JP2011083909A - Image processor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To generate double-side printing image data having a proper density while preventing the occurrence of ink retransfer and paper jamming. <P>SOLUTION: A selection signal is received by a density selection receiving part so as to select whether to apply density lowering processing to only one of the surfaces of two image data for double-side printing or to apply density lowering processing to both of the surfaces. The density lowering processing is applied to only one surface of the two image data or to both surfaces on the basis of the received selection signal. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to an image processing apparatus that performs density conversion processing on two pieces of image data of a front surface and a back surface that are used for duplex printing.

  Conventionally, a thermal head or the like is driven based on image data read from a document by a scanner or the like, and a stencil sheet is melted and perforated to create a plate, and the created plate is wound around a printing drum. Various stencil printing apparatuses that perform printing by supplying ink from the inside of the printing drum and transferring the ink to printing paper using rollers or the like have been proposed.

  As a stencil printing apparatus as described above, for example, Patent Document 1 proposes a stencil printing apparatus for double-sided printing that includes two printing drums. Specifically, the stencil printing apparatus for double-sided printing described in Patent Document 1 performs printing on one side of a printing paper by a first printing drum, and the unprinted side of the printing paper on one side is the second. After the single-sided printed paper is reversed and conveyed so as to face the printing drum, printing is performed on the unprinted side of the single-sided printed paper by the second printing drum.

  Here, in the stencil printing apparatus for double-sided printing described in Patent Document 1, for example, when printing a high-density image by the first printing drum, printing on one side is performed by the first printing drum. After finishing, the other side is printed before the ink on the printing side is sufficiently dried.Therefore, on the printing side of the printing paper to the transport roller, press roller, etc. on the paper passing path after the printing paper is reversed. Ink is transferred, and the ink is transferred again from these rollers to the subsequent printing paper. In addition, when the print density is high, it may be difficult to peel off the printed printing paper from the printing drum due to the adhesive force of the ink. There is a problem that paper jam occurs due to being swung up by the printing drum.

JP 2005-29375 A

  Thus, for example, it is conceivable to reduce the density of the image printed by the first printing drum.

  However, if the density of only the front image is reduced, as shown in FIG. 6, a difference in density appears between the front and back images, resulting in a different finished state. Doing so may make it difficult to see the printed matter or may make it look bad.

  SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide an image processing apparatus capable of generating image data for double-sided printing having an appropriate density without causing retransfer of ink or paper jam. Is.

  An image processing apparatus according to the present invention includes an image data receiving unit that receives input of two image data on the front and back sides used for double-sided printing, and one side of two image data received by the image data receiving unit. 2 based on a selection signal received by the density selection receiving unit and a density selection receiving unit that receives a selection signal for performing a process for reducing the density only or a process for reducing the density on both surfaces. And a density conversion unit that performs a process of reducing the density on only one surface or both surfaces of the image data.

  In the image processing apparatus of the present invention, the image data on the one surface can be used as image data used for the first printing of the two image data.

  Two sheets of image data are used in a stencil printing machine for two-sided printing having two printing units each having a printing drum and a press roller, and one of the two pieces of image data is selected in the density selection receiving unit. When it is selected to perform the process of reducing the density only on the surface, a control signal is output so as to reduce the press pressure of the press roller of the printing unit that performs printing using the image data of the one surface. When it is selected in the density selection accepting unit that processing to reduce the density is performed on both sides of the two pieces of image data, a control signal is output so as to reduce the press pressure of the press rollers of the two printing units. A press pressure control signal output unit can be further provided.

  In addition, two sheets of image data are used in a stencil printing apparatus for double-sided printing that includes a heat generating section that punches a stencil sheet according to the image data, and the density selection receiving section receives two images. When it is selected to reduce the density only on one surface of the data, the heat generation energy is reduced with respect to the heat generating portion only when the plate making is performed using the image data on the one surface. When the density selection receiving unit selects to reduce the density on both sides of the two pieces of image data, plate making is performed using the image data on both sides. A heat generation energy control signal output unit that outputs a control signal for reducing the heat generation energy to the heat generation unit when performing can be further provided.

  In addition, the density selection receiving unit displays a selection screen for selecting whether to perform the process of reducing the density only on one of the surfaces or to perform the process of reducing the density on both surfaces. Can do.

  According to the image processing apparatus of the present invention, it is possible to select whether to perform the process of reducing the density only on one side of the two image data for duplex printing, or to perform the process of reducing the density on both sides. Since the signal is received, and the processing for reducing the density is applied to only one surface or both surfaces of the data of the two images based on the received selection signal, for example, retransfer of ink If you want to prevent the occurrence of paper jams and improve the balance between the density of the front and back surfaces, you can choose to reduce the density on both sides. If you just want to prevent jamming, or if you have an image that represents a photograph that you do not want to reduce the density, you can choose to apply a process that reduces the density on only one side. Suitable for A density conversion processing can be subjected.

  Further, in the image processing apparatus of the present invention, when it is selected that the density reduction process is performed only on one side of the two pieces of image data, printing is performed using the image data on the one side. If it is selected to output a control signal that lowers the press pressure of the press roller of the printing unit that performs printing and to reduce the density on both sides of the two image data, two printing units When a control signal that lowers the press pressure of the press roller is output, it is possible to realize printing at a more appropriate density.

  If it is selected to reduce the density only on one side of the two pieces of image data, only when the plate making is performed using the image data on the one side, the heating part is applied. When it is selected to output a control signal that reduces the heat generation energy and to reduce the density on both sides of the two pieces of image data, plate making is performed using the image data on both sides. When a control signal for reducing the heat generation energy is output to the heat generating portion when performing the above, it is possible to realize printing at a more appropriate density.

  In addition, when a selection screen for selecting whether to reduce the density only on one surface or to decrease the density on both surfaces is displayed, a density conversion process is performed. Can be easily selected.

1 is an overall schematic configuration diagram of a stencil printing system using an embodiment of an image processing apparatus of the present invention. 1 is a block diagram showing a schematic configuration of the printer driver shown in FIG. FIG. 3 is a diagram showing an example of a user interface displayed by the printer driver shown in FIG. Flowchart for explaining the operation of the stencil printing system shown in FIG. The figure which shows an example of the printing state at the time of performing density conversion processing to the image data of both surfaces The figure which shows an example of the printing state at the time of performing a density conversion process only to the image data of the surface Block diagram showing a schematic configuration of another embodiment of a printer driver Block diagram showing a schematic configuration of another embodiment of a printer driver Block diagram showing a schematic configuration of another embodiment of a printer driver

  Hereinafter, a stencil printing system using an embodiment of an image processing apparatus of the present invention will be described in detail with reference to the drawings. The stencil printing system of this embodiment is characterized by the density conversion of image data. First, the overall schematic configuration will be described. FIG. 1 is an overall schematic configuration diagram of a stencil printing system of the present embodiment.

  As shown in FIG. 1, the stencil printing system of the present embodiment has software installed for editing image data on the front and back sides used for double-sided printing, accepts the two image data, and receives PDL (Page Description language) A computer 1 in which a printer driver 25 that converts and outputs print data such as data is installed, and a stencil printing apparatus 2 that performs double-sided printing based on the print data output from the printer driver 25 of the computer 1 It has.

  As shown in FIG. 1, the stencil printing apparatus 2 reads a document image and outputs image data, and performs stencil printing on the stencil sheet M based on the image data read by the image reading unit 10. First and second plate making sections 30 and 35, and first and second printing sections 40 for printing on printing paper P1 using stencil sheet M made by the first and second plate making sections 30 and 35, 50, the paper feeding unit 20 that feeds the printing paper P1 to the first printing unit 40, the printing paper P2 that has been printed on one side in the first printing unit 40 is temporarily stocked, and then the second printing is performed at a predetermined timing. An intermediate stock unit 46 that feeds the paper 50 and a paper discharge unit 70 that discharges the printing paper P3 printed on both sides by the second printing unit 50 are provided.

  The image reading unit 10 includes a line image sensor that photoelectrically reads image information of a document, scans the document with the line image sensor, and outputs image data.

  The first plate making unit 30 has a thermal head 31 in which a plurality of heating elements are arranged in a line, and performs the plate making process on the stencil sheet M fed from the stencil sheet roll using the thermal head 31. Is. The first plate making unit 30 performs plate making processing based on print data output from the printer driver 25 of the computer 1.

  Similarly to the first plate making unit 30, the second plate making unit 35 has a thermal head 36, and performs the plate making process on the stencil sheet M fed from the stencil sheet roll using the thermal head 36. is there. The second plate making unit 35 also performs plate making processing based on the print data output from the printer driver 25 of the computer 1.

  In the present embodiment, two plate making portions are provided. However, the present invention is not limited to this, and only one plate making portion is provided, and the plate making portion is defined as the position of the first plate making portion 30 shown in FIG. You may make it move to the position of the 2nd plate making part 35. FIG.

  The first printing unit 40 presses the printing paper P1 and the first printing drum 41 with a predetermined press pressure against the first printing drum 41 having a cylindrical shape such as a perforated metal plate or a mesh structure. A first press roller 42 and a first stripping claw 43 for stripping the single-side printed paper P2 from the first printing drum 41 are provided. A pre-made stencil sheet M perforated in the first plate making unit 30 is wound around and attached to the outer periphery of the first printing drum 41.

  Similarly to the first printing unit 40, the second printing unit 50 is configured to press the cylindrical second printing drum 51 and the printing paper P2 against the second printing drum 51 with a predetermined press pressure. A press roller 52 and a second peeling claw 53 for peeling the double-side printed paper P3 from the second printing drum 51 are provided. A pre-made stencil sheet M perforated in the second plate making unit 35 is wound around and attached to the outer periphery of the second printing drum 51.

  In the present embodiment, the surface of the printing paper printed by the first printing unit 40 is referred to as the front surface, and the surface of the printing paper printed by the second printing unit 50 is referred to as the back surface.

  The paper supply unit 20 includes a paper supply base 21 on which the print paper P1 is placed, and a primary paper supply roller 22 that takes out the print paper P1 one by one from the paper supply base 21 and sends it to the secondary paper supply roller 23. The leading end of the printing paper P1 that is disposed downstream of the primary paper feeding roller 22 in the carrying direction is temporarily stopped, and the printing paper P1 is transferred to the first printing drum at a predetermined timing. A secondary paper feed roller 23 is provided between 41 and the first press roller 42.

  The paper discharge unit 70 is a paper discharge feeding belt unit 72 that conveys the double-sided printed printing paper P3 to the paper discharge table 71, and a paper discharge on which the double-sided printed printing paper P3 conveyed by the paper discharge feeding belt unit 72 is stacked. A stand 71 is provided.

  Further, a curved conveyance unit 44 is installed between the first printing unit 40 and the intermediate stock unit 46. As shown in FIG. 1, the curved conveyance unit 44 includes a guide plate having a curved surface along the conveyance path. On the curved surface of the guide plate, a conveyor belt provided with a suction port for sucking the printing paper P1 sent out from the first printing unit 40 is installed. A pulley 45 that circulates and moves the transport belt is provided. The curved conveyance unit 44 sucks the single-side printed paper P2 by the suction port of the conveyance belt, and rotates the pulley 45 to convey the single-side printed paper P2 by the conveyance belt along the curved surface of the guide plate. Is.

  Further, between the intermediate stock unit 46 and the second printing unit 50, a pickup roller 47 that picks up the single-side printed printing paper P <b> 2 carried out from the intermediate stock unit 46, and single-sided printing picked up by the pickup roller 47. There is provided a timing roller 48 that sequentially feeds the finished printing paper P2 between the second printing drum 51 and the second press roller 52 at a predetermined timing.

  Next, the printer driver 25 of the computer 1 will be described. FIG. 2 is a block diagram illustrating a schematic configuration of the printer driver 25.

  As shown in FIG. 2, the printer driver 25 receives an image data receiving unit 26 that receives two image data of the front and back sides for duplex printing output from the image data editing software, and an image data receiving unit 26. A density selection receiving unit 27 that receives a selection signal for performing a process of reducing the density only on one surface of the two pieces of image data or performing a process of reducing the density on both surfaces; Based on the selection signal received by the receiving unit 27, a density conversion unit 28 that performs a process of reducing the density only on one surface or both surfaces of the data of the two images, and the density conversion unit 28 A data conversion unit 29 that converts image data subjected to density conversion into print data of PDL data and outputs the print data to the stencil printing apparatus 2 is provided.

  The density selection receiving unit 27 displays a screen as shown in FIG. 3 on the monitor as a user interface. In the user interface shown in FIG. 3, “I = II density follow-up” can be selected by checking the check box (see the dotted line in FIG. 3). Then, when the “I = II density follow-up” check box is checked by the user, the density selection receiving unit 27 receives a selection signal for performing density reduction processing on both surfaces, and “I = II When the user does not check the “Density tracking” check box, a selection signal for performing a process of reducing the density only on one surface is received. If the check box is not checked, the front side print density I printed by the first printing unit 40 and the back side print density II printed by the second printing unit 50 are further calculated. It can be set by pull-down menu whether either one is thinned.

  As described above, the density conversion unit 28 performs a density conversion process for reducing the density of the image data. As the density conversion process, for example, there is a thinning process. Any processing may be used, and density conversion processing using mathematical expressions such as a density conversion curve may be performed.

  Next, the operation of the stencil printing system of this embodiment will be described with reference to the flowchart shown in FIG.

  First, when the computer 1 generates two image data for the front and back surfaces for double-sided printing and receives a signal for instructing double-sided printing based on the two image data, as shown in FIG. A user interface is displayed (S10).

  Next, the user selects whether or not to check the “I = II density tracking” check box.

  Here, as described above, when performing double-sided printing, if the density of the surface to be printed first is high, there is a problem of paper jam or paper stains. If it does in this way, the printing density of the front surface and back surface of a printed matter will differ, and it will be difficult to see as a printed matter, or it may be bad in appearance.

  Therefore, in the stencil printing system of the present embodiment, in order to improve the finish of the printed matter, a check box of “I = II density tracking” is provided, and when this check box is checked, only the surface is checked. In addition, a process for reducing the density of the back surface is also performed, so that the density of the front surface and the back surface can be made equal.

  Specifically, when the check box of “I = II density tracking” is checked (S12, YES), the selection signal is output to the density converter 28, and the density converter 28 receives the two input sheets. Density conversion processing is performed on both of the image data, that is, both of the image data printed by the first and second printing units 40 and 50 (S14).

  On the other hand, for example, when the image data on the back side is image data representing a photograph, for example, there is a case where it is not desired to reduce the density because the print quality decreases when the density is reduced. In such a case, the check box of “I = II density follow-up” is not checked, a light density is selected in the pull-down menu for print density I, and a normal density is selected in the pull-down menu for print density II.

  Then, the selection signal as described above is output from the density selection receiving unit 27 to the density conversion processing unit 28, and the density conversion processing unit 28, that is, the image data of the surface of the input two pieces of image data, that is, Only the image data printed by the first printing unit 40 is subjected to density conversion processing (S16). In this embodiment, when the check box “I = II density follow” is not checked, the print density I on the front surface and the print density II on the back surface can be arbitrarily selected. It is assumed that density conversion processing is performed according to the selected density. However, the present invention is not limited to this, and when the check box of “I = II density follow-up” is not checked, as a default, the front side print density I is light and the back side print density II is normal and automatic. You may make it become.

  The image data subjected to the density conversion processing in the density conversion processing unit 28 is output to the data conversion unit 29, converted into print data of PDL data by the data conversion unit 29, and then output to the stencil printing apparatus 2. (S18, S20).

  Then, the front side printing data is input to the first plate making unit 30 and the plate making process is performed, and the back side printing data is input to the second plate making unit 35 and the plate making process is performed.

  The plate subjected to the plate making process in the first plate making unit 30 is wound around the first printing drum 41, and the plate subjected to the plate making process in the second plate making unit 35 is used as the second printing drum. The print operation is executed (S22).

  Specifically, ink is supplied to the inside of the first and second printing drums 41 and 51 by an ink supply pump (not shown), and the first and second printing drums 41 and 51 are rotationally driven. Then, the printing paper P1 is fed out from the paper feed tray 21 by the primary paper feed roller 22 at a predetermined timing in synchronization with the rotation of the first and second print drums 41 and 51, and once the secondary paper feed roller 23 is reached. 1 is formed by the secondary paper feed roller 23 from the left to the right in FIG. 1 at a predetermined timing, and is supplied between the first printing drum 41 and the first press roller 42. The Then, the printing paper P1 is pressed against the printing paper P1 by the first press roller 42 against the stencil stencil sheet M wound around the outer peripheral surface of the first printing drum 41. Is done.

  Then, when the first printing drum 41 is rotated by a predetermined angle and the single-sided stencil printing on the printing paper P1 is completed, the single-sided printing paper P2 is peeled off from the first printing drum 41 by the peeling claw 43. The single-sided printed printing paper P <b> 2 that has been removed and peeled off is conveyed to the intermediate stock unit 46 by the curved conveyance unit 44.

  The single-sided printed printing paper P2 is once stocked in the intermediate stock unit 46, and then discharged from the intermediate stock unit 46 with the printing surface facing downward (the non-printed surface is the upper side). And is once abutted against the timing roller 48 to form a slack and then supplied between the second printing drum 51 and the second press roller 52 by the timing roller 48 at a predetermined timing.

  Then, the non-printed surface of the single-sided printed paper P2 is pressed against the stencil stencil sheet M wound around the outer peripheral surface of the second printing drum 51 by the second press roller 52, so that the single-sided printing is completed. Stencil printing is performed on the unprinted surface of the printing paper P2.

  When the second printing drum 51 rotates by a predetermined angle and stencil printing on the unprinted surface of the single-sided printed paper P2 is completed, the double-sided printed paper P3 is removed by the second nail 53 by the peeling claw 53. The double-sided printed printing paper P3 that has been peeled off from the printing drum 51 is transported to the paper discharge tray 71 by the paper discharge feed belt 72 and stacked on the paper discharge tray 71.

  Then, the printing paper P1 is again fed out from the paper feed tray 21, and double-sided stencil printing is performed on the printing paper P1 in the same manner as described above.

  Here, FIG. 5 shows an example of the printing state of the front and back surfaces when the “I = II density tracking” check box is checked in the user interface. For comparison, FIG. 6 shows an example of a print state when density conversion processing is performed only on the surface.

  In the stencil printing system of the above embodiment, the density conversion process is switched based on whether or not the “I = II density tracking” check box is checked in the user interface. Alternatively, the press pressures of the press rollers in the first printing unit 40 and the second printing unit 50 may be switched.

  Specifically, as shown in FIG. 7, the printer driver 25 is further provided with a press roller control signal output unit 80. When the check box “I = II density tracking” is checked in the user interface, the selection signal is output to the press roller control signal output unit 80, and the press roller control signal output unit 80 2, the control is performed such that the press pressure of the first press roller 42 of the first printing unit 40 and the press pressure of the second press roller 52 of the second printing unit 50 are lower than the normal press pressure. Output a signal.

  The stencil printing apparatus 2 controls the press pressure of the first press roller 42 and the press pressure of the second press roller 52 to be lower than the normal press pressure in response to the input of the control signal as described above. To do.

  On the other hand, when the check box of “I = II density follow-up” is not checked and a light density is selected in the pull-down menu of print density I, and a normal density is selected in the pull-down menu of print density II, the selection signal Is output from the density selection receiving unit 27 to the press roller control signal output unit 80, and the press roller control signal output unit 80 is configured so that only the press pressure of the first press roller 42 of the first printing unit 40 is a normal press pressure. A control signal that is lower than that is output.

  The stencil printing apparatus 2 controls the press pressure of the first press roller 42 to be lower than the normal press pressure in response to the input of the control signal as described above, and the second press roller 52 The press pressure is controlled to be a normal press pressure.

In short, the density conversion processing unit 28 controls the press pressure of the press roller of the printing unit that prints the image data subjected to density conversion processing to be lower than the normal press pressure.
In the above description, the press roller presses in the first printing unit 40 and the second printing unit 50 are performed together with the density conversion process based on whether or not the check box of “I = II density tracking” is checked. Although the pressure is switched, the heat generation energy of the thermal heads 31 and 36 in the first plate making unit 30 and the second plate making unit 35 may be switched.

  Specifically, as shown in FIG. 8, the printer driver 25 is further provided with a thermal head control signal output unit 81. When the “I = II density tracking” check box is checked in the user interface, the selection signal is output to the thermal head control signal output unit 81, and the thermal head control signal output unit 81 2, a control signal is output so that the heat generation energy of the thermal head 31 of the first plate making unit 30 and the heat generation energy of the thermal head 36 of the second plate making unit 35 are lower than normal heat generation energy.

  The stencil printing apparatus 2 controls the heat generation energy of the thermal head 31 and the heat generation energy of the thermal head 36 to be lower than the normal heat generation energy in response to the input of the control signal as described above.

  On the other hand, when the check box of “I = II density follow-up” is not checked and a light density is selected in the pull-down menu of the print density I and a normal density is selected in the pull-down menu of the print density II, the selection signal Is output from the density selection receiving unit 27 to the thermal head control signal output unit 81, and the thermal head control signal output unit 81 is such that only the heat generation energy of the thermal head 31 of the first plate making unit is lower than the normal heat generation energy. Such a control signal is output.

  The stencil printing apparatus 2 controls the heat generation energy of the thermal head 31 to be lower than the normal heat generation energy in response to the input of the control signal as described above, and the thermal head 36 of the second plate making unit 35. The exothermic energy is controlled so as to be normal exothermic energy.

  In short, control is performed so that the heat generation energy of the thermal head becomes lower than the normal heat generation energy only when plate making is performed by the density conversion processing unit 28 based on the image data subjected to density conversion processing.

  As a method of reducing the heat generation energy, the heat generation time may be shortened or the heat generation temperature may be decreased.

  Further, based on whether or not the check box of “I = II density follow-up” is checked, together with the density conversion process, the press pressure of the press roller in the first printing unit 40 and the second printing unit 50 and the first Both the heat generation energy of the thermal heads 31 and 36 in the plate making unit 30 and the second plate making unit 35 may be switched.

  Specifically, as shown in FIG. 9, the printer driver 25 may be provided with both a press roller control signal output unit 80 and a thermal head control signal output unit 81. The method for controlling the press pressure and the heat generation energy is the same as described above.

  In the stencil printing system of the above embodiment, for example, when page processing such as so-called N-up or booklet is performed, image data of a plurality of pages may be arranged on the front surface or the back surface of the printing paper. In such a case, it is assumed that density conversion processing is performed on the image data of all pages arranged on the front surface or the image data of all pages arranged on the back surface. In short, it is assumed that the density conversion process is performed not on a page basis but on a front or back side image data unit.

  In the stencil printing system of the above embodiment, when the “I = II density tracking” check box is checked, the density conversion process is performed so that the image data on the front side and the image data on the back side have the same density. However, the density does not necessarily have to be the same, and it is sufficient that the density of the image data on one side is closer to the density of the image data on the other side than the normal density.

  In the stencil printing system of the above embodiment, the image processing apparatus of the present invention is mounted on the computer 1 as the printer driver 25. However, the present invention is not limited to this, and the image processing apparatus of the present invention is installed on the stencil printing apparatus 2 side. You may make it provide. In this case, the image data receiving unit 26 can receive the image data read by the image reading unit 10. In this case, the user interface may be displayed on the computer 1 or may be displayed on an operation unit including a touch panel provided in the stencil printing apparatus 2.

DESCRIPTION OF SYMBOLS 1 Computer 2 Stencil printing device 25 Printer driver 26 Image data reception part 27 Density selection reception part 28 Density conversion part 28 Density conversion process part 29 Data conversion part 40 1st printing part 41 1st printing drum 42 1st press roller 46 Intermediate stock section 50 Second printing section 51 Second printing drum 52 Second press roller 80 Press roller control signal output section

Claims (5)

An image data accepting unit that accepts input of two image data on the front side and the back side used for duplex printing;
Density selection that accepts a selection signal for performing a process of reducing the density only on one side of the two pieces of image data received by the image data receiving unit or a process of reducing the density on both sides A reception department;
A density conversion unit that performs a process of reducing the density on only one surface or both surfaces of the data of the two images based on the selection signal received by the density selection receiving unit; An image processing apparatus.   The image processing apparatus according to claim 1, wherein the image data of the one surface is image data used for first printing of the two pieces of image data. The two pieces of image data are used in a stencil printing apparatus for double-sided printing having two printing units each having a printing drum and a press roller,
When the density selection receiving unit selects to reduce the density only on one side of the two pieces of image data, the printing is performed using the image data on the one side When a control signal for lowering the press pressure of the press roller of the unit is output, and it is selected in the density selection receiving unit to perform a process of reducing the density on both surfaces of the two image data The image processing apparatus according to claim 1, further comprising a press pressure control signal output unit that outputs a control signal that lowers a press pressure of the press roller of the two printing units. The two pieces of image data are used in a stencil printing apparatus for double-sided printing provided with a heat generating part that perforates stencil paper according to the image data to make a plate,
When it is selected in the density selection receiving unit that the density reduction process is performed only on one side of the two pieces of image data, only when the plate making is performed using the image data on the one side When a control signal for reducing the heat generation energy is output to the heat generating unit, and the density selection receiving unit is selected to perform a process of reducing the density on both surfaces of the two image data The method further includes a heat generation energy control signal output unit that outputs a control signal for reducing the heat generation energy to the heat generation unit when plate making is performed using the image data of both surfaces. The image processing apparatus according to any one of claims 1 to 3.   The density selection receiving unit displays a selection screen for selecting whether to perform the process of reducing the density only on the one surface or to perform the process of reducing the density on both surfaces. The image processing apparatus according to claim 1, wherein the image processing apparatus is characterized.