JP2008310027A - Image forming apparatus, image forming method, recording medium, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: In which paper an error has occurred when an error (registration failure, verification error, etc.) occurs when registration, verification and deletion of a plurality of paper fingerprints are performed using an ADF (Auto Document Feeder). It was difficult to identify.
An ADF discharge surface is switched according to the result of registration, verification, and deletion of a paper fingerprint.
[Selection] FIG.

Description

  The present invention relates to an image processing apparatus capable of handling paper fingerprint information (hereinafter, paper fingerprint information is also referred to as a paper print), a control method for the image processing apparatus, a program, and a storage medium.

  As one of document forgery prevention techniques, there is a technique called paper fingerprinting, which is a technique for preventing forgery by reading paper fibers and using the fiber pattern as the paper ID from the viewpoint of low cost. See, for example, US Pat.

Further, as a means for guaranteeing the original by paper fingerprint, there is a technique for encoding the read paper fingerprint data into a two-dimensional code image or bar code image and printing the code data on the paper.
JP 2004-151833 A

  Regarding the paper fingerprint described above, it is conceivable to register, collate and delete a paper fingerprint using a plurality of papers using an ADF (Auto Document Feeder). Here, when an error (registration failure, verification error, etc.) has occurred, it is difficult to identify which paper the error has occurred. For example, when a plurality of sheets having the same printing contents are handled at the same time, it is difficult for the user to determine only by notifying the error contents. (For example, 100 sheets of the same printed content are collated and an error occurs on the 50th sheet).

  In addition, it is conceivable that when the error occurs, the paper conveyance is stopped and the user takes the paper, but depending on the document reading method, it may not be possible.

  In order to solve the above problems, the present invention provides the following image forming apparatus and the like.

An image forming apparatus according to the present invention includes a document conveying unit that sequentially feeds and conveys documents one by one from a bundle of documents stacked on a document tray,
Reading means for reading an image on the document conveyed by the document conveying means;
Extraction means for extracting feature data from the image data read by the reading means;
Encoding means for converting the feature data into code data;
Storage means for storing the code data;
Comparison means for comparing the code data read by the reading means with the coat data stored in the storage means;
According to the present invention, there is provided a paper discharge means for switching the paper discharge surface between the case where the judgment result of the comparison means is successful and the case where the result is failure.

  The image forming apparatus of the present invention is characterized in that the feature data is paper fingerprint data.

  The image forming apparatus according to the present invention further includes a paper discharge control unit that does not discharge paper until the determination result of the determination unit notifies the determination result to the paper discharge surface control unit that switches the paper discharge surface.

  The present invention can improve the visibility of a user when an error occurs in each operation during registration, verification, and deletion of a paper fingerprint.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

<Printing system (Fig. 1)>
Next, Example 1 will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a printing system according to an embodiment of the present invention. In this system, the host computer 40 and the three image forming apparatuses (10, 20, 30) are connected to the LAN 50. However, in the printing system according to the present invention, the number of connections is not limited. In this embodiment, LAN is applied as a connection method, but the present invention is not limited to this. For example, an arbitrary network such as a WAN (public line), a serial transmission method such as USB, and a parallel transmission method such as Centronics and SCSI can be applied.

  A host computer (hereinafter referred to as a PC) 40 has a function of a personal computer. The PC 40 can send and receive files and send and receive e-mails using the FTP and SMB protocols via the LAN 50 and WAN. Further, it is possible to issue a print command from the PC 40 to the image forming apparatuses 10, 20, and 30 via a printer driver.

  The image forming apparatuses 10 and 20 are apparatuses having the same configuration. The image forming apparatus 30 is an image forming apparatus having only a print function, and does not have the scanner unit included in the image forming apparatuses 10 and 20. In the following, for the sake of simplicity of explanation, the configuration will be described in detail focusing on the image forming apparatus 10 of the image forming apparatuses 10 and 20.

  The image forming apparatus 10 includes a scanner unit 13 that is an image input device, a printer unit 14 that is an image output device, a controller 11 that controls operation of the entire image forming apparatus 10, and an operation unit 12 that is a user interface (UI). The

<Image Forming Apparatus 10 (FIG. 2)>
An appearance of the image forming apparatus 10 is shown in FIG. The scanner unit 13 has a plurality of CCDs. If the sensitivity of each CCD is different, it is recognized that each pixel has a different density even if the density of each pixel on the document is the same. Therefore, the scanner unit first performs exposure scanning on a white plate (uniformly white plate), converts the amount of reflected light obtained by exposure scanning into an electrical signal, and outputs the electrical signal to the controller 11. As will be described later, the shading correction unit 500 in the controller 11 recognizes the difference in sensitivity of each CCD based on the electrical signal obtained from each CCD (see FIG. 5). Then, using the recognized difference in sensitivity, the value of the electric signal obtained by scanning the image on the document is corrected. Further, when the shading correction unit 500 receives gain adjustment information from a CPU 301 in the controller 11 described later, the shading correction unit 500 performs gain adjustment according to the information. The gain adjustment is used to adjust how an electric signal value obtained by exposing and scanning a document is assigned to a luminance signal value of 0 to 255. By this gain adjustment, the value of the electrical signal obtained by exposing and scanning the document can be converted into a high luminance signal value or converted into a low luminance signal value. Next, a configuration for scanning the image on the document will be described.

  The scanner unit converts the image information into an electrical signal by inputting the reflected light obtained by exposing and scanning the image on the document to the CCD. Further, the electric signal is converted into a luminance signal composed of R, G, and B colors, and the luminance signal is output to the controller 11 as image data.

  The document is set on the tray 202 of the document feeder 201. When the user instructs to start reading from the operation unit 12, a document reading instruction is given from the controller 11 to the scanner unit 13. Upon receiving this instruction, the scanner unit 13 feeds the documents one by one from the tray 202 of the document feeder 201 and performs a document reading operation. Note that the document reading method is not an automatic feeding method by the document feeder 201, but a method of scanning the document by placing the document on a glass surface (not shown) and moving the exposure unit.

  The printer unit 14 is an image forming device that forms image data received from the controller 11 on a sheet. In this embodiment, the image forming method is an electrophotographic method using a photosensitive drum or a photosensitive belt, but the present invention is not limited to this. For example, the present invention can also be applied to an ink jet system that prints on paper by ejecting ink from a micro nozzle array. The printer unit 14 is provided with a plurality of paper cassettes 203, 204, and 205 that allow selection of different paper sizes or different paper orientations. The paper after printing is discharged to the paper discharge tray 206.

<Detailed Description of Controller 11 (FIG. 3)>
FIG. 3 is a block diagram for explaining the configuration of the controller 11 of the image forming apparatus 10 in more detail.

  The controller 11 is electrically connected to the scanner unit 13 and the printer unit 14. On the other hand, the controller 11 is connected to the PC 40 or an external device via the LAN 50 or the WAN 331. As a result, image data and device information can be input and output.

  The CPU 301 comprehensively controls access to various connected devices based on a control program stored in the ROM 303, and also performs overall control of various processes performed in the controller. A RAM 302 is a system work memory for the operation of the CPU 301 and also a memory for temporarily storing image data. The RAM 302 includes an SRAM that retains stored content even after the power is turned off, and a DRAM that erases the stored content after the power is turned off. The ROM 303 stores a boot program for the apparatus. An HDD 304 is a hard disk drive and can store system software and image data.

  The operation unit I / F 305 is an interface unit for connecting the system bus 310 and the operation unit 12. The operation unit I / F 305 receives image data to be displayed on the operation unit 12 from the system bus 310 to the operation unit 12 and outputs information input from the operation unit 12 to the system bus 310.

  A network I / F 306 is connected to the LAN 50 and the system bus 310 to input / output information. The Modem 307 is connected to the WAN 331 and the system bus 310, and inputs and outputs information. A binary image rotation unit 308 converts the direction of image data before transmission. The binary image compression / decompression unit 309 converts the resolution of the image data before transmission into a resolution that matches a predetermined resolution or the partner's ability. For compression and expansion, methods such as JBIG, MMR, MR, and MH are used. The image bus 330 is a transmission path for exchanging image data, and is configured by a PCI bus or IEEE1394.

  The scanner image processing unit 312 corrects, processes, and edits image data received from the scanner unit 13 via the scanner I / F 311. The scanner image processing unit 312 determines whether the received image data is a color document or a monochrome document, a character document, or a photographic document. Then, the determination result is attached to the image data. Such accompanying information is referred to as attribute data. Details of processing performed by the scanner image processing unit 312 will be described later.

  The compression unit 313 receives the image data and divides the image data into blocks of 32 pixels × 32 pixels. The 32 × 32 pixel image data is referred to as tile data. FIG. 4 conceptually shows this tile data. In a document (paper medium before reading), an area corresponding to the tile data is referred to as a tile image. The tile data is added with the average luminance information in the 32 × 32 pixel block and the coordinate position of the tile image on the document as header information. Further, the compression unit 313 compresses image data including a plurality of tile data. The decompression unit 316 decompresses image data composed of a plurality of tile data, raster-expands it, and sends it to the printer image processing unit 315.

  The printer image processing unit 315 receives the image data sent from the decompression unit 316 and performs image processing on the image data while referring to attribute data attached to the image data. The image data after the image processing is output to the printer unit 14 via the printer I / F 314. Details of processing performed by the printer image processing unit 315 will be described later.

  The image conversion unit 317 performs a predetermined conversion process on the image data. This processing unit is composed of the following processing units.

  A decompression unit 318 decompresses received image data. A compression unit 319 compresses the received image data. A rotation unit 320 rotates received image data. The scaling unit 321 performs resolution conversion processing (for example, 600 dpi to 200 dpi) on the received image data. The color space conversion unit 322 converts the color space of the received image data. The color space conversion unit 322 performs a known background removal process using a matrix or a table, performs a known LOG conversion process (RGB → CMY), or performs a known output color correction process (CMY → CMYK). Can be. The binary multi-value conversion unit 323 converts the received two-gradation image data into 256-gradation image data. Conversely, the multi-level binary conversion unit 324 converts the received 256-gradation image data into 2-gradation image data using a technique such as error diffusion processing.

  The synthesizer 327 synthesizes the received two pieces of image data to generate one piece of image data. When combining two pieces of image data, a method of using an average value of luminance values of pixels to be combined as a combined luminance value, or a luminance value of a pixel having a brighter luminance level, A method for obtaining a luminance value is applied. In addition, it is possible to use a method in which the darker pixel is used as a synthesized pixel. Furthermore, a method of determining a luminance value after synthesis by a logical sum operation, a logical product operation, an exclusive logical sum operation, or the like between pixels to be synthesized is also applicable. These synthesis methods are all well-known methods. The thinning unit 326 performs resolution conversion by thinning out the pixels of the received image data, and generates image data such as 1/2, 1/4, and 1/8. The moving unit 325 adds a margin part to the received image data or deletes the margin part.

  The RIP 328 receives intermediate data generated based on PDL code data transmitted from the PC 40 or the like, and generates bitmap data (multi-value).

<Detailed description of automatic document feeder>
In FIG. 10, the ADF 1000 serving as a document transport device is fed from a document stack S set on a document tray 1020 with its surface facing up to a separation unit 1002 from a top document by a pickup roller 1001. The separation unit 1002 is provided with a separation roller on the upper side and a separation pad on the lower side, and performs separation one by one from the uppermost sheet of the document bundle S.

  When reading the image on the front side with a single-sided original, the separated original is subjected to skew correction during separation and conveyance by the first registration roller 1003, and then the first registration roller 1003 to the second registration roller 1004, the first registration roller 1003. The image on the surface is read while being conveyed by the conveyance roller 1005 and being conveyed at the reading position R. When the trailing edge of the document passes the reading position R, the solenoid 1022 is pressurized to nip the document, and the document surface is directed downward onto the sheet discharge tray 1021 by the sheet discharge roller 1008 from the second transport roller 1006. It is discharged in order.

  When reading both front and back images with a double-sided document, the separated document is subjected to skew correction during separation and conveyance by the first registration roller 1003, and then the second registration roller 1004 to the first conveyance roller 1005. The image on the surface is read while being conveyed by the second conveyance roller 1006 and conveyed at the reading position R. When the reading position R passes, the solenoid 1022 is pressed to nip the document. Then, once the edge of the original is conveyed in the direction of the paper discharge tray 1021 by the paper discharge roller 1008 from the second conveyance roller and the rear edge of the original detects that the paper discharge sensor 1013 is OFF, the rear edge of the original is the paper discharge roller 1008. The conveyance is stopped in a state where it is nipped.

  Thereafter, the document is switched back and conveyed, and the skew correction is performed again by the second registration roller 1004. Then, the solenoid 1022 is released, and the second registration roller 1004, the first conveyance roller 1005, and the second conveyance roller 1006 are released. The image on the back surface is read while being conveyed again at the reading position R.

  If the document is discharged from the second conveying roller onto the paper discharge tray 1021 with the paper discharge roller 1008 facing up, the order of the surfaces set on the document tray 1020 will be different. Accordingly, the document whose back side is read is conveyed again in the direction of the sheet discharge tray 1021 by the second conveying roller 1006 and the sheet discharge roller 1008, and when the document trailing end detects that the sheet discharge sensor 1013 is OFF, The conveyance is stopped in a state where the rear end side of the document is nipped by the paper discharge roller 1008, the switchback conveyance is performed, and the paper is conveyed by the second registration roller 1004, the first conveyance roller, and the second conveyance roller, and then by the paper ejection roller 8. The sheets are sequentially discharged onto the sheet discharge tray 1021 with the surface facing down. However, even while the reading position R is being conveyed, the document image is not read during this period.

  A reader unit 1100 optically reads image information recorded on a document, photoelectrically converts it, and inputs it as image data. A scanner unit having an ADF platen 1101, a book platen 1102, a lamp 1103 and a mirror 1104. 1109, mirrors 1105 and 1106, a lens 1107, a CCD sensor 1108, and the like.

  When reading a document image conveyed from the ADF 1000, the reader unit v1100 moves the scanner unit 1109 below the ADF platen 1101, stops it, and displays image information while the document is conveyed on the reading position R. read.

  Further, when reading an image of a document placed on the book platen 1102, the scanner unit 1109 is moved in the sub-scanning direction from a document set reference (not shown) to read image information.

  For reading image information, the lamp 1103 is turned on to irradiate the original. The reflected light of the document is input to the CCD sensor 1108 via the mirrors 1104, 1105, 1106 and the lens 1107. Then, the reflected light of the document input to the CCD sensor 1108 is subjected to an electrical process such as photoelectric conversion, and is subjected to a normal digital process.

  Also, an operation unit and a display unit shown in FIG. 23 are provided, a reading operation start instruction and mode setting are performed by the operation unit, and an operation state and an alarm display are performed on the display unit.

  FIG. 11 is an explanatory diagram of an ADF drive system according to the present invention. The separation unit 1002 and the first registration roller 1003 are the separation motor M1, the second registration roller 1004, the first conveyance roller 1005, and the second conveyance roller 1006. The paper feed motor M2 paper discharge roller 1008 is driven by the paper discharge motor M3.

  The present invention can also be applied as a reading device in which the reader unit 1100 and the document conveying device are integrated.

  FIG. 12 is a control block diagram of the ADF 1000.

  A control means (hereinafter referred to as CPU) 1200, which is a central processing unit, a read only memory (hereinafter referred to as ROM) 1217, a random access memory (hereinafter referred to as RAM) 1218, an output port, and an input port are provided. The ROM 1217 stores a control program, and the RAM 1218 stores input data and work data. In addition, a separation motor M1, a paper feed motor M2, a paper discharge motor M3, a separation solenoid SL, and a paper feed clutch CL are connected to the output port. A post-separation sensor 1210, a registration sensor 1211, a lead sensor 1212, a paper discharge sensor 1213, a document detection sensor 1214, a document length detection sensor 1215, and a document width detection sensor 1216 (not shown) are connected to the input ports.

  The CPU 1200 controls the separation motor M1, the paper feed motor M2, the paper discharge motor M3, the separation solenoid SL, and the paper feed clutch CL in accordance with a control program stored in the ROM 1217 connected thereto via a bus. The CPU 1200 performs serial communication with a central processing unit (CPU) of the reader unit 1100 (not shown), and exchanges control data with the reader unit 1100. Further, a central processing unit (CPU) of the reader unit 1100 (not shown) performs serial communication with the CPU 301 of the controller unit 11 of the image forming apparatus 10 in FIG. 3 to exchange control data.

<Detailed Description of Scanner Image Processing Unit 312 (FIG. 5)>
FIG. 5 shows an internal configuration of the scanner image processing unit 312.

  The scanner image processing unit 312 receives image data composed of RGB 8-bit luminance signals.

  The shading correction unit 500 performs shading correction on the luminance signal. As described above, the shading correction is a process for preventing the brightness of the document from being erroneously recognized due to variations in CCD sensitivity. Further, as described above, the shading correction unit 500 can perform gain adjustment according to an instruction from the CPU 301.

  Subsequently, the luminance signal is converted into a standard luminance signal that does not depend on the CCD filter color by the masking processing unit 501.

  The filter processing unit 502 arbitrarily corrects the spatial frequency of the received image data. This processing unit performs arithmetic processing using, for example, a 7 × 7 matrix on the received image data. By the way, in a copying machine or a multifunction machine, a character mode, a photo mode, or a character / photo mode can be selected as a copy mode by depressing the 704 tab in FIG. When the character mode is selected by the user, the filter processing unit 502 applies a character filter to the entire image data. When the photo mode is selected, a photo filter is applied to the entire image data. When the character / photo mode is selected, the filter is adaptively switched for each pixel in accordance with a character photo determination signal (part of attribute data) described later. In other words, it is determined for each pixel whether to apply a photo filter or a character filter. Note that coefficients for smoothing only high-frequency components are set in the photographic filter. This is because the roughness of the image is not noticeable. In addition, a coefficient for performing strong edge enhancement is set in the character filter. This is to increase the sharpness of the characters.

  The histogram generation unit 503 samples the luminance data of each pixel constituting the received image data. More specifically, luminance data in a rectangular area surrounded by a start point and an end point specified in the main scanning direction and the sub scanning direction are sampled at a constant pitch in the main scanning direction and the sub scanning direction. Then, histogram data is generated based on the sampling result. The generated histogram data is used to estimate the background level when performing background removal processing. The input-side gamma correction unit 504 converts luminance data having nonlinear characteristics using a table or the like.

  A color / monochrome determination unit 505 determines whether each pixel constituting the received image data is a chromatic color or an achromatic color, and the determination result is converted into image data as a color / monochrome determination signal (part of attribute data). Accompany it.

  The character photograph determination unit 506 determines whether each pixel constituting the image data is a pixel constituting a character, a pixel constituting a halftone dot, a pixel constituting a character in a halftone dot, or a pixel constituting a solid image Is determined based on the pixel value of each pixel and the pixel values of peripheral pixels of each pixel. Note that pixels that do not correspond to any of these are pixels that form a white region. Then, the determination result is attached to the image data as a character / photo determination signal (part of the attribute data).

  The paper fingerprint information acquisition unit 507 determines an appropriate region as the paper fingerprint information acquisition region from the RGB image data input from the shading correction unit 500, and acquires the image data of the determined paper fingerprint information acquisition region. . A method for determining an appropriate area as the paper fingerprint information acquisition area will be described later with reference to FIGS.

  FIG. 8 is a flowchart showing a paper fingerprint information acquisition process performed by the paper fingerprint information acquisition unit 507.

  In step 801, the image data acquired by the paper fingerprint information acquisition unit 507 is converted into grayscale image data. In step 802, mask data for collation is created by removing the image that has been converted to grayscale image data in step 801, which may cause misjudgment such as printing or handwritten characters. The mask data is binary data of “0” or “1”. In the grayscale image data, the value of the mask data is set to “1” for a pixel whose luminance signal value is equal to or greater than the first threshold (that is, bright). Further, the mask data value is set to “0” for a pixel whose luminance signal value is less than the first threshold value. The above processing is performed on each pixel included in the grayscale image data. In step 803, two data, the image data converted to gray scale in step 801 and the mask data created in step 802, are acquired as paper fingerprint information. Note that the image data itself converted to gray scale in step 801 may be referred to as paper fingerprint information, but in the present embodiment, the above two data are referred to as paper fingerprint information.

  The paper fingerprint information acquisition unit 507 sends the paper fingerprint information in the paper fingerprint information acquisition area to the RAM 302 using a data bus (not shown).

<Detailed Description of Printer Image Processing Unit 315 (FIG. 6)>
FIG. 6 shows the flow of processing performed in the printer image processing 315.

  The background removal processing unit 601 uses the histogram generated by the scanner image processing unit 312 to remove (remove) the background color of the image data. The monochrome generation unit 602 converts color data into monochrome data. The Log conversion unit 603 performs luminance density conversion. For example, the Log conversion unit 603 converts RGB input image data into CMY image data. The output color correction unit 604 performs output color correction. For example, image data input as CMY is converted into CMYK image data using a table or matrix. The output-side gamma correction unit 605 performs correction so that the signal value input to the output-side gamma correction unit 605 is proportional to the reflection density value after copying output. A halftone correction unit 606 performs halftone processing in accordance with the number of gradations of the printer unit to be output. For example, the received high gradation image data is binarized or binarized.

  Each processing unit in the scanner image processing unit 312 or the printer image processing unit 315 can output the received image data without performing each processing. Such passing of data without performing processing in a certain processing unit will be expressed as “through the processing unit” below.

<Paper fingerprint information registration process>
The CPU 301 can read the paper fingerprint information in a predetermined area sent from the paper fingerprint information acquisition unit 507 to the RAM 302 and register the read paper fingerprint information in a server (not shown). This registration is performed by executing a program stored in the RAM 302.

<Paper fingerprint information matching process>
The CPU 301 can read out the paper fingerprint information sent from the paper fingerprint information acquisition unit 507 to the RAM 302 and perform control so as to collate the read paper fingerprint information with other paper fingerprint information. The other paper fingerprint information means paper fingerprint information registered in the server in this embodiment.

  FIG. 9 is a flowchart showing the paper fingerprint information matching process. Each step of this flowchart is centrally controlled by the CPU 301.

  In step 901, the paper fingerprint information registered in the server is extracted from the RAM 302.

  In step 902, the paper fingerprint information sent (registered) from the paper fingerprint information acquisition unit 507 is compared with the paper fingerprint information taken out in step 901 (which has just been taken out). In collation, first, misregistration correction is performed because there is a possibility that the registered paper fingerprint information and the extracted paper fingerprint information may be acquired from different positions. This misalignment correction is performed as follows.

<Position correction>
First, the error value E (i, j) of two paper fingerprint information (when the position of the two paper fingerprint information is shifted by (i, j)) is expressed by (2n−1) × ( 2m-1) is obtained.

式（１）においてα₁はステップ901で取出された（登録されていた）紙指紋情報中のマスクデータである。ｆ₁はステップ901で取出された（登録されていた）紙指紋情報中のグレイスケール画像データである。α₂はステップ902で紙指紋情報取得部５０７から送られてきた（今、取出されたばかりの）紙指紋情報中のマスクデータである。ｆ₂はステップ902で紙指紋情報取得部５０７から送られてきた（今、取出されたばかりの）紙指紋情報中のグレイスケール画像データである。

In equation (1), α ₁ is mask data in the paper fingerprint information extracted (registered) in step 901. f ₁ is gray scale image data in the paper fingerprint information extracted (registered) in step 901. α ₂ is the mask data in the paper fingerprint information sent from the paper fingerprint information acquisition unit 507 in step 902 (which has just been taken out). f ₂ is grayscale image data in the paper fingerprint information sent from the paper fingerprint information acquisition unit 507 in step 902 (which has just been taken out).

  A specific method will be described with reference to FIGS. FIG. 19 shows an image diagram of the registered paper fingerprint information and the paper fingerprint information obtained this time. Assume that each pixel is composed of horizontal n pixels and vertical m pixels.

  In the function shown in Equation (1), i and j are shifted by 1 pixel in the range of −n + 1 to n−1 and −m + 1 to m−1, respectively, and the registered paper fingerprint information and The (2n−1) × (2m−1) error values E (i, j) of the paper fingerprint information just obtained this time are obtained. That is, E (-n + 1, -m + 1) to E (n-1, m-1) are obtained.

  FIG. 20A shows an image diagram in which the upper left pixel of the registered paper fingerprint information is overlapped by the lower right pixel of the obtained paper fingerprint information. In this state, a value obtained by the function of Expression (1) is assumed to be E (−n + 1, −m + 1). FIG. 20B shows an image diagram in which the paper fingerprint information obtained this time is moved to the right by one pixel as compared with FIG. In this state, a value obtained by the function of Expression (1) is E (−n + 2, −m + 1). Similarly, calculation is performed while moving the paper fingerprint information just obtained this time. In FIG. 20C, the paper fingerprint information just obtained is moved to a position where it overlaps with the registered paper fingerprint information, thereby obtaining E (0,-(m-1)). Further, in FIG. 20D, the paper fingerprint information obtained this time is moved to the right end to obtain E (n−1, −m + 1). In this way, when shifted in the horizontal direction, i of E (i, j) is added one by one.

  Similarly, in FIG. 21A, the paper fingerprint information obtained this time by one pixel is moved downward in the vertical direction as compared with FIG. 20A, and E (−n + 1, −m + 2). Find the value of.

  Further, FIG. 21 (B) moves the paper fingerprint information obtained this time to the right end with respect to FIG. 21 (A) to obtain the value of E (n−1, −m + 2).

  FIG. 22A shows a case where the registered paper fingerprint information and the paper fingerprint information obtained this time are at the same position, and the value of E (i, j) at this time is represented as E (0,0). To do.

  Similarly, the calculation is performed while shifting the images so that each paper fingerprint information overlaps at least one pixel. Finally, E (n-1, m-1) is obtained as shown in FIG.

  In this way, a set of (2n−1) × (2m−1) error values E (i, j) is obtained.

Here, in order to consider the meaning of the expression (1), i = 0, j = 0 and α ₁ (x, y) = 1 (where x = 0 to n, y = 0 to m ) And α ₂ (x−i, y−j) = 1 (where x = 0 to n, y = 0 to m). That is, α ₁ (x, y) = 1 (where x = 0 to n, y = 0 to m) and α ₂ (x-i, y-j) = 1 (where x = 0 E (0,0) in the case of .about.n, y = 0.about.m) is obtained.

  Note that i = 0 and j = 0 indicate that the registered paper fingerprint information and the paper fingerprint information obtained this time are at the same position as shown in FIG.

Here, α ₁ (x, y) = 1 (where x = 0 to n, y = 0 to m) indicates that all pixels of the registered paper fingerprint information are bright. In other words, when the registered paper fingerprint information is acquired, it indicates that no color material such as toner or ink or dust has been placed on the paper fingerprint acquisition area.

Α ₂ (x−i, yj) = 1 (where x = 0 to n, y = 0 to m) indicates that all pixels of the paper fingerprint information acquired this time are bright. In other words, when the paper fingerprint information just acquired is acquired, it indicates that no color material such as toner or ink or dust is on the paper fingerprint acquisition area.

Thus, when α ₁ (x, y) = 1 and α ₂ (xi, y−j) = 1 hold in all pixels, equation (1) is

と表されることになる。

Will be expressed.

This {f ₁ (x, y) -f ₂ (x, y)} ² is the gray scale image data in the registered paper fingerprint information and the gray scale image data in the paper fingerprint information just extracted. The square value of the difference between Therefore, this equation (1) is the sum of the squares of the differences in each pixel between the two pieces of paper fingerprint information. That is, the more pixels f ₁ (x, y) and f ₂ (x, y) are similar, the smaller this E (0,0) will be.

What has been described above is how to obtain E (0,0), but other E (i, j) are obtained in the same manner. By the way, the more pixels f ₁ (x, y) and f ₂ (x, y) are similar, the smaller E (i, j)
If E (k, l) = min {E (i, j)}, the position when the registered paper fingerprint information was acquired and the position when the paper fingerprint information just acquired are acquired It can be seen that they were shifted from each other by k, l.

<Significance of α>
The numerator of formula (1) means the result of multiplying {f ₁ (x, y) -f ₂ (xi, yj)} ² by α ₁ and α ₂ (more precisely, Σ The total value is determined by the symbol). These α ₁ and α ₂ indicate 0 for dark pixels and 1 for light pixels.

Therefore, when one (or both) of α ₁ and α ₂ is 0, α ₁ α ₂ {f ₁ (x, y) −f ₂ (xi, yj)} ² becomes 0. It will be.

  That is, when one or both (or both) of the paper fingerprint information has a dark pixel, the density difference between the pixels is not considered. This is for ignoring pixels on which dust or color material has been placed.

By this process, the total number increases or decreases depending on the Σ symbol, and normalization is performed by dividing by the total number Σα ₁ (x, y) α ₂ (x−i, y−j). Note that an error value E (i, j) at which Σα ₁ (x, y) α ₂ (x−i, y−j) in the denominator of equation (1) becomes 0 is a set of error values (E (-(n-1),-(m-1)) to E (n-1, m-1)) are not included.

<Determination method of matching degree>
As described above, when E (k, l) = min {E (i, j)}, the position when the registered paper fingerprint information was acquired and the paper fingerprint information just acquired are acquired. It can be seen that the positions were shifted by k, l from each other.

  Subsequently, a value indicating how much the two pieces of paper fingerprint information are similar (this value is called a matching degree) is obtained by using the E (k, l) and other E (i, j). .

First, a set of error values obtained by the function (1) (for example, E (0,0) = 10 *, E (0,1) = 50, E (1,0) = 50, E (1,1 ) = 50) to obtain the average value (40). ... (A)
Note that * is not related to the value. They are listed only for your attention. The reason for wanting to pay attention will be described later.

Next, each error value (10 *, 50, 50, 50) is subtracted from the average value (40) to obtain a new set (30 *, -10, -10, -10).・ ・ ・ ・ (B)
Then, a standard deviation (30 × 30 + 10 × 10 + 10 × 10 + 10 × 10 = 1200, 1200/4 = 300, √300 = 10√3 = about 17) is obtained from this new set. Then, the new set is divided by 17 to obtain a quotient (1 *,-1, -1, -1). .... (C)
The maximum value among the obtained values is set as the matching degree (1 *). The value 1 * corresponds to the value E (0,0) = 10 *. E (0,0) is a value satisfying E (0,0) = min {E (i, j)} in this case.

<Conceptual explanation of how to determine the degree of matching>
The process of performing the matching degree determination method eventually calculates how far the smallest error value in the plurality of error value sets is from the average error value (A and B).

  Then, the degree of matching is obtained by dividing the distance by the standard deviation (C).

  Finally, a matching result is obtained by comparing the matching degree with a threshold (D).

  The standard deviation means an average value of “difference between each error value and the average value”. In other words, the standard deviation is a value indicating how much variation occurs in the entire set.

  By dividing the above degree of separation by such an overall variation value, how small min {E (i, j)} is in the set E (i, j) (projectingly small or slightly small) ) Will be understood.

Then, it is determined to be valid when min {E (i, j)} is very protruding and small in the set E (i, j), and is determined to be invalid otherwise. (D)
<Reason to determine that min {E (i, j)} is valid only when the set E (i, j) is very small in the set E (i, j)>
Here, it is assumed that the registered paper fingerprint information and the paper fingerprint information just acquired are acquired from the same paper.

  Then, there should be a place (shift position) where the registered paper fingerprint information and the paper fingerprint information just acquired are very consistent. At this time, E (i, j) should be very small because the registered paper fingerprint information and the paper fingerprint information just acquired at this time are very coincident.

  On the other hand, if the position is slightly shifted from this position, the registered paper fingerprint information and the paper fingerprint information just acquired are no longer relevant. Therefore, E (i, j) should be a normal large value.

  Therefore, the condition that “two pieces of paper fingerprint information are acquired from the same paper” matches the condition that “the smallest E (i, j) protrudes and is small in the set E (i, j)”.

  Return to <Paper fingerprint information collation processing>.

  In step 903, the matching degree of the two pieces of paper fingerprint information obtained in step 902 is compared with a predetermined threshold value to determine “valid” or “invalid”. Note that the degree of matching may be referred to as similarity. A comparison result between the matching degree and a predetermined threshold value may be referred to as a matching result.

  The description of the controller 11 has been described above.

<Explanation of operation screen>
FIG. 7 shows an initial screen in the image forming apparatus 10. An area 701 indicates whether or not the image forming apparatus 10 is ready for copying, and indicates the set number of copies. A document selection tab 704 is a tab for selecting a document type. When this tab is depressed, three types of selection menus of text, photo, and text / photo mode are displayed in a pop-up. A finishing tab 706 is a tab for performing settings related to various finishings. A duplex setting tab 707 is a tab for performing settings relating to duplex reading and duplex printing. A reading mode tab 702 is a tab for selecting an original reading mode. When this tab is depressed, three types of selection menus of color / black / automatic (ACS) are popped up. Note that color copy is performed when color is selected, and monochrome copy is performed when black is selected. When ACS is selected, the copy mode is determined by the monochrome color determination signal described above.

  An area 708 is a tab for selecting a paper fingerprint information registration process. The paper fingerprint information registration process will be described later. An area 709 is a tab for selecting a paper fingerprint information matching process. This paper fingerprint information matching process will be described later. An area 710 is a tab for selecting a paper fingerprint information deletion process. This paper fingerprint information deletion process will be described later.

  An area 711 is a tab for indicating the status of the system. When this tab is depressed, a list of image data stored in the HDD 304 in the image forming apparatus 10 is displayed on the display screen.

<Operation when paper fingerprint information registration process tab is pressed (paper fingerprint information registration process at the time of copying)>
Next, a paper fingerprint information registration process executed when the user presses the paper fingerprint information registration tab 708 shown in FIG. 7 and then presses the start key will be described with reference to FIG.

  In step 1601, the CPU 301 controls the document read by the scanner unit 13 to be sent as image data to the scanner image processing unit 312 via the scanner I / F 311.

  In step 1602, the scanner image processing unit 312 sets a gain adjustment value smaller than a general gain adjustment value in the shading correction unit 500. Then, each luminance signal value obtained by applying the small gain adjustment value to the image data is output to the paper fingerprint information acquisition unit 507. Thereafter, based on the output data, the paper fingerprint information acquisition unit 507 acquires paper fingerprint information. Then, the obtained paper fingerprint information is sent to the RAM 302 using a data bus (not shown).

  In the paper fingerprint acquisition technology, it is essential to obtain dark image data as long as the fiber pattern is acquired from the white area. Therefore, in this embodiment, the scanner image processing unit 312 sets a gain adjustment value smaller than a general gain adjustment value, thereby obtaining dark image data for acquiring paper fingerprint information. However, the method for obtaining dark image data is not limited to this. For example, a method of scanning with a reduced amount of light is also conceivable.

  In step 1603, the CPU 301 issues a management number from the server, and registers the management number, paper fingerprint information, and paper fingerprint information acquisition area information in association with each other. Note that the information in the paper fingerprint information acquisition area is position information indicating where the paper fingerprint information is acquired from.

  In step 1604, the CPU 301 controls to display the management number on the display screen.

<Operation when paper fingerprint information matching tab is pressed>
Next, an operation when the paper fingerprint information collation tab 709 shown in FIG. 7 is pressed by the user and then the start key is pressed after the management number is input will be described with reference to FIG.

  In step 1701, the CPU 301 controls the document read by the scanner unit 13 to be sent as image data to the scanner image processing unit 312 via the scanner I / F 311.

  In step 1702, the scanner image processing unit 312 performs the processing shown in FIG. 5 on the image data, and generates attribute data together with new image data. Further, this attribute data is attached to the image data.

  Further, in step 1702, the CPU 301 determines a paper fingerprint information acquisition area based on the input management number. The paper fingerprint information acquisition unit 507 in the scanner image processing unit 312 acquires paper fingerprint information from the determined paper fingerprint information acquisition area. Then, the obtained paper fingerprint information is sent to the RAM 302 using a data bus (not shown).

  Further, in step 1702, paper fingerprint information registered in the server in a state associated with the input management number is acquired. Then, the acquired information is sent to the RAM 302 using a data bus (not shown).

  In step 1703, the CPU 301 collates the paper fingerprint information registered in the server with the paper fingerprint information acquired through the paper fingerprint information acquisition unit 507. This collation process is as described with reference to FIG. 9 in <Paper fingerprint information collation process>.

  In step 1704, the CPU 301 controls to display the result (valid or invalid) obtained by the <paper fingerprint information matching process> on the display screen of the operation unit 12.

<Operation when the paper fingerprint information deletion tab is pressed>
Next, the paper fingerprint information registration process executed when the user presses the paper fingerprint information deletion tab 710 shown in FIG. 7 and then presses the start key will be described with reference to FIG.

  In step 2401, the CPU 301 controls the document read by the scanner unit 13 to be sent as image data to the scanner image processing unit 312 via the scanner I / F 311.

  In step 2402, the scanner image processing unit 312 sets a gain adjustment value smaller than a general gain adjustment value in the shading correction unit 500. Then, each luminance signal value obtained by applying the small gain adjustment value to the image data is output to the paper fingerprint information acquisition unit 507. Thereafter, based on the output data, the paper fingerprint information acquisition unit 507 acquires paper fingerprint information. Then, the obtained paper fingerprint information is sent to the RAM 302 using a data bus (not shown).

  In the paper fingerprint acquisition technology, it is essential to obtain dark image data as long as the fiber pattern is acquired from the white area. Therefore, in this embodiment, the scanner image processing unit 312 sets a gain adjustment value smaller than a general gain adjustment value, thereby obtaining dark image data for acquiring paper fingerprint information. However, the method for obtaining dark image data is not limited to this. For example, a method of scanning with a reduced amount of light is also conceivable.

  In step 2403, the CPU 301 collates the paper fingerprint information registered in the server with the paper fingerprint information acquired through the paper fingerprint information acquisition unit 507. This collation process is as described with reference to FIG. 9 in <Paper fingerprint information collation process>. If the result is correct, the CPU 301 deletes the paper fingerprint information registered in the server.

  In step 2404, the CPU 301 controls to display on the display screen of the operation unit 12 whether or not the paper fingerprint information deletion process is successful.

<Method for determining paper fingerprint information acquisition area>
FIG. 14 is a flowchart showing <paper fingerprint information acquisition area determination method>. The processing of each process in this flowchart is comprehensively controlled by the CPU 301. This flowchart shows a process of searching an appropriate area as the paper fingerprint information and setting the searched appropriate area as the paper fingerprint information acquisition area.

  In step 3601, the CPU 301 controls to divide the area on the sheet into 1 to n areas. The divided areas are all the same size area, and this size is an appropriate size as a paper fingerprint area.

  In step 3602, the CPU 301 sets k = 1.

  In step 3603, it is determined whether k = n. If k = n, the process proceeds to step 3608. In step 3608, the CPU 301 controls to display on the display screen that the paper fingerprint acquisition area has not been determined.

  In step 3604, the kth area is set as a target area. Then, it is determined whether or not the target area is a paper edge area (area within a predetermined distance from the edge). As a result of the determination, if the target area is not the paper edge area, the process proceeds to step 3605.

  In step 3605, it is determined whether or not the target area is an area close to the boundary line when the paper is equally divided (area within a predetermined distance). Specifically, for example, an area within 1 cm from the boundary line is defined as a near area. If the target region is a region far from the boundary line, the process proceeds to step 3606.

  In step 3606, whether the target area has dots (or is scheduled to be hit) with an area ratio equal to or higher than the first predetermined area ratio (relatively high area ratio) or image data. Determine based on. If the result of determination is that dots have been hit (or will be hit) with an area ratio lower than the first predetermined area ratio, the routine proceeds to step 3607. This is a process for eliminating the black solid area.

  As described in the assignment section, it is basically a white pixel that can be read up to the fiber bundle. Therefore, it is not desirable that the black solid area becomes a paper fingerprint information acquisition area, and thus it is necessary to eliminate the black solid area in this way.

  In step 3607, the target area has dots (or is planned to be hit) with an area ratio higher than the second predetermined area ratio (relatively low area ratio). Judgment based on data. As a result of the determination, if dots are hit with an area ratio higher than the second predetermined area ratio, the routine proceeds to step 3609. This is a process for eliminating the blank area.

  This is because, as described in the problem column, the blank area is easily cut out and pasted on other paper, so it is not desirable to become a paper fingerprint information acquisition area.

  In step 3609, the area that has reached step 3609 is determined as an appropriate paper fingerprint area.

  Finally, how to determine the area ratio where dots are hit (or will be hit) based on image data will be described.

  First, it is defined as (range of luminance signal value− “luminance signal value of each pixel in the target region”) × “number of pixels included in the target region” = “average density of the target region”. When only the luminance signal value of one color (YUV of YUV) can be obtained as the luminance signal value of each pixel in the target region, the “luminance signal value range” is, for example, 255. In addition, if the luminance signal value of each pixel in the target region has three color (all RGB) luminance signal values, the “brightness signal value range” is, for example, 255 × 3.

  In step 3606 and step 3607, the average density value is compared with the first predetermined area ratio and the second predetermined area ratio. (Of course, it goes without saying that the comparison is made after aligning the unit of area ratio and average density).

<Example of paper fingerprint information acquisition area>
It is assumed that FIG. 15 is image data temporarily stored in the HDD. Then, the shaded portion in FIG. 13 is determined based on the luminance signal value (or density signal value) of each pixel in the paper fingerprint information. When the paper fingerprint information is acquired from a certain area where the density signal value is at a certain ratio or more, if that certain area becomes a black solid area due to the image data, the degree of matching becomes low during collation. Therefore, it is not desirable to set the black solid area as the paper fingerprint acquisition area.

  Therefore, the CPU 301 designates, as the paper fingerprint information income prohibited area, an area where dots are hit by the first area ratio or more based on the user-desired image data.

  Further, an area corresponding to the paper edge of the output paper is designated as a paper fingerprint information acquisition prohibited area. This is because the area corresponding to the paper edge of the output paper is easily cut out. If the paper fingerprint acquisition area is cut out and pasted on another paper, the other paper becomes the paper fingerprint acquisition area.

  Furthermore, an area close to the boundary line obtained by equally dividing the output paper is designated as a paper fingerprint acquisition prohibited area. This is because the output sheet is highly likely to be bent by the user around the center area. If it is bent, the degree of matching is lowered, which may cause erroneous determination.

  As described above, the CPU 301 designates the four areas as the paper fingerprint information acquisition prohibited area.

  Of the areas other than the areas specified as described above, an area where dots are hit less than a predetermined area ratio is determined as an area for acquiring paper fingerprint information.

  If FIG. 13 is the image data temporarily stored in the HDD, the hatched portion shown in FIG. 15 and the black solid portion at the lower right are designated as the paper fingerprint information acquisition prohibited area. The other portions are candidates for the paper fingerprint information acquisition area.

  In the above example, it is assumed that the output paper is folded in half, and the area close to the boundary line obtained by equally dividing the paper is designated as the paper fingerprint information acquisition prohibited area. However, depending on the size of the output paper, the paper fingerprint It is also possible to change the information acquisition prohibited area. For example, when the output paper is A3 size, it is conceivable that the paper fingerprint information acquisition prohibited area is determined on the assumption that the output paper is folded in four.

  It is also possible to determine the paper fingerprint information acquisition prohibited area depending on the type of paper. For example, in the case of thick paper, it is usually difficult to fold it in half.

  As described above, in the first embodiment, the input image data is divided into a plurality of regions (1 to n), and the regions after the division are searched in order from 1 in order. Then, when a region satisfying the condition is found, it is determined as a paper fingerprint acquisition region.

It becomes like this when the following conditions are described clearly.
(Condition 1) Is the area not the edge of the paper?
(Condition 2) Is the area far from the boundary line?
(Condition 3) Is the region not a white solid region?
(Condition 4) Is it an area that is not a black solid area?
In this way, as in the condition 3 and the condition 4, the heavy processing necessary to determine “how much dots are to be hit” is deferred and the light process as in the conditions 1 and 2 is deferred. Speeds up processing.

  Then, when a region that satisfies all the conditions is found, the paper fingerprint information acquisition region determination process is completed.

<Discharge processing operation in case of error>
FIG. 18 shows a flowchart when an error occurs in the paper fingerprint information registration process. An error is an over-registration error or double registration.

  When the tab of the paper fingerprint information registration process is pressed, the CPU 301 of the controller unit 11 notifies the CPU 1200 of the ADF 1000 that the process is the paper fingerprint information registration process via the CPU of the reader unit 1100 and the CPU of the reader unit 1100. In the paper feeding (step 1801) and reading (step 1802), the original is conveyed and read as described in <Detailed description of automatic document feeder>. Thereafter, when the paper fingerprint information registration process is received, the CPU 1200 of the ADF 1000 presses the solenoid 1022 and waits for the paper fingerprint information registration result with the document nipped (step 1803). In step 1803, when the paper fingerprint information collation result is successful, the CPU 301 of the controller unit 11 transmits control data to the CPU 1200 of the ADF 1000 so as to perform the same paper discharge as that for single-sided reading, via the CPU of the reader unit 1100. . That is, the document is sequentially discharged from the second transport roller 1006 onto the paper discharge tray 1021 with the surface of the document facing downward by the paper discharge roller 1008 as in the case of reading the single-sided original document described above (step 1804). In step 1805, as shown in <Paper fingerprint information registration processing>, paper fingerprint information is registered in the database. Note that the order of step 1804 and step 1805 does not matter. Then, as shown in FIG. 23A, a message indicating that the paper fingerprint information registration process has been successful is displayed on the operation unit. If the paper fingerprint information collation result fails, the CPU 301 of the controller unit 11 reverses the sheet without reading the image to the CPU 1200 of the ADF 1000 via the CPU of the reader unit 1100 and the CPU of the reader unit 1100 and discharges the paper. The control data is transmitted so that That is, the nipped document is conveyed in a switchback manner, and skew correction is performed again by the second registration roller 1004. Thereafter, the solenoid 1022 is released, and the sheet is conveyed by the second registration roller 1004, the first conveyance roller 1005, and the second conveyance roller 1006. Then, it passes through the reading position R without reading an image, and is discharged from the second transport roller onto the paper discharge tray 1021 with the paper discharge roller 1008 facing upward (step 1807). Then, as shown in FIG. 23B, a message indicating that the paper fingerprint information registration process has failed is displayed on the operation unit.

  Since the paper fingerprint information matching process and the paper fingerprint information deletion process are the same as the paper fingerprint information registration process, the description is omitted. The difference is the error contents, such as a collation error in which the paper fingerprint information does not match in the paper fingerprint information collation process, and a deletion error in which the paper fingerprint information to be deleted is not registered in the paper fingerprint information deletion process. In addition, a message displayed on the operation unit at the time of an error is also a paper fingerprint information matching process (FIG. 23 (c): paper fingerprint information matching error) (FIG. 23 (d): paper fingerprint information unregistered error), a paper fingerprint information deleting process ( FIG. 23 (e): Paper fingerprint information deletion error) differs.

  As another embodiment, the display on the operation unit can be changed to be used for sorting according to whether or not paper fingerprint information is registered.

1 is a diagram illustrating an overall configuration of an image forming system. 1 is an external view of an input / output device of an image forming apparatus. 1 is a diagram illustrating an overall configuration of an image forming apparatus. The figure which shows tile data notionally. The block diagram of a scanner image processing part. FIG. 3 is a block diagram of a printer image processing unit. Explanatory drawing of the copy screen of an operation part. 17 is a flowchart showing processing performed by the paper fingerprint information acquisition unit 507 in S1602 in FIG. The flowchart which shows the process in S1703 in FIG. FIG. 3 is a cross-sectional view of the image reading apparatus. FIG. 3 is an explanatory diagram of a driving system of an automatic document feeder. The block diagram of an automatic document feeder. The figure which shows a paper fingerprint information acquisition area. The figure which shows the flowchart which determines a paper fingerprint information acquisition area. The figure which shows the image data for showing the paper fingerprint information acquisition area | region in FIG. 5 is a flowchart illustrating a paper fingerprint information registration process according to the first embodiment. 5 is a flowchart illustrating paper fingerprint information matching processing according to the first exemplary embodiment. 7 is a flowchart when an error occurs in the paper fingerprint information registration process in the first embodiment. The figure which shows the registered paper fingerprint information and the paper fingerprint information obtained this time. (A) Diagram showing how to find E _{1 × 1} , (B) Diagram showing how to find E _{2 × 1} , (C) Diagram showing how to find E _{n × 1} , (D) E _{2n−1 × The} figure which shows how to obtain | require of ₁ . (A) The figure which shows how to obtain | require E1 _{* 2} and (B) The figure which shows how to obtain | require _{E2n-1 * 2} . (A) The figure which shows how to obtain | require _{En * m} , (B) The figure which shows how to obtain | require _{E2n-1 * 2m-1} . (A) Diagram showing the operation panel when paper fingerprint registration is performed normally, (b) Diagram showing the operation panel when an error occurs in paper fingerprint registration, (c) Collation error occurs in paper fingerprint verification The figure which shows the operation panel at the time of doing, (d) The figure which shows the operation panel when there exists an unregistered document in paper fingerprint registration, (e) The figure which shows the operation panel when an error generate | occur | produces in paper fingerprint deletion. 5 is a flowchart illustrating a paper fingerprint information deletion process according to the first embodiment.

Claims (4)

A document conveying means for sequentially feeding and conveying documents one by one from a bundle of documents stacked on a document tray;
Reading means for reading an image on the document conveyed by the document conveying means;
Extraction means for extracting feature data from the image data read by the reading means;
Encoding means for converting the feature data into code data;
Storage means for storing the code data;
Comparison means for comparing the code data read by the reading means with the coat data stored in the storage means;
An image forming apparatus comprising: a paper discharge unit that switches a paper discharge surface according to a determination result of the comparison unit.   The image forming apparatus according to claim 1, wherein the feature data is paper fingerprint data.   The image forming apparatus according to claim 1, wherein the determination unit is a discharge control unit that does not discharge until a determination result is notified to a discharge surface control unit that switches the discharge surface.   The image forming apparatus according to claim 1, wherein the determination result is a paper discharge unit that switches a paper discharge surface between a case of success and a case of failure.

Images