Image processing apparatus, image processing method, program, method for manufacturing a sleeve printing plate, and method for manufacturing a can

Abstract

To provide a technique capable of suppressing deterioration of appearance.SOLUTION: An image processing device includes: a first background image generating part for generating a first background image obtained by extracting an overlapping region where overlapping images overlap, from a background image including dots out of processing object images composed of the background image and an overlapping image overlapped with the background image; a second background image generating part for generating a second background image having an edging part for edging the overlapping region relative to the first background image generated by the first background image generating part; and an overlapping image generating part for generating the overlapping image out of the processing object image.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to an image processing apparatus, an image processing method, a program, a method for manufacturing a sleeve printing plate, and a method for manufacturing a can.

Background Art

[0002] There is a case where an image in which a character image is superimposed on a background image including halftone dots is printed on a can. In this case, the background image pattern showing the background image and the character image pattern showing the character image are formed on different sleeve bodies, respectively, so that the image is printed on the can.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When an image in which a character image is superimposed on a background image including halftone dots is printed on a can, the halftone dots may enter the characters and reduce readability. Specifically, this will be described using FIG. 15. FIG. 15(A) shows a processing target image which is an original image to be printed on a can. As shown in FIG. 15(A), the processing target image is composed of a character image of the word "can" and a background image including halftone dots. Note that the actual size when the image shown in FIG. 15 is printed on a can is about 4 mm × 2 mm.

[0005] FIG. 15(B) is a diagram showing an image actually printed on a can. As shown in FIG. 15(B), it is shown that the alignment is misaligned, the halftone dots enter the characters, and the readability deteriorates significantly. Such a phenomenon is not limited to characters, but occurs in all images superimposed on a background image including halftone dots, so there is a problem that the appearance deteriorates.

[0006] In view of the above circumstances, the present invention aims to provide a technology that can suppress deterioration of appearance. [Means for solving the problem]

[0007] One aspect of the present invention comprises: a first background image generation unit that generates a first background image from a background image, which is composed of a background image containing halftone dots and a superimposed image superimposed on the background image, by removing the superimposed region in which the superimposed image overlaps; a second background image generation unit that generates a second background image, which is provided with a border portion that outlines the superimposed region in the first background image generated by the first background image generation unit; and a superimposed image generation unit that generates the superimposed image from the image to be processed. The superimposed image is an image containing halftone dots or an image extracted from the image to be processed, and the second background image generation unit sets the color of the border to be the same as the color of the halftone dots. It is an image processing device.

[0008] One aspect of the present invention comprises: a first background image generation step of generating a first background image from a processing target image which is composed of a background image including halftone dots and a superimposed image superimposed on the background image, by removing the superimposed region in which the superimposed image overlaps; a second background image generation step of generating a second background image which is provided with a border step that outlines the superimposed region on the first background image generated by the first background image generation step; and a superimposed image generation step of generating the superimposed image from the processing target image. The superimposed image is an image containing halftone dots or an image extracted from the image to be processed, and the second background image generation step sets the color of the border portion to the same color as the halftone dots. This is an image processing method.

[0009] One aspect of the present invention is a program for causing a computer to function as an image processing device, wherein the computer functions as: a first background image generation unit that generates a first background image by removing the overlapping region where the overlapping image overlaps from the background image of an image to be processed, which is composed of a background image including halftone dots and an overlapping image superimposed on the background image; a second background image generation unit that generates a second background image by providing an outline portion that borders the overlapping region to the first background image generated by the first background image generation unit; and an overlapping image generation unit that generates the overlapping image from the image to be processed. The superimposed image is an image containing halftone dots or an image extracted from the image to be processed, and the second background image generation unit sets the color of the border to be the same as the color of the halftone dots. It is a program.

[0010] One aspect of the present invention is a method for manufacturing a sleeve printing plate, comprising an image pattern forming step of forming an image pattern on a cylindrical sleeve body, and using a laser processing machine equipped with a rotating drum on which the sleeve body can be mounted on its outer circumference, and a laser beam irradiation unit for irradiating the sleeve body mounted on the rotating drum with laser light, wherein the image pattern forming step is performed with the sleeve body mounted on the same rotating drum, the image pattern is based on a second background image and an overlay image generated by the image processing device, and the method for manufacturing a sleeve printing plate is to perform the image pattern forming step based on the second background image and the overlay image.

[0011] One aspect of the present invention is a method for manufacturing a can, comprising a printing step of printing on the outer surface of a cylindrical body, wherein the printing step is performed using a printing apparatus that uses a sleeve printing plate manufactured by the above manufacturing method. [Brief explanation of the drawing]

[0012] [Figure 1] This is a functional block diagram showing the functional configuration of an image processing device. [Figure 2] This figure shows a portion of the image printed on the can and a magnified version of that image. [Figure 3] This figure shows an example of the image to be processed, the first background image, and the second background image. [Figure 4] This figure shows an example of an overlaid image and an example of printing on an actual can. [Figure 5] This flowchart shows the processing flow performed by the image processing device. [Figure 6] This is a diagram showing an example of printing "manufacturing". [Figure 7] This figure shows an example of printing a string consisting of three lines. [Figure 8] This is a perspective view diagram of the sleeve printing plate. [Figure 9] This is an explanatory diagram of the sleeve printing plate viewed from the axial direction. [Figure 10]It is a schematic diagram of a laser processing apparatus for implementing a method for manufacturing a sleeve printing plate. [Figure 11] It is a schematic diagram of a printing apparatus in which a sleeve printing plate is used. [Figure 12] It is a schematic diagram of a cylinder to which a sleeve printing plate is attached. [Figure 13] It is an explanatory diagram showing a state in which a sleeve printing plate is attached. [Figure 14] It is an explanatory diagram showing a state in which a sleeve printing plate is attached. [Figure 15] It is a diagram for explaining the prior art.

Embodiments for Carrying Out the Invention

[0013] Hereinafter, specific configuration examples of the present invention will be described while referring to the drawings. FIG. 1 is a functional block diagram showing the functional configuration of an image processing apparatus 100 according to the present embodiment. The image processing apparatus 100 includes a storage device such as a CPU (Central Processing Unit), a memory, and an auxiliary storage device connected by a bus, and functions as a device including a communication unit 110, an operation display unit 115, a control unit 120, and an image data storage unit 140 by executing an image processing program. Note that all or part of the functions of the communication unit 110, the operation display unit 115, the control unit 120, and the image data storage unit 140 may be realized using hardware such as an ASIC (Application Specific Integrated Circuit), a PLD (Programmable Logic Device), or an FPGA (Field Programmable Gate Array).

[0014] The image processing program may be recorded on a computer-readable recording medium. A computer-readable recording medium is, for example, a portable medium such as a flexible disk, a magneto-optical disk, a ROM, a CD-ROM, etc., or a storage device such as a hard disk built into a computer system, an SSD (Solid State Drive). The image processing program may be transmitted via a telecommunication line.

[0015] The communication unit 110 is a network interface. The communication unit 110 communicates with other devices via a LAN (Local Area Network), the Internet, etc. For example, the communication unit 110 receives image data from other devices or transmits the image data that has been processed by the image processing device to other devices. The operation display unit 115 receives operation inputs from the operator of the image processing device 100 and displays various types of information to the operator. The display of various types of information is performed, for example, by an LCD (Liquid Crystal Display), an organic EL (Electro-Luminescence), etc.

[0016] The image data storage unit 140 is configured using a storage device such as a magnetic hard disk device or a semiconductor storage device. The image data storage unit 140 stores the image data before raster image processing indicating the image to be processed and the image data after raster image processing generated by the image processing device.

[0017] The control unit 120 in FIG. 1 controls the operations of each part of the image processing device 100. The control unit 120 is executed by a device including a processor such as a CPU and a RAM. By executing the image processing program, the control unit 120 functions as an acquisition unit 121, a first background image generation unit 122, a second background image generation unit 123, a superimposed image generation unit 124, and an output unit 125.

[0018] The acquisition unit 121 acquires the image to be processed. The acquisition unit 121 acquires the image to be processed from another device, for example, via the communication unit 110, or acquires the image to be processed that has been previously stored in the image data storage unit 140. In this embodiment, the image to be processed consists of a background image containing halftones and a superimposed image superimposed on the background image. The superimposed image is a character image that shows characters. The image to be processed only needs to include at least a background image containing halftones and a superimposed image superimposed on the background image, and may further include other images. In this embodiment, "halftone" does not refer to a halftone composed of only one of the smallest units (dots) that make up an image or character, but rather to a halftone composed of multiple such smallest units that appear to be a single dot.

[0019] The first background image generation unit 122 generates a first background image by removing the overlapping region where the superimposed image overlaps from the background image of the image to be processed. The second background image generation unit 123 generates a second background image by adding an outline to the first background image generated by the first background image generation unit 122 to outline the overlapping region. In this embodiment, the second background image generation unit 123 sets the color of the outline to the same color as the halftone dots. If the outline is to be a different color from the halftone dots, the second background image generation unit 123 generates raster data corresponding to the outline. Outlines are sometimes provided for characters, and these are sometimes referred to as character outlines; however, the outline in this embodiment includes these character outlines.

[0020] The superimposed image generation unit 124 generates a superimposed image from the image to be processed. In other words, the superimposed image is an image obtained by removing the background image from the image to be processed.

[0021] Specific examples of the first background image, the second background image, and the superimposed image will be explained. Figure 2 shows an example of an image to be printed on a can. Figure 2 shows image 500, which shows a part of the image to be printed on the can, and enlarged image 501, which is an enlarged version of the word "can" contained in image 500. The background of image 500 does not contain halftones, but the background image will be processed as an image containing halftones. Therefore, the image to be processed is the image in which halftones are added to the background of image 500 (see Figure 3(A) described later).

[0022] The output unit 125 stores the second background image as raster data in the image data storage unit 140. In the following description, the raster data of the second background image will also be referred to as background raster data. The output unit 125 stores the superimposed image as raster data in the image data storage unit 140. In the following description, the raster data of the superimposed image will also be referred to as character raster data. The output unit 125 outputs the background raster data and character raster data stored in the image data storage unit 140 to the image data storage unit 140 or to other devices (for example, the laser processing device described later).

[0023] Figure 3 shows an example of the image to be processed, the first background image, and the second background image. Figure 3(A) shows an example of the image to be processed. As shown in Figure 3(A), the image to be processed includes multiple halftone dots 510 and an overlay image 511 representing a "can". Figure 3(B) shows an example of the first background image. As shown in Figure 3(B), the first background image is an image from which the overlay image 511 has been removed. The removed area is referred to as the overlay area 512.

[0024] In this embodiment, the background image in the image to be processed is defined as an image in which the area on which the superimposed image is superimposed is not removed (an image in which the superimposed area also has halftone dots). However, if the background image in the image to be processed is defined as an image from which the superimposed image 511 has been removed, then the background image in the image to be processed and the first background image will be the same. In the latter case, the first background image generation unit 122 simply needs to generate the background image as the first background image.

[0025] Figure 3(C) shows an example of a second background image and an enlarged view 513 of a part of the second background image. As shown in Figure 3(C), a border 514 with a width W is provided to outline the superimposed area 512. As mentioned above, the color of the border may be the same as the color of the halftone dots. By making the color of the border the same as the color of the halftone dots, it is possible to suppress deterioration of appearance more naturally. Even if the color of the border is different from the color of the halftone dots, deterioration of appearance can be suppressed because the halftone dots do not intrude into the characters.

[0026] Figure 4 shows an example of a superimposed image and an example of printing on an actual can. Figure 4(A) shows a superimposed image. As mentioned above, a superimposed image is an image obtained by removing the background image from the image to be processed. Figure 4(B) shows an example of printing on a can. For printing on a can, a sleeve printing plate with an image pattern based on background raster data (hereinafter also referred to as the "background sleeve") and a sleeve printing plate with an image pattern based on character raster data (hereinafter also referred to as the "character sleeve") are first manufactured by the laser processing apparatus described later.

[0027] Then, the background sleeve and character sleeve are fitted into the offset printing machine described later, and the image is printed on the can. Because the printing is done at high speed, there may be some misalignment in the printing position of the background and characters, but the border portion 514 absorbs the misalignment, so that the halftone dots do not encroach on the characters, thereby suppressing deterioration of appearance.

[0028] The width W of the border portion 514 can be, for example, a value between the maximum value of the misalignment and the minimum width printable by an offset printing device (e.g., 0.03 mm). Note that the maximum value of the misalignment does not have to be the exact maximum value, but may be an assumed maximum value. For example, the width W may be an average value determined based on a predetermined number of sampled misalignments. Alternatively, the width W may be a value based on other statistics (such as the standard deviation σ) (for example, if the misalignment follows a normal distribution, the width W = mean value + 2 × σ (= a value that includes approximately 97.7% of the misalignment)).

[0029] The processing flow by the image processing device 100 described above will now be explained using a flowchart. Figure 5 is a flowchart showing the processing flow performed by the image processing device 100.

[0030] In Figure 5, the acquisition unit 121 acquires the image to be processed (step S101). The first background image generation unit 122 generates a first background image (see Figure 3(B)) by removing the overlapping region where the superimposed image overlaps from the background image of the image to be processed (step S102). The second background image generation unit 123 generates a second background image (see Figure 3(C)) by adding an outline portion that borders the overlapping region to the first background image generated by the first background image generation unit 122 (step S103). As described above, the generated second background image is stored in the image data storage unit 140 as background raster data.

[0031] The superimposed image generation unit 124 generates a superimposed image (see Figure 4(A)) from the images to be processed (step S104). As described above, the generated superimposed image is stored in the image data storage unit 140 as character raster data. The output unit 125 stores the background raster data and character raster data stored in the image data storage unit 140 back into the image data storage unit 140 (step S105). In addition to the image data storage unit 140, the laser processing device described later can also be used as an output destination for the background raster data and character raster data.

[0032] In the embodiments described above, an example of application to a single character ("can") was illustrated for clarity. However, printing examples when this embodiment is applied to multiple characters are shown together with examples of printing using the prior art.

[0033] Figure 6 shows an example of printing the word "manufacturing." Figure 6(A) shows an example of printing using the conventional technology, and Figure 6(B) shows an example of printing when this embodiment is applied. As shown in Figure 6(A), in the conventional technology, halftone dots are embedded in the characters, resulting in a significantly worse appearance. However, when this embodiment is applied, it is immediately clear that the deterioration in appearance is suppressed.

[0034] Figure 7 shows an example of printing a string of characters consisting of three lines. Figure 7(A) shows an example of printing using the prior art, and Figure 7(B) shows an example of printing when this embodiment is applied. As shown in Figure 7(A), in the prior art, halftone dots are embedded in the characters, resulting in a significantly worse appearance. However, when this embodiment is applied, it is immediately clear that the deterioration in appearance is suppressed. Compared to Figure 6, Figure 7 is closer to the actual size of the printed characters, and it can be seen that even at this size, the deterioration in appearance is suppressed.

[0035] While printing methods that add outlines to text have existed before, their purpose is purely design. Therefore, in conventional techniques, the outline color is typically a color not used in the background. On the other hand, the effect of this embodiment differs from conventional techniques in that the outline prevents halftone dots from encroaching on the text and also absorbs printing misalignment, thereby preventing deterioration of appearance. For example, in conventional techniques, the outline is thick enough to be visible to the human eye, but in this embodiment, the outline may be so thin that it is not visible to the human eye, as long as it can prevent halftone dots from encroaching on the text and absorb printing misalignment.

[0036] The background raster data and character raster data output in this manner are used as second image data, as described later, in the laser processing device 50. Before describing the laser processing device 50, we will first describe the sleeve printing plate 30 that is processed by the laser processing device 50.

[0037] As shown in Figures 8 and 9, the sleeve printing plate 30 comprises a cylindrical sleeve body 31 extending along the axis O, and a printing plate material 32 disposed on the outer circumference of the sleeve body 31.

[0038] The sleeve body 31 is made of polyethylene terephthalate (PET) resin, with an outer diameter of 100 mm to 300 mm, an axial length in the O direction of 50 mm to 600 mm, and a wall thickness of 0.1 mm to 1.0 mm. The printing plate material 32 is made of, for example, a photosensitive resin that can be engraved with laser light, and is cylindrical in shape with a thickness of 0.5 mm to 1.0 mm. A relief plate 33 having an image pattern is engraved on the outer surface of this printing plate material 32. In this embodiment, as shown in Figures 8 and 9, two relief plates 33 are formed at 180° opposing positions.

[0039] Furthermore, a positioning notch 34 is formed at one end of the sleeve printing plate 30 in the direction of axis O (the left side in Figure 8), which engages with a guide pin 24 erected on the cylinder 21 of the offset printing apparatus 80, which will be described later, to guide the circumferential relative position and the axial relative position in the direction of axis O with respect to the cylinder 21. In this embodiment, as shown in Figures 8 and 9, four positioning notches 34a, 34b, 34c, and 34d are formed at 90° intervals in the circumferential direction.

[0040] The positioning notches 34a and 34c are formed at intermediate positions in the non-image area where the relief plate 33 is not formed, and are arranged at positions 180° opposite to each other. The positioning notches 34b and 34d are formed at intermediate positions in the image area where the relief plate 33 is formed, and are positioned 180° opposite to each other. In addition, a bridge portion 35 is formed at the open end (one end in the direction of axis O) of the positioning notches 34B and 34. In other words, the positioning notches 34a, 34b, 34c, and 34d are arranged axially symmetrically at 90° intervals.

[0041] Next, the laser processing apparatus 50 used in manufacturing the sleeve printing plate 30 of this embodiment will be described with reference to Figure 10.

[0042] As shown in Figure 10, the laser processing apparatus 50 includes a rotating drum 51 having a cylindrical surface 51A on which a cylindrical sleeve body 40 is mounted, a sleeve body support part 53 having a pivot support part 52 that rotatably supports the rotating drum 51, a rotation drive part 55 that rotates the rotating drum 51 about an axis N, a laser beam irradiation part 60 that irradiates the sleeve body 40 mounted on the rotating drum 51 with laser light, a linear motion part 65 that moves the laser beam irradiation part 60 in a direction parallel to the axis N of the rotating drum 51, and a control unit 70 that controls the operation of the rotating drum 51, the linear motion part 65, and the laser beam irradiation part 60.

[0043] The linear motion unit 65 includes a guide bar 66 extending in a direction parallel to the axis N of the rotating drum 51, a support member 67 that moves along the guide bar 66, and an axial position sensor 68 that obtains position information (axis N direction position information Z) of the support member 67. The laser beam irradiation unit 60 is supported by a support member 67 of the linear motion unit 65 and is configured to be movable in a direction parallel to the axis N. The laser beam irradiation unit 60 is also provided with an output regulator 61 for adjusting the laser beam output. In this embodiment, the laser beam irradiation unit 60 is composed of a carbon dioxide laser.

[0044] The control unit 70 includes a storage means 71 for storing first image data indicating the position and shape of the positioning notch and the cutting position and shape, and second image data indicating the position and shape of the image pattern of the relief plate 33, and an energy density adjustment unit 72 for adjusting the energy density of the laser light when cutting and forming the positioning notch based on the first image data and the energy density of the laser light when forming the image pattern of the relief plate 33 based on the second image data, respectively. Then, based on the first and second image data, the operation of the rotating drum 51, the linear motion unit 65, and the laser beam irradiation unit 60 is controlled to cut the sleeve body 40, form the positioning notches 34, and form the relief plate 33. As described above, the second image data consists of background raster data and character raster data output from the image processing device 100. As a method for acquiring the second image data, for example, a communication means is provided in the laser processing device 50, and this communication means is configured to enable communication with the image processing device 100 so that the laser processing device 50 can acquire the downsampled image data.

[0045] Next, a method for manufacturing a sleeve printing plate 30 using a laser processing apparatus 50 configured in this way will be described. First, the sleeve body 40 is attached to the cylindrical surface 51A of the rotating drum 51. At this time, one end of the sleeve body 40 is fitted into the rotating drum 51, and in this state, air is ejected from the air hole by the air ejection mechanism. As a result, the sleeve body 40 expands in diameter due to this air, and the sleeve body 40 is attached to the rotating drum 51. At this time, the axis O of the sleeve body 40 and the axis N of the rotating drum 51 coincide.

[0046] Next, the storage means 71 stores first image data showing the position and shape of the positioning notch and the cutting position and shape, and second image data showing the position and shape of the image pattern of the relief plate 33. Then, the control unit 70 controls the operation of the rotating drum 51, the linear motion unit 65, and the laser beam irradiation unit 60 based on these first and second image data.

[0047] While irradiating the sleeve body 40 with laser light from the laser beam irradiation unit 60, the rotating drum 51 is rotated by the rotation drive unit 55 and moved in the axial direction N by the linear motion unit 65, thereby scanning the entire outer surface of the sleeve body 40 with the laser beam irradiation unit 60.

[0048] In this section, corresponding to the first image data, a command signal is transmitted from the energy density adjustment unit 72 to the output adjuster 61, setting the laser beam output to a higher level, and the entire thickness of the sleeve body 40 is removed. This results in the cutting of the sleeve body 40 and the formation of the positioning notch 34. On the other hand, in the area corresponding to the second image data, a command signal is transmitted from the energy density adjustment unit 72 to the output adjuster 61, setting the laser beam output to a lower level, and a portion of the thickness of the sleeve body 40 is removed. As a result, the image pattern of the relief plate 33 is formed on the sleeve body 40.

[0049] In this way, by adjusting the output of the laser beam, the energy density of the laser beam is adjusted, and by scanning the entire outer surface of the sleeve body 40 once with the laser beam irradiation unit 60, the sleeve body 40 is cut, the positioning notches 34 are formed, and the image pattern of the relief plate 33 is formed. As described above, the sleeve printing plate 30 of this embodiment is manufactured. As mentioned above, a background sleeve based on background raster data and a character sleeve based on character raster data are manufactured. If the border area is to be a different color from the halftone dots, a sleeve printing plate corresponding to the border area is manufactured.

[0050] Next, an offset printing apparatus 80 using the sleeve printing plate 30 of this embodiment will be described. A schematic of the offset printing apparatus 80 is shown in Figure 11. This offset printing apparatus 80 is a can printing apparatus that prints on the outer surface of a cylindrical can. The offset printing apparatus 80 is generally composed of multiple ink application mechanisms 81 and a can moving mechanism 91.

[0051] The ink adhesion mechanism 81 consists of an inker unit 84 that supplies ink, and a blanket wheel 82 which has multiple blankets 83 that come into contact with the inker unit 84 to transfer the ink, and then come into contact with the outer surface of the can cylinder 90 to print (adhere) the ink. The inker unit 84 consists of an ink source 85, a ducting roll 86 that contacts the ink source 85 to receive ink, an ink mixing roll 87 made up of multiple rollers connected to the ducting roll 86, an inking roll 88 connected to the ink mixing roll 87, and a plate cylinder 20 connected to the inking roll 88. A sleeve printing plate 30 with an image pattern to be transferred to the can cylinder 90 is disposed on the outer circumferential surface of the plate cylinder 20. Multiple blankets 83 are provided on the outer circumferential surface of the blanket wheel 82. These blankets 83 are configured to contact the relief plate 33 of the sleeve printing plate 30 disposed on the outer circumferential surface of the plate cylinder 20, as well as the can cylinder 90. The background sleeve and the character sleeve are disposed on different plate cylinders 20 from the multiple plate cylinders 20 shown in Figure 11.

[0052] The can moving mechanism 91 consists of a can chute 92 for taking in the can body 90, a mandrel 93 for rotatably holding the can body 90 supplied from the can chute 92, and a mandrel turret 94 for sequentially rotating the can body 90 mounted on the mandrel 93 toward the ink adhesion mechanism 81.

[0053] As shown in Figures 13 and 14, the printing cylinder 20 is cylindrical and has a cylinder 21 that is cantileverably supported on the shaft portion 95 of the printing device 80. The sleeve printing plate 30, which is the subject of this embodiment, is fitted onto the outer circumference of this cylinder 21. Here, the inner diameter of the sleeve printing plate 30 and the outer diameter of the cylinder 21 are set to be approximately the same. Multiple air holes 22 are formed on the outer circumference of the cylinder 21, and by supplying air from an introduction hole 23 formed on the end face of the cylinder 21 and ejecting it from the air holes 22, the inner diameter of the sleeve printing plate 30 is expanded, allowing it to be attached to and detached from the cylinder 21. In other words, the sleeve printing plate 30 is fixed to the cylinder 21 by the contraction force of the sleeve printing plate 30 trying to return to its original inner diameter, which causes the sleeve printing plate 30 to adhere tightly to the outer circumference of the cylinder 21.

[0054] Furthermore, the cylinder 21 is provided with a guide pin 24 that protrudes radially outward on the shaft portion 95 side of its outer circumferential surface. A positioning notch 34 of the sleeve printing plate 30 engages with the guide pin 24, thereby determining the circumferential position and axial position O of the sleeve printing plate 30 and the cylinder 21. In this embodiment, as shown in Figure 12, the guide pin 24 is detachably mounted in a pin hole 25 drilled on the outer circumferential surface of the cylinder 21. The cylinder 21 has two pin holes 25a and 25b formed at 90° intervals in the circumferential direction, and the guide pin 24 is configured to be selectively mounted in these two pin holes 25a and 25b.

[0055] In this case, when using the positioning notches 34a and 34c formed at the intermediate position of the non-image portion of the sleeve printing plate 30, the guide pin 24 mounted in the pin hole 25a is used, as shown in Figure 13. On the other hand, when using the positioning notches 34b and 34d formed in the middle of the image portion of the sleeve printing plate 30, the guide pin 24 mounted in the pin hole 25b is used, as shown in Figure 14. In other words, the circumferential position of the guide pin 24 can be changed to correspond to the multiple positioning notches 34a, 34b, 34c, and 34d formed in the sleeve printing plate 30.

[0056] In this offset printing apparatus 80, where the sleeve printing plate 30 is arranged, inks of different colors are applied from the ink sources 85 of each inker unit 84 to the relief plate 33 arranged on the outer surface of the plate cylinder 20 via the ducting roll 86, ink mixing roll 87, and inking roll 88. These inks of each color are then placed as a pattern on the blanket 83 on the rotating blanket wheel 82, and this pattern is printed while in contact with the can cylinder 90 held by the mandrel 93.

[0057] As explained above, according to this embodiment, the border prevents halftone dots from encroaching on the characters and also absorbs printing misalignment, thereby suppressing deterioration of appearance. Furthermore, by making the border the same color as the halftone dots, the deterioration of appearance can be suppressed more naturally. In particular, when the superimposed image is a character image representing characters, the readability of the characters can be improved as shown in Figures 6 and 7.

[0058] In the embodiments described above, an example of performing relief printing using raster data generated by the image processing device 100 was explained, but this embodiment can be applied to any printing device that performs printing using raster data. For example, this embodiment can be applied to lithographic printing devices that use flat plates with almost no irregularities on the plate, as well as inkjet printers and electrophotographic printers.

[0059] Furthermore, in this embodiment, a sleeve printing plate 30 was used which was provided with four positioning notches 34a, 34b, 34c, and 34d. However, the positioning notches are not limited to four; one or more are sufficient.

[0060] The functions of the image processing apparatus 100 in the above-described embodiment may be implemented using a computer. In that case, the functions may be implemented by recording a program for implementing these functions on a computer-readable recording medium, loading the program recorded on this recording medium into a computer system, and executing it. Here, "computer system" includes hardware such as an OS and peripheral devices. Furthermore, "computer-readable recording medium" refers to portable media such as flexible disks, magneto-optical disks, ROMs, CD-ROMs, and storage devices such as hard disks built into a computer system. Moreover, "computer-readable recording medium" may also include those that dynamically hold programs for a short period of time, such as communication lines used when transmitting programs via networks such as the Internet or communication lines such as telephone lines, and those that hold programs for a certain period of time, such as volatile memory inside a computer system that acts as a server or client in such cases. Furthermore, the above-mentioned program may only implement a part of the functions described above, and may also be able to implement the above-mentioned functions in combination with programs already recorded in the computer system.

[0061] While several embodiments of the present invention have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These embodiments can be carried out in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims and their equivalents. [Explanation of symbols]

[0062] 30-sleeve print version 31 sleeves 32 Plate material 33 Toppan Printing 50 Laser processing equipment 60 Laser beam irradiation area 61 Output regulator 70 Control Unit 71 Memory means 80 Offset printing press 90 can body 100 Image Processing Devices 110 Communications Department 115 Operation display section 120 Control Unit 121 Acquisition Department 122 First background image generation unit 123 Second background image generation unit 124 Superimposed Image Generation Unit 125 Output section 140 Image data storage unit

Claims

1. A first background image generation unit generates a first background image from the background image of an image to be processed, which is composed of a background image containing halftone dots and a superimposed image superimposed on the background image, by removing the superimposed region where the superimposed image overlaps. A second background image generation unit generates a second background image in which a border portion is provided to outline the superimposed region of the first background image generated by the first background image generation unit, A superimposed image generation unit that generates the superimposed image from the images to be processed, Equipped with, The superimposed image is either an image containing halftone dots or an image extracted from the image to be processed. The second background image generation unit is an image processing device that sets the color of the border portion to the same color as the halftone dots.

2. The image processing apparatus according to claim 1, wherein the superimposed image is a character image showing characters.

3. A first background image generation step, which generates a first background image from the background image of an image to be processed, which is composed of a background image containing halftone dots and a superimposed image superimposed on the background image, by removing the superimposed region where the superimposed image overlaps; A second background image generation step generates a second background image by adding a bordering step that outlines the superimposed region to the first background image generated by the first background image generation step, A superimposed image generation step in which the superimposed image is generated from the images to be processed, Equipped with, The superimposed image is either an image containing halftone dots or an image extracted from the image to be processed. The second background image generation step is an image processing method that sets the color of the border portion to the same color as the halftone dots.

4. The image processing method according to claim 3, wherein the superimposed image is a character image showing characters.

5. A program that makes a computer function as an image processing device, The aforementioned computer, A first background image generation unit generates a first background image from the background image of an image to be processed, which is composed of a background image containing halftone dots and a superimposed image superimposed on the background image, by removing the superimposed region where the superimposed image overlaps. A second background image generation unit generates a second background image in which a border portion is provided to outline the superimposed region of the first background image generated by the first background image generation unit, A superimposed image generation unit that generates the superimposed image from the images to be processed, and make it work The superimposed image is either an image containing halftone dots or an image extracted from the image to be processed. The second background image generation unit is a program that sets the color of the border portion to the same color as the halftone dots.

6. The program according to claim 5, wherein the superimposed image is a character image representing a character.

7. A method for manufacturing a sleeve printing plate, The process includes an image pattern forming step in which an image pattern is formed on a cylindrical sleeve body. Using a laser processing machine equipped with a rotating drum on which the sleeve body can be attached to its outer circumference, and a laser beam irradiation unit that irradiates laser light onto the sleeve body attached to the rotating drum, the image pattern formation process is performed with the sleeve body attached to the same rotating drum. The image pattern is based on a second background image and an overlay image generated by an image processing apparatus according to claim 1 or claim 2, and the method for manufacturing a sleeve printing plate is to carry out the image pattern formation step based on the second background image and the overlay image.

8. A method for manufacturing cans, It includes a printing process for printing on the outer surface of a cylindrical body, A method for manufacturing cans, wherein the printing step is performed using a printing apparatus that uses a sleeve printing plate manufactured by the manufacturing method described in claim 7.

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