JP2010193326A - Image processing apparatus, two-dimensional code superimposing method, and computer program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To embed a two-dimensional code like a security code into the image of a document more appropriately as compared with the prior arts. <P>SOLUTION: In an image forming apparatus 1 including a CPU 1a, a document reader 1j2 and an image forming section 1h1, following processing is executed. The document reader 1j2 reads an image representing a document. The CPU 1a performs processing for superposing a two-dimensional code on ruled lines included in the read image. The image forming section 1h1 then prints an image on which the two-dimensional code has been superposed on a paper sheet. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an apparatus and method for embedding a two-dimensional code such as a security code in an image of a document.

  2. Description of the Related Art In recent years, image forming apparatuses called “multifunction peripherals” or “MFPs (Multi Function Peripherals)” that integrate various functions such as copying, scanning, faxing, network printing, and document servers have become widespread.

  Further, an image forming apparatus having a function for restricting document distribution has been proposed. When the image forming apparatus described in Patent Document 1 receives FAX image data, the image forming apparatus checks whether a security code is superimposed on the image data. If it is superimposed, the security code content is retained and the superimposed security code is erased from the image. A high-resolution security code having the same information as the stored security code is generated. The FAX image is converted into a high resolution image. Then, the FAX image converted to high resolution and the high resolution security code are synthesized and printed.

  An apparatus described in Patent Document 2 is a scanner that reads a recording paper document in which code information is written and converts it into an image file, or a communication unit that receives an image file of a recording paper document in which code information is written; A pattern search is performed on the file, code information detection means for detecting code information together with the position of the file, information extraction means for extracting character information from the detected code information, and new code information based on the character information. File storage means for generating and saving a print file from the image file by processing to generate an image and incorporate it into the arrangement position;

JP 2007-251548 A JP 2007-306228 A

  As described above, a method for managing the security of a document by embedding an image called a “security code” in the document has been proposed, but the position where the security code is embedded is important in order to increase the certainty of reading the security code. .

  Therefore, as described in paragraph 0031 of Patent Document 1, a security code may be repeatedly embedded in the entire document. Alternatively, in order to suppress the embedding redundancy while maintaining the reading reliability as much as possible, the lightness Y is obtained based on the values of R (red), G (Green), and B (Blue) colors of the document. The security code may be embedded only in the condition where Y is compared with the threshold value Th and Y> Th.

  However, it is required to suppress the redundancy of embedding while further increasing the certainty of reading than before.

  Further, when the security code is deleted from the document, the image quality may be deteriorated by the conventional embedding method.

  SUMMARY OF THE INVENTION In view of such problems, the present invention has an object to embed a two-dimensional code such as a security code in an image of an original more preferably than in the past.

  An image processing apparatus according to an aspect of the present invention includes an image acquisition unit that acquires an image representing a document, a two-dimensional code superimposing unit that superimposes a two-dimensional code on a ruled line included in the image, and the two-dimensional code Image output means for outputting the superimposed images.

  Preferably, password input means for allowing a user to input a first password, password determination means for determining a second password indicated in the two-dimensional code included in the acquired image, and the input first And an authentication unit that performs authentication based on the determined password and the determined second password, and the image output unit outputs the image by printing on a sheet when the authentication is successful .

  Alternatively, when the image includes a plurality of ruled lines, the two-dimensional code superimposing means preferentially superimposes the two-dimensional code on a ruled line having a high gradation.

  Alternatively, when the image includes a vertical ruled line and a horizontal ruled line, the two-dimensional code superimposing means preferentially places the two-dimensional code on a ruled line having a higher aspect ratio when printed on paper. Overlapping.

  Alternatively, the two-dimensional code superimposing unit preferentially superimposes the two-dimensional code on a thick ruled line when the image includes a plurality of ruled lines.

  According to the present invention, it is possible to embed a two-dimensional code such as a security code in an image of a document more suitably than in the past.

It is a figure which shows the example of a structure of the network system which has an image forming apparatus. 1 is a diagram illustrating an example of an overall hardware configuration of an image forming apparatus. 2 is a diagram illustrating an example of a hardware configuration related to a copy function of an image forming apparatus. FIG. It is a figure which shows the example of a manuscript image. 2 is a diagram illustrating an example of a functional configuration of an image forming apparatus. FIG. It is a figure which shows the example of a pattern image. It is a figure which shows the example of the original image containing three ruled lines from which thickness differs. It is a figure which shows the example of the original image containing three ruled lines from which density differs. It is a figure which shows the example of the original image containing the some ruled line which cross | intersects. It is a figure which shows the example of an ideal printed matter, and the example of the printed matter distorted in each of the main scanning direction and the subscanning direction. It is a figure which shows the example of the superimposition of the pattern image on the ruled line contained in a document image. 6 is a flowchart illustrating an example of the overall processing flow of the image forming apparatus. 6 is a flowchart illustrating an example of the overall processing flow of the image forming apparatus.

  1 is a diagram showing an example of the configuration of a network system having an image forming apparatus 1, FIG. 2 is a diagram showing an example of the overall hardware configuration of the image forming apparatus 1, and FIG. FIG. 4 is a diagram illustrating an example of the hardware configuration, FIG. 4 is a diagram illustrating an example of the document image G0, and FIG. 5 is a diagram illustrating an example of a functional configuration of the image forming apparatus 1.

  An image forming apparatus 1 illustrated in FIG. 1 is an apparatus in which various functions such as a copy, a scanner, a fax, and a document server are integrated. Sometimes called a multi-function peripheral or MFP (Multi Function Peripherals).

  The “document server” provides a storage area corresponding to a folder or directory in a personal computer, which is called “box” or “personal box” for each user, and the user stores sentences, mathematical formulas, This function allows image data for reproducing symbols, photographs, charts, illustrations, etc. to be saved. Sometimes called “box function”.

  Further, the image forming apparatus 1 is provided with a security function that restricts copying of a document (document). An image representing a password is embedded in advance in a part of the image of the document. The user must input this password to the operation panel in order to copy this document. This security function will be described in detail later.

  As shown in FIG. 2, the image forming apparatus 1 includes a central processing unit (CPU) 1a, a random access memory (RAM) 1b, a read only memory (ROM) 1c, a hard disk 1d, a control circuit 1e, an operation panel 1f, communication The interface unit 1g, the printing unit 1h, the scanner unit 1j, and the facsimile unit 1k are configured.

  The communication interface unit 1g is a NIC (Network Interface Card) for communicating with other devices (for example, the personal computer 2 shown in FIG. 1) using a protocol such as TCP / IP (Transmission Control Protocol / Internet Protocol).

  The facsimile unit 1k transmits the image data obtained by the scanner unit 1j or receives image data transmitted from another fax terminal via the public switched telephone network in accordance with the facsimile standard. A modem or the like is used as the facsimile unit 1k.

  The operation panel 1f is provided with a key 1f1, a touch panel 1f2, and the like, and the user inputs data or commands to the image forming apparatus 1 using them. Various screens are displayed on the touch panel 1f2.

  The scanner unit 1j includes an automatic document feeder 1j1, a document reader 1j2, and the like (see FIG. 3). The scanner unit 1j optically reads an image such as a photograph, a character, a picture, or a chart on a sheet. Generate data.

  The printing unit 1h includes an image forming unit 1h1, an automatic duplex unit 1h2, a paper feeding device 1h3, a paper feeding cabinet 1h4, and the like (see FIG. 3). From the image data obtained by the scanner unit 1j or other devices. An image is printed on paper based on the transmitted image data.

  For example, a tandem laser printer is used as the image forming unit 1h1. Here, with reference to FIG. 3, a copy operation when a tandem laser printer is used will be described.

  The automatic document feeder 1j1 automatically conveys a plurality of documents set on a document feed tray one by one to a predetermined document reading position set on the platen glass of the document reading device 1j2. The automatic document feeder 1j1 has a document setting sensor 1j11 for detecting that a document sheet is set. When the document setting sensor 1j1 detects that a document is set, it sends a signal indicating the result to the CPU 1a.

  The original reading device 1j2 scans the original surface of the paper according to the size of the conveyed paper and converts the incident light into an electric signal, thereby converting the raw data (Raw) of the image written on the original surface of the paper. Data). After the reading, the sheet is discharged onto a document discharge tray. Hereinafter, an image read by the document reading device 1j2 is referred to as “document image G0”. In the present embodiment, an original image G0 including ruled lines is handled as shown in FIG.

  The document reading device 1j2 includes a device lifting sensor 1j21, detects that the automatic document feeder 1j1 is lifted, and sends a signal indicating the result to the CPU 1a. A magnetic sensor is used as the device lifting sensor 1j21.

  The CPU 1a performs various image processing such as shading correction on the document image G0. Then, the document image G0 subjected to the image processing is read for each main scanning line in synchronization with the supply of the copy destination paper, and a signal for driving the laser diode is output to the printing unit 1h.

  The image forming unit 1h1 of the printing unit 1h includes photosensitive drums 31c, 31m, 31y, and 31k for cyan (C), magenta (M), yellow (Y), and black (K) and exposure scanning units 32c and 32m. 32y, 32k, a transfer belt 33, a front door sensor 34, a front door cover for protecting them, and the like.

  Laser light generated by each of the exposure scanning units 32c, 32m, 32y, and 32k based on the signal output from the CPU 1a is exposed and scanned onto the photosensitive drums 31c, 31m, 31y, and 31k.

  The front door sensor 34 includes a known tact switch, detects that the front door cover has been opened, and sends a signal indicating the result to the CPU 1a.

  The transfer belt 33 sequentially superimposes the toner images on the photosensitive drums 31c, 31m, 31y, and 31k corresponding to the colors C, M, Y, and K, and transfers them onto the sheet conveyed from the sheet feeding device 1h3. To do.

  The sheet feeding device 1h3 includes sheet feeding cassettes 1h31 and 1h33 for storing sheets and pickup rollers 1h32 and 1h34 for feeding out the sheets, and supplies the sheets to the image forming unit 1h1.

  Similarly to the paper feeding device 1h3, the paper feeding cabinet 1h4 includes paper feeding cassettes 1h41 and 1h43 for storing paper and pickup rollers 1h42 and 1h44 for feeding out these papers, and passes through the paper feeding device 1h3. Then, the sheet is supplied to the image forming unit 1h1.

  The automatic duplex unit 1h2 enables double-sided printing by temporarily switching back on the sheet passing path and feeding it again in order to reverse the paper on which one side is printed.

  In addition, the image forming apparatus 1 is provided with a sub power switch 1m and the like for the user to directly instruct the transition to the sleep mode that is the power saving operation mode.

  In the hard disk 1d or ROM 1c, a ruled line containing document discriminating unit 101, a document data buffer 102, a ruled line information detecting unit 103, a pattern image detecting unit 104, a pattern image analyzing unit 105, a password issuing unit 106, and new document data registration shown in FIG. Processing unit 107, password acquisition unit 108, authentication processing unit 109, password update unit 121, ruled line processing unit 122, pattern image generation unit 123, embedding position determination unit 124, image composition unit 125, vertical / horizontal flatness detection unit 131, document A program and data for realizing the data storage unit 141, the aspect ratio storage unit 142, and the like are stored. These programs and data are loaded into the RAM 1b as necessary, and the programs are executed by the CPU 1a. The functions of these units may be realized only by hardware such as the control circuit 10e. Next, each part of the image forming apparatus 1 shown in FIG.

  6 is a diagram showing an example of a pattern image G1, FIG. 7 is a diagram showing an example of a document image G0 including three ruled lines G2a to G2c having different thicknesses, and FIG. 8 is three ruled lines G2d to G2f having different densities. FIG. 9 is a diagram illustrating an example of a document image G0 including a plurality of intersecting ruled lines, and FIG. 10 is an example of an ideal printed material and is distorted in each of the main scanning direction and the sub-scanning direction. FIG. 11 is a diagram showing an example of superposition of the pattern image G1 on the ruled line included in the document image G0.

  The user sets a paper sheet to be copied on the paper feed tray of the scanner unit 1j, and presses a copy start button. Then, the document is scanned by the document reading device 1j2, and image data DT0 that is raw data of the document image G0 is obtained.

  The ruled line containing document discriminating unit 101 discriminates whether or not a ruled line is included in the document image G0 based on the obtained image data DT0. That is, the ruled line is detected. At this time, the ruled line-containing document determination unit 101 also determines the position of the ruled line in the document image G0.

  The document data buffer 102 temporarily stores the image data DT0 of the document image G0 when the document image G0 includes a ruled line and the ruled line-containing document determining unit 101 determines that the ruled line is included.

  The ruled line information detection unit 103 detects the size (thickness and length) of the ruled line included in the document image G0 and the gray scale gradation (hereinafter referred to as “density”). The thickness and length are represented by the number of dots.

  The pattern image detection unit 104 detects the pattern image G1 from the ruled lines. A “pattern image” is a two-dimensional code composed of a large number of dots (dots). An image with a black dot on a white background as shown in FIG. 6A or an image with a white dot on a black background as shown in FIG. 6B may be used. Alternatively, two-dimensional codes of various standards may be used as the pattern image G1.

  The pattern image analysis unit 105 analyzes information indicated by the pattern image G1 detected by the pattern image detection unit 104. As described above, a password may be embedded in the document image G0 in order to realize a security function. Therefore, in this embodiment, the password indicated by the pattern image G1 is analyzed.

  As a result of the analysis, if it is found that the pattern image G1 indicating the password is not included in the document image G0, the document image G0 is handled as a new document. Specifically, the following processing is performed by the password issuing unit 106 and the new document data registration processing unit 107.

  The password issuing unit 106 issues a unique password of a character string having a predetermined length and displays it on the touch panel 1f2 of the operation panel 1f. The password can be issued by generating a random number. The user must input this password the next time he or she copies a copy of the original document. That is, copying is restricted. Therefore, the user must remember this password. The mechanism of copy restriction will be described later.

  The new document data registration processing unit 107 stores the image data DT0 stored in the document data buffer 102 in the document data storage unit 141 in association with the password issued by the password issuing unit 106.

  In this manner, the document data storage unit 141 stores the image data DT0 of the document whose copy is to be restricted.

  On the other hand, if it is found as a result of analysis by the pattern image analysis unit 105 that the pattern image G1 indicating the password is included in the document image G0, the copy of the document image G0 is restricted. is there. Therefore, the following processing is performed by the password acquisition unit 108 or the image composition unit 125.

  The password acquisition unit 108 displays a password input screen on the touch panel 1f2 of the operation panel 1f and prompts the user to input the password. Then, the password input by the user is acquired.

  The authentication processing unit 109 verifies whether or not the user has the authority to copy by comparing the password analyzed by the pattern image analysis unit 105 with the password acquired by the password acquisition unit 108. That is, it is determined whether or not copying of the document image G0 is permitted. If both passwords match, copy is permitted, and if they do not match, copy is rejected.

  By the way, when copying the document image G0, the old pattern image G1 is deleted, and instead, a pattern image G1 indicating another new password is embedded.

  Therefore, the password update unit 121 issues another new password. Then, the image data DT0 associated with the password input by the user, that is, the old password is searched from the document data storage unit 141, and the password associated with the image data DT0 is replaced with the issued password. Further, the issued password is displayed on the touch panel 1f2 of the operation panel 1f to notify the user.

  The ruled line processing unit 122 performs a ruled line processing process in order to delete the pattern image G1 from the read document image G0. Specifically, when the pattern image G1 is a pattern image of white dots on a black background as shown in FIG. 6A, the portion where the pattern image G1 is arranged is erased. That is, all the pixels in that portion are made white. On the other hand, when the pattern image G1 is a pattern image of black dots on a white background as shown in FIG. 6B, the portion where the pattern image G1 is arranged is filled. That is, all the pixels in that portion are made black. When the target ruled line is gray, its density (gradation) is detected and painted with the gray color of that density.

  The pattern image generation unit 123 newly generates a pattern image G1 indicating the password newly issued by the password update unit 121.

  The embedding position determination unit 124 determines which ruled line included in the document image G0 the newly generated pattern image G1 is embedded in. That is, the position where the pattern image G1 is embedded is determined. Here, an example of a method for determining an embedding position will be described.

  As shown in FIG. 7, when three ruled lines G2a, G2b, and G2c having different thicknesses are included in the document image G0, it is determined to embed them in the thickest ruled line (that is, ruled line G2a).

  Alternatively, as shown in FIG. 8, when three ruled lines G2d, G2e, and G2f having different densities are included in the document image G0, it is determined to be embedded in the ruled line with the highest density (that is, ruled line G2d).

  Alternatively, as shown in FIG. 9, it is determined to embed on a ruled line around a predetermined distance (position surrounded by a two-dot chain line) from a position where a plurality of ruled lines intersect (position surrounded by a dotted line).

  Alternatively, when a vertical ruled line and a horizontal ruled line are printed by the printing unit 1h, a flattening rate (change rate) of the thickness with respect to the ideally printed ruled line is obtained, and the flattening rate is larger (that is, the thicker one) ) May be determined to be embedded in the ruled line.

  For example, as shown in FIG. 10 (a), a ruled line G2g is formed as a ruled line as shown in FIG. 10 (b) on a copy of an original image G0 including a vertical ruled line G2g and a horizontal ruled line G2h having the same thickness. When printing is finer than G2h, that is, when the flatness ratio of the ruled line G2h is higher than the flatness ratio of the ruled line G2g, it is determined to embed in the ruled line G2h.

  The flatness is determined by printing vertical and horizontal ruled lines having a predetermined thickness W0 on a sheet, scanning the sheet, measuring the thicknesses W1 and W2 of the respective ruled lines, and measuring the thicknesses W1 and W2 with respect to the thickness W0. It can be obtained by calculating the rate of change. This process is performed by the aspect ratio detecting unit 131. Each flatness is stored in the vertical / horizontal flatness storage unit 142. The flatness may be recalculated periodically.

  Returning to FIG. 5, the image composition unit 125 superimposes the new pattern image G <b> 1 generated by the pattern image generation unit 123 on the document image G <b> 0 processed by the ruled line processing unit 122. At this time, the image is superimposed on the position determined by the embedding position determination unit 124. Further, when the pattern image G1 is an image in which a black dot is formed on a white background, the pattern image G1 is superimposed as shown in FIG. 11A. When the pattern image G1 is an image in which a white dot is applied on a black background, the pattern image G1 is superimposed as shown in FIG. Match. In this way, the pattern image G1 is embedded in the document image G0.

  If the new pattern image G1 is a pattern image consisting of black dots on a white background and is arranged at a position different from the previous one, the previous position portion of the ruled line G2 is restored.

  Further, when the image data DT0 of the document image G0 is stored in the document data storage unit 141, by using the stored image data DT0 instead of the image data DT0 obtained by performing the current scan, Superposition processing may be performed. As a result, it is possible to prevent image deterioration due to repeated copying. When the stored image data DT0 is used, the processing by the ruled line processing unit 122 is not necessary.

  The document image G0 combined with the pattern image G1 by the image combining unit 125 is printed on a sheet by the printing unit 1h. Thereby, a copy of the original image G0 in which the new password is embedded is completed.

  12 and 13 are flowcharts illustrating an example of the overall processing flow of the image forming apparatus 1.

  Next, the flow of processing of the image forming apparatus 1 when copying the document image G0 will be described with reference to the flowcharts of FIGS.

  The image forming apparatus 1 reads the document image G0 from the paper set on the document feed tray (# 11 in FIG. 12), and tries to detect a ruled line included in the document image G0 (# 12).

  If the ruled line can be detected (Yes in # 13), the image forming apparatus 1 detects information such as the size and density of the ruled line (# 14). Further, it tries to detect the pattern image G1 included in the ruled line (# 15).

  If the pattern image G1 cannot be detected (No in # 16), a unique password is issued (# 17), and the original image data DT0 of the read original image G0 is associated with the issued password and saved as original data. Is stored in the unit 141 (# 18).

  On the other hand, if the pattern image G1 can be detected (Yes in # 16), the password shown in the pattern image G1 is analyzed (# 19), and a screen requesting input of the password is displayed (# 20). Authentication is performed by comparing the password shown in the pattern image G1 with the input password (# 21). If they match, that is, if the authentication is successful (Yes in # 22), a new unique password is newly created. Issue (# 23). Then, the image data DT0 associated with the password input by the user, that is, the old password is searched from the document data storage unit 141, and the password associated with the image data DT0 is replaced with the issued password (# 24). ).

  The password issued in step # 17 or # 23 is displayed on the touch panel 1f2 of the operation panel 1f to notify the user (# 25 in FIG. 13).

  A processing for deleting the pattern image G1 from the ruled line included in the read document image G0 is performed as necessary (# 26).

  A pattern image G1 indicating the password issued in step # 17 or # 23 is generated (# 27), and a position where the pattern image G1 is embedded is determined (# 28).

  Then, the generated pattern image G1 is superimposed on the original document image G0 processed as necessary (# 29) and printed on paper (# 30). Note that the original image G0 of the image data DT0 stored in the original data storage unit 141 may be superimposed. In this case, the image data DT0 corresponding to the password acquired in step # 20 is called from the document data storage unit 141 and used.

  According to this embodiment, the pattern image G1 can be embedded in the document image G0 more suitably than in the past.

  In the present embodiment, the pattern image G1 indicating the password is embedded in the document image G0. However, the pattern image G1 indicating other information may be embedded. Alternatively, a plurality of pattern images G1 may be embedded. When embedding a plurality of pattern images G1, it is preferable to embed a pattern image G1 indicating important information in a ruled line that is easily detected.

  For example, the pattern image G1a indicating a password, the pattern image G1b indicating the number of copies to be copied, and the pattern image G1c indicating the number of copies to be copied (that is, the number of generations) are converted into the three pattern images G1 shown in FIG. It is assumed that it is embedded in the image G0. The password, the number of copies, and the number of generations are assumed to have the highest importance in this order. In such a case, the image forming apparatus 1 superimposes the pattern image G1a on the ruled line G2a, superimposes the pattern image G1b on the ruled line G2b, and superimposes the pattern image G1c on the ruled line G2c. In addition, when the pattern image G1 indicating information input or edited by the user through the operation panel 1f is superimposed, the importance of the information and other information is appropriately compared, and the position of the pattern image G1 indicating the information is determined. Just decide.

  In addition, the configuration of the entire image forming apparatus 1 or each unit, processing contents, processing sequence, and the like can be appropriately changed in accordance with the spirit of the present invention.

1 Image forming device (image processing device)
105 Pattern image analysis unit (password discrimination means)
108 Password acquisition unit (password input means)
109 Authentication processing unit (authentication means)
125 Image composition unit (two-dimensional code superimposing means)
1f Operation panel (password input means)
1h Printing unit (image output means)
1j Scanner unit (image acquisition means)
G0 Document image G1 Pattern image (two-dimensional code)

Claims (8)

Image acquisition means for acquiring an image representing a document;
Two-dimensional code superimposing means for superimposing a two-dimensional code on a ruled line included in the image;
Image output means for outputting the image on which the two-dimensional code is superimposed;
An image processing apparatus comprising: A password input means for allowing the user to input a first password;
Password discrimination means for discriminating a second password shown in the two-dimensional code included in the acquired image;
Authentication means for performing authentication based on the input first password and the determined second password, and
The image output means outputs the image by printing on paper when the authentication is successful.
The image processing apparatus according to claim 1. The two-dimensional code superimposing means preferentially superimposes the two-dimensional code on a ruled line having a high gradation when the image includes a plurality of ruled lines.
The image processing apparatus according to claim 1. The two-dimensional code superimposing means preferentially superimposes the two-dimensional code on a ruled line having a higher aspect ratio when printed on paper when the image includes a vertical ruled line and a horizontal ruled line,
The image processing apparatus according to claim 1. The two-dimensional code superimposing means preferentially superimposes the two-dimensional code on a thick ruled line when the image includes a plurality of ruled lines.
The image processing apparatus according to claim 1. When the image includes a plurality of ruled lines, the two-dimensional code superimposing means preferentially superimposes the two-dimensional code at a position away from an intersection of the plurality of ruled lines by a predetermined distance.
The image processing apparatus according to claim 1. A two-dimensional code superimposing method for superimposing a two-dimensional code on an image representing a document,
Superimposing the two-dimensional code on a ruled line included in the image;
A two-dimensional code superimposing method characterized by the above. A computer program used in an image processing apparatus for inputting and outputting images,
In the image processing apparatus,
Processing to obtain an image representing the document;
A process of superimposing a two-dimensional code on a ruled line included in the image;
And outputting the image on which the two-dimensional code is superimposed.
A computer program characterized by the above.

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