JP2008199622A - Recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To maintain security even if a general user watches a pattern such as a dot pattern meaning specific information. <P>SOLUTION: A pattern (dot pattern 103) meaning specific information is superimposed on a document surface on which a document image is recorded on a recording medium such as writing paper. The specific information meant by the pattern (dot pattern 103) is information which is recognized by the image processor when reading a document image recorded on the recording medium by an image processor for causing the image processor to perform predetermined control. The pattern (dot pattern 103) is generated as a composite pattern 103b resulting from composing a plurality of fundamental patterns 103a comprising a unit meaning the specific information by combining a plurality of components. The user cannot visually confirm the fundamental patterns 103a from the composite pattern 103b, and thereby security is maintained. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a recording medium having specific information, for example, a pattern meaning output prohibition.

  In recent years, due to improvements in image processing technology and image forming technology, when copying banknotes and securities using a digital color copying machine, it is possible to make faithful copies that cannot be easily distinguished from the original copy. It has become. For this reason, it is necessary to take measures so that special manuscripts such as banknotes and securities cannot be copied at all or cannot be copied correctly.

  For example, in a company, even in the case of general documents other than special manuscripts such as banknotes and securities, there are many confidential documents that are prohibited from being output such as copying from the viewpoint of maintaining confidentiality of the document contents. It is necessary to take measures to prevent such confidential documents from being copied at all, or from being copied correctly.

  For this reason, various inventions have been made in the past that aim to exert restrictions on copying special manuscripts and confidential documents. Hereinafter, specific examples of such invention will be introduced.

  First, as a method for discriminating special manuscripts such as banknotes and securities, the input image data is compared with a specific mark (pattern data) registered in advance by a pattern matching method, and a specific mark exists. A method for discriminating that a document is a special document has been proposed. The inventions described in Patent Document 1 and Patent Document 2 are typical examples. Thus, when it is determined that the document is a special document, it is easy to prohibit the copying, that is, not to copy.

  Next, as an invention for discriminating a confidential document prohibited from being copied, for example, Patent Document 3 and Patent Document 4 describe an invention in which a mark indicating a confidential document attached to a confidential document is detected. ing. This utilizes the fact that a copy-prohibited confidential document is generally stamped with a mark indicating that it is a confidential document consisting of a confidential seal, a copy-prohibited mark, and the like. Thus, when it is determined that the original is a confidential document, it is easy to prohibit copying, that is, not to copy.

  Further, Patent Documents 5 and 6 propose a technique for suppressing copying by embedding a background pattern in an original image that is desired to be prohibited from copying. This is to use a sheet on which a background pattern having a base area and a message area is created on the background of the sheet used for the original image. The copy-forgery-inhibited pattern does not stand out so much in the original image, and does not hinder the interpretation of information included in the original image. However, when a document image in which such a tint block pattern is embedded is copied, for example, a message area pattern emerges. Therefore, by giving characters such as “copy prohibited” as the pattern of the message area, it becomes obvious at a glance that the copy was a confidential document prohibited from copying. Can be generated.

Japanese Patent Laid-Open No. 6-125259 JP 2001-86330 A JP-A-7-36317 JP 7-87309 A Japanese Patent Laid-Open No. 9-164739 JP 2001-197297 A

  As introduced in Patent Documents 5 and 6, for example, a confidential document is generated as a manuscript image in which a background pattern is embedded in the background, and when such a confidential document is copied, a part of the background pattern appears. In this case, it is possible to psychologically generate a regulatory force for copying. However, such a method using a tint block pattern only provides a copy suppression effect, and does not restrict the copying act itself. For this reason, there is a problem that a confidential document can be copied for a person who does not mind that the tint block pattern is raised.

In order to avoid such problems, the techniques introduced in Patent Documents 1 and 2 or Patent Documents 3 and 4 are effective. That is, according to the techniques described in Patent Documents 1 and 2, input image data is compared with a specific mark (pattern data) registered in advance by a pattern matching method, and copying is prohibited when they match. Therefore, it is possible to copy special manuscripts such as banknotes and securities.
Copying can be prevented. Further, according to the techniques described in Patent Documents 3 and 4, copying of a confidential document is prevented by prohibiting copying when a mark indicating a confidential document such as a confidential mark is detected. be able to.

  However, in the techniques described in Patent Documents 1 and 2, all pattern data of a document to be prohibited from copying must be registered in advance. Therefore, even if it is effective for special manuscripts such as banknotes and securities, it is extremely difficult to apply it to an unspecified number of general manuscripts such as confidential documents. Further, in the techniques described in Patent Documents 3 and 4, when an image reading operation is executed by covering a mark portion indicating a confidential document such as a confidential mark with paper or the like, naturally, However, there is a problem that it is impossible to determine the presence of a mark indicating that the document is a confidential document, and therefore, even a confidential document that should be prohibited from being copied cannot be prevented from being copied.

  For this reason, the inventors of the present application superimpose a pattern meaning specific information, for example, a dot pattern on a document surface for document image recording, and when the document image is read, And a patent application has been filed (for example, Japanese Patent Application No. 2002-213761, July 2002). 23rd application).

  However, a pattern to be detected, for example, a dot pattern, rotates in accordance with the rotation of the original when the original is inclined with respect to the original reading apparatus, that is, when the original is rotated. End up. For this reason, it is necessary to take measures such as having a number of dictionary patterns such as dot patterns corresponding to a plurality of representative rotation angles and recognizing the dot patterns according to the inclination of the document. Such a method can be said to be a method that is relatively suitable for real-time processing. However, when such a method is adopted, the following problems occur.

(First issue)
In order to improve the recognition accuracy, it is necessary to have a large number of dictionary patterns corresponding to a large number of representative rotation angles, and for each recognition, it is necessary to compare the image-read dot pattern etc. with a large number of dictionary patterns by pattern matching etc. . However, this increases the burden of comparison processing such as pattern matching during recognition processing, making real-time processing difficult. In other words, improvement in recognition accuracy and real-time processing are contradictory and difficult to achieve.

  Therefore, an object of the present invention is to achieve both improvement in recognition accuracy and real-time processing.

  (Second problem) Due to differences in various reading conditions when reading an image of a document image, it is not always possible to detect all of the patterns that mean specific information such as dot patterns. Since there is a possibility that a pattern that coincides with such a pattern appears in a document image composed of general dots, it is determined that the document controls the output when even one pattern that means specific information is detected. Is not valid. It is reasonable to determine that the document meaning the specific information is a document whose output is controlled for the first time by detecting a certain number of patterns and density. From such a background, there is a demand for generating as many patterns as possible for specific information, for example, dot patterns, on the entire surface of the document image as much as possible in order to improve recognition accuracy.

  However, when simply arranging patterns that mean specific information, for example, dot patterns, if the excess density is too high, the dots that are adjacent to the adjacent dot pattern are too close to form an isolated dot pattern. Dot recognition becomes difficult.

  Therefore, an object of the present invention is to prevent erroneous recognition of isolated dots in adjacent dot patterns while satisfying the demand for generating as many patterns as possible on the entire surface of the original image, such as dot patterns that mean specific information. Is to do so.

(Third issue)
Assuming that a pattern that means specific information, for example, a dot pattern is not a uniform pattern, if such a non-uniform dot pattern is simply placed on the document surface, the background pattern of the background will be uniform. This results in inconvenience that the background is not smooth and the original document information (characters, ruled lines, etc.) is difficult to see.

  In addition, as one aspect of the dot pattern, there is a tint block pattern introduced in Patent Documents 5 and 6. When using a pattern that has the effect of highlighting characters where the dots disappear without being reproduced during copying, a pattern that does not erase a pattern such as a dot pattern that represents specific information. If it is used, the problem that it becomes difficult to see the white letters that emerge.

  Accordingly, an object of the present invention is to prevent the visibility of original document information in a document image from being hindered by a pattern such as a dot pattern meaning specific information.

(Fourth issue)
When a pattern such as a dot pattern meaning specific information is arranged on a document surface, it is usually found that the pattern is generated by a general user who viewed the document image. For this reason, there is also an unfavorable security problem that an attack by a malicious user is facilitated.

  Therefore, an object of the present invention is to maintain security even when a general user sees a pattern such as a dot pattern meaning specific information.

(Fifth issue)
Assuming that there is only one type of pattern that means specific information, for example, a dot pattern, false detection may occur between existing patterns made up of halftone dots or dots of various lines that may exist on the document surface. There is a possibility of being made.

  Accordingly, an object of the present invention is to prevent erroneous detection between an existing pattern or the like that may exist on a document surface and a pattern such as a dot pattern that represents specific information.

  The invention according to claim 1 is a recording medium having a pattern which means specific information superimposed on an original surface for recording an original image, and the specific information meaning the pattern is the recording medium Information that is recognized by the image processing apparatus when the image image is read by the image processing apparatus and causes the image processing apparatus to execute predetermined control, and the pattern is a combination of a plurality of components Is generated as a combined pattern in which a plurality of basic patterns constituting the unit indicating the specific information are combined.

  According to a second aspect of the present invention, in the recording medium according to the first aspect, the composite pattern is generated by overlapping a plurality of constituent elements of the basic pattern.

  According to a third aspect of the present invention, in the recording medium according to the first aspect, the composite pattern has a dummy pattern separately from the basic pattern.

  According to a fourth aspect of the present invention, in the recording medium according to the first aspect, the composite pattern has a plurality of basic patterns obtained by rotating 360 degrees by integer division and rotating 360 degrees by the division number. .

  According to a fifth aspect of the invention, in the recording medium according to the first aspect, the composite pattern has a plurality of the basic patterns rotated by a predetermined angle, and the plurality of basic patterns rotated by a predetermined angle are set as the set. Constitutes a unit meaning the information.

  According to a sixth aspect of the present invention, in the recording medium according to any one of the first to fifth aspects, the constituent elements of the basic pattern are dots.

  According to a seventh aspect of the present invention, in the recording medium according to any one of the first to sixth aspects, the predetermined control that the specific information causes the image processing apparatus to execute is performed on the original image recorded on the original surface. This is output prohibition processing.

  According to an eighth aspect of the present invention, in the recording medium according to the seventh aspect, the output prohibiting process is a process for prohibiting print output of the document image.

  According to the first, sixth, seventh, and eighth aspects of the invention, a basis for solving the above problem can be obtained, and in particular, the basic pattern cannot be visually confirmed from the composite pattern. The fourth problem can be solved.

  According to the second, sixth, seventh, and eighth aspects of the invention, more accurate detection can be realized by increasing the number of patterns that can be arranged per unit area of the document surface. Thereby, the solution of said 2nd subject can be aimed at.

  According to the third, sixth, seventh, and eighth aspects of the invention, the uniformity of the whole density is increased so that the original image is easy to read, and the white that appears when used for the pattern that does not disappear in the background pattern effect. It is possible to make it easy to see the blank characters and at the same time make it difficult to find the basic pattern by inspection. As a result, the third problem can be solved.

  According to the fourth, sixth, seventh, and eighth aspects of the invention, the real-time processing can be realized by reducing the number of pattern matching for the rotation variation. Thereby, the first problem can be solved.

  According to the fifth, sixth, seventh, and eighth aspects of the invention, the redundancy of the pattern is increased, and the possibility of erroneous detection caused by the presence of an existing pattern composed of halftone dots or dots of various lines is reduced. be able to. Thereby, the fifth problem can be solved.

  An embodiment of the present invention will be described with reference to FIGS.

1. Recording Medium First, the recording medium in the present embodiment will be described with reference to FIGS.

(1) Patterns Presupposed for Explaining Patterns Meaning Specific Information in the Present Embodiment FIGS. 1 to 12 illustrate patterns meaning specific information in the present embodiment.
In other words, the recording medium has a precondition pattern.

  FIG. 1 is a front view illustrating a document image. FIG. 2 is a schematic diagram illustrating an example of a copy of an original image in which a dot pattern embedded in the original image is raised. FIG. 3 is a schematic diagram showing another example of a copy of an original image in which a dot pattern embedded in the original image appears floating. FIG. 4 is an enlarged schematic diagram illustrating the dot pattern illustrated in FIG. FIG. 5 is an enlarged schematic diagram illustrating the dot pattern illustrated in FIG.

  Document image 101, a document sheet 102 as a recording medium for creating document image 101, which is a contract in the example shown in FIG. 1, is a document in which a dot array for output prohibition determination, that is, dot pattern 103 is embedded in the background. A sheet 102 is used. However, as another configuration example, it is possible to use the original paper 102 on which the dot pattern 103 is not formed and simultaneously form the dot pattern 103 when the original image 101 as a contract is created. That is, the dot pattern 103 may be preliminarily printed on the original paper 102 or may be simultaneously formed when characters, graphics, or the like are formed on the original paper 102.

  The dot pattern 103 described with reference to FIGS. 1 to 5 includes a base area 104 and a message area 105. The base area 104 is a ground area that occupies most of the original paper 102. The message area 105 is an area for expressing a message distributed in the base area 104. The base area 104 and the message area 105 are not different from each other in the basic configuration of the dot pattern 103 itself, and are divided into the base area 104 and the message area 105 as human value judgment for the dot pattern 103. It ’s just that. In the present embodiment, the message area 105 is composed of characters “copy prohibited”. As characters constituting such a message area 105, any characters, symbols, and the like can be used in addition to “copy prohibited”.

  In the original image 101 created using such original paper 102, when the original image 101 is copied, a part of the dot pattern 103 emerges. In this case, in the document image 101 illustrated in FIG. 2, the message area 105 expressed by the characters “copy prohibited” appears, and in the document image 101 illustrated in FIG. 3, the base area 104 appears.

  As described above, when the original image 101 in which the dot pattern 103 is embedded is copied, either the message area 105 or the base area 104 in the dot pattern 103 appears. The other area 104 or 105 is copied. This is because it is difficult to (reproduce). In other words, when the region 104 or 105 that does not rise up disappears, the remaining region 104 or 105 appears to rise up.

  The dot pattern 103 that causes such a phenomenon is constituted by a set of two types of dots 106 having different sizes as exemplified in FIGS. 4 and 5. That is, of these two types of dots 106, the small dots 106b are difficult to be copied (reproduced), and the large dots 106a are copied (reproduced). Therefore, in the dot pattern 103 illustrated in FIG. 2 in which the message area 105 rises after copying, as shown in FIG. 5, a small dot 106 b is used for the base area 104, and a larger dot is used for the message area 105. Dots 106a are used. On the other hand, in the dot pattern 103 illustrated in FIG. 3 in which the base area 104 is lifted after copying, as shown in FIG. 4, a small dot 106 b is used for the message area 105, and the base area 104 is formed. Large dots 106a are used.

  As another configuration example of the dot pattern 103, the message area 105 or the base area 104 that emerges is not limited to a dot, but can be configured by a thin line pattern, a specific pattern pattern, or the like.

  Here, the message area 105 or the base area 104 can be treated as a feature amount. The feature amount referred to here is, for example, a certain feature included in image data obtained by reading the document image 101. Thus, the message area 105 or the base area 104 means specific information. Such a characteristic can function as predetermined information included in the image data. For example, if the message area 105 or the base area 104 that emerges is composed of dots 106, the size, density (number of dots per unit area), the distance between dots, and the dot arrangement are determined according to the message area 105 or base that emerges. If the area 104 is composed of a thin line pattern, the width of the line is assumed, and if the message area 105 or the base area 104 is formed with a specific pattern pattern, the characteristics of the pattern are characterized. Can be used as a quantity. In this embodiment to be described later, the dot pattern constituting the message area 105 or the base area 104 that emerges has a characteristic amount, and such dot pattern has specific information that has meaning.

  In the above example, the feature quantity for the message area 105 or the base area 104 that emerges is limited. However, as such a feature quantity, the base area 104 or the message area 105 that does not emerge, or the message area 105 or the base area 104 that emerges. For each of the base region 104 or the message region 105 that does not appear, the respective feature amounts may be obtained. In short, if one or both of the base area 104 and the message area 105 can be read as data when the original image 101 on which the image data with the dot pattern 103 embedded is recorded is read, Can be treated as a feature quantity. Or, in the image data in which the dot pattern 103 existing in the form of data is embedded, if either or both of the base area 104 and the message area 105 constituting the dot pattern 103 can be read as data, Can be treated as a feature quantity.

  As another configuration example, as described above, the dot pattern 103 may have a pattern other than the dot pattern 103 having the base region 104 and the message region 105 as illustrated in FIGS. 6 and 7. FIG. 6 is a front view illustrating a document image and its dot pattern as a configuration example different from that described with reference to FIGS. 1 to 5, and FIG. 7 is a document image and its dots different from FIG. It is a front view which illustrates a pattern. The dot pattern 103 illustrated in FIGS. 6 and 7 is composed of dots 106 having a single size. The dot pattern 103 illustrated in FIGS. 6 and 7 is the same as the pattern corresponding to only the base region 104 and the pattern corresponding to only the message region 105 in the dot pattern 103 illustrated in FIGS. It can be grasped as a thing. That is, even if the dot pattern 103 corresponds to the base area 104 or the dot pattern 103 corresponding to the message area 105, the dot pattern 103 is used as data when the document image 101 having such a dot pattern 103 is read. If it can be read, it can be treated as a feature quantity.

  A dot pattern 103 illustrated in FIG. 6 is configured as a background image of the original image 101 drawn on the original paper 102. In this sense, the background dot pattern is the same as the dot pattern 103 illustrated in FIGS. On the other hand, the dot pattern 103 illustrated in FIG. 7 is drawn on the original image 101 drawn on the original paper 102. Therefore, the dot pattern 103 illustrated in FIG. 7 is not a background dot pattern, but a so-called foreground dot pattern.

  Here, the dot patterns 103 shown in FIGS. 2 to 5, 6, and 7 are all dot patterns 103 in which the relationship between single dots 106 constituting the dot pattern 103 has a characteristic amount. That is, the feature amount of the dot pattern 103 shown in FIGS. 2 to 5, 6, and 7 can include the dot density (the number of dots per unit area) and the inter-dot distance. Are included in the relationship between the single dots 106 constituting the dot pattern 103. Therefore, a feature amount called dot density and a feature amount called inter-dot distance are compared and considered.

  First, the dot density, which is the density of the dots 106, is the number of dots per unit area, as described above. This feature amount can be determined by counting the number of dots in a certain unit area to be determined. When counting the actual number of dots, some detection omissions and false detections occur. Therefore, by setting a certain allowable value (threshold) for the number of dots counted, the feature amount can be detected using the density of the dots 106 as a feature amount. In this case, if the threshold value to be set with respect to the number of counted dots is a strict value, that is, a value with a small allowable range, a determination omission is likely to occur. If the value is a loose value, that is, a value with a large allowable range, it is difficult to cause omission of determination.

  However, referring to the dot pattern 103 illustrated in FIG. 6, a certain dot 106 included in the dot pattern 103 is undetectable by the document image 101 drawn on the document sheet 102. On the other hand, in the dot pattern 103 illustrated in FIG. 7, since the dot pattern 103 is drawn on the original image 101 drawn on the original paper 102, each dot pattern 103 illustrated in FIG. In this state, the dots 106 are easily detected. However, the dots 106 that overlap the original image 101 drawn on the original paper 102 are not always correctly detected. For this reason, the degree to which the number of dots can be detected is greatly affected by the form of the original image 101 drawn on the original paper 102. Therefore, when the dot density is a feature amount, it can be said that even if a certain allowable value (threshold value) is set for some of the counted number of dots, a determination omission is likely to occur in the determination of the feature amount.

  Next, the case where the distance between dots, which is the distance d between adjacent dots 106, is used as a feature amount will be described with reference to FIGS. FIG. 8 is a schematic diagram illustrating a dot pattern 103 in which the distance between dots is d. FIG. 9 represents the distance distribution between adjacent dots 106 with the distance between dots on the horizontal axis and the appearance frequency on the vertical axis. It is a graph to do. FIG. 10 is a schematic view illustrating a dot pattern.

  As shown in FIG. 8, in a dot pattern 103 (see FIG. 10A) in which the distance d between two adjacent dots 106 is constant, two adjacent dots 106 constituting this dot pattern 103 are displayed. The inter-dot distance, which is the distance d between the two dots 106, is a feature amount. In this case, when the dot 106 is detected from the dot pattern 103 and a plurality of distances d between the adjacent dots 106 are determined, the distance d between the correct dots 106 as shown in the graph of FIG. Draws a sharp mountain distribution with a peak value of. Therefore, by setting a certain allowable value (threshold value) for the distance d, the distance d between the dots 106 can be detected as a feature amount. In this case, as is apparent from the graph of FIG. 9A, if the threshold value set for the distance d is a strict value, that is, if the allowable range is small, determination omission is likely to occur. On the other hand, if the threshold value to be set is a loose value, that is, a value with a large allowable range, it is difficult to cause omission of determination.

  However, when the distance d between the two dots 106 in the dot pattern 103 in which the distance d between two adjacent dots 106 is constant is used as the feature amount, the pattern illustrated in FIG. The pattern illustrated in b) cannot be distinguished. Here, FIG. 10A illustrates a dot pattern in which there are four other dots 106 separated by a distance d when viewed from the target dot 106, and FIG. 10B illustrates the dot pattern viewed from the target dot 106. A dot pattern having three other dots 106 separated by a distance d is illustrated. In this case, as an example, assuming that FIG. 10A is the dot pattern 103 to be detected, a pattern of dots 106 as illustrated in FIG. 10B on the original image 101 drawn on the original paper 102. Is included, or vice versa, the dot pattern 103 as a detection target can be detected when the dot density is a feature amount, whereas the inter-dot distance is a feature amount. In this case, it becomes impossible to detect the dot pattern 103 that is the detection target. That is, overdetection is likely to occur when the dot pattern 103 in which the distance d between two adjacent dots 106 is constant is to be detected.

  Therefore, FIG. 10C illustrates a dot pattern 103 that can correctly detect the dot pattern 103 that is a detection target using the inter-dot distance as a feature amount. In the dot pattern 103 illustrated in FIG. 10C, a plurality of types of distances d between dots are set, and the frequency of each type of inter-dot distance d is set to be different. For this reason, as shown in FIG. 9B, the peak value distribution of the distance between adjacent dots has a feature amount. Therefore, by detecting such a feature quantity as the peak value distribution of the distance between adjacent dots, the dot pattern 103 to be detected can be detected without overdetection.

  As described above, each of the dot patterns 103 shown in FIGS. 2 to 5, 6, and 7 has a characteristic amount in the relationship between the single dots 106 constituting the dot pattern 103. On the other hand, FIGS. 11 and 12 show an example in which the dot pattern 103 itself or the set of dot patterns 103 has a feature amount. That is, as illustrated in FIG. 11, the distance α−β between the dots α and β, the distance β−γ between the dots β and γ, and the distance between the dots α and γ. α-γ is set to be different from each other, and a set of dot patterns 103 is constituted by these dots α, β, and γ. Such a dot pattern 103 can be easily determined by pattern matching as an example. Then, the dot pattern 103 itself as illustrated in FIG. 11 or a set of such dot patterns 103 has a feature amount. As a method for giving a feature amount to a set of dot patterns 103, for example, the density per unit area of the dot patterns 103 as illustrated in FIG. 11 can be adopted.

  Note that the dot pattern 103 merely exemplifies specific information included in the image data, that is, an arrangement of dots that is one aspect of a certain characteristic included in the image data. The specific information included in the image data, that is, the characteristic included in the image data may be a representation of a line other than a dot or other shape, or may be a color other than the shape or other image feature. .

(2) Pattern meaning specific information in the present embodiment The pattern meaning specific information in the present embodiment is formed as a dot pattern 103 as in the configuration example shown in FIGS. 11 and 12. The dot pattern 103 is generated as a composite pattern 103b in which a plurality of basic patterns 103a constituting a unit that represents specific information is combined by a combination of dots 106 as a plurality of constituent elements. That is, in this embodiment, the dot pattern 103 illustrated in FIGS. 11 and 12 is set as the basic pattern 103a, and specific information is given to the basic pattern 103a. In addition, a plurality of such basic patterns 103a are combined to form a dot pattern 103 as a combined pattern 103b.

  FIGS. 13 to 18 illustrate a plurality of types of dot patterns 103 according to the present embodiment.

  FIG. 13 is a schematic view illustrating an example of a method for generating the dot pattern 103 (composite pattern 103b) in the present embodiment. In FIG. 13, what is indicated by the characters “basic pattern” is the basic pattern 103 a that is the same as the dot pattern 103 illustrated in FIGS. 11 and 12. In FIG. 13, what is indicated by the characters “a pattern obtained by rotating the basic pattern by 180 degrees” is a basic pattern 103a ′ obtained by rotating the basic pattern 103a by 180 degrees. The synthesized pattern 103b is generated by synthesizing such a basic pattern 103a and a basic pattern 103a ′ obtained by rotating the basic pattern 103a by 180 degrees. In this case, the dot α in the basic pattern 103a and the dot γ in the basic pattern 103a ′ rotated by 180 degrees are superimposed, and the dot γ in the basic pattern 103a and the dot α in the basic pattern 103a ′ rotated by 180 degrees are superimposed. Thus, a composite pattern 103b is configured.

  As described above, according to the composite pattern 103b of the present embodiment, the basic patterns 103a and 103a ′ cannot be visually confirmed from the composite pattern 103b. For this reason, security can be maintained even when a general user views the composite pattern 103b, which is the dot pattern 103 that means specific information. Thereby, the fourth problem is solved.

  Further, since the composite pattern 103b is composed of a combination of two basic patterns 103a and 103a 'rotated by 180 degrees, in order to improve recognition accuracy, a large number of dictionary patterns corresponding to the representative rotation angle over 360 degrees. In other words, by having a dictionary pattern corresponding to the representative rotation angle within a range of 180 degrees, the image-read synthesized pattern 103b is compared with a plurality of dictionary patterns by pattern matching or the like, and the synthesized pattern 103b What is necessary is just to determine whether is a pattern meaning specific information. For this reason, real-time processing can be realized by reducing the number of pattern matching with respect to the rotation variation to ½. Thereby, improvement of recognition accuracy and real-time processing can both be achieved. Thereby, the first problem is solved.

  Here, the composite pattern 103b for solving the first problem is not limited to a pattern configured by a combination of two basic patterns 103a and 103a ′ rotated by 180 degrees, and 360 degrees is obtained by dividing 360 degrees into integers. May be constituted by a combination of a plurality of basic patterns 103a rotated by an angle divided by the number of divisions. As an example, the composite pattern 103b may be configured by a combination of three basic patterns 103a rotated by 120 degrees.

  Furthermore, in the present embodiment, the dot 106 that is a component of the plurality of basic patterns 103a, that is, the dot α in the basic pattern 103a, the dot γ in the basic pattern 103a ′ rotated 180 degrees, the dot γ in the basic pattern 103a, The composite pattern 103b is generated by overlapping the dots α in the basic pattern 103a ′ rotated by 180 degrees. For this reason, while satisfying the request to generate as many synthetic patterns 103b as the dot patterns 103 that mean specific information on the entire surface of the original image 101, the isolated dots of the basic patterns 103a that are adjacent dot patterns 103 can be obtained. Misrecognition can be prevented. Thereby, the second problem is solved.

  FIG. 14 is a schematic diagram showing another example of the dot pattern 103 (composite pattern 103b). FIG. 15 is a schematic diagram illustrating an example of a document image 101 having the dot pattern 103 (composite pattern 103b) illustrated in FIG. In the example shown in FIG. 14, the composite pattern 103b illustrated in FIG. 13 is set as a basic pattern 103a, the basic pattern 103a, a basic pattern 103a ′ obtained by rotating the basic pattern 103a by 180 degrees and inverted, and a basic pattern 103a. A basic pattern 103a ″ rotated by a predetermined α degree and a basic pattern 103a ″ obtained by further rotating the basic pattern 103a ′ rotated by a predetermined α degree by combining the basic pattern 103a ″ rotated by 180 degrees and reversed. 103b is generated.

  According to the composite pattern 103b of the present embodiment, the basic patterns 103a, 103a ′, 103a ″, and 103a ″ cannot be visually confirmed from the composite pattern 103b. For this reason, security can be maintained even when a general user views the composite pattern 103b, which is the dot pattern 103 that means specific information. Thereby, the fourth problem is solved.

  Further, the composite pattern 103b is a basic pattern 103a, 103a ′ obtained by rotating the basic pattern 103a variously by using a composite pattern 103b constituted by a combination of two basic patterns 103a, 103a ′ rotated 180 degrees as a basic pattern 103a. Since it is composed of a combination of 103a ″ and 103a ″, it is not necessary to have many dictionary patterns corresponding to the representative rotation angle over 360 degrees in order to improve recognition accuracy, that is, an angle of 180 degrees By having a dictionary pattern corresponding to the representative rotation angle within the range or within a certain angle range, the composite pattern 103b that has been read is compared with a plurality of dictionary patterns by pattern matching or the like, and the composite pattern 103b stores specific information. Determine if pattern is meaningful It may be Re. For this reason, real-time processing can be realized by reducing the number of pattern matching with respect to the rotation variation to ½. Thereby, improvement of recognition accuracy and real-time processing can both be achieved. Thereby, the first problem is solved.

  In addition, in the present embodiment, a unit representing specific information can be configured by the pair of basic patterns 103a and 103a ′ rotated by a predetermined α degree and the basic patterns 103a ″ and 103a ″. . For this reason, it is possible to prevent erroneous detection between an existing pattern or the like that may exist on the document surface and the composite pattern 103b that is the dot pattern 103 that means specific information. That is, the redundancy of the pattern increases, and the possibility of erroneous detection caused by the presence of an existing pattern or the like composed of halftone dots or dots of various lines can be reduced. Thereby, the fifth problem can be solved.

  FIG. 16 is a schematic diagram showing another example of the dot pattern 103 (composite pattern 103b). FIG. 17 is a schematic diagram illustrating an example of a document image 101 having the dot pattern 103 (composite pattern 103b) illustrated in FIG. In this embodiment, dummy dots 107 shown as white circles are added to the composite pattern 103b illustrated in FIGS. The dummy dots 107 have a pattern form as a dummy pattern 103c. As a result, the uniformity of the overall density of the original image 101 is increased and the original image 101 is easy to read. The presence of the composite pattern 103b can prevent the original document information visibility in the document image 101 from being hindered. As a result, the third problem can be solved.

  FIG. 18 is a schematic diagram showing still another example of implementation of the dot pattern 103 (composite pattern 103b). In the present embodiment, a white character (letter T) that disappears due to the tint block effect is superimposed as a message area 105 on the composite pattern 103b illustrated in FIGS. Therefore, the composite pattern 103b is used as the base region 104 which is a pattern that does not disappear in the tint block effect. As described above, when using the message area 105 having the effect of raising the character (the letter “T”) at the portion where the dot 106 disappears without being reproduced at the time of copying, the composite pattern 103b is added to the base area 104 that does not disappear in the background pattern effect. When is used, it becomes easier to see the white letters (T-shaped) that appear. At the same time, the basic pattern 103a constituting such a composite pattern 103b can also be made difficult to find with the eyes. As a result, the third problem can be solved.

2. Image Processing Device Next, an image processing device that detects a dot pattern 103 (composite pattern 103b), which is a pattern meaning specific information in the present embodiment, will be described. This image processing apparatus recognizes the specific information that the dot pattern 103 (composite pattern 103b) means as information for confidential document determination or output prohibited document determination.

(1) Hardware Configuration FIG. 19 is a block diagram illustrating hardware resources of the image processing apparatus. FIG. 20 is a vertical side view of a scanner as an image input unit.

  As shown in FIG. 19, the image processing apparatus according to the present embodiment has a digital copier configuration in which a scanner 201 as an image reading apparatus, an image processing unit 202 with a digital circuit configuration, and a plotter 203 are controlled by a system controller 204. ing. The system controller 204 constitutes a part of the computer 1001, and utilizes computer functions constructed from a built-in CPU (Central Processing Unit) 204a, ROM (Read Only Memory) 204b, and RAM (Random Access Memory) 204c, The scanner 201, the image processing unit 202, and the plotter 203 are controlled according to an instruction from the operation display unit 205, and necessary information is returned to the operation display unit 205 for display.

  Here, the scanner 201 will be described in detail with reference to FIG. As shown in FIG. 20, an ADF (Automatic Document Feeder) 3 that is an automatic document feeder is provided on a scanner main body 2 of a scanner 201 so as to be freely opened and closed by a support shaft 3a. The mode and the sensor movement type reading operation mode are freely selectable. The scanner body 2 is provided with a rectangular contact glass 4 on which a document sheet 102 (not shown in FIG. 20) is placed. The scanner body 2 facing the contact glass 4 includes an optical glass. A unit 5 is provided. The optical unit 5 is generally called a contact image sensor, and includes a light source (not shown) and a large number of image sensors (CCD: Charge Coupled Device) corresponding to a document reading width. And a line sensor (not shown) arranged in a line. In the optical unit 5, the arrangement direction of these image pickup elements is a main scanning direction B (a direction orthogonal to the paper surface of FIG. 20). A driving motor 6 that is a stepping motor is connected to the optical unit 5 by a pulley, a wire, or the like, and the optical unit 5 is movable in the sub-scanning direction A. This optical unit 5 is normally positioned on the upstream side in the sub-scanning direction A shown in FIG. 20 as the home position HP, and in the process of moving to the downstream side, the light source is placed on the original paper 102 placed on the contact glass 4. The original image 101 (not shown in FIG. 20) is irradiated, and the line sensor receives the reflected light from the original paper 102, whereby the original image 101 is read and scanned.

  Such scanning of the original image 101 by the optical unit 5 is executed under the setting of the book mode which is a sensor movement type reading operation mode. The ADF mode, which is the type reading operation mode, is also set as an operation mode so that it can be switched in an operation display unit 205 (see FIG. 19) described later. Under the setting of the ADF mode, the original image 101 is read and scanned by sequentially transporting the original paper 102 by the ADF 3 with the optical unit 5 set at the home position HP.

  The ADF 3 includes a document tray 7, a pickup roller 8, a pair of registration rollers 9, a transport drum 10, a pair of transport rollers 11, a pair of paper discharge rollers 12, and the like on the optical unit 5 positioned at the home position HP. Are sequentially conveyed in the sub-scanning direction A and discharged onto the paper discharge tray 13. The paper discharge tray 13 is provided on the upper surface of the document cover 14, and the document cover 14 can be opened and closed with respect to the contact glass 4. A stepping motor (not shown) is connected to the pickup roller 8, the registration roller 9, the conveyance drum 10, the conveyance roller 11, and the paper discharge roller 12 of the ADF 3 by a gear train or the like.

  Next, the image processing unit 202 will be described. The image processing unit 202 includes a reproduction image processing unit 211, an information extraction unit 212, and an output control unit 213.

  The reproduction image processing unit 211 includes a filter processing unit 206, a scaling processing unit 207, a γ processing unit 208, and a gradation processing unit 209 as shown in FIG. Each of these units 206, 207, 208, and 209 is not different from an equivalent circuit configuration provided in a general digital copying machine, and a description thereof will be omitted. Such a reproduction image processing unit 211 can be constructed by a digital circuit, a processor such as SIMD, or the like.

  The output control unit 213 determines whether to output image data of an image read by the scanner 201 to the plotter 203 according to a determination result described later in the information extraction unit 212.

  As illustrated in FIG. 19C, the information extraction unit 212 includes a dot pattern detection unit 212a and an output prohibited document determination unit 212b. The dot pattern detection unit 212a and the output prohibition document determination unit 212b are hardware having a digital circuit configuration that detects and determines an output prohibition document such as a confidential document and prohibits copying. As another embodiment, the information extraction unit 212 may be configured by a processor such as SIMD.

  The dot pattern detection unit 212a uses a method such as pattern matching to convert the basic pattern 103a included in the dot pattern 103 for confidential document determination or output prohibited document determination included in the image data of the original image 101 from image data. A process for detecting, a process for comparing the detected basic pattern 103a with a reference pattern for comparison determination stored in a storage area (not shown) as an output-prohibited dot pattern, and a detected basic pattern 103a and a reference pattern for comparison determination And processing for determining whether or not identity is recognized between the two. Thereby, regardless of the type of document image, the feature amount of the basic pattern 103a included in the detected dot pattern 103 and the feature amount of the reference pattern for comparison determination stored in a storage area (not shown) are identical. By confirming this, it is possible to determine whether or not output of image data of the document image 101 should be prohibited.

  When the output prohibited document determination unit 212b determines that the document image 101 read by the scanner 201 is an output prohibited document, the output prohibited document determination unit 212b transmits to the system controller 204 that an output prohibited document has been detected. In response to this, the system controller 204 prohibits post processing after detection of the output prohibited document, that is, copying operation (print output operation) in the plotter 203. As a result, when the original image 101 read by the scanner 201 is an output prohibited document such as a confidential document, copying (reproduction) is prevented.

  In this embodiment, copying is prohibited as an example of prohibiting output of an output-prohibited document. However, this is merely an example. For example, scanner distribution is performed on image data of an original image 101 read by the scanner 201. It is also possible to adopt an output prohibition mode that prohibits. In this case, as a delivery method, it is possible to send an output prohibited document as a text or an attached document by e-mail, facsimile transmission, or data transmission. Such various distribution modes are prohibited.

  As another embodiment, the system controller 204 performs post-processing after detection of an output-prohibited document in a state where the copy result of the original document image 101 cannot withstand use as a copy or in an unreadable state. The image signal of the original document image 101 may be changed so as to be output from As an example, a process of changing the image signal to a certain pixel value and filling it in is performed. In this case, it is possible to paint in gray (128 in 256 gradations), white, black, or the like. As another example, the image signal may be changed so that some pattern is repeatedly generated.

  Alternatively, a communication processing unit connected to, for example, the system controller 204 indicates that a copy-prohibited document has been read or output as an aspect of suppressing output even if the output of the output-prohibited document itself is not prohibited. Notification may be made to the external remote control unit 215 via 214. The remote operation unit 215 as a notification destination in this case is an example, but is preferably a broad computer used by various managers such as a personal computer, a mobile computer, a mobile phone, and the like.

  On the other hand, when the original image 101 read by the scanner 201 is not an output prohibited document such as a confidential document, a normal copying operation (print output operation) is executed. That is, the image data of the original image 101 read by the scanner 201 is processed by the image processing unit 202, and the result is output by the plotter 203.

(2) Processing Process The example in which the dot pattern detection unit 212a and the output prohibited document determination unit 212b are configured as a processor such as a digital circuit or SIMD has been described above. On the other hand, in the implementation, the computer 1001 detects the dot pattern based on the computer software installed in the HDD 216 or the like that can be used as the firmware in the ROM 204b of the system controller 204 and can be used as the other example. The functions of the unit 212a and the output prohibited document determination unit 212b may be realized. In this case, it is preferable that all or a part of the computer software installed in the HDD 216 or the like is copied to the RAM 204c included in the system controller 204 and executed.

  Here, processing contents of the dot pattern detection unit 212a and the output prohibited document determination unit 212b executed by the computer 1001 based on the computer software will be described based on the flowchart shown in FIG.

  First, the processing routine shown in FIG. 21 is executed at a certain time, and it is repeatedly determined whether the document image 101 is read by the scanner 201 and image data is input (step S201).

  When it is determined that the original image 101 is read and image data is input by the scanner 201 (Y in step S201), the input image data is copied into an image memory included in a memory represented by a comprehensive concept such as the RAM 204c, for example. (Step S202).

  On the other hand, when it is not determined that the original image 101 is read by the scanner 201 and the image data is input (N in step S201), whether the original image 101 is read by the scanner 201 and the image data is input. Wait for the decision.

  Then, the dot 106 is detected from the image data copied to such an image memory (step S203). As a detection method in this case, various conventional methods for detecting an image pattern by computer processing, for example, pattern matching can be used.

  Next, a specific dot pattern 103 is detected and created by the arithmetic function of the CPU 204a, and the presence or absence of the basic pattern 103a included in the dot pattern 103 is detected. In this case, a reference pattern for comparison determination serving as a reference for determining an output-prohibited document such as a confidential document is stored in storage areas existing inside and outside the system controller 204, for example, the HDD 216, the ROM 204b, and the RAM 204c. In S204, it is detected whether or not the basic pattern 103a identical to the reference pattern for comparison determination exists in the image data of the original image 101 read by the scanner 201. As a detection method in this case, various conventional methods for detecting an image pattern by computer processing, for example, pattern matching can be used.

  Next, the density within a certain area is calculated for the basic pattern 103a included in the dot pattern 103 detected in step S204 by the calculation function of the CPU 204a (step S205). This calculation is performed by obtaining the number of basic patterns 103a detected in step S204 within a certain area.

  Next, a reference pattern density for comparison determination serving as a reference for determining an output-prohibited document such as a confidential document is stored in storage areas existing inside and outside the system controller 204, such as the HDD 216, the ROM 204b, and the RAM 204c. Therefore, in step S206, it is determined whether or not the density of the basic pattern 103a obtained by the calculation process in step S205 matches the density of the reference pattern for comparison determination. As a result, if the determination result is affirmative (Y in step S206), for example, the number of dot patterns that match the storage area of the RAM 204c is accumulated (step S207), and the process proceeds to step S208, and the determination result is negative. If yes, the process proceeds to step S208 without performing step S207. In step S208, for example, it is determined whether or not the number of basic patterns 103a accumulated in the storage area of the RAM 204c is within a certain threshold (step S208), and output prohibited document determination processing is executed according to the result. (Step S209).

  Thus, in the present embodiment, regardless of the type of document image, the detected feature quantity of the basic pattern 103a (the form of the dot pattern 103) and the feature quantity of the comparison determination pattern stored in the storage area are the same. It is possible to determine whether the output of the image data of the document image 101 should be prohibited by checking the property.

3 is a front view illustrating a document image. FIG. FIG. 6 is a schematic diagram illustrating an example of a copy of an original image in which a dot pattern embedded in the original image is seen floating. FIG. 10 is a schematic diagram illustrating another example of a copy of an original image in which a dot pattern embedded in the original image is raised. FIG. 3 is a schematic diagram illustrating an enlarged dot pattern illustrated in FIG. 2. It is a schematic diagram which expands and shows the dot pattern illustrated in FIG. FIG. 6 is a front view illustrating a document image and its dot pattern as another dot pattern example. FIG. 7 is a front view illustrating a document image different from FIG. 6 and its dot pattern. It is a schematic diagram which illustrates the dot pattern which makes the distance between dots d. It is a graph which expresses the distance distribution between adjacent dots, taking the distance between dots on the horizontal axis and taking the appearance frequency on the vertical axis. It is a schematic diagram which illustrates various dot patterns. It is a schematic diagram which illustrates another dot pattern. FIG. 12 is a schematic diagram illustrating an example of a document image having a dot pattern illustrated in FIG. 11. It is a schematic diagram which illustrates an example of the production | generation method of the dot pattern (composite pattern) in this Embodiment. It is a schematic diagram which shows an example of another implementation of a dot pattern (composite pattern). FIG. 15 is a schematic diagram illustrating an example of a document image having a dot pattern illustrated in FIG. 14. It is a schematic diagram which shows an example of another implementation of a dot pattern (composite pattern). FIG. 17 is a schematic diagram illustrating an example of a document image having a dot pattern illustrated in FIG. 16. It is a schematic diagram which shows an example of another implementation of a dot pattern (composite pattern). 1 is a block diagram illustrating hardware resources of an image processing apparatus configured as a digital copying machine as an example of an image processing apparatus that detects a dot pattern according to the present embodiment; FIG. It is a vertical side view of a scanner. FIG. 20 is a flowchart illustrating an example of a flow of processing executed by computer software corresponding to processing in the dot pattern detection unit and output prohibited document determination unit illustrated in FIG. 19. FIG.

Explanation of symbols

101 Original image 102 Recording medium (original paper)
103a Basic pattern 103b Composite pattern 106 Element of basic pattern, dot 107 Dummy pattern

Claims (1)

A recording medium having a pattern which is superimposed on a document surface for recording a document image and signifies specific information,
The specific information meaning the pattern is recognized by the image processing apparatus when the original image recorded on the recording medium is read by the image processing apparatus, and causes the image processing apparatus to execute predetermined control. Information,
The pattern is generated as a composite pattern in which a plurality of basic patterns constituting a unit that means the specific information is combined by a combination of a plurality of components.
A recording medium characterized by the above.

Images