth digit is the back side density determination result (1304), and is 1 when the density is equal to or higher than the threshold value, and is 0 when the density is lower than the threshold.

  By doing so, the four-digit code is as shown in FIG. The column denoted by reference numeral 1406 is an example of an image when printed (not limited to the one shown in the figure). Codes denoted by reference numeral 1401 are nine types of 0000, 1000, 1100, 0010, 0011, 1010, 1110, 1011 and 1111. As shown in the figure, a code 1401 is printed in a table print (print determination result on the front (front) surface) shown in a column 1402, and a table density (printed on the front (front) surface) shown in a column 1403 is displayed. Density determination result), back printing (printing determination result on the back side) shown in a column 1404, and back density (density determination result on the back side) shown in a column 1405.

  The image indicated by reference numeral 1501 in FIG. 15 is indicated by reference numeral 606 in FIG. 6 in which the secret part of the distributed material is an encrypted code, and the image indicated by reference numeral 1502 in FIG. 15 is indicated by reference numeral 607 in FIG. Things. In reading the encrypted code, the positions indicated by numerical values (1 to 5) described below the images of the respective encrypted codes denoted by reference numerals 1501 and 1502 are the same as those at the same position at the time of decryption. Become. These are represented by the code value (1401) at the time of decoding shown in FIG. Note that reference numeral 1503 in FIG. 15 indicates that the code values corresponding to the first to fifth cells of the reference numerals 1501 and 1502 are 0000, 1100, 0000, 0010, 0011, respectively.

  FIG. 16 shows a four-digit code value (reference numeral 1603) obtained by decrypting encrypted codes 1601 and 1602 (1000 and 1001 in FIG. 10) of an illegally copied distribution material, similar to that shown in FIG. Is represented. In the example of FIG. 16, as the show-through removal processing, copying is performed when the threshold density for show-through removal is set to a high value (here, 220 or more) as shown in FIG. Similarly, FIG. 17 shows four-digit code values obtained when the encrypted codes 1701 and 1702 (1200 and 1201 in FIG. 12) obtained by illegally copying the distributed material are decrypted. In the example of FIG. 17, as the show-through removal processing, copying is performed when the threshold density for show-through removal is set to a low value (here, 150 or more) as shown in FIG. Such illegally copied data cannot be accurately copied by the show-through removal function or the like, and a correct result cannot be obtained in decrypting the encrypted code.

  The density threshold for printing the image data of the encrypted code and the density threshold for decoding the encrypted code and converting it to a code value can also be set to be variable. By changing the density threshold 1901 as shown in FIG. 18, the density of the encrypted code at the time of printing and the conversion of the code value of the decryption result are changed. This makes it possible to finely adjust the threshold value according to the variation in the characteristics and performance of each device, and when the reading threshold value at the time of decoding is different for each region as described later, decoding is more performed. It becomes difficult and security can be increased.

  Next, a processing flow for generating an encryption code and performing printing with the encryption code added will be described with reference to the flowchart of FIG. In the following description, it is assumed that the original has image data only on the front side.

  First, in step 1901, the CPU 214 of the image forming apparatus determines whether or not it is specified whether or not to add a secret part of a document to be read as an encryption code. Here, if the secret part is not added as an encryption code (no encryption specified: No in step 1901), the image forming apparatus reads the document as it is and prints it (normal copying) (step 1912). . On the other hand, if the confidential part is to be added as an encryption code (with encryption specified: Yes in step 1901), in step 1902, the operation unit 215 of the image forming apparatus receives the specification of the paper type by the user.

  In the present embodiment, data on the value of the read density value due to show-through from the front side is stored in the HDD 213 in advance according to the paper type (or paper thickness) and the print density on the back side. By specifying the paper type here, the corresponding print density value on the back side is determined. In step 1901 and step 1902, designation of whether or not to encrypt and designation of the paper type are performed by the operation unit 215 by a user operation, and are processed by the CPU 214 or the CPU 208. The data of the read density value due to show-through based on the paper type is stored in the HDD 213 or the like, and the read density value due to show-through is specified by the CPU 214 or the CPU 208.

  In step 1903, the image forming apparatus reads a document including a confidential part installed in the image forming apparatus, and stores and holds the read image data. Here, the image data transferred from the reading control unit 202 by reading is converted from linear reflection data read by the reading unit 201 by the scanner correction processing unit 400 to linear density data. The converted data is passed from the I / F unit 401 to the I / F unit 206 via the path 418, and is transmitted from the I / F unit 206 to the HDD 213, the memory 216, or the memory via the data bus 211 and the controller ASIC 212. 207 is stored.

  In step 1904, the operation unit 215 of the image forming apparatus displays the read original, and receives an instruction from the user for an area in the original that is to be kept secret. Here, for example, the read image data is displayed on the operation unit 215 in which the operation unit and the display unit such as a touch panel are integrated, and the information of the area of the confidential portion designated by the user from the operation unit 215 is displayed. , From the operation unit 215 to the memory 216 or the like.

  In step 1905, the image forming apparatus starts image formation, and reads out the image data of the document stored and held and the area information of the secret part. At this time, the CPU 214 or the CPU 208 reads out the data stored and held in the HDD 213 or the like, and instructs the image processing control unit 200 to perform various image processing (the filter unit 402, the background removal / show-through removal unit 403, the color correction unit 404, the scaling unit). 405). The processed data is transferred to the gradation correction unit 406 via the path 419 via the I / F unit 206.

  The encryption unit 407 acquires the image data of the document from the gradation correction unit 406 and the area information of the secret part, and determines whether or not the obtained image data is the area of the secret part (step 1906). If the area is a confidential area (Yes in step 1906), in step 1907, the image data is subjected to encryption processing. If not (No in step 1906), the image forming apparatus proceeds to step 1909.

  In step 1908, the image forming apparatus generates image data of the encryption code. Here, data that has been converted into an encrypted code by the encryption unit 407 is generated as image data to be printed by the code generation unit 408 (code data generation). The generated image data is the image data of the front surface and the back surface.

  In step 1909, the image forming apparatus generates image data in which the image data other than the secret part and the image data of the encryption code generated in step 1908 are combined. The image data other than the concealed part is transferred as it is in the encryption unit 407 and the code generation unit 408, and only the confidential part area is passed to the tint block synthesis unit 409 as image data when the encrypted code is printed. The copy-forgery-inhibited pattern synthesizing unit 409 adjusts the printing position of the document image and the encryption code. The copy-forgery-inhibited pattern synthesis unit 409 determines whether or not a copy-forgery-inhibited pattern is added according to the processing setting by the user.

  In step 1910, the image forming apparatus prints the front (front) surface. Here, predetermined processing is performed on the image data from the copy-forgery-inhibited pattern synthesizing section 409 in the printer correction processing section 410, and printing is performed by the writing control section 204.

  In step 1911, the image forming apparatus prints the back surface. When printing on the front (front) surface in step 1910 is completed, printing on the back surface is started. In this example, the print data on the back side is only the image data of the encryption code, and is sequentially printed line by line. The copy-forgery-inhibited pattern synthesis unit 409 performs printing on the back surface by transferring the image data (image data on the back surface) of the encrypted code generated by the code generation unit 408 in accordance with the timing of the position to be printed.

  As described above, a document including the image of the encryption code is formed.

  Next, a processing flow when decrypting the confidential portion from the document in which the confidential portion has been encrypted will be described with reference to the flowchart in FIG. The following description is a flow of the process after the user specifies the process to perform the decryption.

  In step 2001, the image forming apparatus reads a document. Here, the reading unit 201 reads both sides of the document set in the reading unit 201 under the control of the reading control unit 202.

  In step 2002, the image forming apparatus detects the region of the encryption code in the document image at the same time as reading the document in step 2001, and acquires image data in the region of the encryption code. Here, the image data of the document read in step 2001 is converted from linear reflection data to linear density data by the scanner correction processing unit 400, and the image data is transmitted to the I / F unit 206 via the I / F unit 401. In addition to this, it is also passed to the code detection unit 412. Then, the code detection unit 412 detects the area of the encrypted code in the received image data (described above), and specifies the position.

  In step 2003, the image forming apparatus stores and holds the area information of the encrypted code detected by the code detecting unit 412 and the image data of the read original. The area information of the encrypted code is transmitted from the code detection unit 412 via the I / F unit 206, and the image data of the document is transmitted from the scanner correction processing unit 400 via the I / F unit 401 and the I / F unit 206. , Will be transferred. The transferred encrypted code area information is stored and held in the memories 207 and 216, and the image data of the document is stored and held in the HDD 213.

  In step 2004, the image forming apparatus starts the image forming process, and reads out the image data of the document stored and held in step 2003 and the detected encrypted code area information. The image data of the document read from the HDD 213 is passed through the I / F unit 206 and the I / F unit 401 to the filter unit 402, the background removal / show-through removal unit 403, the color correction unit 404, and the scaling unit 405. Each process is performed. The decryption unit 413 receives the area information of the encrypted code via the I / F unit 206 and the I / F unit 401. The decoding unit 413 receives image data of a document from the background removal / show-through removal unit 403.

  In step 2005, the image forming apparatus determines whether the image data to be processed is data at the position of the area of the encryption code. Here, the decoding unit 413 makes that determination.

  When the processing target is the image data in the area of the encryption code (Yes in step 2005), the image forming apparatus selects the decryption data as the printing target (step 2006). Here, first, the decryption unit 413 transfers the image data in the area of the encrypted code to the decrypted data generation unit 414, and the decrypted data generation unit 414 decrypts the encrypted code (details will be described later). (Decoded data) is generated. The generated image data (decoded data) is passed to the color correction unit 404.

  On the other hand, if the processing target is not the data in the area of the encryption code (No in step 2005), the image forming apparatus selects the image data (document data) of the document as the printing target (step 2008). In step 2006 and step 2008, the color correction unit 404 receives the decoded data from the decoded data generation unit 414 and the original data from the background removal / show-through removal unit 403. The data is selected and transferred to the scaling unit 405, and if the decoded data is not received, the original data is transferred to the scaling unit 405.

  In step 2007, the image forming apparatus performs printing. The printing here is performed in the same manner as in steps 1909 to 1911 described above (however, in this case, the original data and the decoded data are combined), and the image is formed.

  The first embodiment has been described above. As described above, in the present embodiment, when the encryption code is printed as an image, the encryption code is printed on the front side and the back side, and the printed image on the back side is treated as show-through information when reading from the front side. By making the density of the printed image on the back side difficult to copy by distinguishing it from the density of the printed image on the front side, the type of printing paper used for copying is further reduced by show-through removal processing by the show-through removal function etc. Is not necessarily the same as that of the original document, which makes it difficult to make a faithful copy. In this manner, when a document whose concealed portion is printed as an image of the encrypted code is copied, the decryption cannot be performed accurately from the image of the encrypted code. Security can be improved.

(Second embodiment)
Next, a description will be given of a second embodiment in which a margin position on both sides of a document is detected and an encryption code is printed on the margin portion to effectively utilize the margin.

  In the example shown in FIG. 21, there are print images on both sides of the document, and a print image (2102) also exists on the back surface of the confidential portion (2101). In this case, a blank portion (a portion having no image) on both sides is detected, and the encrypted code is printed. As shown in FIG. 22, a margin indicated by reference numeral 2201 exists on the front (front) surface, and a margin indicated by reference numeral 2202 exists on the back surface. A portion having blank spaces on both sides is a portion indicated by reference numeral 2201. In the present embodiment, an encrypted code is printed on this portion.

  Next, a process of detecting the margin positions on both sides of the print portion of the encryption code and printing the encryption code in the detected margin portion will be described with reference to the processing flow of FIG.

  In step 2301, the CPU 214 of the image forming apparatus determines whether it is specified whether or not to add a secret part of the document to be read as an encryption code. Here, if the secret part is not added as an encryption code (no encryption specified: No in step 2301), the image forming apparatus reads the document as it is and performs printing (normal copying) (step 2315). . On the other hand, if the confidential part is to be added as an encryption code (with encryption specified: Yes in step 2301), in step 2302, the operation unit 215 of the image forming apparatus receives the specification of the paper type by the user.

  In step 2303, the image forming apparatus reads a document including a confidential portion provided in the image forming apparatus, and stores and holds the read image data. In the case of double-sided printing, image data of both sides is stored and held.

  In step 2304, the operation unit 215 of the image forming apparatus displays the read original, and accepts a user's instruction of an area to be a secret part in the original. The steps up to this point are the same as steps 1901 to 1904 described above with reference to FIG.

  In step 2305, the encryption unit 407 encrypts the image data of the confidential area specified in step 2304, and the code generation unit 408 generates the image data of the encrypted code. At this time, the code generation unit 408 acquires the size information of the image data coded as the encryption. The encrypted image data is temporarily stored in a storage device (the memories 207 and 216 or the HDD 213) like the read image of the document.

  In step 2306, the code generation unit 408 detects whether or not image data exists on the back surface of the concealed portion of the designated front surface. This detection can be determined based on whether the corresponding area is not a white background or a white background.

  If there is no image data in the corresponding area on the back surface (No in step 2306), the image forming apparatus proceeds with the process to step 2310. On the other hand, when the image data exists in the corresponding portion on the back surface (Yes in step 2306), in step 2307, the code generation unit 408 detects a margin portion on the front (front) surface and the back surface. In the example of FIG. 22, the blank portions indicated by reference numerals 2201 and 2202 are detected as described above.

  If it is determined in step 2308 that there is no margin as a result of the detection in step 2307 (No in step 2308), in step 2316, the image forming apparatus issues a message indicating that there is no printable portion of the encrypted code due to insufficient margin (cannot be created). Message) is displayed on the operation unit 215, and the series of processing ends.

  When it is determined that there is a margin as a result of the detection in step 2307 (Yes in step 2308), in step 2309, the code generation unit 408 determines the size and the size of the margin from the size information of the image data of the encrypted code acquired in step 2305. Then, it is determined whether or not the size of the image data of the encryption code is a printable size. If the size of the image data of the encryption code is larger than the margin size (No in step 2309), printing cannot be performed, and the image forming apparatus does not have enough printable portions of the encryption code due to insufficient margin according to this determination result. Is displayed on the operation unit 215, and the series of processes is terminated.

  On the other hand, if the size of the image data of the encrypted code is smaller than the margin size (Yes in step 2309), the image forming apparatus proceeds to step 2310 to perform image forming processing.

  In step 2310, the image forming apparatus starts image forming processing and reads out image data of the document stored and held.

  In step 2311, the code generation unit 408 deletes the image data of the confidential area specified in step 2304 from the image data of the document.

  Next, in step 2312, the copy-forgery-inhibited pattern combining unit 409 combines the image data of the document other than the confidential portion from which the image data of the confidential portion has been deleted with the image data of the encryption code generated in step 2305. Generate. At this time, the copy-forgery-inhibited pattern synthesizing unit 409 adjusts the positions of the image data of the document other than the confidential portion and the image data of the encryption code.

  Note that, in the present embodiment, the front-side margin area is managed by area information indicating the position of each front-side margin area. Similarly, the back side manages the margin area with area information indicating the position. Then, from each margin area on the front and back sides, a portion where the front and back sides have margins is determined. A printable area is identified from the size of the area of the front and back margins and the image size of the encryption code. An encryption code is printed by selecting one of the printable areas.

  In the following step 2313, the image forming apparatus prints the front side using the image data synthesized in step 2312.

  Next, in step 2314, the CPU 208 of the image forming apparatus determines whether printing on both sides has been completed, and if not completed (No in step 2314), returns the processing to step 2310, and executes the previously executed table (front). ) Printing on the back side is performed in the same manner as the processing on the side. However, the image data used here is the image data of the encryption code for the back side. The processing in each processing unit of the image processing control unit 200 in each step is performed in the same manner as the corresponding processing described in the first embodiment.

  Finally, in step 2314, it is determined whether printing on both sides is completed, and it is determined that both sides are completed (Yes in step 2314), and the image forming apparatus ends a series of processes.

  In the present embodiment, by performing the above processing, as shown in FIG. 24, the confidential portion becomes a blank (2401), and the encryption code of the confidential portion is the double-sided margin of the front (front) surface. It is printed in the margin 2402 and the margin 2403 on the back side.

  The second embodiment has been described above. In the present embodiment, the image of the encryption code is automatically detected and printed by automatically detecting portions where the opposite sides of the original have a blank space on each of the front (front) surface and the back surface of the document, so that the image is independent of human hands. Thus, the printing location of the encrypted code can be easily determined.

(Third embodiment)
Next, a third embodiment will be described. This embodiment not only makes the density value of each part variable when printing the image data of the encryption code as in the above-described embodiment, but also converts (decrypts) the encryption code into a code value. This is an embodiment in which the density threshold can be changed for each area. Since it is necessary to set a variable density threshold value for each area, it is more difficult to illegally decrypt (decrypt) the encrypted code, thereby enhancing security. The method will be described below.

  When an encryption code as shown in FIG. 25 exists, the image area on which the encryption code is printed is divided. In the example of FIG. 25, the area is divided into four areas 2500, 2501, 2502, and 2503. Then, the threshold for each of the four divided areas is made different, and the generation and decryption of the encrypted code are performed for each area as in the first embodiment. This requires threshold value information for each area, making it more difficult to decrypt the encrypted code.

  For example, as shown in FIG. 26 (A), when focusing on one horizontal line composed of five cells indicated by reference numeral 2505 (portion indicated by reference numeral 2505 in FIG. 25), reference numeral 2506 indicates the boundary between the boundary indicated by reference numeral 2506 (see FIG. 25). The threshold indicated by 2600 is different. The result of the conversion of the encrypted code into the code value is as shown by 2601 in FIG. When the threshold value for each area is the same as indicated by reference numeral 2700 in FIG. 27A, even if the encrypted data has the same print density, the code value at the time of decryption as indicated by reference numeral 2701 in FIG. Will be different. Therefore, different threshold values are required for each region in order to perform normal decoding, and decoding can be made more difficult.

  Further, when the density threshold is changed for each area as shown in FIG. 26, in order to obtain a code value at the time of decoding equivalent to the case where the density threshold shown in FIG. 27 is not changed, as shown in FIG. ), The threshold value of the density needs to be changed. When the print result 2505 of an encrypted code whose density threshold does not differ for each area and the print result of an encrypted code whose density threshold differs for each area are the same, to obtain the same code value by decryption, FIG. As shown in A), the density of the print portion indicated by reference numeral 2802 is changed as indicated by reference numeral 2800. In the example of FIG. 28, the density value is set to be more white. As a result, the print result 2505 of the encrypted code whose density threshold value does not differ for each region and the print result 2801 of the encrypted code whose density threshold value differs for each region (2701 in FIG. 7B, FIG. 28B ) 2803).

  As described above, by changing the threshold values of the print density and the read density for each area, it is possible to make decoding (decoding) more difficult.

(Fourth embodiment)
A method that enables the encryption code to be decrypted by reading from the front (front) surface and the decryption by reading from the back surface, and that the encryption code can be set to be read from the front surface and the back surface for each area. Will be described.

  As described above, when a printed version of the encrypted code of the secret part is read for decryption, printing of the encrypted code as indicated by reference numeral 2900 in FIG. Can be converted to a value. The printed encrypted code is read from the back side and the same decryption is performed under the threshold indicated by reference numeral 3001 to obtain the printed encrypted code as indicated by reference numeral 3000 in FIG. Left and right are in reverse order. In the reading, the density of show-through is different from the density of the front (front) surface. As a result, the conversion of the decoding code value is as shown in FIG. 30B, and not only the order of right and left is different as shown by the reference numeral 3002 but also is different depending on the show-through state (for example, FIG. Reference numeral 2903 in FIG. 30B and reference numeral 3003 in FIG. 30B).

  In this embodiment, for each area, the encryption code is a combination of an encryption code for reading a front surface and an encryption code for reading a back surface. Since the combination of reading the front side and reading the back side of the encrypted code can be easily changed, it is possible to make unauthorized decryption (decryption) more difficult.

  FIG. 31 is a diagram illustrating the area division of the encryption code of the secret part in the present embodiment. In the example shown in the figure, the area is divided into four areas 3100, 3101, 3102, and 3103. The back surfaces of the portions denoted by reference numerals 3100, 3101, 3102, and 3103 are portions denoted by reference numerals 3106, 3107, 3104, and 3105, respectively. The areas to be read and decoded from the front side are areas indicated by 3100 and 3103, and the areas to be read and decoded from the back side are areas indicated by reference numerals 3101 (3107 on the back side) and 3102 (3104 on the back side).

  On the front (front) side, the encrypted code of FIG. 31 is printed as it is. The back side is printed in such a manner that the left and right sides of the encryption code on the front side (front side) are reversed for reading and decoding from the back side. As shown in FIG. 32, the image data to be read and decoded from the front side of the encrypted code is indicated by reference numerals 3200 and 3201. The corresponding encrypted codes on the back side are denoted by reference numerals 3202 and 3203, respectively. On the other hand, as shown in FIG. 33, the image data to be read from the back side of the encrypted code and to be decrypted is represented by reference numerals 3302 and 3303. The corresponding surface image data are indicated by reference numerals 3301 and 3302, respectively. In this way, it is possible to easily generate an encrypted code and convert (decode) the code value of the encrypted code on both sides, and to make decryption (illegal decryption) more difficult. Here, reversing the left and right here means reversing the arrangement of the encryption codes in the main scanning direction.

  Note that, in the present embodiment, the code generation unit 408 performs part of the image of the encrypted code read from the table of the document (the part denoted by reference numeral 3200 and the reference numeral 3201) when the decryption unit 413 decrypts the encrypted code. And a portion excluding a portion corresponding to the above portion of the image of the encrypted code read from the back of the document (the portions indicated by reference numerals 3302 and 3303) so that the encrypted code can be decrypted. Generate image data.

  As described above, decoding (illegal decoding) can be made more difficult by performing decoding by reading the front surface and decoding by reading the back surface for each region.

  The embodiments of the image forming apparatus as the image processing apparatus have been described above. According to the above-described image processing apparatus, it is possible to improve security when copying a document in which a secret part is protected as an encryption code.

  In the above embodiments, an image forming apparatus has been described as an example of an image processing apparatus according to the present invention. Can be applied to a multifunction peripheral having at least two functions. In the case where a personal computer, a scanner and a printer are used instead of the image forming apparatus, the personal computer functions as an image processing apparatus according to the present invention. Can also be used.

  Further, when the image processing device according to the present invention is realized by an information processing device such as a personal computer or a portable information terminal, the image processing program executed by the information processing device is installed in an installable format or an executable format. The file is provided by being recorded on a computer-readable recording medium such as a CD-ROM, a flexible disk (FD), a CD-R, and a DVD (Digital Versatile Disk).

  The image processing program may be stored on a computer connected to a network such as the Internet, and may be configured to be provided or distributed by being downloaded via the network, or may be provided by being incorporated in a ROM or the like in advance. It may be configured as follows.

  Further, when the image processing apparatus according to the present invention is implemented by an information processing apparatus, as actual hardware, a CPU (processor) provided in the information processing apparatus executes the image processing program from a storage medium provided in the information processing apparatus. The image processing function and the control functions of the image processing control unit 200 and the CPUs 208 and 214 described above are realized by loading and executing the program on the main storage device.

101 Document 102 Encryption Code 103 Copy Document 104 Document Decrypted from Document 105 Document Decrypted from Copy Document 200 Image Processing Control Unit 201 Reading Unit 202 Read Control Unit 203 Writing Unit 204 Writing Control Unit 205 Image Processing Unit 206 I / F Unit 207 Memory 208 CPU
209 Memory 210 Data bus 211 Data bus 212 Controller ASIC
213 HDD
214 CPU
215 operation unit 216 memory 217 network 301 input processing unit 302 output processing unit 303 input data processing unit 304 decryption control unit 305 output data processing unit 306 encryption control unit 400 scanner correction processing unit 401 I / F unit 402 filter unit 403 background removal * Off-set removal unit 404 Color correction unit 405 Zoom unit 406 Gradation correction unit 407 Encryption unit 408 Code generation unit 409 Background pattern synthesis unit 410 Printer correction processing unit 412 Code detection unit 413 Decoding unit 414 Decryption data generation unit

JP 2012-22210A

Claims (9)

Encryption means for using a secret part of the read image as an encryption code;
When the encryption code is image-formed on the front and back of the medium, the encryption code formed on one side of the medium is removed so that the encryption code becomes one encryption code. As such , an encrypted image generating means for generating image data when forming an image of the encrypted code,
An image processing apparatus comprising: Encryption code detection means for detecting an image of the encryption code read from the medium,
Decryption means for decrypting the encrypted code from the image of the encrypted code detected by the encrypted code detection means,
The image processing device according to claim 1, further comprising: The encrypted image generation unit detects a margin on both sides of the medium as a position where an image of the encryption code is formed on the front and back of the medium, and detects the margin on a common margin between the front and back of the medium. The image processing device according to claim 1, wherein the image processing device generates image data for forming an image of the encryption code. It is possible to change a density value of the image data when generating the image data of the encryption code by the encrypted image generation unit and a density threshold value used when decoding the image of the encryption code by the decryption unit. The image processing apparatus according to claim 2, wherein the image processing apparatus can be set to:   The image processing apparatus according to claim 4, wherein the density value and the threshold value of the density can be changed for each divided area of the image of the encrypted code. The encrypted image generating means includes:
When decrypting the encrypted code by the decrypting means, a part of the image of the encrypted code read from the front of the medium and the part of the image of the encrypted code read from the back of the medium Generating image data of the encrypted code so that the encrypted code can be decrypted from a portion excluding a portion corresponding to
The decoding means,
Upon decryption of the encrypted code, the part of the image of the encrypted code read from the front of the medium and the part of the image of the encrypted code read from the back of the medium correspond to the part. Decrypting the encrypted code from the part excluding the part,
The image processing device according to claim 2 . An image processing apparatus according to any one of claims 1 to 6,
Image reading means for reading an image on a medium and outputting the read image data to the image processing apparatus;
Image forming means for forming an image output as image data for the image formation from the image processing apparatus on a medium,
An image forming apparatus comprising: A method implemented in an image processing device, comprising:
An encryption step of using a secret part of the read image as an encryption code;
When the encryption code is image-formed on the front and back of the medium, the encryption code formed on one side of the medium is removed so that the encryption code becomes one encryption code. in so that the encrypted image generating step of generating image data at the time of image forming the encrypted code,
An image processing method including: An encryption step of using a secret part of the read image as an encryption code;
When the encryption code is image-formed on the front and back of the medium, the encryption code formed on one side of the medium is removed so that the encryption code becomes one encryption code. so that the, the encrypted image generating step of generating image data at the time of image forming said encryption code, an image processing program for causing a computer to execute.

Images