JP2009267899A - Image reading apparatus, image forming apparatus and image reading program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To correctly detect a special pattern included in a document image. <P>SOLUTION: A special pattern detecting section compares an image shown by target pixels of a document image with a special pattern, and calculates the degree of similarity. If the degree of similarity is not less than a threshold, a special pattern counting section increments a count value. After the processing is repeated over the entire of the document image, and if the count value is not less than a criterion value, a special pattern determination section determines that a copy-prohibited information is contained in the document image. A breaking pattern inserting section inserts a breaking pattern into the document image which has been determined to include the copy-prohibited information and the document image is broken. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image reading apparatus, an image forming apparatus, and an image reading program capable of detecting a special pattern from a document image in which a special pattern for preventing copying is incorporated.

  As a method for suppressing copying of confidential documents, a method using a copy-forgery-inhibited pattern image in which a warning character appears when the confidential document is copied by a copying machine is known. When a document is created using such a copy-forgery-inhibited pattern image, there is a psychological deterrent effect against unauthorized copying, and the original and the copy can be distinguished.

  However, although the method using the copy-forgery-inhibited pattern image has a psychological deterrent effect on illegal copying, it cannot physically prevent copying and cannot completely prevent information leakage. Therefore, a copy guard function that detects a special pattern from an original image and prohibits copying of the original when the special pattern is detected, or prints a predetermined destruction image without printing the original to suppress information leakage of the original. A copier equipped with is known.

Further, in Patent Document 1, when a special pattern is detected from an original image, normal copying or printing is performed by inserting a destructive image from the middle of the print image and printing, or outputting or transmitting a blank image. A technique for preventing reading is disclosed. Further, Patent Document 2 discloses a technique for detecting a copy-forgery-inhibited pattern pattern that prohibits copying from a document image, and stopping the reading of the document when this copy-forgery-inhibited pattern is detected.
JP 2006-173757 A JP 2007-251634 A

  As a method of determining whether or not a special pattern of the original image is included, the similarity is calculated by comparing the special pattern with the pattern included in the original image. Many methods for determining that a pattern is included are used. At this time, the threshold is set to a special pattern in consideration of the characteristics of the scanner that reads the document image (lamp light quantity, CCD (Charge Coupled Device) sensor spectral characteristics, electrical characteristics such as noise, etc.), and wrinkles and dirt on the document. If a detected pattern such as about 80% is recognized as a special pattern with a predetermined probability without being set to a numerical value (for example, 100%) indicating that the original pattern completely matches, a special pattern is added to the original image. Is supposed to be included.

  On the other hand, if the similarity threshold is set too low, a pattern other than the special pattern may be recognized as a special pattern. For example, when a document having a pattern similar to a special pattern is read by a copying machine having a copy guard function, the copying machine includes a special pattern even though the pattern is not a special pattern. This causes the inconvenience that a normal copy is not performed. This causes a loss of convenience. As described above, when the similarity threshold is increased, it is difficult to detect the special pattern, and when the threshold is decreased, the possibility that the similar pattern is detected as the special pattern is increased.

  The present invention has been made to solve the above-described problem, and prevents a document image including copy restriction information from being erroneously printed, and accurately detects a special pattern included in the document image. It is intended.

  An image reading apparatus according to a first aspect of the present invention is a reading unit that reads a document image from a document, a special pattern storage unit that stores a predetermined special pattern, and whether the special pattern is included in the document image. Detecting means for detecting whether or not, counting means for counting the number of detected special patterns, and copy restriction information is included in the original image when the counted number is equal to or greater than a criterion value And a judging means for judging.

  According to a fifth aspect of the present invention, there is provided an image reading program comprising: a computer; a reading unit that reads a document image from a document; a detection unit that detects whether or not the document image includes a special pattern; It is characterized by functioning as counting means for counting the detected number, and determining means for determining that the copy restriction information is included in the document image when the counted number is equal to or greater than a determination reference value. .

  According to the present invention, when a special pattern is detected from a document image at a determination reference value or more, it is determined that the special pattern is incorporated in the document image. For example, even if a special pattern is incorporated in the original image, even if the special pattern cannot be detected from an area of the original image due to the contamination of the original image or the characteristics of the reading means, If the special pattern is detected from the judgment reference value or more, it can be judged that the special pattern is incorporated in the original image.

  Furthermore, even if a special pattern is detected as a special pattern even if a special pattern is not included in the original image, the special pattern is included in the original image if this pattern is not detected above the criterion value. It is not judged that In other words, since it is unlikely that many patterns similar to the special pattern exist in the document image, the probability of determining that the special pattern is incorporated in this document image is extremely low. Can be accurately determined.

  According to a second aspect of the present invention, in the image reading apparatus according to the first aspect, a determination reference value receiving unit that receives a setting input of the determination reference value, and a setting input received by the determination reference value receiving unit. And determining means for determining the determination reference value based on the determination reference value.

  According to this invention, the user can arbitrarily set the determination reference value via the determination reference value receiving means. Therefore, it is possible to set an appropriate determination reference value according to the characteristics of the reading unit.

  The invention described in claim 3 is the image reading apparatus according to claim 1 or 2, wherein an authentication password storage unit stores an authentication password for each user, and an authentication password reception unit receives an input of the authentication password. The determination means includes a setting input received by the determination reference value receiving means when the authentication password received by the authentication password receiving means matches the authentication password stored in the authentication password storage means. The determination reference value is determined based on the above.

  According to the present invention, since the determination standard value is set to the password system, only a person who is appropriate for setting the determination standard value (such as an administrator of the image reading apparatus or a serviceman and a technician of the manufacturer) determines the determination standard. You can set and change values. Since the judgment reference value is an important setting that serves as a judgment reference as to whether or not a special pattern is incorporated in the original image, only a person who is familiar with the operation of the image reading apparatus can set the judgment reference value. It is possible to prevent the inconvenience that a confidential document in which a special pattern is incorporated is accidentally copied or cannot be copied normally.

  An image reading apparatus according to a fourth aspect of the present invention is the image processing apparatus according to any one of the first to third aspects, and the determination unit determines that the special pattern is incorporated in the document image. In this case, the image forming apparatus includes: an insertion unit that inserts a destruction pattern into the document image to destroy the document image; and an image forming unit that forms the document image on a recording medium.

  According to the present invention, the same effects as in the first to third aspects can be achieved.

  Even if a special pattern is incorporated in the original image, even if the special pattern cannot be detected from one area of the original image due to the contamination of the original image or the characteristics of the reading means, the special pattern is judged from other areas. If the reference value or more is detected, it can be determined that the copy restriction information is included in the document image.

  Furthermore, even if a copy image does not contain copy restriction information, even if a pattern similar to a special pattern is detected as a special pattern, copy restriction information is not included in the original image unless this pattern is detected above the criterion value. Is not determined to be included. In other words, since it is unlikely that many patterns similar to the special pattern exist in the original image, the probability of determining that this original image contains copy restriction information is extremely low, and the presence or absence of copy restriction information is accurately determined. Judgment can be made.

  Hereinafter, an image reading apparatus, an image forming apparatus, and an image reading program according to the present invention will be described. An image forming apparatus according to the following embodiment includes the image reading apparatus according to the present invention, and a copying machine will be described as an example of the image forming apparatus. In addition, it may be a multifunction machine having functions such as a copy, a scanner, a facsimile, and a printer.

  FIG. 1 is a schematic configuration diagram of a copying machine 1 according to the present embodiment. The copying machine 1 includes a document reading unit 12, an image forming unit 16, and an input operation unit 17. The document reading unit 12 includes an automatic document feeder unit (Auto Document Feeder) 21 and a scanner unit 22. The automatic document feeding unit 21 passes the documents set by the operator one by one to the scanner unit 22. The scanner unit 22 reads an image on a document passed by the automatic document feeder unit 21 and transmits the read document image to a control unit to be described later every time reading of one document is completed.

  The image forming unit 16 heats a recording unit on which an image is formed, and a developing unit 31 having a photosensitive drum or the like that forms an image on a sheet conveyed by a conveyance path that conveys the sheet loaded in a sheet feeding cassette. And a fixing unit 32 for fixing the image formed by the image forming unit to the recording paper.

  FIG. 2 is a functional block diagram showing an electrical configuration of the copying machine 1 according to the present embodiment. The copier 1 includes a control unit 10, a storage unit 11, a document reading unit 12, an image memory 13, an image processing unit 14, a paper feeding unit 15, an image forming unit 16, an input operation unit 17, and a network I / F unit 18. Configured.

  The control unit 10 is configured by a CPU (Central Processing Unit) or the like, reads a program stored in the storage unit 11 in accordance with an input instruction signal or the like, executes a process, and sends the processing to each functional unit. The copier 1 is comprehensively controlled by outputting an instruction signal, transferring data, and the like. The control unit 10 includes a special pattern detection unit 101, a special pattern count unit 102, a special pattern determination unit 103, a destruction pattern insertion unit 104, and a dot pattern generation unit 105.

  The special pattern detection unit 101 detects a special pattern stored in the storage unit 11 from the document image read by the document reading unit 12. Here, the “special pattern” is a dot pattern for prohibiting normal copying or scanning in a copying machine or a scanner having a copy guard function. In the present embodiment, an example will be described in which the special pattern is an image image expressed by combining a plurality of different dot patterns 62 and 63 as shown in FIG. It is not necessary to express the special pattern as an image, and a dot pattern having a specific dot size, number of lines, or the like may be used as the special pattern. The special pattern is mainly printed by being embedded in a confidential document or the like, and serves as copy restriction information for instructing the control unit 10 to prohibit printing of a document image or to insert a destruction pattern.

  The special pattern count unit 102 counts the number of special patterns detected by the special pattern detection unit 101. The special pattern judgment unit 103 compares the count value counted by the special pattern count unit 102 with a preset judgment reference value. If the count value is equal to or larger than the judgment reference value, the copy restriction information is included in the document image. Judge that On the other hand, when the count value is smaller than the determination reference value, it is determined that the copy restriction information is not included in the document image.

  The destruction pattern insertion unit 104 inserts the destruction pattern into the document image determined to include the special pattern by the special pattern determination unit 103. Alternatively, the original image and the destruction pattern may be replaced as long as they can be changed to an image pattern irrelevant to the read original image. Here, the destruction pattern is a predetermined image (a black solid image or an abstract image that does not make sense). In addition, the destruction pattern may be a pattern without an image.

  The dot pattern generation unit 105 includes, for example, a dot pattern incorporating printing information such as a user name and personal identification number printed using the copying machine 1, a serial number of the copying machine 1 and a printing date, and copying prohibition information. A dot pattern (special pattern) is generated. The information embedded in the dot pattern can be restored by reading the printed matter on which the dot pattern as the print information is printed into a device that can decode the dot pattern. Since the restored information can be used to specify, for example, the user who performed the printing, the copying machine, the scanner, or the like, it is possible to prevent information leakage due to inadvertent printing or illegal copying. The dot pattern generated by the dot pattern generation unit 105 is superimposed on the document image read by the control unit 10 in the document reading unit 12, and the superimposed image is printed by the image forming unit 16.

  The storage unit 11 stores programs, data, and the like for realizing various functions provided in the copying machine 1. In the present embodiment, the storage unit 11 stores a special pattern detection program 111. The special pattern detection program 111 is a program for detecting a special pattern from a document image read by the document reading unit 12. The storage unit 11 also functions as a special pattern storage unit 112 that stores a special pattern. The special pattern storage unit 112 stores a pattern 61 having a mark 611 as shown in FIG. 3 as a special pattern.

  The document reading unit 12 reads a document with an image sensor such as a CCD sensor or a CMOS (Complementary Metal Oxide Semiconductor) sensor, and converts the read image into image data.

  The image memory 13 temporarily stores image data read by the document reading unit 12 and image data transmitted from an external device via the network I / F unit 18. The image processing unit 14 performs image processing such as image correction and enlargement / reduction on the image data stored in the image memory 13. The sheet feeding unit 15 feeds sheets one by one from the sheet feeding cassette and conveys them to the image forming unit 16.

  The image forming unit 16 forms an image on the paper based on the image data output from the image memory 13. The input operation unit 17 includes a display panel and various operation buttons, and outputs an operation signal to the control unit 10 when an operation is performed by a user. The network I / F unit 18 includes a communication module such as a LAN board, and transmits / receives various data to / from an external device via a network (not shown) connected to the network I / F unit 18.

  Next, an example of the flow of processing by each functional unit of the control unit 10 will be specifically described with reference to FIG. For example, it is assumed that the document reading unit 12 reads a document image 5 as shown in FIG. A special pattern 51 is printed on the background of the original image 5 on the entire paper surface.

  First, the special pattern detection unit 101 uses the upper left coordinate of the document image 5 as a target pixel, and an image represented by a pixel (target pixel 52) within a predetermined range centered on the target pixel and a pattern stored in the special pattern storage unit 112. 61 is compared to calculate the similarity. As an example of the comparison method, the special pattern detection unit 101 calculates the ratio of the dot pattern 62 and the dot pattern 63 in the image represented by the target pixel 52, and calculates the ratio and the ratio of the dot pattern 62 and the dot pattern 63 in the pattern 61. The comparison result may be the similarity. Alternatively, an image represented by the boundary between the dot pattern 62 and the dot pattern 63 in the image represented by the target pixel 52, and an image (that is, the outline of the mark 611) that is also represented by the boundary between the dot pattern 62 and the dot pattern 63 in the pattern 61. The result of comparing (image) may be used as the similarity.

  When the calculated similarity is greater than or equal to a preset threshold value, the special pattern count unit 102 increases the count value by one. Next, the target pixel is shifted to the right by a predetermined number of coordinates, and the image of the target pixel centered on the target pixel is compared with the pattern 61 to calculate the similarity. This process is performed over the entire document image 5.

  When the detection of the special pattern in the entire document image 5 is completed, the special pattern determination unit 103 determines whether the count value is equal to or greater than the determination reference value. The determination reference value is a numerical value set by the user, and the user sets it via the input operation unit 17.

  The determination reference value may be set in advance before printing, or may be set as appropriate according to the characteristics of the document reading unit 12, and the control unit 10 displays the input operation unit 17. A determination reference value setting screen is displayed on a panel or the like, and the user sets the determination reference value. If the criterion value is too high, it will be difficult to determine that the original image contains a special pattern, and the original image will be printed correctly by mistake even though the special pattern is actually included. There is a high possibility that On the other hand, if the judgment reference value is too low, the special pattern detection unit 101 detects that a pattern similar to the special pattern is equal to or greater than the judgment reference value even though the original image does not actually contain a special pattern. It is determined that the pattern is included, and normal printing is not performed.

  In order to prevent such inconvenience that confidential documents are accidentally copied or cannot be copied normally in this way, the input of the judgment reference value is set by a password system or the like for a specific person (service of the copier 1 administrator or manufacturer). It is desirable that it is set so that only a person such as a man or engineer can perform.

  The special pattern determination unit 103 determines that the copy restriction information is included in the document image 5 if it is equal to or greater than the determination reference value, and the destruction pattern insertion unit 104 inserts the destruction pattern into the document image 5. Then, the image forming unit 16 performs printing based on the image data of the image in which the destruction pattern is inserted. If the count value is smaller than the determination reference value, the special pattern determination unit 103 determines that the copy restriction information is not included in the document image 5. Thereafter, the document image 5 is printed by the image forming unit 16.

  FIG. 5 is a flowchart showing a flow when the control unit 10 executes a process according to the special pattern detection program 111. When a document image is read by the document reading unit 12 (step S11), the special pattern count unit 102 sets the count value to 1 (step S12). This count value is a variable set in a work memory (not shown) included in the special pattern count unit 102.

  Subsequently, the special pattern detection unit 101 compares the image indicated by the target pixel in the document image with the special pattern stored in the special pattern storage unit 112, and calculates the similarity (step S13). If the similarity is equal to or greater than a preset threshold value (step S14; YES), the special pattern count unit 102 adds 1 to the count value (step S15). When the target pixel is not the last target pixel, that is, when the detection of the special pattern has not yet been performed over the entire document image (step S16; NO), the control unit 10 determines the target pixel (the coordinate value of the target pixel). Shift (step S17), the process proceeds to step S13.

  On the other hand, when the target pixel is the last target pixel, that is, when the special pattern is detected over the entire document image (step S16; YES), the special pattern determination unit 103 compares the count value with the determination reference value. (Step S18). If the count value is greater than or equal to the determination reference value (step S18; YES), the special pattern determination unit 103 determines that the copy restriction information is included in the document image (step S19), and the control unit 10 ends the process. To do. When the count value is smaller than the determination reference value (step S18; NO), the special pattern determination unit 103 determines that the copy restriction information is not included in the document image (step S20), and the control unit 10 ends the process.

  Thereafter, the destruction pattern insertion unit 104 inserts the destruction pattern into the document image determined to include the copy restriction information, and destroys the document image. Then, the image forming unit 16 executes printing based on the image data of the image in which the destruction pattern is inserted.

  As described above, when a special pattern is detected from a document image at a determination reference value or more, the special pattern determination unit 103 determines that the copy restriction information is included in the document image. Even if the copy restriction information is included, even if the special pattern cannot be detected from an area of the original image due to the contamination of the original image or the characteristics of the original reading unit 12, the special pattern is determined from other areas. If the reference value or more is detected, it can be determined that the copy restriction information is included in the document image.

  Furthermore, even if a copy image does not contain copy restriction information, even if a pattern similar to a special pattern is detected as a special pattern, copy restriction information is not included in the original image unless this pattern is detected above the criterion value. Is not determined to be included. That is, since it is unlikely that many patterns similar to the special pattern exist in the original image, the probability that the original image is judged to include copy restriction information is extremely low. It can be judged accurately. In addition, since the user can arbitrarily set the determination reference value via the input operation unit 17, an appropriate determination reference value can be set according to the characteristics of the document reading unit 12.

1 is a diagram illustrating a schematic configuration of a copying machine. 1 is a block diagram showing an electrical configuration of a copying machine. The figure which shows an example of a special pattern. The figure for demonstrating the flow of a process by each function part of a control part. The flowchart which shows the flow of a special pattern detection process.

Explanation of symbols

1 Copier 10 Control Unit (Determining means, judgment reference value receiving means, password receiving means)
101 Special pattern detection unit (detection means)
102 Special pattern counting unit (counting means)
103 Special pattern judgment unit (judgment means)
104 Destruction pattern insertion part (insertion means)
105 dot pattern generation unit 11 storage unit 111 special pattern detection program 112 special pattern storage unit (special pattern storage unit)
12 Document reading section (reading means)
13 Image memory 14 Image processing unit 15 Paper feed unit 16 Image forming unit (image forming unit)
17 Input operation section (judgment reference value acceptance means, password acceptance means)
18 Network I / F section

Claims (5)

Reading means for reading a document image from a document;
Special pattern storage means for storing a predetermined special pattern;
Detecting means for detecting whether or not the special pattern is included in the document image;
Counting means for counting the number of detected special patterns;
A determination means for determining that the copy restriction information is included in the document image when the counted number is equal to or greater than a determination reference value;
An image reading apparatus comprising: A determination reference value receiving means for receiving a setting input of the determination reference value;
A determination unit that determines the determination reference value based on a setting input received by the determination reference value reception unit;
The image reading apparatus according to claim 1, further comprising: An authentication password storage means for storing an authentication password for each user;
An authentication password receiving means for receiving an input of the authentication password;
The determination means includes a setting input received by the determination reference value receiving means when the authentication password received by the authentication password receiving means matches the authentication password stored in the authentication password storage means. The image reading apparatus according to claim 1, wherein the determination reference value is determined based on the determination value. The image reading apparatus according to any one of claims 1 to 3,
An insertion means for destroying the original image by inserting a destruction pattern into the original image when the determination means determines that the special pattern is incorporated in the original image;
Image forming means for forming the original image on a recording medium;
An image forming apparatus. Computer
Reading means for reading a document image from a document;
Detecting means for detecting whether or not a special pattern is included in the document image;
Counting means for counting the number of detected special patterns;
Determining means for determining that the copy restriction information is included in the document image when the counted number is equal to or greater than the determination reference value;
An image reading program for functioning as