JP3997720B2 - Image processing apparatus and image forming apparatus - Google Patents

Image processing apparatus and image forming apparatus Download PDF

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Publication number
JP3997720B2
JP3997720B2 JP2001107497A JP2001107497A JP3997720B2 JP 3997720 B2 JP3997720 B2 JP 3997720B2 JP 2001107497 A JP2001107497 A JP 2001107497A JP 2001107497 A JP2001107497 A JP 2001107497A JP 3997720 B2 JP3997720 B2 JP 3997720B2
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Japan
Prior art keywords
image
data
specific
information
specific symbol
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JP2002305646A (en
Inventor
隆信 大坪
純一 松野下
功幸 河野
裕之 河野
弘 関根
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富士ゼロックス株式会社
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Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image processing apparatus and an image forming apparatus, and more particularly, to an image processing apparatus for adding copy prevention image data for preventing illegal copying to specific document data prohibited from unauthorized copying, and a copy prevention image. The present invention relates to an image forming apparatus capable of preventing unauthorized copying of a specific document.
[0002]
[Prior art]
In recent years, along with the spread of personal computers and higher performance of printers and copiers, illegal copying and unauthorized use of confidential printed documents such as family register copies and contracts have become a problem. Conventionally, special paper called copy forgery prevention paper has been used to suppress such illegal copying and unauthorized use of confidential documents. The copy forgery prevention paper is a paper on which a special pattern is printed in advance, which is hard to be seen by human eyes, but which has a warning character or the like concealed when copied by a copying machine. When a document printed on this copy-forgery prevention paper is copied with a copying machine, warning characters such as “copy prohibited” will stand out prominently on the copied material, so psychologically against illegal copying In addition to being a deterrent, it is possible to distinguish between original and compound by warning characters.
[0003]
The image processing apparatus described in Japanese Patent Application Laid-Open No. 7-231384 generates a pattern image that can obtain the same effect as the copy forgery prevention paper described above by image processing. In this apparatus, when copying and recording based on image data read by a CCD or the like, a pattern image subjected to dither processing in which a warning character portion embedded as a latent image and a background portion are different from each other at a specific common density, By synthesizing it with the document image, it is possible to obtain the same print as when using copy forgery prevention paper using normal paper.
[0004]
Japanese Patent Laid-Open No. 10-285385 discloses a recording medium output method for embedding information such as a network address of a printer device and a print date and time in an image to be printed with a dot pattern of a color that is difficult to visually identify. Proposed. Information such as the network address can be left in an image printed out using this method. By analyzing this information, the outflow route of the document can be identified from the output printer device and the output date and time. can do.
[0005]
Further, by combining the method described in Japanese Patent Laid-Open No. 10-285385 with the function of prohibiting the copying operation by recognizing that the object to be copied in the copying machine is a confidential document prohibited from copying, Not only can unauthorized copying and unauthorized use of confidential documents be prevented, but unauthorized copying and unauthorized use can be reliably prevented. For example, if a machine-readable code such as a barcode is added to an image and printed out, the copying machine can be recognized as a confidential document.
[0006]
[Problems to be solved by the invention]
However, as in the device described in Japanese Patent Laid-Open No. 7-231384, it is not possible to take measures such as identifying a person who has performed an illegal act and preventing recurrence only by raising a warning character or the like.
[0007]
Further, in the method described in Japanese Patent Laid-Open No. 10-285385, a dot pattern is formed using yellow toner in order to make it difficult to identify visually, so this method cannot be applied to a monochrome printer. There is a problem of lack of versatility. In addition, when a printed image is copied with a black and white copying machine, the dot pattern formed using yellow toner is not copied, so it is easy to delete the added information, and the outflow path can be traced. There is a problem that it becomes difficult.
[0008]
Further, even if the method described in Japanese Patent Laid-Open No. 10-285385 is combined with a function for prohibiting a copying operation by recognizing that an object to be copied in a copying machine is a confidential document for which copying is prohibited. Since the barcode position can be clearly determined in the printed image, there is a problem that information added by copying without the barcode can be easily deleted. On the other hand, it is conceivable to add a barcode to the entire printed image so that it cannot be easily deleted. In this case, however, there is a problem that the barcode arranged on the entire surface impairs the image quality.
[0009]
Furthermore, the present applicant, when generating a pattern image (hereinafter referred to as a copy forgery prevention image) having the same effect as the copy forgery prevention paper by image processing, the latent image portion or background constituting the copy forgery prevention image By applying a fine pattern constituting one of the parts as a machine-readable code, the same effect as that of a copy forgery prevention sheet can be obtained, and a technique for embedding arbitrary digital information using the machine-readable code has already been filed ( Japanese Patent Application No. 2000-168287 ). According to this technology, information indicating copy prohibition is embedded in a copy-forgery-prevented image with a machine-readable code, and the copying machine is provided with a decoding function for the machine-readable code so that an unauthorized copy of a document that is prohibited from being copied It is also possible to prevent copying. However, if the information embedded in the machine-readable code is decoded one by one to determine whether or not the information indicates copy prohibition, the processing time becomes long and the productivity of the copying machine decreases.
[0010]
The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to provide an image for preventing unauthorized copying of a specific document image prohibited from unauthorized copying without impairing image formation efficiency. An object of the present invention is to provide an image processing apparatus for synthesizing image data to be used. Another object of the present invention is to provide an image forming apparatus capable of reliably preventing illegal copying of a specific document image for which unauthorized copying is prohibited without impairing image forming efficiency.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, an image processing apparatus according to the present invention includes data input means for inputting document data to which predetermined information is added, and the predetermined information is specific document data prohibited from unauthorized copying. If it contains specific information indicating A specific symbol representing specific document data is generated based on the specific information, and at least a part of the predetermined information is encoded to generate a machine-readable code, and the specific symbol and the machine-readable code are latent images. The machine-readable code is a fine pattern that is included in a part of the background image in which is embedded and forms either the latent image portion or the background portion. The image forming apparatus includes a generating unit that generates image data, and a combining unit that combines the generated image data and specific document data.
[0012]
In the image processing apparatus according to the present invention, when document data to which predetermined information is added is input from the data input means, the predetermined information includes specific information indicating that the specific data is prohibited from unauthorized copying. Means that the generation means A specific symbol representing specific document data is generated based on the specific information, and at least a part of the predetermined information is encoded to generate a machine-readable code, and the specific symbol and the machine-readable code are latent images. The machine-readable code is a fine pattern that is included in a part of the background image in which is embedded and forms either the latent image portion or the background portion. Generate image data. The synthesizing unit synthesizes the generated image data and the specific document data. If an image formed on the basis of the data synthesized by the image processing apparatus is read by the image forming apparatus of the present invention, it is possible to easily determine whether or not the document data is specified by the presence or absence of a specific symbol, thereby impairing image forming efficiency. Therefore, it is possible to reliably prevent unauthorized copying of specific document images for which unauthorized copying is prohibited.
[0013]
Also, In the above-described image processing apparatus, the generation unit generates a machine-readable code by encoding at least a part of the predetermined information, and an image having the specific symbol and the machine-readable code as a part of the background image in which the latent image is embedded. Generate data So Any digital information can be embedded in the background image by machine readable code.
[0014]
As the background image in which the latent image is embedded, an image in which the latent image portion and the background portion have substantially the same density, and one of the latent image portion and the background portion is copied and reproduced, and the other is not copied and reproduced can be used. This image is called a copy forgery prevention image. Before copying, the latent image portion and the background portion are substantially equal in density and the latent image is not visualized, but one of the latent image portion and the background portion is copied and reproduced, and the other is copied. Since it is not reproduced, the embedded latent image is visualized after copying. As a result, the act of copying illegally becomes a psychological deterrent, and the original and the compound can be distinguished from each other by the emerged image.
[0015]
Further, the generation means may generate image data so that the specific symbol becomes a latent image, or may generate image data so that the specific symbol is included in the background portion.
[0016]
The machine-readable code can represent copy prohibition information for prohibiting unauthorized copying. Since the machine-readable code represents the copy prohibition information, it is possible to determine whether or not the specific document data is prohibited from being copied by decoding the machine-readable code, so that unauthorized copying can be prevented more reliably.
[0017]
The predetermined information to be encoded includes information for identifying the image processing apparatus in which the image is generated, information for identifying the specific document data, information regarding the date and time when the image was generated, and the confidential level of the specific document data. It is preferable to include at least one of information, information on access qualification for specific document data, and information for identifying the source of the specific document data.
[0018]
The image forming apparatus according to the present invention includes an image reading unit that reads a specific document image obtained by combining an image having a specific symbol representing machine specific document data and a machine readable code as a part of a background image embedded with a latent image. Detecting means for detecting a specific symbol based on the read image; and decoding means for decoding the machine-readable code based on the read image when the specific symbol is detected by the detecting means. It is characterized by comprising.
[0019]
In the image forming apparatus according to the present invention, the image reading unit generates a specific document image obtained by combining an image having a specific symbol representing machine specific data and a machine readable code as a part of a background image embedded with a latent image. When read, the detection means detects a specific symbol based on the read image. Next, the decoding means decodes the machine-readable code based on the read image when the specific symbol is detected by the detection means. Thus, before decoding the machine-readable code, the specific symbol is detected from the read image, and when the specific symbol is detected, the machine-readable code is decoded. It is possible to easily determine whether the data is data, and it is possible to reliably prevent unauthorized copying of a specific document image in which unauthorized copying is prohibited without impairing image formation efficiency.
[0020]
An image processing apparatus according to the present invention includes an image reading unit that reads a specific document image obtained by combining an image having a specific symbol representing machine specific document data and a machine readable code as a part of a background image embedded with a latent image. Detecting means for detecting a specific symbol based on the read image; decoding means for decoding a machine-readable code based on the read image when the specific symbol is detected by the detecting means; and the decoding And control means for controlling the image output to be prohibited or the image quality of the output image to be deteriorated when the information decoded by the converting means represents copy prohibition information. be able to. In this way, when the decrypted information represents copy prohibition information, control is performed so that image output is prohibited or the image quality of the output image is deteriorated. Can be prevented.
[0021]
An image reading unit that reads a specific document image in which an image having a specific symbol representing machine specific data and a machine readable code as a part of a background image embedded with a latent image is combined, and based on the read image Detecting means for detecting a specific symbol, decoding means for decoding the machine-readable code based on the read image when the specific symbol is detected by the detecting means, and authentication information input for inputting authentication information Even if the information decrypted by the means and the decryption means represents copy prohibition information, if authentication is obtained by the authentication information input means, a high-quality image is output and authentication is obtained. And an image forming apparatus configured to include a control unit that performs control so that image output is prohibited when the output is not performed, or that the image quality of the output image is degraded. It may be. In this way, if the user inputs authentication information and authentication is not obtained, control is performed so that image output is prohibited, or control is performed so that the image quality of the output image deteriorates. Can be guaranteed.
[0022]
Furthermore, an image reading means for reading a specific document image in which an image having a specific symbol representing specific document data as a part of a background image embedded with a latent image is combined, and a specific symbol based on the read image And a control unit for controlling image output to be prohibited when the specific symbol is detected by the detection unit, or for controlling the image quality of the output image to be deteriorated. An image forming apparatus may be configured. When a specific symbol is detected from the read image and the specific symbol is detected, control is performed such that image output is prohibited or the image quality of the output image is deteriorated. It is possible to easily determine whether or not the document data is specific document data, and it is possible to reliably prevent illegal copy of a specific document image prohibited from unauthorized copy without impairing image formation efficiency.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
(First embodiment)
As shown in FIG. 1, the image processing system according to the first embodiment includes client devices 71 and 72 configured by a personal computer, a print server 73 incorporating the image processing device of the present invention, and a print function. A multi-function device 74 having a copy function is connected to a network 75 such as the Internet. The multi-function device 74 corresponds to the image forming apparatus of the present invention. In this image processing system, when document data is printed by an instruction from the client devices 71 and 72, the document data is described in PDL (Printer Description Language) by a printer driver built in the client device. Converted into (PDL data), and the PDL data is transmitted to the print server 73 via the network 75. The print server 73 determines whether or not the document is a confidential document based on the received PDL data. If it is determined that the document is a confidential document, the PDL data is processed as described later, and the processed PDL data is transferred to the network 75. To the multi-function device 74. The multi-function device 74 converts the received PDL data into raster image data and performs print output.
[0024]
Next, the configuration of the image processing apparatus built in the print server 73 will be described. As shown in FIG. 2, the image processing apparatus includes a print data input unit 1, a document image generation unit 2, a document image buffer 3, an additional information extraction unit 4, a latent image generation unit 5, an additional information encoding unit 6, and a pattern. The storage unit 7, the pattern image generation unit 8, the pattern image buffer 9, the image synthesis unit 10, and the image output unit 11 are configured.
[0025]
PDL data transmitted from an external computer or the like is input to the print data input unit 1. In the header portion of this PDL data, the IP (Internet Protocol) address of the computer that sent the print job, the user name that sent the print job, the IP address of the print server, the name of the document file to be printed, and the print server identify the PDL data Additional information includes the document ID to be allocated, the time stamp of the document to be printed, the security level set in the document file, the encoding information such as the password set in the document file, and the latent image shape information embedded as a latent image. It has been added.
[0026]
Since the additional information is added only to a confidential document that needs to be prohibited from being copied, when the additional information is extracted, it is determined that the document is a confidential document. When specific additional information such as a confidential level is extracted, it may be determined that the document is a confidential document. In particular, in the present embodiment, the shape of the image embedded as a latent image also functions as a specific symbol for recognizing on the copier side that the confidential document is prohibited from being copied. The function of the specific symbol will be described later.
[0027]
The document image generation unit 2 rasterizes the PDL data input from the print data input unit 1 and generates document image data converted into a binary image. The document image buffer 3 temporarily stores the document image data generated by the document image generation unit 2.
[0028]
The additional information extraction unit 4 extracts the additional information added to the header portion of the PDL data from the PDL data input to the print data input unit 1, and converts the extracted additional information into latent image shape information and coded information. Decompose. The latent image generation unit 5 rasterizes the latent image shape information input from the additional information extraction unit 4 and generates latent image data converted into a binary image. The additional information encoding unit 6 performs error correction encoding on the encoded information input from the additional information extracting unit 4 and refers to the latent image data input from the latent image generating unit 5 to perform error correction encoding. The code information is converted into code data.
[0029]
The pattern storage unit 7 includes, for example, 3 of a right-down oblique line pattern 0 shown in FIG. 3A, a left-down oblique line pattern 1 shown in FIG. 3B, and a dot pattern 2 shown in FIG. Stores types of patterns. The pattern image generation unit 8 selects a pattern corresponding to each value of the code data from the three types of patterns stored in the pattern storage unit 7 and generates a pattern image composed of the three types of patterns. The pattern image buffer 9 temporarily stores the pattern image generated by the pattern image generation unit 8.
[0030]
The image composition unit 10 superimposes and combines the pattern image read from the pattern image buffer 9 on the document image data read from the document image buffer 3. That is, a pattern image (a copy forgery prevention image) in which a latent image shape for preventing forgery by copying is embedded is synthesized with document image data related to a confidential document or the like. On the other hand, since no additional information is added to the document image data related to a document other than a confidential document, the pattern image is not synthesized.
[0031]
The image output unit 11 outputs document image data in which pattern images are combined.
[0032]
Next, the operation of this image processing apparatus will be described. When PDL data transmitted from an external computer or the like is input to the print data input unit 1, the input PDL data is interpreted and raster-developed by the document image generation unit 2, and converted into binary image data. Is stored in the document image buffer 3.
[0033]
Further, additional information added to the header portion of the PDL data is extracted by the additional information extraction unit 4. When the additional information is not extracted from the PDL data, it is determined that the document is not a confidential document, and a signal (not shown) indicating that the additional information is not extracted is generated from the additional information extraction unit 4 to generate a latent image. Is transmitted to the unit 5, the additional information encoding unit 6, the pattern image generation unit 8, and the image synthesis unit 10. Processing in each unit that receives this signal is not performed, and the document image data read from the document image buffer 3 passes through the image composition unit 10 and is output to the image output unit 11 as it is.
[0034]
When additional information is extracted from PDL data, the extracted additional information is decomposed into latent image shape information and coded information by the additional information extraction unit 4. Of these, the latent image shape information is output to the latent image generation unit 5, and the encoded information is output to the additional information encoding unit 6. Further, in parallel with the above processing, the PDL data is stored in a document data storage unit (not shown) in the print server 73, and the document extracted by the additional information extraction unit, ID, print date and time, IP address of the client PC The name of the user who sent the print job and the storage address of the PDL data are added to the log file stored in the document data storage unit (not shown) and stored.
[0035]
When the latent image shape information is input to the latent image generation unit 5, the input latent image shape information is raster-developed using a predetermined font, and binary image data is generated as a binary image. The font to be used is set with a relatively large number of points (for example, 48 points) in order to exhibit the same effect as the copy forgery prevention paper described above. However, the latent image is converted into a binary image so as to satisfy the relationship of the following expressions (1) and (2).
[0036]
Latent image resolution = printer resolution / number of horizontal pixels of the pattern (1)
Number of vertical and horizontal pixels of the latent image = number of vertical and horizontal pixels of the document image ÷ number of horizontal pixels of the pattern (2)
For example, when the printer resolution is 600 dpi, the pattern has 12 horizontal pixels, and the document image data has vertical and horizontal pixel counts of 4960 × 7015 pixels, the resolution of the latent image is 50 dpi and the vertical and horizontal pixel count is 413. × 584 pixels. That is, one pixel of the latent image is set to correspond to one pattern size. The latent image data generated by the latent image generating unit 5 is output to the additional information encoding unit 6.
[0037]
Here, FIG. 4A shows an example of a pattern image printed out. In this example, a white document image is synthesized so that the latent image portion is clear. FIG. 4A shows the entire pattern image printed out. The document image data is a binary image of 1 bit / pixel. The area of the “confidential” symbol in FIG. 4A is a latent image portion that emerges when copied by a copying machine, and the surrounding area is a background portion. In this figure, the “confidential” symbol can be identified, but the density of the latent image area (black pixel area per unit area) is the same as the density of the background area. The “secret” symbol is difficult to identify.
[0038]
FIG. 4C is an image obtained by enlarging the area surrounded by the square in FIG. 4A, and the printed document image is composed of patterns 0 to 2 shown in FIGS. 3A to 3C. The dot pattern 2 is arranged inside the latent image portion, and the hatched pattern 0 or 1 is arranged in the background portion.
[0039]
The patterns 0 to 2 have different shapes as described above, but the number of black pixels constituting each pattern is substantially the same, and the density when printed out is almost the same regardless of the pattern arrangement. It is configured. Actually, even if the number of pixels is the same due to the printer characteristics, the density differs slightly depending on the pattern. Therefore, the number of black pixels and the pattern shape are set so that the density after print output matches exactly. Yes.
[0040]
As shown in FIGS. 3A and 3B, the oblique line patterns 0 and 1 arranged in the background are linear fine patterns drawn obliquely, and the patterns are not reproduced when copied by a copying machine. Has reproducible characteristics. On the other hand, the dot pattern 2 arranged inside the latent image portion is a pattern in which isolated dots are sparsely arranged as shown in FIG. It has characteristics that are difficult to reproduce.
[0041]
For this reason, when the pattern image shown in FIG. 4A is copied by a copying machine, the background portion is copied at a high density, and the image is lost inside the latent image portion. As shown in FIG. A white “secret” symbol appears in the object.
[0042]
When the encoded information is input from the additional information extracting unit 4 and the latent image data is input from the latent image generating unit 5 to the additional information encoding unit 6, the input encoded information is converted into the additional information encoding unit 6. Is subjected to error correction coding. The encoded information subjected to error correction coding is represented by a bit string of “0” and “1”. The bit string is read bit by bit, and the read bit string is converted into a two-dimensional array (unit two-dimensional unit) of a predetermined size. Sort by (array). The outermost peripheral bits of the unit two-dimensional array are all bits 1 in order to facilitate the positioning and extraction of the code data.
[0043]
This unit two-dimensional array is further repeatedly arranged in the vertical direction and the horizontal direction to form a two-dimensional array having a size corresponding to the number of pixels of the latent image. Thereafter, when the pixel of the latent image data is referred to and the pixel of the latent image data is a black pixel, the value of the element of the two-dimensional array corresponding to the position of the black pixel is forcibly copied. It is replaced with a value “2” for selecting a pattern that is difficult to reproduce. As described above, the code data (two-dimensional array code) that has been subjected to error correction coding, rearranged into a two-dimensional array, and subjected to code conversion according to the latent image data is output to the pattern image generation unit 8.
[0044]
Next, when the two-dimensional array code is input to the pattern image generation unit 8, one pattern is selected from the pattern storage unit 7 according to the value of each element of the input two-dimensional array code, and the selected pattern is selected. Is read. For example, when the value of the element is “0”, the diagonally downward slanting pattern 0 shown in FIG. 3A is selected, and when the value of the element is “1”, the downward slope shown in FIG. When the diagonal line pattern 1 is selected and the element value is “2”, the dot pattern 2 shown in FIG. 3C is selected. The read patterns 0 to 2 are written at corresponding positions in the pattern image buffer 9.
[0045]
The above processing is repeated for all of the two-dimensional array codes having a size corresponding to the number of pixels of the latent image, whereby the pattern image buffer 9 is configured with the above three types of patterns and has the same size as the document image data. Pattern image data is formed and stored.
[0046]
In the image synthesizing unit 10, when the document image data is read from the document image buffer 3 and the pattern image data is read from the pattern image buffer 9, the pixels of both image data are synthesized by a logical sum operation, and the pattern image is synthesized. The obtained document image data is output to the image output unit 11. Then, the image output unit 11 outputs the document image data combined with the pattern image to the multi-function device 74 via the network 75. The multi-function device 74 prints out the document image in which the pattern image is synthesized based on the document image data by the print function.
[0047]
In the pattern image, a diagonally downward slanting pattern 0 corresponding to bit “0” is arranged in the background portion, and a diagonally descending diagonal pattern 1 corresponding to bit “1” is arranged. Since the pattern shapes of the pattern 0 and the hatched pattern 1 are different, the bit “0” and the bit “1” can be discriminated by the machine according to the pattern shape. That is, a machine-readable code can be configured using these two types of patterns, and information such as the printer IP address and output date can be embedded in the output image as a machine-readable code. Note that the hatched pattern 1 may correspond to the bit “0” and the hatched pattern 0 may correspond to the bit “1”.
[0048]
By embedding machine-readable code (digital code) in the output image in this way, it is possible to specify the outflow route of the output print from the embedded information, and even if it is illegally copied, it is reproduced in a copy It is possible to easily trace the outflow path of the print output from the generated machine readable code.
[0049]
In the above, the pattern image data is formed by three patterns of two oblique line patterns and one dot pattern constituting the machine readable code. However, it is sufficient that specific information can be displayed as the machine readable code. Types are not limited to three. In addition, the process for generating the pattern image data may be executed by hardware or may be executed by software.
[0050]
Next, the configuration of the multi-function device 74 that is the image forming apparatus of the present invention will be described. As shown in FIG. 5, the multi-function device 74 includes an image input unit 20 that inputs a document as a read image, an image processing unit 21 that processes the input image, and an image output unit that performs image output and records it on a sheet. 22. A specific symbol detection unit 23 for detecting a specific symbol indicating a copy-prohibited document from the input image, a code decoding unit 24 for detecting a two-dimensional array code from the input image and decoding it to the original information, and compose the PDL data An image generation unit 25 for generating an image, a control unit 26 for controlling the entire multifunction device, a control panel 27 for displaying information and inputting keys to the user, and a network interface for connecting to the network 75 shown in FIG. 28, a selector 60 that selects an input from the image processing unit 21 and an input from the image generation unit 25 and outputs the selected input to the image output unit 22; And a page buffer 29 for storing an image of interests.
[0051]
Next, the copying operation of the printed document image will be described. First, the image input unit 20 reads a document to which a pattern image shown in FIG. 4A is added, and the read image data is input. The input image data is temporarily stored in the page buffer 29 and input to the specific symbol detector 23. The specific symbol detection unit 23 performs a specific symbol detection process and determines whether or not a specific symbol is included. Then, the determination result is output to the control unit 26.
[0052]
Here, a method for determining a specific symbol in the present embodiment will be described. In this embodiment, regardless of the orientation of the original including the specific symbol, the orientation of the original is determined so that it can be accurately determined whether or not the input image data includes the specific symbol. The characteristic value and the degree of coincidence that are almost independent are used. The characteristic values to be used are the total number of on pixels and the total number of on / off inversions in a circle area set in advance according to a specific symbol, and the first circumference set in advance according to the specific symbol. The total number of on pixels and the total number of on / off inversions are four. The degree of coincidence used is calculated based on the image pattern (one-dimensional pattern) on the second circumference set in advance according to the specific symbol and the normal pattern set in advance according to the specific symbol. Is obtained. In the present embodiment, the result of comparing each characteristic value and the allowable range of each characteristic value set according to the specific symbol, and the result of comparing the degree of coincidence and a predetermined allowable range, Since the specific symbol is detected on the basis of this, the specific symbol can be detected with high accuracy almost without depending on the orientation of the document.
[0053]
It should be noted that the first circumference and the second circumference do not need to coincide with each other, but are preferably different. On “total number of pixels” refers to the number of on-pixels in the area, and “on / off inversion total number” refers to pixels that change from on to off or off to on in the area in the main and sub-scanning directions. Number (number of times). Further, the “circle region” is a region surrounded by a circle having a specific diameter with the center position of the specific symbol determined from the size of the specific symbol to be detected, the reading resolution of the document, and the like. The “specific diameter” is desirably set to the minimum length that allows the specific symbol to be accommodated in the circular area, from the viewpoint of suppressing an increase in memory capacity and processing amount.
[0054]
Further, “on the first circumference” is an area through which the circumference of the circle having the first radius passes, and the “first radius” satisfies the following relationship.
(First radius) x 2 <(specific diameter)
Further, the center point and the first radius of the first circumference are set so that the first circumference passes through a portion that clearly represents the characteristics of the specific symbol. The relationship and setting policy described above are the same for the center point of the second circumference and the second radius.
[0055]
The configuration and operation of the specific symbol detection unit 23 that detects the characteristic values, calculates the degree of coincidence, and detects specific symbols using these characteristic values will be described with reference to FIG. As already described, in the present embodiment, the “confidential” symbol in the pattern image illustrated in FIG. 4 is a specific symbol to be detected.
[0056]
As shown in FIG. 6, noise is removed from the image data input to the specific symbol detection unit 23 by a noise removal circuit 31. Here, the noise is an image other than the oblique line pattern constituting the two-dimensional array code. For example, characters, figures, photographs, etc. constituting the document image are removed as noise. Specifically, an isolated dot pattern and an image having a size (number of connected pixels) larger than the oblique line pattern are removed. Thereby, the occurrence probability of erroneous determination is reduced. The image data from which noise has been removed by the noise removal circuit 31 is temporarily stored in the first buffer memory 32.
[0057]
Next, the image data stored in the first buffer memory 32 is read out and input to the reduction circuit 33 for reduction processing. Here, the reduction ratio is set to 1 / hatched pattern interval. For example, when the resolution of the input image is 400 dpi and the interval between the hatched patterns is 0.5 mm (8 pixels at 400 dpi), the reduction ratio is set to 1/8, that is, 12.5%. Due to this reduction processing, black pixels are connected in the vertical and horizontal directions in the area where the diagonal line pattern exists, and only the part where the diagonal line pattern does not exist is whitened out, and only the “confidential” symbol part from the image shown in FIG. Becomes an almost black solid image. The image data reduced by the reduction circuit 33 is temporarily stored in the second buffer memory 34.
[0058]
The image data stored in the second buffer memory 34 includes a circular area on-pixel total number detection circuit 35, a circular area on / off inversion total number detection circuit 36, a first on-circumference on-pixel total number detection circuit 37, a first Are input to the on-circumference on-off inversion total number detection circuit 38 and the second on-circumference data coincidence calculation circuit 39, the respective characteristic values are detected / calculated.
[0059]
That is, every time the circular area is moved, the circle area ON pixel total number detection circuit 35 detects the number of ON pixels in the circle area, and the circle area ON / OFF inversion number detection circuit 36 detects the number of ON pixels in the circle area. Each time is moved, the number of pixels that change from on to off and from off to on in the circular area in both the main and sub scanning directions is detected. The first on-circumference on-pixel total number detection circuit 37 detects the number of on-pixels on the first circumference having the first radius each time the circular area is moved, and on the first circumference The on / off inversion total number detection circuit 38 detects the on / off inversion total number in the circumferential direction on the first circumference every time the circular area is moved.
[0060]
The detection method of each characteristic value by these circuits 35-38 is arbitrary. For example, in the circle-area on-pixel total number detection circuit 25, the detection result immediately before moving the circle area in the main scanning direction (or sub-scanning direction) is held, and the circle area is moved in the main scanning direction (or sub-scanning direction). The detection result may be obtained based on the pixel newly entered into the circle area when moved to the pixel, the pixel that has moved out of the circle area, and the immediately preceding detection result. Each time the area is moved, all pixels in the circular area may be examined to obtain a detection result.
[0061]
The second on-circumference data coincidence detection circuit 39 performs a calculation based on the image pattern and the normal pattern on the second circumference having the second radius with the center point of the specific symbol as the center. Thus, the degree of coincidence between the image to be scanned and the specific symbol is calculated.
[0062]
Each of the characteristic values detected / calculated by the circuits 35 to 39 is input to the determination circuit 40, and is compared with the characteristic value of a specific symbol registered in advance in the determination circuit 40 to determine whether or not the specific symbol is included. Is determined.
[0063]
If the specific symbol detection unit 23 determines that the input image data does not include the specific symbol, the control unit 26 determines that the input image data is not image data related to confidential documents that are prohibited from being copied. The copying operation is continued as it is. That is, the image data stored in the page buffer 29 is read out and input to the image processing unit 21. The image processing unit 21 performs image processing for reproduction reproduction such as gradation processing and outputs the image data to the image output unit 22. Thus, image formation on the paper is performed.
[0064]
On the other hand, if the specific symbol detection unit 23 determines that the input image data includes a specific symbol, the input image data is image data related to a confidential document or the like for which copying is prohibited. 26 temporarily stops the copying operation, reads out the image data stored from the page buffer 29, inputs it to the code decoding unit 24, decodes the two-dimensional array code input in the code decoding unit 24, Detect the security level of image data.
[0065]
As shown in FIG. 7, noise is removed from the image data input to the code decoding unit 24 by a noise removal circuit 41. This noise removal processing is performed in the same manner as in the noise removal circuit 31 of the specific symbol detection unit 23. The image data from which noise has been removed by the noise removal circuit 41 is input to the pattern detection circuit 42.
[0066]
In the pattern detection circuit 42, two types of oblique line patterns are detected, and bit data corresponding to the detected pattern is output in combination with the pixel value of the detected coordinate. Here, when the oblique line pattern is not detected, a value other than 0 and 1 (for example, 2) is output as the pixel value of the coordinates. The output data of the pattern detection circuit 42 is temporarily stored in the buffer memory 43.
[0067]
The image data stored in the buffer memory 43 is read out and input to the skew angle detection circuit 44. The skew angle detection circuit 44 calculates the skew angle of the input image data. The skew angle is calculated by performing a Hough transform on a pixel having a pixel value of 0 or 1, and obtaining a peak of the projection distribution on the angle axis. The calculated skew angle is output to the code detection circuit 45.
[0068]
Next, the image data temporarily stored in the buffer memory 43 is read and input to the code detection circuit 45. The code detection circuit 45 scans the image along the skew angle calculated by the skew angle detection circuit 44, and reads a bit string composed of pixel values of 0 or 1 (corresponding to 0 or 1 of the bit). Next, a synchronization code is detected from the read bit string. The synchronization code is defined as a code composed of all bits 1 surrounding a rectangular area having a predetermined vertical and horizontal size, for example. The bit array surrounded by the synchronization code is the unit two-dimensional array described above. The code detection circuit 45 rearranges this bit array into a one-dimensional bit string for each unit two-dimensional array, and outputs it to the error correction decoding circuit 46.
[0069]
The error correction decoding circuit 46 performs a predetermined error correction decoding process on the input one-dimensional bit string. This error correction decoding process corresponds to the error correction encoding process applied when the print server 73 generates a two-dimensional array code. The error-corrected decrypted data (decoded data) includes information such as a document ID, a confidential level, a password, and an IP address of the print server. Then, the data decoded by the code decoding unit 24 is output to the control unit 26.
[0070]
The control unit 26 extracts confidential level information from the input decrypted data, and performs processing according to the confidential level. For example, three levels of confidentiality can be set as follows.
[0071]
Confidential level (1): Copying is unconditionally prohibited.
[0072]
Security level (2): normal copying is permitted only to a specific user having a predetermined password.
[0073]
Security level (3): Only a specific user having a predetermined password is permitted to copy with high image quality, and a user who does not have the predetermined password is permitted to perform normal copying.
[0074]
In the case of the confidential level (1) where copying is unconditionally prohibited, the control unit 26 displays on the control panel 27 that the copy is prohibited and stops the copying operation. As a result, if the read original contains a specific symbol, copying is unconditionally prohibited.
[0075]
In the case of the confidential level (2) in which normal copying is permitted only to a specific user having a predetermined password, the control unit 26 displays a message prompting the user to input a user ID and password on the control panel 27, and When the user ID and password are input from the control panel 27, it is determined whether or not the input password matches the password included in the decrypted data.
[0076]
If the passwords do not match, the control unit 26 displays on the control panel 27 that the document is prohibited from being copied, and stops the copying operation. On the other hand, if the passwords match, the control unit 26 resumes the normal copying operation. That is, the image data stored in the page buffer 29 is read out and input to the image processing unit 21. The image processing unit 21 performs image processing for reproduction reproduction such as gradation processing and outputs the image data to the image output unit 22. Thus, image formation on the paper is performed.
[0077]
Therefore, even when a specific symbol is included in the read original, when a specific user inputs a predetermined password, the normal copying operation is resumed. When the original with the pattern image shown is copied by a copying machine as usual, the background portion is copied at a high density, and the image is lost inside the latent image portion. As shown in FIG. A blank “confidentiality” symbol appears, revealing that the manuscript is prohibited from being copied.
[0078]
Regardless of whether or not the passwords match, the control unit 26 extracts the IP address of the print server included in the decrypted data, and sends the network interface 28 and the print server 73 specified by the IP address. The decrypted data and the user ID are transmitted via the network 75. As shown in FIG. 8, the print server 73 determines the document ID, the print (copy) date and time, the IP address of the MFP (client) that sent it, and the user name sent from the MFP as shown in FIG. Record it in the log file as history. Note that the entered password may be recorded in the log file as a history. In addition, when performing normal copying, the PDL data storage address is not recorded.
[0079]
In the case of the confidential level (3) in which only a specific user having a predetermined password is permitted to make a copy with high image quality and a user who does not have the predetermined password is permitted to perform normal copying, the control unit 26 controls When a message prompting the user ID and password to be input is displayed on the panel 27, and the user ID and password are input from the control panel 27 by the user, whether or not the input password matches the password included in the decrypted data Determine whether.
[0080]
If the passwords do not match, the control unit 26 resumes the normal copying operation. That is, the image data stored in the page buffer 29 is read out and input to the image processing unit 21. The image processing unit 21 performs image processing for reproduction reproduction such as gradation processing and outputs the image data to the image output unit 22. Thus, image formation on the paper is performed. Therefore, when a specific symbol is included in the read original and a specific user inputs a password other than the predetermined password, the normal copy operation is resumed and the original is prohibited from being copied. It becomes clear that.
[0081]
On the other hand, if the passwords match, the control unit 26 extracts the IP address of the print server included in the decrypted data, and sends it to the print server 73 specified by the IP address via the network interface 28 and the network 75. Then, the decrypted data and the user ID are transmitted, and the transmission of the document data (PDL data) related to the document ID included in the decrypted data is requested.
[0082]
The print server 73 extracts the document ID from the transmitted decrypted data, refers to the log file, reads the PDL data corresponding to the document ID acquired from the PDL data storage address, and performs image processing built in the print server 73. In the apparatus, pattern image data for preventing forgery by copying is generated, combined with PDL data, and transmitted to the multi-function device 74.
[0083]
As already explained, information such as document ID, security level, password, and IP address of the print server is embedded in the pattern image using a two-dimensional array code composed of diagonal lines, and copying as a latent image is prohibited. A specific symbol for recognizing on the copying machine side is embedded. The document ID is newly issued at the time of reprinting.
[0084]
When the PDL data is received on the multi-function device 74 side, the control unit 26 generates a raster image from the PDL data received by the image generation unit 25 and outputs the raster image to the image output unit 22 to form an image on a sheet. . Therefore, when a specific symbol is included in the read document and a specific user inputs a predetermined password, a pattern image is generated based on the PDL data transmitted from the print server 73. The added document image is printed out (reprinted), and an output image with higher image quality than when the read original is copied as usual can be obtained.
[0085]
Further, as shown in FIG. 8, the print server 73, based on the transmitted data, transmits the document ID, the confidential level, the print (reprint) date and time, the IP address of the MFP (client) that has transmitted, and the MFP. The stored PDL data storage address corresponding to the user name, password, and document ID is recorded in the log file as a history. That is, in the log file of the print server 73, not only the print history information of the confidential document but also the copy history information of the confidential document printed out remains, and the administrator simply refers to the log file of the confidential document. It becomes possible to grasp the distribution situation.
[0086]
(Second Embodiment)
The image processing system according to the second embodiment uses a pattern image in which a specific symbol for recognizing on the copier side that a confidential document is prohibited from being copied as a fine pattern in the background portion, Except for detecting this specific symbol, it is the same as in the first embodiment, and therefore, the description of the same part is omitted, and only the difference is described.
[0087]
FIG. 9 shows an example of a pattern image used in the present embodiment. FIG. 9A shows the entire pattern image printed out. The document image data is a binary image of 1 bit / pixel. The character area “COPY” in FIG. 9A is a latent image portion that emerges when copied by a copying machine, and the surrounding area is a background portion. In this figure, the character “COPY” can be identified, but the density of the latent image portion (black pixel area per unit area) is the same as the density of the background portion, and actually “COPY” of the latent image portion. "Is difficult to identify.
[0088]
FIG. 9C is an image obtained by enlarging the area (C) enclosed by the square in FIG. 9A, and the printed image is composed of the patterns 0 to 2, and the latent image portion. The dot pattern 2 is arranged inside the hatched pattern, and the hatched pattern 0 or 1 is arranged in the background portion.
[0089]
FIG. 9D is an image obtained by enlarging the area (D) enclosed by the square in FIG. 9A, and the background portion includes a two-dimensional array code portion configured with a diagonal pattern 0 or 1, and 10 are alternately arranged with the portions formed by the circular pattern 3 which is the fourth pattern shown in FIG. The portion constituted by the circle pattern 3 becomes a specific symbol portion for recognizing on the copier side that the confidential document is prohibited from being copied.
[0090]
Although the patterns 0 to 3 have different shapes as described above, the number of black pixels constituting each pattern is substantially the same, and the density (black pixels per unit area) when printed out regardless of the pattern arrangement. The surface areas of the two are the same. For this reason, the image shown in FIG. 9A appears as a uniform gray background to the human eye. Actually, even if the number of pixels is the same due to the printer characteristics, the density differs slightly depending on the pattern. Therefore, the number of black pixels and the pattern shape are set so that the density after print output matches exactly. Yes.
[0091]
The hatched patterns 0 and 1 and the circle pattern 3 arranged in the background portion have a characteristic that the pattern is reproduced when copied by a copying machine. On the other hand, the dot pattern 2 in which isolated dots arranged in the latent image portion are sparsely has a characteristic that the pattern is difficult to be reproduced when copied by a copying machine. For this reason, when the pattern image shown in FIG. 9A is copied by a copying machine, the background portion is copied at a high density, and the image is lost inside the latent image portion, as shown in FIG. 9B. A white “COPY” character appears in the object.
[0092]
Next, the copying operation of the printed document image will be described. First, the image input unit 20 reads a document with a pattern image shown in FIG. 9A and inputs the read image data. The input image data is temporarily stored in the page buffer 29 and input to the specific symbol detector 23. As shown in FIG. 11, in the present embodiment, the configuration of the specific symbol detector 23 of the multifunction machine is also different from that of the first embodiment. The noise from the image data input to the specific symbol detector 23 is removed by the noise removal circuit 51. The image data from which noise has been removed by the noise removal circuit 31 is temporarily stored in the buffer memory 52.
[0093]
Next, the image data stored in the buffer memory 52 is read out and input to the circle pattern detection circuit 53. The circle pattern detection circuit 53 detects the number of specific circle patterns (in this embodiment, the circle pattern 3 shown in FIG. 10) by template matching, and outputs the detection result to the count circuit 54. The count circuit 54 counts the number of specific circle patterns detected by the circle pattern detection circuit 53 and outputs the counted number to the determination circuit 55. The determination circuit 55 determines that a specific symbol has been detected when the number of detected specific circle patterns input from the count circuit 54 exceeds a preset threshold value, and outputs the determination result to the control unit 26. .
[0094]
If the specific symbol detection unit 23 determines that the input image data does not include the specific symbol, the control unit 26 determines that the input image data is not image data related to confidential documents that are prohibited from being copied. The copying operation is continued as it is. That is, the image data stored in the page buffer 29 is read out and input to the image processing unit 21. The image processing unit 21 performs image processing for reproduction reproduction such as gradation processing and outputs the image data to the image output unit 22. Thus, image formation on the paper is performed.
[0095]
On the other hand, if the specific symbol detection unit 23 determines that the input image data includes a specific symbol, the input image data is image data related to a confidential document or the like for which copying is prohibited. In the same manner as in the first embodiment, 26 temporarily stops the copying operation, reads out the stored image data from the page buffer 29, inputs it to the code decoding unit 24, and is input in the code decoding unit 24 Perform decryption processing of the two-dimensional array code, extract confidential level information from the input decrypted data, perform processing according to the confidential level, extract the IP address of the print server included in the decrypted data, The decrypted data and the user are transmitted to the print server 73 specified by the IP address via the network interface 28 and the network 75. To send a D. Based on the transmitted data, the print server 73 records the document ID, the date of printing (copying), the IP address of the multifunction device (client) that has transmitted, and the user name transmitted from the multifunction device as a history in a log file. To do.
[0096]
As described above, in the first and second embodiments, the copier side indicates that the copy forgery prevention image combined with the document image prohibited from copying is a confidential document prohibited from copying. The copy prohibition information is embedded as a machine readable code (two-dimensional array code) that can be read by the copying machine, together with a specific symbol for recognition in (1).
[0097]
In the first and second embodiments, when a document image combined with the copy forgery prevention image is copied on the multifunction peripheral, the specific symbol is detected simultaneously with the reading of the image information, and the specific symbol is detected. Since the copy control is performed by decrypting the two-dimensional array code only in the case of copying, unauthorized copying can be prevented without degrading the copy efficiency when copying a normal document image. At the same time, since it is possible to determine whether or not the document is to be subjected to copy control based on both the specific symbol and the decoded data of the machine-readable code, unauthorized copying can be prevented more reliably.
[0098]
In addition, the specific symbol and the machine-readable code are embedded as a constituent element of the copy forgery prevention image and synthesized with the document image. However, the copy forgery prevention image has a uniform light gray background on the printed matter. In addition, the position where the machine-readable code is embedded is unknown, and it is difficult to perform an illegal act such as deleting a specific symbol or the machine-readable code, and the image quality of the document image such as readability of the document on a printed matter may be impaired. Absent.
[0099]
In addition, for each document image, when a password is embedded as a machine-readable code that can be read by the copying machine in the copy forgery prevention image, whether or not the password entered by the user matches the embedded password, Different copying operations can be performed.
[0100]
In addition, the specific symbol and machine-readable code embedded in the document image are reproduced when copied normally by a copying machine, so even if it is copied illegally, it is copied from the specific symbol reproduced on the copy. Is revealed to be a prohibited confidential document, and the outflow path of the print output from the machine readable code reproduced in the copy can be easily traced.
[0101]
In addition, a document image with a copy-forgery-prevention image combined with it will cause warning characters, etc., embedded as a latent image to emerge when it is illegally copied with a copying machine. In addition to being suppressed, it is possible to distinguish between the original and the compound by the image that appears.
[0102]
In addition, since machine-readable codes that have been error-corrected encoded are used and many machine-readable codes are repeatedly arranged on the entire screen, some machine-readable codes are lost by embedding latent images or synthesizing them with document images. However, the embedded information can be accurately decoded.
[0103]
(Third embodiment)
The image processing system according to the third embodiment embeds a specific symbol for recognizing on the copier side that a confidential document is prohibited from being copied as a latent image, and has 1 dot as a fine pattern inside the latent image. A pattern image composed of an isolated dot pattern in which dots of a size are randomly arranged and a halftone dot pattern of about 45 degrees and 50 lines is used as a background fine pattern. The copier side detects this specific symbol, and when a specific symbol is detected, it is the same as the first embodiment except that the copying operation is unconditionally stopped. Will be omitted, and only the differences will be described.
[0104]
FIG. 12 shows an example of a pattern image used in the present embodiment. FIG. 12A shows the entire pattern image printed out. The document image data is a binary image of 1 bit / pixel. The area of the “confidential” symbol in FIG. 12A is a latent image portion that emerges when copied by a copying machine, and the surrounding area is a background portion. In this figure, the “confidential” symbol can be identified, but the density of the latent image portion (black pixel area per unit area) is the same as the density of the background portion. The “secret” symbol is difficult to identify.
[0105]
FIG. 12C is an image obtained by enlarging the area (E) surrounded by the square in FIG. The interior of the latent image portion is composed of small dot patterns arranged relatively densely, and this pattern has a characteristic that is difficult to reproduce when copied by a copying machine. On the other hand, the background portion is composed of a large dot pattern arranged relatively coarsely, and this pattern has a characteristic that is reproduced when copied by a copying machine. For this reason, when the pattern image shown in FIG. 12A is copied by a copying machine, the background portion is copied at a high density, and the image is lost inside the latent image portion. As shown in FIG. A white “secret” symbol appears in the object. The inside of the latent image portion may be constituted by a large dot pattern arranged relatively coarsely, and the background portion may be constituted by a small dot pattern arranged relatively densely.
[0106]
As shown in FIG. 13, the multi-function device of this embodiment is different from the first embodiment in that it does not include a code decoding unit. Other configurations are the same as the configuration of the MFP according to the first embodiment shown in FIG.
[0107]
Next, the copying operation of the printed document image will be described. First, the image input unit 20 reads a document to which a pattern image shown in FIG. 12A is added, and the read image data is input. The input image data is temporarily stored in the page buffer 29 and input to the specific symbol detector 23. The specific symbol detection unit 23 performs a specific symbol detection process and determines whether or not a specific symbol is included. Then, the determination result is output to the control unit 26.
[0108]
Here, a method for determining a specific symbol in the present embodiment will be described. In this embodiment, regardless of the orientation of the original including the specific symbol, the orientation of the original is determined so that it can be accurately determined whether or not the input image data includes the specific symbol. The characteristic value and the degree of coincidence that are almost independent are used. The characteristic values to be used are the total number of on pixels and the total number of on / off inversions in a circle area set in advance according to a specific symbol, and the first circumference set in advance according to the specific symbol. The total number of on pixels and the total number of on / off inversions are four. The degree of coincidence used is calculated based on the image pattern (one-dimensional pattern) on the second circumference set in advance according to the specific symbol and the normal pattern set in advance according to the specific symbol. Is obtained. In the present embodiment, the result of comparing each characteristic value and the allowable range of each characteristic value set according to the specific symbol, and the result of comparing the degree of coincidence and a predetermined allowable range, Since the specific symbol is detected on the basis of this, the specific symbol can be detected with high accuracy almost without depending on the orientation of the document.
[0109]
It should be noted that the first circumference and the second circumference do not need to coincide with each other, but are preferably different. On “total number of pixels” refers to the number of on-pixels in the area, and “on / off inversion total number” refers to pixels that change from on to off or off to on in the area in the main and sub-scanning directions. Number (number of times). Further, the “circle region” is a region surrounded by a circle having a specific diameter with the center position of the specific symbol determined from the size of the specific symbol to be detected, the reading resolution of the document, and the like. The “specific diameter” is desirably set to the minimum length that allows the specific symbol to be accommodated in the circular area, from the viewpoint of suppressing an increase in memory capacity and processing amount.
[0110]
Further, “on the first circumference” is an area through which the circumference of the circle having the first radius passes, and the “first radius” satisfies the following relationship.
(First radius) x 2 <(specific diameter)
Further, the center point and the first radius of the first circumference are set so that the first circumference passes through a portion that clearly represents the characteristics of the specific symbol. The relationship and setting policy described above are the same for the center point of the second circumference and the second radius.
[0111]
The configuration and operation of the specific symbol detection unit 23 that detects the characteristic values, calculates the degree of coincidence, and detects a specific symbol using them will be described with reference to FIG. As already described, in the present embodiment, the “confidential” symbol in the pattern image illustrated in FIG. 12 is a specific symbol to be detected.
[0112]
As shown in FIG. 6, noise is removed from the image data input to the specific symbol detection unit 23 by a noise removal circuit 31. Here, the noise is an image other than the halftone dot pattern constituting the two-dimensional array code. For example, characters, figures, photographs, etc. constituting the document image are removed as noise. Specifically, the isolated dot pattern and the image having a size (number of connected pixels) larger than the halftone dot pattern are removed. Thereby, the occurrence probability of erroneous determination is reduced. The image data from which noise has been removed by the noise removal circuit 31 is temporarily stored in the first buffer memory 32.
[0113]
Next, the image data stored in the first buffer memory 32 is read out and input to the reduction circuit 33 for reduction processing. Here, the reduction ratio is set to 1 / half the dot pattern interval. For example, when the resolution of the input image is 400 dpi and the dot-dot pattern interval is 0.5 mm (8 pixels at 400 dpi), the reduction ratio is set to 1/8, that is, 12.5%. By this reduction processing, in the area where the halftone dot pattern exists, the black pixels are connected vertically and horizontally, and only the part where the halftone dot pattern does not exist is whitened out. From the image shown in FIG. "Only the symbol portion is white and the image is substantially black. The image data reduced by the reduction circuit 33 is temporarily stored in the second buffer memory 34.
[0114]
The image data stored in the second buffer memory 34 includes a circular area on-pixel total number detection circuit 35, a circular area on / off inversion total number detection circuit 36, a first on-circumference on-pixel total number detection circuit 37, a first Are input to the on-circumference on-off inversion total number detection circuit 38 and the second on-circumference data coincidence calculation circuit 39, the respective characteristic values are detected / calculated.
[0115]
That is, every time the circular area is moved, the circle area ON pixel total number detection circuit 35 detects the number of ON pixels in the circle area, and the circle area ON / OFF inversion number detection circuit 36 detects the number of ON pixels in the circle area. Each time is moved, the number of pixels that change from on to off and from off to on in the circular area in both the main and sub scanning directions is detected. The first on-circumference on-pixel total number detection circuit 37 detects the number of on-pixels on the first circumference having the first radius each time the circular area is moved, and on the first circumference The on / off inversion total number detection circuit 38 detects the on / off inversion total number in the circumferential direction on the first circumference every time the circular area is moved.
[0116]
The detection method of each characteristic value by these circuits 35-38 is arbitrary. For example, in the circle-area on-pixel total number detection circuit 25, the detection result immediately before moving the circle area in the main scanning direction (or sub-scanning direction) is held, and the circle area is moved in the main scanning direction (or sub-scanning direction). The detection result may be obtained based on the pixel newly entered into the circle area when moved to the pixel, the pixel that has moved out of the circle area, and the immediately preceding detection result. Each time the area is moved, all pixels in the circular area may be examined to obtain a detection result.
[0117]
The second on-circumference data coincidence detection circuit 39 performs a calculation based on the image pattern and the normal pattern on the second circumference having the second radius with the center point of the specific symbol as the center. Thus, the degree of coincidence between the image to be scanned and the specific symbol is calculated.
[0118]
Each of the characteristic values detected / calculated by the circuits 35 to 39 is input to the determination circuit 40, and is compared with the characteristic value of a specific symbol registered in advance in the determination circuit 40 to determine whether or not the specific symbol is included. Is determined.
[0119]
If the specific symbol detection unit 23 determines that the input image data does not include the specific symbol, the control unit 26 determines that the input image data is not image data related to confidential documents that are prohibited from being copied. The copying operation is continued as it is. That is, the image data stored in the page buffer 29 is read out and input to the image processing unit 21. The image processing unit 21 performs image processing for reproduction reproduction such as gradation processing and outputs the image data to the image output unit 22. Thus, image formation on the paper is performed.
[0120]
On the other hand, if the specific symbol detection unit 23 determines that the input image data includes a specific symbol, the input image data is image data related to a confidential document or the like for which copying is prohibited. 26 displays on the control panel 27 that the document is prohibited from being copied, and stops the copying operation. As a result, if the read original contains a specific symbol, copying is unconditionally prohibited.
[0121]
As described above, in the third embodiment, the copying machine recognizes that a copy-forgery-prevented image combined with a copy-prohibited document image is a confidential document that is prohibited from being copied. A specific symbol is embedded. In the third embodiment, when a document image combined with this copy forgery prevention image is copied on the multifunction peripheral, the specific symbol is detected simultaneously with the reading of the image information, and the specific symbol is detected. Since copying is prohibited, unauthorized copying can be prevented without reducing the copying efficiency when copying a normal document image.
[0122]
In addition, the specific symbol is embedded as a component of the copy forgery prevention image and synthesized with the document image. However, the copy forgery prevention image has a uniform and light gray background on the printed matter, so the specific symbol is embedded. The position is unknown, it is difficult to perform an illegal act such as deleting a specific symbol, and the image quality of the document image such as the readability of the document on the printed matter is not impaired.
[0123]
In addition, if a document image composed of a copy-forgery prevention image is illegally copied with a copying machine, a specific symbol embedded as a latent image will appear. At the same time, even if an illegal copy is made, the original and the copy can be distinguished from the specific symbol reproduced on the copy.
[0124]
In the first to third embodiments, illegal copying is performed by stopping the copying operation when it is determined to be a confidential document, or by performing a normal copying operation when a predetermined password is not input. Although an example of preventing unauthorized use has been described, a black solid image may be formed on a sheet in the same case.
[0125]
In the first and second embodiments described above, an example in which a user ID and a password are input from the control panel when copying a confidential document has been described. The user ID and password recorded on the card may be read.
[0126]
In the first and second embodiments, the print server newly issues a document ID upon reprinting and records the PDL data storage address corresponding to the new document ID in the log file. The PDL data storage address corresponding to the document ID may be recorded in the log file.
[0127]
In the first and second embodiments, the case where the print output operation and the copy operation are performed by the same apparatus has been described. However, a system configuration in which a plurality of printers and multi-function peripherals are connected is used. The output operation and the copy operation can be performed by different apparatuses.
[0128]
In the first and second embodiments, the example in which the specific symbol indicating that the document is a confidential document prohibited from copying is different from the shape of the fine pattern of the background portion representing the two-dimensional array code has been described. Both may have the same shape. In this case, the specific symbol detection unit 23 shown in FIG. 11 detects a specific pattern using the pattern detection circuit 42 shown in FIG. 7 instead of the circle pattern detection circuit 53, and counts the detected number by the count circuit 54. Based on the result, the determination circuit 55 determines whether the confidential document is prohibited from being copied.
[0129]
In the third embodiment, the latent image portion and the background portion are each composed of a dot pattern. However, instead of the relatively coarsely arranged large dot pattern constituting the background portion, the minute circle pattern shown in FIG. 10 is used. It can also be used. In this case, the specific symbol is detected when the number of specific circle patterns is detected by template matching and the number of detected specific circle patterns exceeds a preset threshold value, as in the second embodiment. It is determined that a specific symbol has been detected. Accordingly, the shape of the latent image can be set to an arbitrary shape.
[0130]
The specific symbol may be embedded as a latent image as in the first and third embodiments, or may be embedded as a fine pattern in the background portion as in the second embodiment. The specific symbol extraction method can be changed according to the form of the specific symbol as described below.
[0131]
(1) A pixel block having a specific size is extracted as a specific symbol.
For example, if the outermost periphery of the N × N window centered on the target pixel is not all white pixels, it is deleted as too small, and the outermost periphery of the M × M window centered on the target pixel is deleted. Are not black pixels, they are deleted as being too large (N <M). In this way, a pixel block having a specific size can be extracted as a specific symbol. Alternatively, the area of the pixel block may be obtained by labeling, and pixels with a label of a predetermined number or more may be deleted.
[0132]
(2) A pixel block having a specific shape is extracted as a specific symbol by pattern matching.
For example, when extracting the minute circle pattern shown in FIG. 10, the pattern shown in FIG. 10 is applied to the target pixel, and each pixel around the target pixel is black at the position of the black pixel in FIG. The number of whites at the position of 10 white pixels is counted, and a circle pattern can be extracted as a specific symbol as long as it is a predetermined number or more. Note that even a diagonal pattern can be extracted in the same manner as a circular pattern.
[0133]
(3) Pixels having a predetermined number of lines are extracted as specific symbols.
For example, if the latent image / background pattern to be extracted is repeated at a predetermined interval and the background pattern is a 45 degree 50 line halftone dot pattern, a halftone dot region extraction process around 50 lines is performed, Extract only pixels.
[0134]
【The invention's effect】
The image processing apparatus of the present invention Image data for forming an image that can prevent the illegal copying of specific document images that cannot be illegally copied without compromising image forming efficiency, and that it is difficult to delete the constituent elements and that it is difficult to perform an illegal act. The effect is that it can be synthesized. In addition, the image forming apparatus of the present invention has an effect that it is possible to reliably prevent unauthorized copying of a specific document image in which unauthorized copying is prohibited without impairing image forming efficiency.
[Brief description of the drawings]
FIG. 1 is a configuration diagram illustrating a configuration of an image processing system according to a first embodiment.
FIG. 2 is a block diagram illustrating a configuration of an image processing apparatus of the image processing system according to the first embodiment.
FIGS. 3A to 3C are diagrams showing three types of dot patterns stored in a pattern storage unit. FIGS.
4A is a conceptual diagram showing an example of a document image printed out in the first embodiment, and FIG. 4B is a conceptual diagram showing an image when (A) is copied by a copying machine. (C) is the elements on larger scale of (A).
FIG. 5 is a block diagram illustrating a configuration of a multifunction peripheral of the image processing system according to the first embodiment.
FIG. 6 is a block diagram illustrating a configuration of a specific symbol detection unit of the multifunction machine according to the first embodiment.
FIG. 7 is a block diagram illustrating a configuration of a code decoding unit of the multifunction machine according to the first embodiment.
FIG. 8 is a diagram illustrating an example of a log file in which a print history is recorded.
9A is a conceptual diagram showing an example of a document image printed out in the second embodiment, and FIG. 9B is a conceptual diagram showing an image when (A) is copied by a copying machine. , (C) and (D) are partially enlarged views of (A).
FIG. 10 is a diagram showing a fourth pattern stored in the pattern storage unit.
FIG. 11 is a block diagram illustrating a configuration of a specific symbol detection unit of the multifunction machine according to the second embodiment.
12A is a conceptual diagram showing an example of a document image printed out in the third embodiment, and FIG. 12B is a conceptual diagram showing an image when (A) is copied by a copying machine. (C) is the elements on larger scale of (A).
FIG. 13 is a block diagram illustrating a configuration of a multifunction peripheral of an image processing system according to a third embodiment.
[Explanation of symbols]
1 Print data input section
2 Document image generator
3 Document image buffer
4 Additional information extraction unit
5 Latent image generator
6 Additional information encoding unit
7 Pattern storage
8 Pattern image generator
9 Pattern image buffer
10 Image composition part
11 Image output unit
20 Image input section
21 Image processing unit
22 Image output unit
23 Specific symbol detector
24 Code decoding unit
25 Image generator
26 Control unit
27 Control panel
28 Network interface
29 page buffer
71, 72 Client device
73 Print server
74 Printer
75 network

Claims (12)

  1. Data input means for inputting document data to which predetermined information is added;
    When the predetermined information includes specific information indicating that the specific document data is prohibited from unauthorized copying, a specific symbol indicating specific document data is generated based on the specific information, and the predetermined information Encode at least a portion to generate a machine-readable code, and have the specific symbol and the machine-readable code in a part of a background image in which a latent image is embedded and constitute either the latent image portion or the background portion Generating means for generating image data having a fine pattern as a machine-readable code;
    A synthesis means for synthesizing the generated image data and the specific document data;
    An image processing apparatus.
  2. Data input means for inputting document data to which predetermined information is added;
    When the predetermined information includes specific information indicating that the specific document data is prohibited from unauthorized copying, a specific symbol indicating specific document data is generated based on the specific information, and the predetermined information A machine-readable code is generated by encoding at least a part, and the specific symbol is embedded as a latent image in a part of a background image, and a fine pattern constituting either the latent image part or the background part of the background image Generating means for generating image data to be machine-readable code;
    A synthesis means for synthesizing the generated image data and the specific document data;
    An image processing apparatus.
  3. Data input means for inputting document data to which predetermined information is added;
    When the predetermined information includes specific information indicating that the specific document data is prohibited from unauthorized copying, a specific symbol indicating specific document data is generated based on the specific information, and the predetermined information Encoding at least a part to generate a machine-readable code so that the specific symbol is included in a background part of a background image in which a latent image is embedded, and a fine pattern constituting the background part is a machine-readable code Generating means for generating image data;
    A synthesis means for synthesizing the generated image data and the specific document data;
    An image processing apparatus.
  4. The image processing apparatus according to claim 3, wherein the specific symbol is represented by a fine pattern other than the machine-readable code constituting the background portion .
  5.   5. The background image in which the latent image is embedded, the latent image portion and the background portion have substantially the same density, and one of the latent image portion and the background portion is reproduced and the other is not reproduced. The image processing apparatus according to claim 1.
  6.   The image processing apparatus according to claim 1, wherein the machine-readable code represents copy prohibition information for prohibiting illegal copying.
  7.   The predetermined information to be encoded includes information for identifying the image processing apparatus in which the image is generated, information for identifying the specific document data, information regarding the date and time when the image was generated, and the confidential level of the specific document data. The image processing apparatus according to claim 2, wherein the image processing apparatus is at least one of information, information related to access qualification for specific document data, and information for identifying a source of the specific document data.
  8. Image reading means for reading a specific document image obtained by combining an image having a specific symbol representing machine specific document data and a machine readable code as a part of a background image embedded with a latent image;
    Detection means for detecting a specific symbol based on the read image;
    Decoding means for decoding the machine-readable code based on the read image when a specific symbol is detected by the detection means;
    An image forming apparatus including:
  9. Image reading means for reading a specific document image obtained by combining an image having a specific symbol representing machine specific document data and a machine readable code as a part of a background image embedded with a latent image;
    Detection means for detecting a specific symbol based on the read image;
    Decoding means for decoding the machine-readable code based on the read image when a specific symbol is detected by the detection means;
    When the information decoded by the decoding means represents copy prohibition information, control means for controlling the image output to be prohibited or controlling the image quality of the output image to deteriorate;
    An image forming apparatus including:
  10. Image reading means for reading a specific document image obtained by combining an image having a specific symbol representing machine specific document data and a machine readable code as a part of a background image embedded with a latent image;
    Detection means for detecting a specific symbol based on the read image;
    Decoding means for decoding the machine-readable code based on the read image when a specific symbol is detected by the detection means;
    An authentication information input means for inputting authentication information;
    Even when the information decrypted by the decryption means represents copy prohibition information, when authentication is obtained by the authentication information input means, a high-quality image is output and authentication is not obtained. Control means for controlling image output to be prohibited in the case, or controlling the image quality of the output image to deteriorate,
    An image forming apparatus including:
  11. An image processing system in which a client apparatus, a print server, and an image forming apparatus are connected via a network,
    A client device for transmitting document data to the print server;
    A data receiving unit that receives the document data via the network, an information extracting unit that extracts specific information indicating that the illegal copying is prohibited from predetermined information added to the document data ; A specific symbol representing the specific document data is generated based on the extracted specific information, and at least a part of the predetermined information is encoded to generate a machine-readable code. The specific symbol and the machine-readable Image data generating means for generating image data having a code as a part of a background image in which a latent image is embedded and using a fine pattern constituting either the latent image portion or the background portion as a machine readable code said image processing unit comprising a synthesizing means for synthesizing the image data and the said specific document data, synthesized data via the network A data transmission unit that transmits to the image forming apparatus, and a data storage unit that stores the document data received by the data reception unit and the specific information extracted by the information extraction unit as print history information. Server,
    An image forming apparatus including: a data receiving unit that receives print data via the network; and a print function unit that forms an image based on the print data received via the network;
    An image processing system comprising:
  12. The image forming apparatus includes an image reading unit for reading an image, a symbol detector for detecting the specific symbol from the read image, when the specific symbol is detected by the symbol detection unit, wherein the read image Machine A code decoding unit that decodes the readable code; a composite data transmission unit that transmits the decoded decoded data to the print server ; and a copy function unit that forms an image based on the read image ;
    The image processing system according to claim 11, wherein the print server stores the decoded data received from the image forming apparatus as copy history information in the data storage unit .
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