JP2016034081A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus that can provide an image with high quality as a whole.SOLUTION: An MFP includes an image reading part that reads an image from a document, a white top board that is arranged opposite to the image reading part to hold the document with the image reading part during the reading of the image by the image reading part, and a black top board that has higher color density than that of the white top board and can be replaced with the white top board. The MFP determines whether or not set-off occurs on an image read by the image reading part on the basis of the image read by the image reading part; when determined that set-off has occurred while the white top board is arranged opposite to the image reading part, notifies a user of proposal of replacement to the black top board (S181), causes the image reading part to re-read the image after the notification of the proposal of replacement to the black top board (S190 or S192); and replaces the image previously read by the image reading part with the image re-read by the image reading part only for pages determined that set-off has occurred (S191).SELECTED DRAWING: Figure 12

Description

  The present invention relates to an image forming apparatus that reads an image from a document.

  Conventionally, as an image forming apparatus that reads an image from a document, an image reading unit that reads an image from the document, a white member that is disposed opposite to the image reading unit and sandwiches the document together with the image reading unit, and the color density of the white member An image forming apparatus including a dark white member and a replaceable black member is known (see, for example, Patent Document 1). In the conventional image forming apparatus, when the background color of the document is white, the white member is arranged to face the image reading unit, so that white is read from the document with high accuracy when the image reading unit reads the document. be able to. Further, in the conventional image forming apparatus, when the surface of the document opposite to the surface read by the image reading unit is not white due to, for example, printing or handwriting, the black member is used as the image reading unit. By disposing them facing each other, it is possible to suppress the occurrence of show-through in the image read by the image reading unit.

JP 2012-191694 A

  However, in the conventional image forming apparatus, since only one of the white member and the black member is arranged to face the image reading unit, the images of all pages are read by the image reading unit. There is a problem that an image whose image quality is not optimal is included.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus capable of obtaining a high-quality image as a whole.

  An image forming apparatus according to the present invention includes an image reading unit that reads an image from a document, and a first member that is disposed opposite the image reading unit and sandwiches the document together with the image reading unit when the image reading unit reads an image. A second member having a color density higher than that of the first member and replaceable with the first member; and a show-through occurrence page for determining whether or not the image read by the image reading unit is a show-through page. Determining means; second member replacement notification means for notifying the replacement proposal for the second member; and the image reading section after the replacement proposal for the second member is notified by the second member replacement notification means. Re-reading means for re-reading the image by means of the above, and the show-through occurrence page determination means determines whether or not the page is a page where the show-through occurs based on the image read by the image reading unit. The second member replacement notifying unit is configured such that when the first member is disposed to face the image reading unit and the page where the show-through occurs is determined by the show-through occurrence page determining unit, The re-reading means notifies the replacement proposal to the second member, and when the show-through occurs, only the page determined by the show-through occurrence page determination means, the image read again by the image reading unit, It is characterized in that it is replaced with the image previously read by the image reading unit.

  With this configuration, the image forming apparatus of the present invention can read an image of a page that is determined not to show show-through by the image reading unit when the first member is disposed to face the image reading unit. In addition, since the image of the page on which the show-through is determined is the image read by the image reading unit when the second member is disposed facing the image reading unit, the overall image quality is high. An image can be obtained.

  In the image forming apparatus of the present invention, when the second member replacement notification unit notifies the replacement proposal to the second member, the show-through occurrence page determination unit determines that the show-through occurs. The show-through occurrence page determination means may receive designation of a page on which show-through occurs and determine the received page as a page on which show-through occurs.

  With this configuration, the image forming apparatus according to the present invention replaces an image only on a page determined by the user when the show-through occurs after the user visually recognizes the document of the page determined that the show-through occurs. be able to.

  Further, in the image forming apparatus of the present invention, the second member replacement notifying unit is read by the image reading unit when notifying a page determined by the show-through occurrence page determining unit when show-through occurs. An image may be notified.

  With this configuration, the image forming apparatus according to the present invention can replace the image only on the page determined by the user when the show-through occurs after allowing the user to visually recognize the actually read image.

  In the image forming apparatus according to the aspect of the invention, the rereading unit may cause the image reading unit to read the image again only for the page to be replaced with the image read by the image reading unit last time.

  With this configuration, the image forming apparatus of the present invention reads the image again only for the page to be replaced, so that efficiency can be improved.

  The image forming apparatus according to the present invention further includes an automatic document feeder that automatically conveys the document to the image reading unit, and the rereading unit is configured to read all images when the image reading unit reads the image again. When the document is conveyed by the automatic document feeder, the automatic document feeding is performed without causing the image reading unit to read the image again with respect to a page other than the page to be replaced with the image previously read by the image reading unit. You may perform the conveyance by an apparatus.

  With this configuration, the image forming apparatus of the present invention can improve efficiency because the user does not need to extract the pages to be replaced from the entire pages of the document.

  In the image forming apparatus according to the aspect of the invention, the show-through occurrence page determining unit may include the other side of the document when pixels having a specific density or more exist in the image read by the image reading unit from one side of the document. It may be determined that show-through occurs in the image read by the image reading unit from the side.

  With this configuration, the image forming apparatus of the present invention is read by the image reading unit from the other side of the document when pixels having a specific density or more exist in the image read by the image reading unit from the one side of the document. Since it is determined that show-through occurs in the image, and when it is determined that show-through occurs when the first member is arranged to face the image reading unit, a replacement proposal for the second member is notified. It is not necessary for the user to look at the document to determine whether or not show-through occurs in the image read by the reading unit, and convenience can be improved.

  In the image forming apparatus according to the aspect of the invention, the show-through occurrence page determination unit may determine that the image read by the image reading unit from one side of the document has a specific number or more of pixels having the specific density or more. It may be determined that show-through occurs in the image read by the image reading unit from the other side of the document.

  With this configuration, the image forming apparatus of the present invention allows pixels having a specific density or higher to be specified even when pixels having a specific density or higher exist in an image read by the image reading unit from one side of the document. When it is less than the number, since it is not determined that show-through occurs in the image read by the image reading unit from the other side of the document, a slight show-through that does not matter much to the user is not a problem and is convenient. Can be improved.

  The image forming apparatus of the present invention can obtain a high-quality image as a whole.

1 is a block diagram of an MFP according to an embodiment of the present invention. FIG. 2 is an external perspective view of the MFP shown in FIG. 1 in a state where a lid on which a white top plate is mounted is opened. FIG. 2 is an external perspective view of the MFP shown in FIG. 1 in a state where a lid on which a black top board is mounted is opened. (A) is front sectional drawing of a part of scanner shown in FIG. 2 in the state in which the lid | cover with which the white top plate is mounted | worn is closed. FIG. 4B is a front sectional view of a part of the scanner shown in FIG. 2 in a state where the lid on which the white top plate is mounted is closed and the document is sandwiched between the image reading unit and the white top plate. . 3 is a flowchart of the operation of the MFP shown in FIG. 1 when designation of a show-through determination density threshold and a show-through determination pixel count threshold is accepted. It is a figure which shows an example of the criteria setting screen displayed on the display part shown in FIG. 3 is a flowchart of the operation of the MFP shown in FIG. 1 when accepting designation of a document type. It is a figure which shows an example of the original document mode setting screen displayed on the display part shown in FIG. 2 is a flowchart of the operation of the MFP shown in FIG. 1 when executing a copy job for printing images on both sides of a document on both sides or one side of a recording medium. 10 is a flowchart continued from FIG. 9. It is a flowchart following FIG. 9 and FIG. FIG. 12 is a flowchart continued from FIG. 11. It is a figure which shows an example of the back paper original mode top board exchange notification screen displayed on the display part shown in FIG. It is a figure which shows an example of the cardboard original mode top plate exchange notification screen displayed on the display unit shown in FIG. It is a figure which shows an example of the black top board installation notification screen displayed on the display part shown in FIG. It is a figure which shows an example of the preview screen displayed on the display part shown in FIG. FIG. 17 is a diagram showing a document on which a preview image shown on the preview screen shown in FIG. 16 is based. It is a figure which shows an example of the re-read selection screen displayed on the display part shown in FIG.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  First, the configuration of an MFP (Multifunction Peripheral) as an image forming apparatus according to the present embodiment will be described.

  FIG. 1 is a block diagram of MFP 10 according to the present embodiment.

  As illustrated in FIG. 1, the MFP 10 includes an operation unit 11 that is an input device such as buttons for inputting various operations, and a display unit 12 that is a display device such as an LCD (Liquid Crystal Display) that displays various information. And a scanner 13 that reads an image from a document, a printer 14 that performs printing on a recording medium such as paper, and an external facsimile apparatus (not shown) and a communication line such as a public telephone line A fax communication unit 15 that is a fax device that performs fax communication in a network, a network communication unit 16 that is a network communication device that communicates with an external device via a network such as a LAN (Local Area Network), the Internet, Remembering E PROM (Electrically Erasable Programmable Read Only Memory), an HDD (Hard Disk Drive) storage unit 17 is a storage device such as, and a control unit 18 which controls the entire MFP 10.

  FIG. 2 is an external perspective view of the MFP 10 in a state where the lid 13a on which the white top plates 13e and 13f are mounted is opened.

  As shown in FIG. 2, the scanner 13 includes a lid 13a that can be opened and closed, an ADF (Auto Document Feeder) 13b provided on the top of the lid 13a, and a user when the ADF 13b is not used. An image reading unit 13c that reads an image from a document that is manually set page by page, an image reading unit 13d that reads an image from a document automatically conveyed by the ADF 13b when the ADF 13b is used, and a lid 13a White top plates (hereinafter referred to as “white top plates”) 13e and 13f are provided as detachable first members.

  FIG. 3 is an external perspective view of the MFP 10 with the lid 13a on which the black top plates 13g and 13h are attached being opened.

  As shown in FIG. 3, the scanner 13 serves as a second member replaceable with the white top plates 13e and 13f (see FIG. 2). Say 13g, 13h.

  FIG. 4A is a front sectional view of a part of the scanner 13 in a state where the lid 13a on which the white top plate 13e is mounted is closed. FIG. 4B shows the front of a part of the scanner 13 in a state where the lid 13a on which the white top plate 13e is mounted is closed and the document 90 is sandwiched between the image reading unit 13c and the white top plate 13e. It is sectional drawing.

  As shown in FIG. 4A, the white top plate 13e is disposed to face the image reading unit 13c. As shown in FIG. 4B, the white top plate 13e sandwiches the document 90 together with the image reading unit 13c when the image reading unit 13c reads an image. Although the relationship between the image reading unit 13c and the white top plate 13e has been described, the relationship between the image reading unit 13d (see FIG. 2) and the white top plate 13f (see FIG. 2), the image reading unit 13c, and the black sky plate The same applies to the relationship with the plate 13g (see FIG. 3) and the relationship between the image reading unit 13d and the black top plate 13h (see FIG. 3).

  As shown in FIG. 1, in the storage unit 17, white top plates 13 e and 13 f (hereinafter simply referred to as “white top plate”) are used as image reading units 13 c and 13 d (hereinafter simply referred to as “image reading unit”). A white top plate correction table 17a for performing color correction processing according to the white top plate for an image read by the image reading unit when arranged opposite to each other, and black top plates 13g and 13h (hereinafter simply referred to as “top plate”). A black top plate for performing color correction processing according to the black top plate for an image read by the image reading unit when the “black top plate” is disposed facing the image reading unit. The correction table 17b is stored. In addition, the storage unit 17 includes a show-through determination density threshold value 17c indicating a specific density as a reference for determining whether or not show-through occurs in the image read by the image reading unit based on the pixel density. A show-through determination pixel number threshold value 17d indicating a specific number as a reference for determining whether or not show-through occurs in the image read by the image reading unit based on the number of pixels is stored.

  The storage unit 17 uses a document in which the back side of the surface read by the image reading unit is used by printing, handwriting, or the like (hereinafter referred to as a “back paper document”) as a document having a high possibility of show-through. A backing paper document flag 17e indicating whether or not to be used is stored. Further, the storage unit 17 stores a thick paper document flag 17f indicating whether or not a document having a specific thickness or more (hereinafter referred to as “thick paper document”) is used as a document with a low possibility of show-through. doing.

  The control unit 18 includes, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory) storing programs and various data, and a RAM (Random Access Memory) used as a work area of the CPU. Yes. The CPU executes a program stored in the ROM or the storage unit 17.

  The control unit 18 executes a program stored in the ROM or the storage unit 17 to determine whether the image read by the image reading unit is a page where the show-through occurs or not. The black top board replacement notification means 18b as the second member replacement notification means for notifying the black top board replacement proposal, and the black top board replacement notification means 18b is notified of the replacement proposal for the black top board. It functions as re-reading means 18c that causes the image reading unit to read the image again later.

  The MFP 10 stores a copy job in which an image read from a document by the scanner 13 is printed on a recording medium by the printer 14, stores an image read from the document by the scanner 13 in the storage unit 17, and transmits the image to an external device by the network communication unit 16. Various jobs for processing the image read from the document by the scanner 13 can be executed, such as a scan job to be performed or a fax job in which an image read from the document by the scanner 13 is faxed by the fax communication unit 15.

  Next, the operation of the MFP 10 will be described.

  FIG. 5 is a flowchart of the operation of the MFP 10 when the designation of the show-through determination density threshold 17c and the show-through determination pixel count threshold 17d is accepted.

  When the start of processing for accepting designation of the show-through determination density threshold 17c and the show-through determination pixel count threshold 17d is instructed via the operation unit 11, the control unit 18 performs the operation shown in FIG.

  As shown in FIG. 5, the control unit 18 displays the determination criterion setting screen 20 shown in FIG. 6 for accepting designation of the show-through determination density threshold 17 c and the show-through determination pixel number threshold 17 d on the display unit 12. (S101).

  FIG. 6 is a diagram illustrating an example of the determination criterion setting screen 20 displayed on the display unit 12.

  The determination criterion setting screen 20 shown in FIG. 6 includes a text box 21 for accepting designation of the show-through determination density threshold 17c, a text box 22 for accepting designation of the show-through determination pixel number threshold 17d, and show-through. The cancel button 23 for canceling the designation acceptance of the determination density threshold 17c and the show-through determination pixel count threshold 17d, and the designation acceptance of the show-through determination density threshold 17c and the show-through determination pixel count threshold 17d are executed. And an OK button 24. The user can input values into the text box 21 and the text box 22 via the operation unit 11. When the cancel button 23 or the OK button 24 is pressed, the display on the determination criterion setting screen 20 is terminated.

  As shown in FIG. 5, when the process of S101 is completed, the control unit 18 determines whether or not the OK button 24 is pressed via the operation unit 11 (S102).

  When determining in S102 that the OK button 24 has not been pressed, the control unit 18 determines whether or not the cancel button 23 has been pressed via the operation unit 11 (S103).

  When determining in S103 that the cancel button 23 has been pressed, the control unit 18 ends the execution of the process of FIG.

  If the control unit 18 determines in S103 that the cancel button 23 has not been pressed, the control unit 18 executes the process of S102.

  When the control unit 18 determines in S102 that the OK button 24 has been pressed, the value input to the text box 21 at the time when the OK button 24 was pressed is used as the newly specified show-through determination density threshold value 17c. Accept and update the show-through determination density threshold 17c on the storage unit 17 with the accepted value (S104). For example, when the value input to the text box 21 when the OK button 24 is pressed is “128, 128, 128” shown in FIG. 6, the control unit 18 sets the show-through determination density threshold 17c to “ Update as “RGB (128, 128, 128)”.

  After the processing of S104, the control unit 18 accepts the value input to the text box 22 when the OK button 24 is pressed as the newly specified show-through determination pixel number threshold 17d. The show-through determination pixel number threshold 17d on the storage unit 17 is updated with the value (S105). For example, when the value input to the text box 22 when the OK button 24 is pressed is “1000” shown in FIG. 6, the control unit 18 sets the show-through determination pixel number threshold 17d to “1000”. Update.

  The control unit 18 ends the operation illustrated in FIG. 5 after the process of S105.

  FIG. 7 is a flowchart of the operation of the MFP 10 when accepting designation of the type of document.

  When the start of the process for accepting the specification of the document type is instructed via the operation unit 11, the control unit 18 executes the operation shown in FIG.

  As shown in FIG. 7, the control unit 18 displays on the display unit 12 a document mode setting screen 30 shown in FIG. 8 for accepting designation of the document type (S111).

  FIG. 8 is a diagram showing an example of a document mode setting screen 30 displayed on the display unit 12.

  The document mode setting screen 30 shown in FIG. 8 includes a radio button 31 for accepting designation of a normal document (hereinafter referred to as “normal document”) that is neither a thick paper document nor a back paper document, and designation of a thick paper document. A radio button 32 for accepting, a radio button 33 for accepting designation of a back-sheet manuscript that is not a thick paper manuscript, a cancel button 34 for stopping accepting designation of a manuscript type, and accepting designation of a manuscript type And an OK button 35 for executing. One of the radio buttons 31 to 33 is always selected. The user can select any of the radio buttons 31 to 33 via the operation unit 11. When the cancel button 34 or the OK button 35 is pressed, the display on the document mode setting screen 30 is terminated.

  As shown in FIG. 7, when the process of S111 is completed, the control unit 18 determines whether or not the OK button 35 has been pressed via the operation unit 11 (S112).

  When determining in S112 that the OK button 35 has not been pressed, the control unit 18 determines whether or not the cancel button 34 has been pressed via the operation unit 11 (S113).

  If the control unit 18 determines in S113 that the cancel button 34 has been pressed, the control unit 18 ends the execution of the process of FIG.

  When determining in S113 that the cancel button 34 has not been pressed, the control unit 18 executes the process of S112.

  When determining in S112 that the OK button 35 has been pressed, the control unit 18 determines the type of document selected by the radio buttons 31 to 33 when the OK button 35 is pressed (S114).

  When determining in S114 that the normal document has been selected, the control unit 18 defeats the back paper document flag 17e and the thick paper document flag 17f (S115).

  If the controller 18 determines in S114 that a thick paper document has been selected, the controller 18 defeats the back paper document flag 17e and raises the thick paper document flag 17f (S116). That is, the control unit 18 accepts designation of a thick paper document.

  When the control unit 18 determines in S114 that the back paper document has been selected, the control unit 18 defeats the thick paper document flag 17f and sets the back paper document flag 17e (S117). That is, the control unit 18 accepts designation of a back paper document.

  When the process of S115, S116, or S117 ends, the control unit 18 ends the execution of the process of FIG.

  FIG. 9 is a flowchart of the operation of the MFP 10 when executing a copy job for printing images on both sides of a document on both sides or one side of a recording medium. FIG. 10 is a flowchart subsequent to FIG. FIG. 11 is a flowchart following FIG. 9 and FIG. FIG. 12 is a flowchart subsequent to FIG.

  When the start of execution of a copy job for printing images on both sides or one side of a recording medium is instructed via the operation unit 11, the control unit 18 executes the operations shown in FIGS. 9 to 12. .

  Note that when the copy job that has started execution is a job that does not use the ADF 13b, the control unit 18 uses the white sky plate, the black top plate, and the image reading unit in the operations shown in FIGS. The board 13e, the black top board 13g, and the image reading unit 13c are to be processed. On the other hand, when the copy job that has started execution is a job that uses the ADF 13b, the control unit 18 operates as a white top plate, a black top plate, and an image reading unit in the operations shown in FIGS. The board 13f, the black top board 13h, and the image reading unit 13d are to be processed.

  As shown in FIGS. 9 to 12, the control unit 18 determines which of the white top plate and the black top plate is attached to the lid 13a (S121).

  The control unit 18 can determine which of the white top plate and the black top plate is attached to the lid 13a based on the detection result of a sensor not shown. For example, when there is a difference in the shape of the white top plate and the black top plate, such as when the white top plate and the black top plate have respective notches, the control unit 18 determines the difference in the shape of the white top plate and the black top plate. By detecting with a contact sensor or a non-contact sensor, it is possible to determine which of the white top plate and the black top plate is attached to the lid 13a. Further, the control unit 18 determines which of the white top plate and the black top plate is attached to the lid 13a by detecting the color of the white top plate and the black top plate attached to the lid 13a with an optical sensor. It is also possible to do.

  When it is determined in S121 that the white top plate is attached to the lid 13a, the black top plate replacement notifying means 18b determines whether the back paper document flag 17e is set (S122).

  When determining in S122 that the back paper original flag 17e is set, the black top board replacement notifying means 18b displays a back paper original mode top board replacement notification screen 40 shown in FIG. 13 on the display unit 12 (S123).

  FIG. 13 is a diagram showing an example of the back paper original mode top board replacement notification screen 40 displayed on the display unit 12.

  The back paper original mode top board exchange notification screen 40 shown in FIG. 13 confirms that the user has read the message 41 and the message 41 for notifying the back paper original mode and the replacement proposal for the black top board. And an OK button 42. When the OK button 42 is pressed, the display on the back paper original mode top board replacement notification screen 40 is terminated.

  The user is prompted to exchange the top board mounted on the lid 13a from the white top board to the black top board by reading the message 41 on the back paper original mode top board exchange notification screen 40.

  As shown in FIGS. 9 to 12, the control unit 18 determines whether or not the OK button 42 has been pressed until it is determined that the OK button 42 has been pressed after the processing of S123 (S124).

  If it is determined in S124 that the OK button 42 has been pressed, the control unit 18 determines whether or not it has been replaced with a black top plate based on the detection result of a sensor (not shown) until it is determined that it has been replaced with a black top plate. (S125).

  When the control unit 18 determines in S125 that the black top plate has been replaced, the control unit 18 sets the black top plate correction table 17b as a correction table for performing color correction processing (S126).

  Next, the control unit 18 repeats the processes of S128 and S129 in order one by one with respect to the originals until reading of all the originals is completed (S127).

  That is, the control unit 18 uses the black table correction table 17b set in S126 to read the image on the surface of the document by the image reading unit (S128), and then the black table correction table 17b set in S126. Is used to read the image on the back side of the document by the image reading unit (S129).

  When the control unit 18 determines in S127 that the reading of all the originals has been completed, the printer 14 prints the images read by the processes of S128 and S129 on the recording medium on the recording medium (S130). -The operation | movement shown in FIG. 12 is complete | finished.

  If the control unit 18 determines in S122 that the back paper original flag 17e is not set, it determines whether or not the thick paper original flag 17f is set (S131).

  When determining in S131 that the thick paper original flag 17f is set, the control unit 18 sets the white top plate correction table 17a as a correction table for performing color correction processing (S132).

  Next, the control unit 18 executes the processing of S127 to S129 using the white table correction table 17a set in S132, and then executes the processing of S130 and ends the operations shown in FIGS. .

  When the control unit 18 determines in S121 that the black top is attached to the lid 13a, the control unit 18 determines whether or not the backing paper document flag 17e is set (S141).

  If the control unit 18 determines in S141 that the back paper document flag 17e is set, the process of S126 to S130 is executed, and the operations shown in FIGS. 9 to 12 are terminated.

  When the control unit 18 determines in S141 that the back paper document flag 17e is not set, the control unit 18 determines whether or not the thick paper document flag 17f is set (S142).

  When determining in S142 that the thick paper original flag 17f is set, the control unit 18 displays a thick paper original mode top plate replacement notification screen 50 shown in FIG. 14 on the display unit 12 (S143).

  FIG. 14 is a diagram showing an example of a cardboard original mode top plate replacement notification screen 50 displayed on the display unit 12.

  A cardboard mode top board replacement notification screen 50 shown in FIG. 14 is a message 51 for notifying that the cardboard mode is selected and a replacement proposal for a white top board, and OK for confirming that the message 51 has been read. Button 52. When the OK button 52 is pressed, the display on the cardboard mode top board replacement notification screen 50 is terminated.

  By reading the message 51 on the cardboard mode top board replacement notification screen 50, the user is prompted to replace the top board mounted on the lid 13a from a black top board to a white top board.

  As shown in FIGS. 9 to 12, the control unit 18 determines whether or not the OK button 52 has been pressed until it is determined that the OK button 52 has been pressed after the process of S143 (S144).

  When determining in S144 that the OK button 52 has been pressed, the control unit 18 determines whether or not it has been replaced with a white top plate based on the detection result of a sensor (not shown) until it is determined that the OK plate 52 has been replaced with a white top plate ( S145).

  If the control unit 18 determines in S145 that the white top plate has been replaced, the control unit 18 executes the processes of S132 and S127 to S130, and ends the operations shown in FIGS.

  If the control unit 18 determines in S142 that the thick paper document flag 17f is not set, the control unit 18 displays the black top board installation notification screen 60 shown in FIG. 15 on the display unit 12 (S146).

  FIG. 15 is a diagram illustrating an example of the black top board attached notification screen 60 displayed on the display unit 12.

  The black top board installation notification screen 60 shown in FIG. 15 informs the MFP 10 that the black top board is installed and a message 61 for notifying the replacement of the white top board, and that the white top board is to be replaced. And a button 63 for notifying the MFP 10 that the white top plate will not be replaced. When the button 62 or the button 63 is pressed, the display on the black top board attached notification screen 60 is terminated.

  The user can determine whether or not to replace the top board mounted on the lid 13a from the black top board to the white top board by reading the message 61 on the black top board attached notification screen 60. For example, when an image is read by the image reading unit with the black top plate mounted, the image is brightened by the color correction processing using the black top plate correction table 17b, and thereby the influence of the black top plate. Although the darkness of the image is improved, the non-dark colors included in the image are also brightened at the same time, and the entire image is whiteout. A user who desires to avoid such overexposure can select to replace the top plate mounted on the lid 13a from a black top plate to a white top plate.

  As shown in FIGS. 9-12, the control part 18 judges whether the replacement | exchange to a white top board was instruct | indicated after the process of S146 (S147). Here, when the button 62 is pressed on the black top board installation notification screen 60, the control unit 18 determines that the replacement with the white top board is instructed.

  If it is determined in S147 that the replacement to the white top plate is not instructed, the control unit 18 determines whether or not it is instructed not to replace the white top plate (S148). Here, when the button 63 is pressed on the black top board attached notification screen 60, the control unit 18 determines that it is instructed not to replace the white top board.

  If the control unit 18 determines in S148 that it is not instructed not to replace the white top plate, the process of S147 is executed.

  If the control unit 18 determines in S148 that it has been instructed not to replace the white top plate, the process of S126 to S130 is executed, and the operations shown in FIGS. 9 to 12 are terminated.

  If the control unit 18 determines in S147 that the replacement to the white top plate has been instructed, it determines whether or not the white top plate has been replaced based on the detection result of the sensor (not shown) until it is determined that the white top plate has been replaced. (S149).

  When the control unit 18 determines in S131 that the thick paper original flag 17f is not set or determines in S149 that the card has been replaced with a white top plate, the control unit 18 sets the white top plate correction table 17a as a correction table for performing color correction processing. (S161).

  Next, the show-through occurrence page determination means 18a defeats a show-through occurrence flag indicating whether or not show-through occurs (S162).

  Next, the show-through occurrence page determination unit 18a repeats the processing of S164 to S179 one by one for the originals until the processing for all the originals is completed (S163).

  That is, first, the show-through occurrence page determination means 18a reads the image on the surface of the document by the image reading unit using the white top plate correction table 17a set in S161 (S164).

  Next, the show-through occurrence page determination unit 18a sets the number of high density pixels for counting the high density pixels in the document image to 0 (S165).

  Next, the show-through occurrence page determination unit 18a repeats the processes of S167 and S168 sequentially for each pixel until the process for all the pixels in the front image read in S164 is completed (S166).

  That is, first, the show-through occurrence page determination unit 18a determines whether or not the density value of the target pixel is equal to or less than the show-through determination density threshold value 17c (S167). It should be noted that the density value comparison is performed by converting the RGB values to the gray scale and then comparing the density values in the gray scale. Further, the density value indicates that the smaller the value is, the higher the density is. For example, the lowest value is 0 (black) and the highest value is 255 (white).

  When the show-through occurrence page determination unit 18a determines in S167 that the density value of the target pixel is equal to or less than the show-through determination density threshold value 17c, the number of high-density pixels is increased by 1 (S168). On the other hand, the show-through occurrence page determination unit 18a does not change the number of high-density pixels when it determines in S167 that the density value of the target pixel is larger than the show-through determination density threshold value 17c.

  If the show-through occurrence page determination unit 18a determines in S166 that the processing for all the pixels in the surface image read in S164 has been completed, it is determined whether or not the number of high-density pixels is greater than or equal to the show-through determination pixel number threshold 17d. Is determined (S169).

  If the show-through occurrence page determination means 18a determines in S169 that the number of high-density pixels is greater than or equal to the show-through determination pixel number threshold value 17d (S170), a show-through occurrence flag is set (S170), and a page on which show-through occurs (hereinafter referred to as a show-through occurrence page). The page on the back side is stored as “show-through page” (S171).

  On the other hand, if the show-through occurrence page determination unit 18a determines in S169 that the number of high-density pixels is less than the show-through determination pixel number threshold value 17d, the show-through occurrence flag is not changed and the show-through occurrence page is changed. I do n’t remember.

  The show-through occurrence page determination means 18a determines in S169 that the number of high-density pixels is less than the show-through determination pixel number threshold 17d, or when the processing in S171 ends, the white table correction table 17a set in S161. Is used to read the image on the back side of the document by the image reading unit (S172).

  Next, the show-through occurrence page determination unit 18a sets the number of high density pixels to 0 (S173).

  Next, the show-through occurrence page determination unit 18a repeats the processes of S175 and S176 sequentially for each pixel until the process for all the pixels in the back-side image read in S164 is completed (S174).

  That is, first, the show-through occurrence page determination unit 18a determines whether or not the density value of the target pixel is equal to or less than the show-through determination density threshold value 17c (S175).

  When the show-through occurrence page determining unit 18a determines in S175 that the density value of the target pixel is equal to or less than the show-through determination density threshold 17c, the number of high-density pixels is increased by 1 (S176). On the other hand, the show-through occurrence page determination unit 18a does not change the number of high-density pixels when it determines in S175 that the density value of the target pixel is larger than the show-through determination density threshold value 17c.

  If the show-through occurrence page determination unit 18a determines in S174 that the processing for all the pixels in the back-side image read in S172 has been completed, whether or not the number of high-density pixels is greater than or equal to the show-through determination pixel number threshold 17d. Is determined (S177).

  If the show-through occurrence page determination means 18a determines in S177 that the number of high-density pixels is equal to or greater than the show-through determination pixel number threshold 17d (S178), the show-through occurrence flag is set (S178). (S179).

  On the other hand, if the show-through occurrence page determination means 18a determines in S177 that the number of high-density pixels is less than the show-through determination pixel number threshold 17d, the show-through occurrence flag is not changed and the show-through occurrence page is not changed. I do n’t remember.

  If the show-through occurrence page determining unit 18a determines in S163 that the processing for all the originals has been completed, the show-through occurrence page determining unit 18a determines whether show-through occurs in the image read by the image reading unit (S180). Here, the show-through occurrence page determination means 18a determines that the show-through occurs when the show-through occurrence flag is set, and determines that no show-through occurs when the show-through occurrence flag falls.

  When it is determined in S180 that no show-through occurs, the control unit 18 prints the images read by the processes in S164 and S172 on the recording medium on the recording medium by the printer 14 (S130). The operation shown in FIG.

  When it is determined in S180 that the show-through occurs, the black top board replacement notifying means 18b displays the preview screen 70 shown in FIG. 16 on the display unit 12 (S181).

  FIG. 16 is a diagram illustrating an example of a preview screen 70 displayed on the display unit 12.

  The preview screen 70 shown in FIG. 16 includes a message 71 for notifying on which page the show-through has occurred and a proposal for replacement to the black top plate, and the first page read by the image reading unit. The preview image 72a of the image (hereinafter referred to as “first page image”; the same applies to the second and subsequent pages) and the show-through discrimination indicating whether show-through has occurred in the first page image. An image 72b, a preview image 73a of the second page image, a show-through distinguishing image 73b indicating whether show-through has occurred in the second page image, a preview image 74a of the third page image, and a third page A show-through distinguishing image 74b indicating whether or not show-through has occurred in the eye image, a preview image 75a of the fourth page image, and a back showing whether or not show-through has occurred in the fourth page image. Ri includes a distinguished image 75b, and a button 76 for transmitting to perform job to replace the black top plate MFP 10. When the button 76 is pressed on the preview screen 70, the display on the display unit 12 ends.

  In the preview screen 70 shown in FIG. 16, a total of four pages of originals are taken as an example, but any number of originals may be used.

  FIG. 17 is a diagram showing a document on which the preview images 72a, 73a, 74a and 75a shown on the preview screen 70 shown in FIG. 16 are based.

  As shown in FIG. 17, the document 201 on the first page is the surface 200 a of the first document 200. The document 202 on the second page is the back surface 200 b of the first document 200. The third page original 211 is the front surface 210 a of the second original 210. The fourth page of the document 212 is the back surface 210 b of the second document 210.

  The original 201 on the first page includes an image 201a having a higher color density, an image 201b having a color density lighter than that of the image 201a, an image 201c having a color density lighter than that of the image 201b, and a color density lower than that of the image 201c. An image 201d is included. The original 202 of the second page includes an image 202a having a color density lighter than the image 201a and darker than the image 201b. The document 211 on the third page includes an image 211a whose color density is lighter than the image 202a and darker than the image 201b. The document 212 of the fourth page includes an image 212a whose color density is lighter than the image 202a and darker than the image 211a, and an image 212b whose color density is lighter than the image 202a and darker than the image 212a.

  As shown in FIGS. 16 and 17, the preview image 72a of the first page image includes images 72c, 72d, 72e, and 72f obtained by reading the images 201a, 201b, 201c, and 201d of the original 201 on the first page, respectively. An image 72g in which the image 202a of the document 202 of the second page is shown through is included. The preview image 73a of the second page image includes an image 73c obtained by reading the image 202a of the second page of the original 202 and an image 73d in which the image 201a of the first page of the original 201 is shown through. The preview image 74a of the third page image includes an image 74c obtained by reading the image 211a of the third page original 211, and images 74d and 74e obtained by showing back the images 212a and 212b of the fourth page original 212. include. The preview image 75a of the fourth page image includes images 75c and 75d obtained by reading the images 212a and 212b of the document 212 of the fourth page, respectively.

  In the preview screen 70 shown in FIG. 16, the show-through distinguishing images 72b, 73b, 74b, and 75b are displayed through the operation unit 11 to display “NG” indicating that show-through has occurred. It is possible to switch to an “OK” display indicating that no show-through has occurred. Although not shown in the figure, a button that can display “OK” or “NG” at once for all pages may be separately provided.

  When the display of the preview screen 70 on the display unit 12 is started, the black top board replacement notifying unit 18b displays “NG” for displaying the show-through distinguishing image for the page stored as the show-through occurrence page in the processing of S171 or S179. ”Display, and the display of the show-through distinction image for the page that is not stored as the show-through occurrence page in the processing of S171 or S179 is referred to as“ OK ”display.

  The user can switch the display of the pressed show-through distinguishing images 72b, 73b, 74b, and 75b by pressing the show-through distinguishing images 72b, 73b, 74b, or 75b via the operation unit 11. For example, a user who has seen the preview image 73a of the second page image has a small size of the image 73d in which the image 201a of the original document 201 of the first page is shown back, and the position of the image 73d is close to the edge. Considering the above, it may be determined that the show-through is not so much of interest, and the show-through distinguishing image 73b is switched from “NG” display to “OK” display. In addition, the user who has seen the preview image 74a of the third page image considers the thinness of the color density of the images 74d and 74e in which the images 212a and 212b of the document 212 of the fourth page are show-through, respectively. It can be considered that the show-through distinguishing image 74b is switched from the “NG” display to the “OK” display by judging that the show-through is not of interest. On the other hand, the user looks at the preview image of the image of the page determined not to be the show-through occurrence page by the show-through occurrence page determination means 18a, determines that the show-through is anxious, and determines the show-through discrimination image. It is also possible to switch from “OK” display to “NG” display.

  As shown in FIGS. 9 to 12, the show-through occurrence page determination means 18a determines whether or not the button 76 has been pressed until it is determined that the button 76 has been pressed after the processing of S181 (S182).

  When it is determined in S182 that the button 76 has been pressed, the show-through occurrence page determination means 18a determines whether or not all the pages are show-through occurrence pages (S183). Here, the show-through occurrence page determination means 18a accepts and accepts the page for which the show-through distinguishing image is “NG” displayed when the button 76 is pressed as the page designated as the show-through occurrence page. Page is determined as the show-through occurrence page. On the other hand, the show-through occurrence page determination means 18a determines a page in which the show-through distinguishing image is “OK” displayed when the button 76 is pressed as a page where no show-through occurs.

  Next, the control unit 18 determines whether or not a show-through occurrence page has been determined in S183 (S184).

  When determining in S184 that the show-through occurrence page has not been determined, the control unit 18 prints the images read by the processing of S164 and S172 on the recording medium on the recording medium by the printer 14 (S130). -The operation | movement shown in FIG.

  When it is determined in S184 that the show-through occurrence page has been determined, the reread unit 18c displays the reread selection screen 80 shown in FIG. 18 on the display unit 12 (S185).

  FIG. 18 is a diagram illustrating an example of the reread selection screen 80 displayed on the display unit 12.

  The re-reading selection screen 80 shown in FIG. 18 displays a message 81 for notifying selection of a re-reading method and instructing execution of re-reading, and re-reading in which all pages of the document are set in the ADF 13b. Radio button 82 for accepting designation, radio button 83 for accepting designation of re-reading in which only an NG document, that is, a document determined in S183 as a show-through occurrence page is set, and an instruction to execute re-reading And a button 84 for accepting. One of the radio buttons 82 and 83 is always selected. The user can select one of the radio buttons 82 and 83 via the operation unit 11. When the button 84 is pressed on the reread selection screen 80, the display by the display unit 12 ends.

  As shown in FIGS. 9 to 12, the re-reading means 18c determines whether or not the button 84 has been pressed until it is determined that the button 84 has been pressed after the processing of S185 (S186).

  If it is determined in S186 that the button 84 has been pressed, the rereading means 18c determines whether or not it has been replaced with a black top plate based on the detection result of a sensor (not shown) until it is determined that the button has been replaced with a black top plate. (S187).

  If the rereading unit 18c determines in S187 that the black top plate has been replaced, it sets the black top plate correction table 17b as a correction table for performing color correction processing (S188).

  Next, the rereading unit 18c determines the rereading method selected when the button 84 is pressed on the reread selection screen 80 (S189). Here, when the radio button 82 is selected at the time when the button 84 is pressed, the rereading unit 18c determines rereading in which all pages of the document are set as a rereading method. Further, when the radio button 83 is selected when the button 84 is pressed, the rereading unit 18c determines rereading in which only an NG document is set as a rereading method.

  When the rereading unit 18c determines in S189 that rereading in which only the NG document is set is a rereading method, the image reading is performed by using the black top plate correction table 17b set in S188 for the number of pages of the NG document. The image is read again from the original by the unit (S190), and the image read in S190 is replaced with the image of the NG original read by the process of S164 or S172 (S191). For example, when the total of the third page and the eighth page of the 10-page document is a NG document, the re-reading unit 18c reads the image of the first page read after the start of the re-read as the third page. The image of the page read next is replaced with the image of the eighth page.

  When the rereading unit 18c determines that the rereading in which all pages are set is determined as a rereading method in S189, the black top plate set in S188 is performed only on the pages of the NG document while carrying all the pages by the ADF 13b. The image is read again from the original by the image reading unit using the correction table 17b (S192), and the image read in S192 is replaced with the image of the NG original read in the process of S164 or S172 (S191). For example, when the total of the third and eighth pages of the 10-page original is a NG original, the re-reading unit 18c carries the ADF 13b for all 10 pages, but starts re-reading. Later, page 1 and page 2 were skipped again, the image of page 3 was reread and replaced with the previous page 3 image, page 4 to page 7 were skipped and page 8 was skipped. The reread image of the original of the eye is replaced with the previous image of the eighth page, and rereading of the ninth and tenth pages is skipped.

  The MFP 10 deletes the image of the page to be replaced in S191 from among the images read by the processing of S164 or S172 before the image is replaced with the black top board and is read again (S190 or S192). The storage capacity required for reading a document can be reduced.

  After the process of S191, the control unit 18 reads all the originals by the processes of S164 and S172, and prints an image at least partially replaced by the process of S191 on the recording medium by the printer 14 (S130). ), The operation shown in FIGS.

  In the above description, the copy job for printing the images on both sides of the document on both sides or one side of the recording medium has been described, but the same applies to the copy job for printing an image on one side of the document on one side or both sides of the recording medium. It is. However, in the case of a copy job in which an image on one side of a document, that is, an image on the front side is printed on one side or both sides of the recording medium, only the front side of the document is copied. The processing of S129 is unnecessary, and the processing of S165 to S171 only for judging the show-through of the image read by the image reading unit from the back side of the document is also unnecessary.

  Although the execution of the copy job has been described above, the same applies to the execution of various jobs such as a scan job and a fax job that process an image read from the document by the scanner 13.

  As described above, the MFP 10 replaces the image that has been read again by the image reading unit (S190 or S192) only with the page that has been determined to cause show-through (S183) with the image that was previously read by the image reading unit. (S191). For this reason, the MFP 10 sets the image of the page determined to show no show-through as an image read by the image reading unit (S164 or S172) when the white top plate is arranged facing the image reading unit (S164 or S172). The image of the page determined to cause show-through is assumed to be an image read by the image reading unit (S190 or S192) when the black top is placed facing the image reading unit. Therefore, the MFP 10 can obtain a high-quality image as a whole.

  When the MFP 10 notifies the replacement proposal to the black top board (S181), the MFP 10 notifies the image read by the image reading unit by a preview image. Then, the MFP 10 receives the designation of the page where the show-through occurs, and determines the received page as the page where the show-through occurs (S183). Therefore, the MFP 10 allows the user to visually recognize the actually read image, and can replace the image only on the page determined by the user when the show-through occurs.

  When notifying the replacement proposal to the black top board (S181), the MFP 10 does not notify the image read by the image reading unit with the preview image, but only notifies the page determined that the show-through occurs. You may do it. In this case, the MFP 10 allows the user to visually recognize the original of the page determined to show through, and can replace the image only on the page determined by the user to show through.

  In addition, when notifying the replacement proposal to the black top board (S181), the MFP 10 does not need to notify the page that is determined that the show-through occurs. In this case, the MFP 10 cannot adopt re-reading only for NG originals as a re-reading method, but can adopt re-reading for all pages of originals as a re-reading method.

  Since the MFP 10 causes the image reading unit to read the image again only for the page to be replaced with the image previously read by the image reading unit, the efficiency can be improved. In particular, when reading a document of a plurality of pages, when the user manually sets the document to the image reading unit 13c page by page without using the ADF 13b, the MFP 10 improves the efficiency of re-reading, User's work stress can be reduced.

  Note that the MFP 10 may be a hand that causes all pages to be read again by the image reading unit regardless of the page to be replaced with the image previously read by the image reading unit. That is, the MFP 10 may replace only some pages of the images read again by the image reading unit for all pages.

  When the MFP 10 causes the image reading unit to read the image again, when all the originals are conveyed by the ADF 13b, the image reading unit applies an image to a page other than the page to be replaced with the image previously read by the image reading unit. Is carried out by the ADF 13b without reading again (S192). With this configuration, the MFP 10 can improve efficiency because the user does not need to extract pages to be replaced from the entire pages of the document.

  The MFP 10 is a pixel having a specific density or higher in an image read by the image reading unit from one side of the document, that is, a pixel having such a high density that it can be seen through the other side of the document when viewed from the other side of the document. Is determined (YES in S167 or YES in S175), it is determined that show-through occurs in the image read by the image reading unit from the other side of the document (YES in S180). When the MFP 10 determines that a show-through occurs when the white top plate is disposed facing the image reading unit (white in S121), the MFP 10 proposes replacement to the black top plate. Notification is made (S181). Therefore, the MFP 10 does not require the user to determine whether or not show-through occurs in the image read by the image reading unit, and can improve convenience. That is, the user may first execute image reading in a state where the white top plate is mounted on the lid 13a. Then, only when the MFP 10 determines that the show-through occurs and the MFP 10 notifies the user of the replacement proposal for the black top board, the user only needs to replace the black top board and read the image again. .

  Further, when there are a specific number or more of pixels having a specific density or more in an image read by the image reading unit from one side of the original (YES in S169 or YES in S177), the MFP 10 starts from the other side of the original. It is determined that show-through occurs in the image read by the image reading unit. That is, the MFP 10 has pixels with a specific density or higher even when pixels having a specific density or higher exist in an image read by the image reading unit from one side of the document (YES in S167 or YES in S175). When the number is less than the specific number (NO in S169 or NO in S177), it is not determined that show-through occurs in the image read by the image reading unit from the other side of the document (NO in S180). Therefore, the MFP 10 can improve convenience without causing a problem of slight show-through that does not bother the user.

  The MFP 10 accepts designation of the show-through determination density threshold value 17c and the show-through determination pixel number threshold value 17d, and therefore the criterion for determining whether or not show-through occurs in the image read by the image reading unit is the user's preference. Can be adjusted to

  When the white top plate is arranged to face the image reading unit (white in S121), the MFP 10 receives an instruction that the document is highly likely to show through, that is, a backing document. (S122: YES), a replacement proposal for the black top board is notified (S123), so the convenience can be improved.

  When the MFP 10 accepts a document with a low possibility of show-through, that is, a thick paper document (YES in S131 and YES in S142), the black top plate faces the image reading unit. When it is placed (black in S121), a proposal to replace the white top plate is notified (S143), and when the white top plate is placed facing the image reading unit (white in S121), show-through occurs. Does not determine whether or not to do. Therefore, the MFP 10 can improve convenience.

  In this embodiment, a back paper document is used as a document with a high possibility of show-through, but a document other than a back paper document is used as a document with a high possibility of show-through. May be adopted. In this embodiment, a thick paper document is used as a document with a low possibility of show-through, but a document other than a thick paper document is used as a document with a low possibility of a show-through. May be.

  In the image forming apparatus of the present invention, the first member and the second member are the white top plate and the black top plate, respectively, in the present embodiment. However, if the color density of the second member is higher than that of the first member, It may be other than a plate or a black top plate. For example, when the first member is a white top plate, the second member may be a gray top plate, a green top plate, or a blue top plate.

  The image forming apparatus of the present invention is an MFP in the present embodiment, but may be an image forming apparatus other than an MFP, such as a copy-only machine, a scanner-only machine, or a fax-only machine, as long as it includes a scanner.

10 MFP (image forming apparatus)
13b ADF (automatic document feeder)
13c, 13d Image reading unit 13e, 13f White top plate (first member)
13g, 13h Black top plate (second member)
17c Density threshold for show-through determination (specific density)
17d Threshold for pixel count for show-through determination (specific number)
18a Show-through occurrence page determination means 18b Black top board replacement notification means (second member replacement notification means)
18c Rereading means 72a, 73a, 74a, 75a Preview image 90 Original 200, 201, 202 Original 210, 211, 212 Original

Claims (7)

An image reading unit for reading an image from a document;
A first member disposed opposite to the image reading unit and sandwiching a document together with the image reading unit when the image reading unit reads an image;
A second member having a darker color density than the first member and exchangeable with the first member;
Show-through occurrence page determination means for determining whether or not the image read by the image reading unit is a page where show-through occurs;
Second member replacement notification means for notifying the replacement proposal to the second member;
Re-reading means for re-reading the image by the image reading unit after the replacement proposal to the second member is notified by the second member replacement notification means;
The show-through occurrence page determination means determines whether the show-through occurs or not based on the image read by the image reading unit,
The second member replacement notifying unit is configured such that when the first member is disposed to face the image reading unit and the page where the show-through occurs is determined by the show-through occurrence page determining unit, Notify the replacement proposal for the second part,
When the show-through occurs, the re-reading unit replaces the image read again by the image reading unit with the image read by the image reading unit only for the page determined by the show-through occurrence page determining unit. An image forming apparatus. The second member replacement notification means notifies the page determined by the show-through occurrence page determination means when show-through occurs when notifying the replacement proposal to the second member,
The image forming apparatus according to claim 1, wherein the show-through occurrence page determination unit receives designation of a page on which show-through occurs and determines the received page as a page on which show-through occurs.   The second member replacement notifying unit notifies an image read by the image reading unit when notifying a page determined by the show-through occurrence page determining unit when a show-through occurs. Item 3. The image forming apparatus according to Item 2.   The re-reading unit causes the image reading unit to read the image again only for a page that is replaced with the image read by the image reading unit last time. Image forming apparatus. An automatic document feeder that automatically conveys a document to the image reading unit;
When the image reading unit causes the image reading unit to read the image again, the rereading unit replaces a page other than the page that is replaced with the image read previously by the image reading unit when all the documents are conveyed by the automatic document feeder. The image forming apparatus according to claim 4, wherein the automatic document feeder performs conveyance without causing the image reading unit to read the image again.   The show-through occurrence page determination means is read by the image reading unit from the other side of the document when pixels having a specific density or more exist in the image read by the image reading unit from the one side of the document. 6. The image forming apparatus according to claim 1, wherein it is determined that show-through occurs in the image.   The show-through occurrence page determination unit is configured to read the image from the other side of the document when the image read by the image reading unit from one side of the document has a specific number or more of pixels. The image forming apparatus according to claim 6, wherein it is determined that show-through occurs in the image read by the section.