JP4551391B2 - Image forming apparatus and digital watermark determination method - Google Patents

Description

  The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus capable of detecting digital watermark data.

  At the time of output, in addition to the original image (original image) to be output, copy prohibition information indicating copy prohibition is output (printed) on paper as a digital watermark, and the copy prohibition information is detected when copying the printed matter. A system for stopping notification or copying is disclosed (Patent Document 1).

In the above patent document, the entire image is temporarily stored in an image memory at the time of copying, and a digital watermark is detected.
JP 2001-215852 A

  However, in order to detect the digital watermark mixed in the printed document image, it is necessary to temporarily store the entire document in the image memory as described above and detect the presence or absence of the digital watermark. Also, the digital watermark detection process requires a certain amount of time due to the complexity of the process. For this reason, if a general manuscript that does not include an electronic watermark is also subjected to detection processing, it takes a long time to copy, which is an obstacle to high-speed copying. Note that dedicated hardware is required to increase the detection speed of the digital watermark, and the cost of the image forming apparatus cannot be avoided.

  The present invention has been made in view of the above-described problems in the prior art, and prevents an increase in image processing cost while preventing a decrease in speed when copying a general document that does not include a digital watermark. The object is to provide a generation device or the like.

To achieve the above object, an image forming apparatus provided by the present invention, a document, together with the read sequentially over the loading completion area from the read start region constituting the document, and a document reading means for sequentially electronic data, the without waiting for electronic data to the read termination area of the electronic data generated by the document reading unit, with the electronic data corresponding to the already read start region generated, first detection for detecting a predetermined dot pattern means and, if the predetermined dot pattern has been detected by the first detecting means, and output stop means for stopping the output to the outside of the image forming apparatus of the electronic data by the output means, the predetermined by the first detection means If the dot pattern is detected, test for all electronic data of a document including the detected start reading regions of watermarking A second detecting means for performing, when the electronic watermark by the second detection means is not detected, when to release the output stop of the output means by the output stop means, the digital watermark is detected, Output control means for not releasing the output stop .

According to the above, a predetermined dot pattern is detected for the electronic data corresponding to the read start area that has already been generated without waiting for the electronic data to be generated until the read end area of the generated electronic data, and according to the result Since the output to the outside is stopped, it is not necessary to detect the presence or absence of the digital watermark for all the electronic data for all the originals. Therefore, it is possible to prevent a decrease in speed when copying a general original that does not include the digital watermark. . In addition, since only the reading start area is checked without waiting for digitization until the reading end area, the reading is completed for a relatively long time from completion of reading of the reading start area to completion of reading of the reading end area. The start area can be checked. For this reason, the first detection means does not require, for example, a high-speed device (chip or the like) that leads to increased cost. Naturally, since the second detection means checks only a document that is suspected of containing a digital watermark, a high-speed device that leads to an increase in hardware cost is also unnecessary. The output to the outside of the image forming apparatus is a transfer output of electronic data to paper, a fax transmission of electronic data, or a transmission of electronic data to another network terminal. Further, the detection of the predetermined dot pattern by the first detection means is performed by determining whether or not there is a dot of a predetermined size in the electronic data corresponding to the reading start area, and the dot position rule in the electronic data corresponding to the reading start area. Including at least one of sex. In addition, the original is sequentially read from the reading start area to the reading end area constituting the original, and the original reading step for sequentially converting to electronic data and the conversion to electronic data up to the reading end area of the generated electronic data are awaited. In addition, a first detection step for detecting a predetermined dot pattern for electronic data corresponding to a read start area that has already been generated, and image formation of electronic data by the output step when the predetermined dot pattern is detected An output stop step for stopping output to the outside of the apparatus, and a second detection for detecting digital watermark for all electronic data of the document including the detected reading start area when the predetermined dot pattern is detected And when the digital watermark is not detected, the output stop step It cancels the output stop of the force means, in the case where the electronic watermark is detected, it is possible to provide an electronic watermark determination method and an output control step that does not release the output stop.

  By adopting the above configuration, it is possible to provide an image generation apparatus or the like that prevents a reduction in speed when copying a general document that does not include a digital watermark, and avoids an increase in image processing cost.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings for understanding of the present invention. The following embodiment is an example embodying the present invention, and does not limit the technical scope of the present invention.

  The image forming apparatus according to the present invention corresponds to, for example, a printer alone or a multi-function machine equipped with a printer, a copy, a fax, and the like.

  As an example, the operation of the image forming apparatus when copying using a multifunction machine will be briefly described.

  When a user prints a document on a transfer medium such as printing paper using a multifunction machine, the document is placed on the document table 103 or the table 105 shown in FIG. 1 and is placed on an operation panel provided near the document table. A print instruction is issued to the user. When the instruction is given, printing is performed by the operation of each driving unit described below.

  That is, as shown in FIG. 1, the image forming apparatus 100 according to the present embodiment includes a main body 101 and a platen cover 102 attached above the main body 101. A document table 103 is provided on the upper surface of the main body 101, and the document table 103 is opened and closed by a platen cover 102. The platen cover 102 is provided with an automatic document feeder 104, a placing table 105, and a sheet discharging table 109.

  The automatic document feeder 104 includes a document conveyance path 108 formed inside the platen cover 102, a pickup roller 106 and a conveyance roller 107 provided inside the platen cover 102, and the like. The document conveyance path 108 is a document conveyance path that leads from the placement table 105 to the sheet discharge table 109 via a reading position P where reading is performed by the reading unit 110 provided in the main body 101.

  The automatic document feeder 104 pulls out each document placed on the table 105 to the inside of the transport path 108 by the pickup roller 107, and discharges the document pulled out by the transport roller 106 and the like through the reading position P. The paper is discharged onto the table 109. When the document passes the reading position P, the document is read by the reading unit 110.

  The reading unit 110 is provided below the document table 103. The reading unit 110 includes a light source 111 that illuminates the document table 103 in the main scanning direction, mirrors 112, 113, and 114 that guide light from the document table, and an image sensor 115 that images light guided by the mirror. Has been.

  When the automatic document feeder 104 conveys a document, the light source 111 moves to a position where the reading position P can be irradiated and emits light. Light from the light source 111 is reflected by a document that passes through the document table 103 and passes through the reading position P, and is guided to the image sensor 115 by mirrors 112, 113, and 114. The image sensor 115 captures received light to generate image data of the original.

  The reading unit 110 can read not only the document conveyed by the automatic document feeder 104 but also the document placed on the document table 103. When reading a document placed on the document table 103, the reading unit 110 moves the light source 111 in the sub-scanning direction while emitting light, and irradiates the entire document table 103. In order to guide the reflected light from the document table 103 to the image sensor 115, the mirror 112 moves together with the light source 111, and in order to make the optical path length from the light source 111 to the image sensor 115 constant, the mirrors 113 and 114 include the light source 111 and The mirror 112 moves at half the speed.

  The image sensor 115 reads the image data of the document placed on the document table 103 based on the light guided to the mirrors 112, 113, 114, as in the case of the document conveyed to the automatic document feeder 104. Generate.

  A printing unit 120 that prints image data is provided below the reading unit 110 of the main body 101. Image data that can be printed by the printing unit 120 is generated by the image sensor 115 as described above, or transmitted from a terminal such as a personal computer connected to the image forming apparatus 100 and a network such as a LAN. is there.

  As a printing method performed by the printing unit 120, for example, an electrophotographic method is used. That is, the photosensitive drum 121 is uniformly charged by the charger 122, and then the photosensitive drum 121 is irradiated by the laser 123 to form a latent image on the photosensitive drum 121, and toner is attached to the latent image by the developing device 124. Printing is performed by forming a visual image and transferring the visible image onto a sheet by the transfer roller 125.

  The paper on which the visible image is printed is placed on a paper feed tray such as the manual feed tray 131 and the paper feed cassettes 132, 133, and 134.

  When performing printing, the printing unit 120 pulls out one sheet of printing paper from any one of the paper feed trays using the pickup roller 135, and transfers the drawn printing paper to the photosensitive drum 121 by the transport roller 137 or the registration roller 138. Feed between rollers 125.

  When the visible image is transferred to the printing paper fed between the photosensitive drum 121 and the transfer roller 125, the printing unit 120 sends the printing paper to the fixing device 127 by the conveyor belt 126 in order to fix the visible image. The fixing device 127 includes a heating roller 128 with a built-in heater and a pressure roller 129 pressed against the heating roller 128 with a predetermined pressure. When the printing paper passes between the heating roller 128 and the pressure roller 129, the visible image is fixed on the paper by heat and pressing force on the printing paper. The printing unit 120 discharges the printing paper that has passed through the fixing device 127 to the paper discharge tray 130.

  The basic copy processing in the image forming apparatus 100 has been described above.

  The image forming apparatus 100 includes a CPU (Central Processing Unit) 201, a RAM (Random Access Memory) 202, a ROM (Read Only Memory) 203, an HDD (Hard Disk Drive), as shown in the schematic configuration diagram of FIG. 204 and a driver 205 corresponding to each drive unit in the printing process are connected via an internal bus 206. The CPU 201 uses, for example, the RAM 202 as a work area, executes a program stored in the ROM 203, the HDD 204, and the like, and exchanges data and commands with the driver 205 based on the execution result, as shown in FIG. The operation of each driving unit is controlled.

  Next, details of the image forming apparatus 100 according to the present invention will be described with reference to FIGS. 1 and 3 to 8. For the sake of understanding, the case of reading a document placed on the document table 103 will be described. However, the processing for the generated electronic data is the same even when the document placed on the automatic document feeder 104 is processed. It is.

  FIG. 3 is a schematic functional block diagram of the image forming apparatus 100, and FIG. 4 is a schematic top view of the image forming apparatus. FIG. 4 shows a view from above of the image forming apparatus 100 in a state where the platen cover 102 is omitted.

  Now, based on the above configuration, processing when the image forming apparatus 100 reads a document will be described.

  When the original is read by the image forming apparatus 100, the original reading surface is arranged to face the contact glass 401 of the mounting table 103. At this time, the original is placed so that the corner of the original coincides with the reference point 404 defined by the original placement plate 402 which is a convex portion with respect to the contact glass 401. When the reading process is started after the original is placed and the platen cover 102 is attached to the upper part of the original (the state shown in FIG. 1), the reading unit 110, that is, the moving carriage 405 moves below the scanning line including the reference point 404.

  Subsequently, the light source 111 on the movable carriage 405 irradiates the original with light from the irradiation surface direction which is the lower surface of the contact glass 401. The irradiated light is reflected on the reading surface of the document according to its density, and is reflected by the mirror 112 provided in the reading unit 110 via the slit 406.

  The light reflected by the mirror 112 is sequentially reflected by the reflection mirrors 113 and 114, so that the optical path is changed and received by the image sensor 115.

  When the reflected light of the document is received by the image sensor 115, the image sensor 115 converts the received light into an electrical signal to digitize, for example, an image for one line in the scanning direction of the document. That is, the moving carriage 405, the mirror 112, the reflection mirrors 113 and 114, and the image sensor 115 constitute the document reading unit 301 in FIG.

  The moving carriage 405 moves in the sub-scanning direction, and sequentially converts the light received sequentially based on the movement, so that one original is moved from the reading start area 501 to the reading end area 502 shown in FIG. Read sequentially. Finally, the entire surface from the reading start area 501 to the reading end area 502 through the second area,..., The nth area is converted into electronic data and acquired. The acquired electronic data is stored in the storage means 302 sequentially.

  Here, the partial electronic data corresponding to the reading start area 501 that are read and generated as the moving carriage 405 moves are sequentially transmitted to the first detecting means 303 (FIG. 6: S601).

  Next, the first detection means that has received the partial electronic data corresponding to the reading start area 501 among the partial electronic data does not wait for the electronic data up to the reading end area 502 and waits for the reading start area 501. A predetermined dot pattern is detected for the electronic data corresponding to (FIG. 6: S602). Note that “without waiting for conversion to electronic data up to the reading end area 502” means that, for example, when the reading of the reading start area 501 is completed or the reading of the second area continuous to the reading start area 501 is performed. This includes the time of transfer.

  The predetermined dot pattern is detected as follows. That is, FIG. 7 is a partially enlarged view 703 of a reading start area 501 having a width of 10 mm in the sub-scanning direction from a reading start line 702 parallel to the scanning direction on the document 701.

  The first detection unit 303 determines the presence / absence of dots of a predetermined size and / or regularity of dot positions in the reading start area 501. Here, the presence / absence of a dot of a predetermined size is detection of the presence of a point composed of, for example, 1 × 1 dot. Further, the regularity of the dot positions can be rephrased as periodicity. For example, the partial electronic data corresponding to the reading start area 501 is subjected to, for example, a smoothing filter such as a Gaussian filter process, and the density after the process It is possible to determine the presence or absence of regularity by calculating the magnitude of the variation.

  In this example, first, it matches the predetermined dot pattern as described above, that is, for example, it is constituted by 1 × 1 dot in the partial electronic data corresponding to the reading start area 501 by determining whether or not there is a dot of a predetermined size. It is determined that no isolated point exists. This is because each dot constituting a digital watermark usually does not use 1 × 1 dots, but increases, for example, 3 × 3 dots (for example, point 704 shown in FIG. 7) as one minimum in order to increase the tolerance of the information. It uses the characteristics of units. On the contrary, error diffusion for expressing the density of the image is classified into FM screen, and an isolated point (for example, a point 801 shown in FIG. 8B) composed of 1 × 1 dots for expressing the density of the image by the number of dots. ) Exists. Therefore, by determining (detecting) the presence of an isolated point composed of 1 × 1 dots, it is determined whether it is a part of a normal image (for example, FIG. 8B) or a digital watermark.

  If the dot position regularity is a halftone image having no regularity, the first detection unit 303 determines that the read start area 501 is likely to be a part of a digital watermark. To do. This is because a plurality of dots constituting a digital watermark, that is, a dot pattern, repeats a dot pattern obtained by encrypting information stored in a digital watermark in an area of, for example, 20 mm × 20 mm. The feature that it does not become a repetitive pattern is used. That is, if there is no repeating pattern in a size smaller than the size constituting one digital watermark (tile), it can be determined that there is a possibility of a digital watermark. It can be determined as a halftone screen.

  Further, when the above does not match the predetermined dot pattern, that is, for example, there is no dot in the area (FIG. 8A) or there is an isolated point composed of 1 × 1 dots (FIG. 8B), The first detection unit 303 determines that the reading start area 501 is not part of the digital watermark.

Here, the first detection means, when the electronic data reading start area 501 is judged not a part of the digital watermark detection electronic watermark in the electronic data the second detecting means 306 to be described later without being out is subjected to output of printing are stored conventionally storage unit 302 (FIG. 6: S603NO → S604 → S611) .

  On the other hand, if the first detection unit determines that there is a high possibility that the electronic data in the reading start area 501 is a part of the digital watermark, the output detection unit 304, the warning transmission unit 308, and the second detection unit 306 are notified. Notify that.

Output stop means 304 which has received the above effect is to stop the output to the image forming apparatus outside the electronic data, output means 305 by the driver, and transmits a signal to the driving unit, the outside of the image forming apparatus The output of the electronic data is stopped (FIG. 6: S603 YES → S605). Here, the output to the outside of the image forming apparatus corresponds to transfer output of electronic data to paper, fax transmission of electronic data, transmission of electronic data to another network terminal, or the like.

  In response to the above, the warning transmission means 308 sends a message to the operation panel, for example, to check the digital watermark such as “There is a possibility that the document is a security document. Security check will be performed.” Output (FIG. 6: S606).

  Further, the second detection unit 306 that has received the above-mentioned information waits until all the electronic data for one document is stored in the storage unit 302 by the document reading unit 301. For all electronic data, the presence or absence of a digital watermark is detected (FIG. 6: S607), and if there is a digital watermark, the information stored in the digital watermark is extracted (FIG. 6: S608).

Here, when the second detection unit 306 does not detect the digital watermark, the fact is transmitted to the warning transmission unit 308 and the output control unit 307 (FIG. 6: S607 NO → S610). The same applies to the case where the stored information is not information that prohibits output to the outside even when a digital watermark is detected (FIG. 6: S609 NO → S610). Output control means 307 which has received the effect sends an instruction to cancel the output stop against output means 305 (FIG. 6: S610). Also, the warning transmission means 308 that has received the above message outputs a message to the effect that the electronic watermark is not present or that output is not prohibited, and the electronic data is printed as in the case where there is no electronic watermark. And output to the outside of the apparatus such as transmission (FIG. 6: S611).

When the second detection unit 306 detects a digital watermark, or when the second detection unit 306 detects the digital watermark, and the stored information is information that prohibits output to the outside, a warning transmission unit 308 is notified to that effect. And it transmits to the output control means 307 (FIG. 6: S609 YES). Output control means 307 which has received the effect will not release the output stop for output means 305. Further, the warning transmission means 308 that has received the above message outputs a message to the effect that the output is prohibited by the digital watermark, and transmits an e-mail message to that effect to the administrator as needed (FIG. 6: S609 YES → S612).

  As described above, the first detection unit does not wait for the generation of electronic data up to the reading end area of the generated electronic data, and generates a predetermined dot pattern for the electronic data corresponding to the already generated reading start area. Detect and stop the output to the outside according to the result. As a result, it is only necessary to check only the reading start area of the original, that is, it is not necessary to detect the presence or absence of the electronic watermark of all the electronic data for all the originals. Can be prevented.

  In addition, since only the reading start area is checked without waiting for digitization until the reading end area, the reading is completed for a relatively long time from completion of reading of the reading start area to completion of reading of the reading end area. Since the start area can be checked, the first detection means does not require, for example, a high-speed device (such as a chip) that leads to increased cost. Naturally, since the second detection means checks only a document that is suspected of containing a digital watermark, a high-speed device that leads to an increase in hardware cost is also unnecessary.

  In the above-described embodiment, the present invention is applied to a multifunction machine, but the present invention is not limited to this. The present invention can be applied to an image forming apparatus such as a copying machine, a facsimile, or a printer, or an image forming apparatus such as a scanner. Furthermore, the present invention can be applied to an image forming apparatus including an information processing apparatus such as a personal computer and a scanner. For example, the present invention can be applied to an image processing program such as a printer driver, a printer server program, or a scanner control driver that operates on a computer.

  According to the image forming apparatus or the like according to the present invention, since the presence of a digital watermark can be determined at high speed, it is possible to prevent a decrease in speed when copying a general document that does not include a digital watermark and to avoid an increase in image processing cost. It is useful as a simple image forming apparatus.

1 is a schematic configuration diagram of a multifunction peripheral according to an image forming apparatus of the present invention. 1 is a block diagram illustrating a mechanical configuration of an image forming apparatus. 1 is a schematic functional block diagram of an image forming apparatus. FIG. 3 is a top view of a document placement table of the image forming apparatus. The figure which shows each area | region which comprises a document. 6 is a flowchart showing processing of the image forming apparatus. The elements on larger scale of the reading start area. The figure which shows an example of a reading start area | region.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Image forming apparatus 301 Document reading means 302 Storage means 303 First detection means 304 Output stop means 305 Output means 306 Second detection means 307 Output control means 308 Warning transmission means

Claims (4)

Document reading means for sequentially reading a document from a reading start area to a reading end area constituting the document, and sequentially converting the document into electronic data;
Without waiting for electronic data to the read termination area of the electronic data generated by said original reading means, with the electronic data corresponding to the read start region already generated, first detecting the predetermined dot pattern Detection means;
An output stopping means for stopping the output of the electronic data by the output means to the outside of the image forming apparatus when a predetermined dot pattern is detected by the first detecting means;
Second detection means for detecting a digital watermark for all electronic data of a document including the detected reading start area when a predetermined dot pattern is detected by the first detection means;
Output control that releases the output stop of the output means by the output stop means when the digital watermark by the second detection means is not detected, and does not release the output stop when the digital watermark is detected Means,
An image forming apparatus.   The image forming apparatus according to claim 1, wherein the output to the outside of the image forming apparatus is transfer output of electronic data to paper, fax transmission of electronic data, or transmission of electronic data to another network terminal. The detection of the predetermined dot pattern by the first detection means is
2. The image forming apparatus according to claim 1, comprising at least one of presence / absence of a dot of a predetermined size in electronic data corresponding to the reading start area and regularity of dot positions in electronic data corresponding to the reading start area. . A document reading step for sequentially reading a document from a reading start area to a reading end area constituting the document and sequentially converting the document into electronic data;
Without waiting for electronic data to the read termination area of the electronic data generated, with the electronic data corresponding to the read start region already generated, a first detection step of detecting a predetermined dot pattern,
An output stop step for stopping output of electronic data to the outside of the image forming apparatus by the output step when the predetermined dot pattern is detected;
A second detection step of detecting a digital watermark for all electronic data of the document including the detected reading start area when the predetermined dot pattern is detected;
When the digital watermark is not detected, cancel the output stop of the output means by the output stop step, and when the digital watermark is detected, an output control step that does not cancel the output stop;
An electronic watermark determination method comprising:

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