JP3868690B2 - Printing apparatus and printing method capable of adjusting ink amount - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing apparatus and a printing method capable of adjusting an ink amount, and in particular, a printing apparatus and an independent adjustment in which an ink amount supplied to a printing plate can be independently adjusted for each divided region divided into a plurality of regions. The present invention relates to a printing method for performing printing.
[0002]
[Prior art]
In digital printing machines, etc., in order to supply the optimal amount of ink to the printing plate and improve the print quality of the printed matter, the network is continuously supplied with an amount of ink corresponding to the amount of ink consumed by repeated printing. Print a point image. The control of the ink supply amount for the printing plate is configured such that it can be independently adjusted for each of the divided areas divided into a plurality of the printing plate. For example, the central portion of the printing plate increases the amount of ink supplied because the density of the printed image is absolutely high. Conversely, the ink supply amount is absolutely low at both ends because the image density is absolutely light. To do.
[0003]
Note that the halftone dot size actually printed depends on the printing conditions such as halftone dot shape, number of screen lines, printing paper type, and ink type when printing a halftone image on a digital printer. The density of the printed matter may slightly deviate from the ideal density. In the case of color printing, the hue changes particularly. In order to correct such a defect, image data used for recording a printing plate is usually corrected with a correction characteristic called a dot gain curve, and the corrected data is used for image recording and ink supply amount of the printing plate. Used for adjustment.
[0004]
[Problems to be solved by the invention]
In the above conventional technique, the ink supply amount is determined for each divided region divided with respect to the printing plate based on the image data corrected with the correction characteristic called the dot gain correction curve, and the ink amount based on the determined ink supply amount is supplied. A halftone image is printed. However, as a result of adjusting the ink supply amount based on such image data, the ink supply amount may be set very large or may be set very small depending on the divided area. In such a case, the ink is excessively placed on the part of this region, or the ink is not placed on the contrary, and the texture of the ink surface is different from the case where the standard ink is placed, and as a result, Good quality printed matter cannot be obtained. In particular, in the case of color printing in which printing is performed using a plurality of colors of ink, the desired hue is different. In addition, it is conceivable that the ink supply amount determined based on the image data is manually adjusted by an operator, but even if such manual adjustment is used, there are many cases where appropriate adjustment cannot be made and the result is good. May not be able to obtain a print of a high quality.
[0005]
When such a printing defect occurs, it is conceivable to print the image data by applying different correction characteristics and repeating the same process. However, performing correction processing or the like again on the image data in this way is a waste of time, resulting in an increase in printing cost. In addition, when the image data is data expressed in a page description language, the raster conversion process must be performed again, which further increases the time required, resulting in a further increase in printing cost.
[0006]
An object of the present invention is to solve the above-described problems, to provide a printing apparatus and a printing method capable of suppressing the occurrence of printing defects and obtaining a good printed matter in a short time.
[0007]
[Means for solving the problems and their functions and effects]
As means for solving at least a part of the problems described above, the following configuration is adopted. One invention includes a printing plate on which an image is recorded in accordance with image data representing a page, and the amount of ink supplied to the printing plate can be independently adjusted for each divided region divided into a plurality of regions. In the printing apparatus capable of adjusting the ink amount, the partial image data corresponding to at least one of the divided areas of the image data is corrected with the first correction characteristics, and the partial image data corresponding to the other divided areas is corrected. Correction means for generating corrected image data by correcting with a second correction characteristic different from the first correction characteristic, and means for determining the amount of ink to be supplied to each of the divided areas based on the corrected image data. Determining means for determining the amount of ink to be supplied to each of the divided areas based on the portion of the corrected image data corresponding to each of the divided areas; and a printing plate based on the corrected image data. Comprising recording means for image recording, and a printing means for printing an image on a print sheet while supplying ink corresponding to the ink amount for each division region determined on the printing plate by said determining means.
[0008]
According to this printing apparatus, the amount of ink supplied to the printing plate can be adjusted independently for each of the divided areas, and correction characteristics applied to image data corresponding to at least one divided area It can be made different from the correction characteristics applied to the image data corresponding to the other divided areas, and the ink amount supplied to each divided area is determined based on the corrected image data. Accordingly, corrected image data to which optimum correction characteristics are applied can be obtained in each divided area, and an optimum ink amount can be determined, so that a good printed matter can be obtained for the entire image.
[0009]
Further, in this printing apparatus, the recording unit records a halftone image on a printing plate, and the printing unit prints a halftone image on a printing paper, and the first and second correction characteristics are: It is preferable that the dot gain correction characteristic is for correcting dot gain generated when a halftone image is printed on printing paper.
[0010]
According to this printing apparatus, since the correction characteristic for correcting the dot gain generated when printing a halftone image is applied to the image data, the density change due to the dot gain can be prevented and the dot gain for each divided region can be prevented. The ink amount in consideration of the characteristics can be determined, and a good halftone image print can be obtained for the entire image.
[0011]
Further, in this printing apparatus, the correction unit statistically processes the portion of the partial image data corresponding to the divided region for each divided region, and applies to the partial image data based on the result of the statistical processing. It is preferable that a correction characteristic to be determined is determined and corrected based on the determined correction characteristic to generate the corrected image data.
[0012]
According to this printing apparatus, the correction characteristic can be determined for each divided area based on the result of statistical processing of the portion of the partial image data corresponding to the divided area. Therefore, the optimum correction characteristic is automatically determined. As a result, a good printed product can be obtained for the entire image.
[0013]
In the printing apparatus, the correction unit corrects the entire image data with a second correction characteristic to generate overall correction data, and at least one of the image data. The image data of the portion corresponding to the region is corrected with the first correction characteristics, and the partial correction means for generating partial correction data, the partial image data is overwritten and combined with the overall correction data, and the corrected image data is And generating synthesis means.
[0014]
According to this printing apparatus, since it is possible to perform correction by applying the second correction characteristic to the entire image data, it is not necessary to select a segmented area to which the second correction characteristic is applied, and as a result operation Improves.
[0015]
Another invention includes a printing plate on which an image is recorded in accordance with image data representing a page, and the amount of ink supplied to the printing plate is independent for each divided region divided into a plurality of regions. In the printing apparatus capable of adjusting the ink amount that can be adjusted, the image data is corrected based on a first correction characteristic, and a correction unit that generates first correction image data; and the correction unit that generates the first correction image data based on the first correction image data. First means for determining the amount of ink to be supplied to each divided area based on a portion of the first corrected image data corresponding to each divided area. Determining means; first recording means for recording an image of the printing plate based on the first corrected image data; and supplying ink of an ink amount of each divided area determined by the first determining means to the printing plate For printing A first printing unit that prints an image, a change setting unit that sets at least one section area as a change section area, and image data corresponding to the change section area is different from the first correction characteristic. Partial correction means for performing partial correction based on the correction characteristics of 2 to generate changed partial image data; and second determination means for determining the amount of ink to be supplied to the changed section area based on the changed partial image data; The second corrected image data is generated by replacing a portion corresponding to the changed section area of the first corrected image data with the changed partial image data, and an image is recorded on a new printing plate based on the second corrected image data. And a second recording means for changing the ink amount of the change section area to the ink amount determined by the second determining means and printing the image on the printing paper while supplying the ink. And means, the.
[0016]
According to this printing apparatus, in the printed matter obtained by the first printing means, only for the change classification area including the defective print portion, the correction characteristics are changed to generate corrected image data and determine the ink amount. With respect to the other divided areas, already obtained corrected image data and ink amount can be used, so that the processing time required for changing the correction characteristics can be minimized. In addition, for the segmented area that is printed well in the printed matter obtained by the first printing unit, the same corrected image data and ink amount are used in the second printing unit, so that it is not affected by the reset condition of the changed segmented area. Thus, a good image can be obtained. Further, since the modification section area is also set for correction characteristics, a good image can be obtained.
[0017]
Further, in this printing apparatus, the first and second recording means record a halftone image on a printing plate, and the first and second printing means print a halftone image on a printing paper, The first correction characteristic and the second correction characteristic are preferably dot gain correction characteristics for correcting dot gain generated when a halftone image is printed on printing paper.
[0018]
According to this printing apparatus, since the correction characteristic for correcting the dot gain generated when printing a halftone image is applied to the image data, the density change due to the dot gain can be prevented and the dot gain for each divided region can be prevented. The ink amount in consideration of the characteristics can be determined, and a good halftone image print can be obtained for the entire image.
[0019]
Further, in the printing apparatus, the image data is expressed in a page description language, and the printing apparatus further converts the image data expressed in the page description language into raster format image data. Means and storage means for storing the raster-format image data, wherein the partial correction means further reads out the raster-format image data of the change section area from the storage means, and reads the read-out image data Is preferably corrected.
[0020]
According to this apparatus, even when image data is expressed in a page description language, an image in a raster format obtained by raster conversion of image data expressed in the page description language is stored in the storage unit. In addition, by reading out from the storage means and using the image data of the divided area that needs to change the correction characteristics, it is not necessary to perform raster conversion again on the image data expressed in the page description language. , Processing time can be shortened.
[0021]
In addition, the method invention records an image on a printing plate according to image data representing a page, and independently adjusts the amount of ink supplied for each divided area divided into a plurality of areas on the printing plate. In the printing method for performing printing, (a) the partial image data corresponding to at least one of the segmented areas of the image data is corrected with the first correction characteristics, and the partial image data corresponding to the other segmented areas is corrected. Correcting with a second correction characteristic different from the first correction characteristic to generate corrected image data; and (b) means for determining the amount of ink to be supplied to each segmented area based on the corrected image data A step of determining an amount of ink to be supplied to each divided area based on a portion of the corrected image data corresponding to each divided area; and (c) an image on a printing plate based on the corrected image data. And a step of recording, and a step for printing an image ink corresponding to the amount of ink to the printing paper while supplying to the printing plate of each divisional area is determined by; (d) determining means.
[0022]
Further, in this method invention, the step (c) records a halftone image on a printing plate, and the step (d) prints a halftone image on a printing paper. The correction characteristic is preferably a dot gain correction characteristic for correcting a dot gain generated when a halftone image is printed on printing paper.
[0023]
Further, in this method invention, the step (a) further includes (a1) statistically processing a portion of the partial image data corresponding to the divided region, and (a2) the step (a) a1) determining a correction characteristic to be applied to the partial image data based on the result of the process, and (a3) generating the corrected image data by correcting based on the determined correction characteristic. It is preferable to provide.
[0024]
In the method invention, the step (a) includes (a4) generating the whole correction data by correcting the whole of the image data with a second correction characteristic, and (a5) Correcting a portion of the image data corresponding to at least one of the divided regions with a first correction characteristic to generate partial correction data; and (a6) combining the partial image data over the entire correction data. And generating the corrected image data.
[0025]
According to these printing methods, the same operation and effect as the above-described apparatus invention can be obtained.
[0026]
According to another method invention, an image is recorded on a printing plate according to image data representing a page, and the amount of ink supplied to each divided area divided into a plurality of areas on the printing plate is independent. In the printing method for performing printing by adjusting, (a) correcting the image data based on a first correction characteristic to generate first corrected image data; and (b) based on the first corrected image data. Determining the amount of ink to be supplied to each of the divided areas, and determining the amount of ink to be supplied to each of the divided areas based on the portion of the first corrected image data corresponding to each of the divided areas. (C) a step of recording an image of the printing plate based on the first corrected image data; and (d) supplying ink of an ink amount of each divided area determined by the first determining means to the printing plate. While printing the image on the paper A step of performing printing, (e) a step of setting at least one segmented region as a modified segmented region, and (f) a second image different from the first correction characteristic in image data corresponding to the modified segmented region. (G) a step of generating partial modified image data by performing partial correction based on the correction characteristics; (g) a step of determining an ink amount to be supplied to the modified section area based on the modified partial image data; A portion corresponding to the changed section area of the first corrected image data is replaced with the changed partial image data to generate second corrected image data, and an image is recorded on a new printing plate based on the second corrected image data. And (i) changing the amount of ink in the changed section area to the amount of ink determined in step (g), and printing an image on printing paper while supplying ink.
[0027]
In addition, it is preferable that the printing method further includes a step (j) of repeating and executing the steps (e) to (i).
[0028]
In this printing method, the steps (c) and (h) record halftone images on a printing plate, and the steps (d) and (i) are steps for printing halftone images on printing paper. The first correction characteristic and the second correction characteristic are preferably dot gain correction characteristics for correcting dot gain generated when a halftone image is printed on printing paper.
[0029]
Further, in this printing method, the image data is expressed in a page description language, and the printing method further includes: (j) converting the image data expressed in the page description language into raster format image data. And (k) storing the image data in the raster format, and the step (f) further includes the step of storing the change section area from the image data in the raster format stored in the step (k). It is preferable to read out raster-format image data and correct the read-out image data.
[0030]
According to these printing methods, the same effects as those of the apparatus invention can be obtained. Further, when the steps (e) to (i) are repeatedly executed (j), the optimum correction characteristic for each divided region can be set while simulating printing by the second printing means.
[0031]
DETAILED DESCRIPTION OF THE INVENTION
[Schematic configuration of printing system]
[0032]
Embodiments of the present invention will be described based on examples. FIG. 1 is a configuration diagram of a printing system according to the present invention. This printing system includes a digital printing machine 2, a controller 1, and a plurality of front-end computers 3. The front-end computer 3 generates page description data PD to be printed by the digital printer 2, and the page description data PD is expressed in a page description language.
[0033]
The page description data may also be referred to as data expressed in an object format. The controller 1 receives the page description data PD via the network 4 and controls the digital printer 2 so as to print an image based on the page description data PD. The digital printing machine 2 can perform image recording (exposure), development, and printing on the printing plate PL.
[0034]
The processes executed by the digital printing machine 2 are roughly divided into a preparation process, an exposure process, a development process, and a printing process. The preparation process is a preparation process for printing on a new printing plate, and is replaced with a new printing plate PL. The exposure process is a process of recording an image by exposing the newly mounted printing plate PL. The subsequent development process is a process of developing the exposed printing plate PL. The printing process is a process in which ink is applied to the developed printing plate PL and the same image is repeatedly printed on a large number of printing papers PA. When this printing process is completed, the process returns to the preparation process for printing the next page description data PD, the printing plate PL is replaced, and the above four processes are repeated.
[0035]
[Configuration of controller and digital printing machine]
FIG. 2 is a diagram showing a detailed configuration of the controller 1 and the digital printing machine 2. The controller 1 receives an interface 11 for receiving the page description data PD via the network 4, a RIP processing unit 12 for converting the page description data PD into raster format image data (hereinafter referred to as “raster data RD”), a raster The correction conversion unit 13 converts the data RD into high-resolution and low-resolution correction raster data RH and RL according to the correction characteristics of the dot gain correction curve, and further converts the high-resolution correction raster data RH into a binary halftone dot signal RDD. A halftone signal generator 14 for conversion is provided. Further, ink supply for determining ink supply amount data SA1 to SA8 (when divided into eight regions) of each region divided with respect to the digital printing press 2 printing plate PL based on the low-resolution corrected raster data RL. The amount determining unit 15 includes a user interface unit 16 including a monitor and a keyboard for displaying processing contents to the operator and receiving an instruction input from the operator.
[0036]
The memory 17 also temporarily stores page description data PD, raster data RD, high-resolution correction raster data RH, low-resolution correction raster data RL, ink supply amount data SA, and the like. The memory 17 is composed of a hard disk, but may be a semiconductor memory. These processing units are controlled by the control unit 20. The halftone dot signal RDD is supplied to the driver 62 of the digital printing machine 2 and is used for recording (exposing) a halftone dot image on the printing plate PL. The ink supply amount data SA1 to SA8 are supplied to the driver 95 of the digital printing machine 2 and used for controlling the ink supply amount.
[0037]
In addition, the RIP processing unit 12, the correction conversion unit 13, the halftone signal generation unit 14, and the ink supply amount determination unit 15 of the controller 1 are configured to realize the same function by executing a software program on the CPU. May be.
[0038]
The digital printing machine 2 includes a printing plate exchanging unit 50 that exchanges the printing plate PL in a preparation process, a recording unit 60 that exposes and records an image based on the halftone signal RDD on the printing plate PL in an exposure process, and a developing process. The developing unit 70 that develops the exposed printing plate PL and the printing unit 80 that performs printing using the printing plate PL developed in the printing process. In the recording unit 60, first, the driver 62 controls ON / OFF of the light source 63 based on the binary halftone signal RDD. Thereby, a halftone image corresponding to the image represented by the page description data PD is formed on the printing plate PL.
[0039]
The printing unit 80 includes a plate cylinder 81 on which the printing plate PL is mounted, an ink unit 90 that applies ink to the developed printing plate PL, a transfer cylinder 82 to which an ink image formed on the printing plate PL is transferred, a transfer cylinder An impression cylinder 83 is provided to apply pressure to further transfer the ink image transferred to 82 onto the printing paper PA. By rotating the plate cylinder 81, the transfer cylinder 82, and the impression cylinder 83 in the direction of the arrow, a print image (halftone dot image) is formed on the printing paper PA sequentially supplied between the transfer cylinder 82 and the impression cylinder 83.
[0040]
The ink unit 90 is an opening for controlling the amount of ink supplied to the printing plate PL by adjusting the ink fountain 91 containing ink, the flow valve 92 serving as an ink supply port, and the opening of the flow valve 92. Ink supply amount data SA1 to SA8 from the controller 1 for the degree adjustment motor 93, the inking roller 94 for uniformly supplying the ink from the flow rate valve 92 to the printing plate PL, and the opening degree adjustment motor 93. The driver 95 is driven based on the above.
[0041]
The ink unit 90 is configured such that the ink supply amount can be independently adjusted for each divided region in which the region of the printing plate PL is divided with respect to the rotation axis direction of the plate cylinder 81. That is, the flow valve 92 is composed of a plurality of valves so that the opening degree can be independently adjusted corresponding to the divided areas, and further, the opening degree is individually adjusted so that the opening degree can be adjusted for each valve. A degree adjusting motor 93 is provided. By this mechanism, the amount of ink supplied to the printing plate PL can be adjusted independently for each divided region.
[0042]
FIG. 3 is an overview perspective view showing the flow valve 92 in an enlarged manner. The two metal plates 96a and 96b form an opening 95 which is an ink supply port. One metal plate 96a has elasticity, and a plurality of cuts are made on the opening 95 side, whereby a plurality of ink keys 98 are formed. A flexible resin sheet 97 is bonded to the inside of the metal plate 96a to prevent ink from flowing out from the cut. By independently adjusting the force 99 applied to each ink key 98 by each opening adjustment motor 93, the opening for each ink key 98 is changed and the amount of ink supplied to the printing plate PL is changed for each region. It can be divided and controlled.
[0043]
[First embodiment of the present invention]
FIG. 4 is a control flowchart of one embodiment of the present invention. This control flowchart is realized by the controller 1. This will be described with reference to the configuration of the controller 1 shown in FIG. FIG. 5 schematically shows data generated by the processing steps according to this embodiment. This embodiment shows a process of generating a halftone dot signal RDD and ink supply amount data SA to be supplied to the digital printing machine 2 from page description data PD or raster data RD. This embodiment is premised on a printing method or apparatus in which the amount of ink to be supplied can be adjusted independently for each divided region with respect to the printing plate PL on which an image is recorded.
[0044]
First, in step ST1, page description data PD from the front-end computer 3 is received via the interface 11, and the data is temporarily stored in the memory 17. In step ST2, an output condition for recording (exposing) a halftone image on the printing plate PL is set. At this time, the output condition setting window W 1 shown in FIG. 6 is displayed on the monitor of the user interface unit 16. This window W1 is a sub-window SW11 for setting the output condition of the screen line number C1 and the halftone dot shape C2, and a partition line DL for dividing an area in which the ink supply amount can be independently adjusted in the image expressed by the page description data PD. , A sub-window SW12 displaying a superimposed image, a sub-window SW13 for setting a dot gain correction curve applied to each of the divided areas A1 to A8, and “execute” and “cancel” It consists of a sub-window SW14 containing command buttons.
[0045]
In the sub-window SW11, the operator sets the screen line number C1 and the dot shape C2 of the dot image recorded on the printing plate PL by selecting from the drop-down list. The screen line number C1 is the resolution of the screen line number of the halftone image. A halftone dot shape C2 is a halftone dot shape of a halftone dot image, and is selected from square, round, chain, and the like. Further, the operator selects a dot gain correction curve to be applied to each divided area by clicking an option button in the sub-window SW13. The option buttons are grouped for each area, and only one option button can be selected as the grouped option button.
[0046]
In the example of FIG. 6, the segment areas A1 to A4 and A6 to A8 are display examples when the dot gain correction curve DGa is selected, and the segment area A5 is a dot gain correction curve DGb. When the setting of these output conditions is completed, the operator clicks the execution command button in the sub window SW14 to instruct the controller 1 to start execution. When the command buttons DGBa, DGBb, DGBc are clicked, another window is opened, and each dot gain correction curve can be displayed as a graph in that window. In the window, the dot gain correction curve can also be corrected.
[0047]
In step ST3, the RIP processing unit 12 performs raster conversion processing according to the screen line number set in step ST2, and outputs raster data RD. The raster data RD is stored in the memory 17.
[0048]
In step ST4, the raster data RD is corrected and converted with the dot gain correction curves DGa and DGb. This correction conversion is different for each of the printing plate segmented areas A1 to A8 (divided into eight areas in this example) corresponding to the segmented areas in which the ink supply amount can be adjusted independently in the digital printing machine 2. A dot gain correction curve of correction characteristics is used. In other words, at least one of the eight divided areas is subjected to correction conversion using a dot gain correction curve different from that of the other divided areas. In this example, in step ST2, the condition is set so that the segmented area A5 is converted by the dot gain correction curve DGb and the other segmented areas are converted by the dot gain correction curve DGa. The partial raster data RD1 to RD4 and RD6 to RD8 are corrected by the dot gain correction curve DGa, while the partial raster data RD5 of the segmented area A5 is corrected by the dot gain correction curve DGb.
[0049]
This correction conversion outputs high-resolution correction raster data RH and low-resolution correction raster data RL. The high-resolution corrected raster data RH is data used for recording the printing plate PL, while the low-resolution corrected raster data RL determines the ink supply amount data SA supplied to the digital printing machine 2. The data used for the recording is coarser than the data actually recorded. Note that the two corrected raster data represent images having essentially the same content except for the resolution.
[0050]
By this correction conversion, the following four data are output.
(1) High-resolution corrected raster data RHa obtained by correcting and converting the partial raster data RD1 to RD4 and RD6 to RD8 by the dot gain correction curve DGa.
(2) Low-resolution corrected raster data RLa obtained by correcting and converting the partial raster data RD1 to RD4 and RD6 to RD8 by the dot gain correction curve DGa.
(3) High-resolution correction raster data RHb obtained by correcting and converting the partial raster data RD5 using the dot gain correction curve DGb.
(4) Low-resolution correction raster data RLb obtained by correcting and converting the partial raster data RD5 using the dot gain correction curve DGb.
[0051]
The high-resolution correction raster data RHa includes high-resolution partial correction raster data RH1a, RH2a, RH3a, RH4a, RH6a, RH7a, and RH8a. The high-resolution correction raster data RHb is a high-resolution partial correction raster data RHb. Data RH5b is included. The low-resolution correction raster data RLa includes low-resolution partial correction raster data RL1a, RL2a, RL3a, RL4a, RL6a, RL7a, and RL8a. The low-resolution correction raster data RLb includes low-resolution partial correction raster data RLb. Data RL5b is included. These correction conversion processes are performed by a correction conversion processing unit.
[0052]
Subsequently, in step ST5, optimum ink supply amount data SAa and SAb for each divided region are determined based on the low-resolution corrected raster data RLa and RLb. The ink supply amount data SAa includes ink supply amount data SA1a to SA4a and SA6a to SA8a of the divided areas A1 to A4 and A6 to A8. Further, the ink supply amount data SAb includes ink supply amount data SA5b of the divided area A5. The ink supply amount data SA is determined by statistics of the density of pixels included in each divided area. The determination method will be described later.
[0053]
Next, in step ST6, processing is performed to synthesize high-resolution corrected raster data RHa and RHb that have been corrected and converted using dot gain correction curves having different correction characteristics. By this combining process, combined corrected raster data RHM is obtained. The combined correction raster data RHM includes partial correction raster data RH1a, RH2a, RH3a, RH4a, RH5b, RH6a, RH7a, and RH8a. In other words, the combined correction raster data RHM is obtained by replacing only the portion corresponding to the divided area A5 with the partial correction raster data RH5b that has been corrected and converted with a dot gain correction curve different from that of the other divided areas.
[0054]
In addition, the ink supply amount data SAa and SAb are combined in the same manner as the high resolution corrected raster data RH. The ink supply amount data SA synthesized by this combination processing includes ink supply amount data SA1a, SA2a, SA3a, SA4a, SA5b, SA6a, SA7a, and SA8a for each segmented area. Note that these combining processes are realized by the control unit 20.
[0055]
Further, in step ST7, the combined corrected raster data RHM is converted into a binary halftone dot signal RDD in accordance with a preset output condition (halftone dot type).
[0056]
In step ST8, the halftone dot signal RDD and the ink supply amount data SA are supplied to the digital printing machine 2, and in step ST9, the digital printing machine 2 receives these data and each ink key according to the ink supply amount data. After adjusting the amount of ink supplied to each of the divided areas by adjusting the opening degree, a halftone image is printed on the printing paper PA.
[0057]
[Correction conversion with dot gain correction curve]
FIG. 7 shows an example of a dot gain correction curve. The dot gain correction curve corrects the phenomenon that when the image is recorded with halftone dots, it becomes larger or smaller than the theoretical halftone dot due to the shape of the halftone dots and ink characteristics. Because. This correction is performed by adding the correction value DD represented by the dot gain correction curve to the density value of the image of each pixel of the raster data RD given in the range of 0 to 100%.
[0058]
In the case of the dot gain correction curve DGa shown in FIG. 7A, a pixel having a density of 75% in the raster data RD is output as a pixel having a density value of 77% obtained by adding a correction value of 2% thereto. In the case of the dot gain correction curve DGb shown in FIG. 7B, it is output as a pixel having a density value of 78% obtained by adding 3% from 75%. This correction is performed on all the pixels of the raster data RD. The correction conversion of the raster data RD using such a dot gain correction curve is performed by the correction conversion unit 13.
[0059]
[Procedure for determining ink supply data]
FIG. 8 is a diagram showing a procedure for determining the ink supply amount data SA of each divided region. When the low-resolution corrected raster data RL is given, average density values (average halftone dot%) ME1 to ME8 are calculated for each of the eight divided areas A1 to A8. Subsequently, the average halftone dots% ME1 to ME8 are corrected by the ink supply amount correction curve IS to obtain ink supply amount data SA1 to SA8. For example, when the average halftone dot percentage is “52%”, the ink supply amount data “75” is output. The ink supply amount correction curve IS depends on the type of ink, printing paper, printing plate and the like used in the digital printing machine 2 and also depends on the ink supply characteristics of the ink unit 90 of the digital printing machine 2. Therefore, the ink supply amount correction curve IS is determined as an eigenvalue of the digital printing machine 2 based on the result of simulation printing that has been repeated many times. These processes are performed by the ink supply amount determination unit 15.
[0060]
[Modification of First Embodiment]
In this embodiment, the correction by the dot gain correction curve DGa is performed on the area excluding the partial raster data RD5. However, partial correction raster data RH1a is obtained by performing correction conversion on all the divided areas. To RH8a are generated, and the partial correction raster data RH5a is replaced with the correction raster data RHb (partial correction raster data RH5b) corrected and converted by the dot gain correction curve DGb (similar to the overwriting process). Thus, the synthesis process may be realized, and the final synthesized synthesized corrected raster data RHM may be generated.
[0061]
Note that a segmented area that is corrected and converted with a dot gain correction curve different from that of other segmented areas is a part where the density is absolutely high, or a part where the density is light, or a part whose image properties are different from other parts. . The selection of these divided areas may be made by the operator referring to the contents of the image of the page description data and making selections based on the contents. Alternatively, the raster data RD is statistically processed for each divided area, and the statistical processing is performed. A dot gain correction curve may be automatically determined based on the result. Here, the statistical processing is, for example, processing for generating a histogram for the pixel density values of the corrected image data belonging to each segmented area, or the average density, maximum density, minimum density or density of the image data belonging to each segmented area. This is a process for calculating the variance value. The dot gain correction curve is determined based on the generated histogram pattern and the calculated average density, maximum density, minimum density, and density dispersion value.
[0062]
[Second Embodiment of the Present Invention]
FIG. 9 is a control flowchart of one embodiment of the present invention. This control flowchart is realized by the controller 1. 10 and 11 schematically show data generated by the processing steps according to this embodiment. In the second embodiment, similarly to the first embodiment, a process of generating a halftone signal RDD and ink supply amount data SA given to the digital printing machine 2 from page description data PD or raster data RD. Show. Further, it is premised on a printing method or apparatus in which the amount of ink to be supplied can be adjusted independently for each divided area for a printing plate on which a halftone image is recorded. The first embodiment differs from the first embodiment in that the first embodiment is a one-time process and the halftone signal RDD and the ink supply amount data SA are supplied to the digital printing machine 2, whereas the first embodiment is different from the first embodiment. The second embodiment is to supply a halftone dot signal RDD and ink supply amount data SA that can finally obtain a print of good quality while repeating the printing simulation.
[0063]
FIG. 10 shows the entire process based on this concept. This process basically includes a combination of the process PR1, the process PR2, the process PR3, the test printing process, and the main printing process. The process PR1 performs correction conversion with one dot gain correction curve based on the data of the entire area of the page description data PD or the raster data RD, and finally the halftone signal RDD and the ink supply amount data corresponding thereto. This is a process for generating SA. Step PR2 is a step of manually adjusting the ink supply amount of the digital printing machine 2. In the process PR3, at least one region of the page description data PD or the raster data RD is corrected with a dot gain correction curve different from that in the process PR1, and the halftone dot signal RDD and the ink supply amount data already generated are corrected. In this step, a halftone dot signal RDD and ink supply amount data SA are generated by replacing a part of SA. Step PR2 and step PR3 are repeated.
[0064]
As shown in FIG. 10, test printing is performed after the processes PR1, PR2, and PR3. The trial printing is performed to check the quality of the printed material, and printing is performed on several tens to several hundreds of printing paper PA.
[0065]
When the operator evaluates the printed matter obtained by the trial printing and determines that the quality of the printed matter is good as a result of the evaluation, the main printing is started, and the preset number of prints are continuously performed. Do. On the other hand, if it is determined that the evaluation result is defective, the process proceeds to the next step.
[0066]
Based on the flowchart shown in FIG. 9, the processing steps of the second embodiment will be described with reference to FIG. 2, FIG. 10, and FIG.
[0067]
First, the process PR1 will be described. The process PR1 corresponds to a process realized by steps ST11 to ST17. First, in step ST11, page description data PD from the front-end computer 3 is received through the interface 11, and the data is temporarily stored in the memory 17.
[0068]
In step ST12, output conditions are set. At this time, an output condition setting window W 2 shown in FIG. 12 is displayed on the monitor of the user interface unit 16. This window W2 includes a sub-window SW21 for setting the output conditions of the screen line number C1 and the halftone dot shape C2, and a partition line DL for dividing an area where the ink supply amount can be independently adjusted in the image expressed by the page description data PD. It consists of a sub-window SW22 for displaying the superimposed image superimposed, a sub-window SW23 for selecting a dot gain correction curve, and a sub-window SW24 including “execute” and “cancel” buttons.
[0069]
The operator sets the screen line number C1 and the dot shape C2 in the sub-window SW21. The screen line number C1 is the resolution of the screen line number of the halftone image to be printed. The halftone dot is the halftone dot shape of the halftone image to be printed, and is selected from square, round, chain, and the like. Further, the operator selects which dot gain correction curve is to be applied to the entire image in the sub window SW23. The example of FIG. 12 is a display example when the dot gain correction curve DGa is selected for the entire image. When the setting of these output conditions is completed, the operator clicks the execution button of the sub window SW24 to instruct the controller 1 to start execution. When the command buttons DGBa, DGBb, DGBc are clicked, another window is opened, and each dot gain correction curve can be displayed as a graph in the window, and the curve can be corrected.
[0070]
In step ST13, the RIP processing unit 12 performs raster conversion processing according to the screen line number set in step ST2, and outputs raster data RD. The raster data RD is stored in the memory 17. The raster data RD stored in the memory 17 is stored so as to be readable for each divided area.
[0071]
In step ST14, the entire area of the raster data RD is corrected and converted by the dot gain correction curve DGa. This correction conversion outputs high-resolution correction raster data RH (1) and low-resolution correction raster data RL (1). The high-resolution corrected raster data RH (1) is data used to record the printing plate PL, while the low-resolution corrected raster data RL (1) is the amount of ink supplied to the digital printing machine 2. Data used to determine the data SA (1), which is coarser than the data actually recorded.
[0072]
By this correction conversion, the following two data are output.
(1) High-resolution correction raster data RH (1) obtained by correcting and converting the raster data RD using the dot gain correction curve DGa.
(2) Low-resolution corrected raster data RL obtained by correcting and converting the raster data RD using the dot gain correction curve DGa.
These correction conversion processes are performed by the correction conversion unit 13.
[0073]
Subsequently, in step ST15, the optimum ink supply amount data SA (1) for each divided region is determined based on the low resolution corrected raster data RL. The ink supply amount data SA (1) includes ink supply amount data SA1 to SA8 of the divided areas A1 to A8. The ink supply amount data SA is determined based on the density statistics of the pixels included in each divided region, and the determination can be realized by the procedure described with reference to FIG.
[0074]
In step ST16, the halftone dot signal generation unit 17 performs halftone dot signal generation processing, and the halftone dot signal RDD is generated from the high-resolution corrected raster data RH (1) based on the set halftone dot shape. (1) is output. Subsequently, in step ST17, the halftone dot signal RDD (1) and the ink supply amount data SA (1) obtained by the processes so far are supplied to the digital printer 2. The above process corresponds to the process PR1 shown in FIG.
[0075]
Subsequently, in step ST18, after the ink key opening is adjusted based on the ink supply amount data SA (1) in the digital printing machine 2, the printing plate exposed based on the halftone signal RDD (1) is applied. A test print is made.
[0076]
In step ST19, it is determined whether or not there is no problem in quality as a result of the operator's evaluation of the printed matter that has been trial printed, that is, whether or not the ink supply amount has been properly adjusted. If it is appropriate, the operator gives an instruction for actual printing to the digital printing machine 2. On the other hand, if there is a quality problem, the process proceeds to the next step PR2.
[0077]
The process PR2 is a process of adjusting the ink supply amount of the digital printing machine 2, and corresponds to step ST20. The operator looks at the printed matter that has been trial printed, and identifies a portion having a quality problem. For example, suppose that it is determined that the portion of the printed matter corresponding to the segmented area A5 has a lot of ink paste, and therefore, a faithful density, hue, or texture is not reproduced. In such a case, the ink supply amount corresponding to the divided area A5 is finely adjusted manually. In the case of manual adjustment, a window W3 shown in FIG. 13 is displayed on the monitor of the user interface unit 16.
[0078]
The window W3 includes a sub-window SW32 in which an image in which the ink supply amount is independently adjusted on the image expressed by the page description data PD is displayed, and a subwindow SW32 on which the partition line DL is displayed. The sub window SW33 displays a button for manually setting the ink supply amount to be applied, and the sub window SW34 displays the currently set ink supply amount data as a bar graph. In addition, the ink supply amount of each divided area set at this time is determined by the process PR1.
[0079]
In the sub window SW33, the operator clicks a button for adjusting the divided area where the quality of the printed matter is poor, and finely adjusts the ink supply amount.
[0080]
In step ST21, after such manual adjustment of the ink supply amount in step PR2, test printing is performed. In this trial printing, printing is performed using a printing plate on which a halftone dot image was recorded last time, except that the ink supply amount is different from the trial printing performed after the process PR1. The manual adjustment and the trial printing in the process PR2 may be repeated many times. In step ST22, it is determined whether or not there is no quality problem as a result of the operator's evaluation of the printed material for trial printing. If not, the process proceeds to step ST28, and the operator instructs the digital printing machine 2 to perform main printing. On the other hand, if a printed matter with good quality cannot be obtained even after manual adjustment in step PR2, the process proceeds to the next step PR3.
[0081]
The process PR3 is a process of creating the halftone dot signal RDD and the ink supply amount data SA of the part of the divided area where good quality was not obtained in the previous evaluation, and corresponds to step ST23 to step ST28 and step ST17.
[0082]
First, in step ST23, if the operator determines that the print quality of the portion of the divided area A5 is poor according to the processes so far, the divided area A5 is set as the changed divided area and corresponds to the divided area. The partial raster data RD5 is set to apply a dot gain correction curve DGb different from that used in step PR1. FIG. 14 shows a window W4 displayed on the monitor at that time.
[0083]
This window W4 is divided into a sub window SW41 that displays the output conditions of the screen line number C1 and the halftone dot shape C2 that have already been set, and an area in which the ink supply amount can be independently adjusted in the image represented by the page description data PD. A sub-window SW42 on which an image in which the division lines DL are overlapped is displayed, a sub-window for selecting a segment area to change the dot gain correction curve to be applied and a dot gain correction curve to be applied to the segment area SW 43 and sub window SW 44 including “execute” and “cancel” buttons.
[0084]
In the sub window SW43, the operator selects an area where the quality defect of the printed matter has occurred as a change section area, and further selects a dot gain correction curve to be applied to the partial raster data in the change section area. The example of FIG. 14 is a display example when the dot gain correction curve DGb is selected for the segmented area A5. When the resetting of these output conditions is completed, the operator clicks the execution button of the sub window SW44 and instructs the controller 1 to start execution. When the command buttons DGBa, DGBb, DGBc are clicked, another window is opened, and each dot gain correction curve can be displayed in a graph in that window, and can be corrected.
[0085]
In step ST24, the partial raster data RD5 of the section area A5 stored in the memory 17 is read out and subjected to correction conversion using a dot gain correction curve DGb having a correction characteristic different from that used in the process PR1. This correction conversion outputs high-resolution partial correction raster data RH5 (2) and low-resolution partial correction raster data RL5 (2). Subsequently, in step ST25, the optimum ink supply amount data SA5b of the segmented area A1 is determined based on the low-resolution partial correction raster data RL5 (2). The ink supply amount data SA5b is determined based on the density statistics of the pixels included in the divided area A1. The determination method is as described above.
[0086]
Next, in step ST26, the partial correction raster data RH5 (2) and the ink supply amount data SA (2) created as data for the divided area A5 are used as the correction raster data RH (1) and the ink generated in the process PR1. The supply amount data SA (1) is overwritten and combined to generate new corrected raster data RH (2) and ink supply amount data SA (2). That is, only the data corresponding to the divided area A5 is replaced and output. The corrected raster data RH (2) corresponds to the combined corrected raster data RHM of the first embodiment, and corresponds to the ink supply amount data SA (2) and the ink supply amount data SA of the first embodiment. . Note that these overwriting synthesis (replacement) processing is realized by the control unit 20.
[0087]
Furthermore, step ST27 corrected raster data RH (2) is converted into a binary halftone signal RDD (2) according to a preset output condition (type of halftone dot).
[0088]
In step ST17, the halftone dot signal RDD (2) and the ink supply amount data SA (2) obtained by the above process are supplied to the digital printer 2. In step ST18, the digital printing machine 2 receives these data and performs printing while adjusting the ink supply amount. If there is no quality problem as a result of the operator evaluating the printed matter that has been trial printed, the process proceeds to step ST28, and the operator instructs the digital printing machine 2 to perform the actual printing. On the other hand, if there is a quality problem, the process proceeds to the next step PR2. Hereinafter, these steps are repeated.
[0089]
In this way, if printed matter of good quality cannot be obtained even if the ink supply amount is automatically adjusted, the ink supply amount is automatically adjusted after correction conversion with only a different dot gain correction curve for the defective quality division area. Further, it is possible to obtain a high-quality printed matter for the entire image, and furthermore, since the data to be processed again is reduced, the processing time for redoing can be shortened.
[0090]
[Modification of Second Embodiment]
In the above-described embodiment, one divided area is set as the changed divided area. However, a plurality of divided areas may be set. In this case, the same dot gain correction curve may be applied to a plurality of divided regions, or dot gain correction curves having different correction characteristics may be applied. .
[0091]
[Modifications common to the first embodiment and the second embodiment]
In the embodiment described above, the correction conversion process is performed after the raster conversion process is completed. However, the raster conversion process and the correction conversion process may be executed sequentially for each line of image data. Good.
[0092]
In the above embodiment, high-resolution and low-resolution correction raster data is generated by correction conversion processing. However, only high-resolution correction raster data may be generated. In this case, the ink supply amount data SA is calculated based on high-resolution corrected raster data.
[0093]
In the above-described embodiment, the single-color digital printing machine 2 including one printing plate PL and one ink unit 90 has been described. However, a color printing apparatus including a plurality of printing plates and a plurality of ink units 90 corresponding thereto is used. You may comprise using a digital printing machine. In this case, each ink portion is configured such that the ink supply amount can be independently adjusted for each divided region, and a different dot gain correction curve is applied to the raster data RD for each divided region and each color component data. Configured as follows.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a printing system according to the present invention.
FIG. 2 is a diagram illustrating detailed configurations of a controller 1 and a digital printing machine 2;
FIG. 3 is an enlarged overview of a flow valve portion.
FIG. 4 is a control flowchart of the first embodiment of the present invention.
FIG. 5 is a schematic diagram of a data generation process according to the first embodiment of the present invention.
FIG. 6 is a display example of an output condition setting window in the first embodiment of the present invention.
FIG. 7 is a diagram illustrating an example of a dot gain correction curve.
FIG. 8 is a diagram illustrating a procedure for determining ink supply amount data.
FIG. 9 is a control flowchart of the second embodiment of the present invention.
FIG. 10 is a schematic view showing a process of the second embodiment of the present invention.
FIG. 11 is a schematic diagram of a data generation process according to the second embodiment of the present invention.
FIG. 12 is a display example of an output condition setting window in the second embodiment of the present invention.
FIG. 13 is a display example of an ink supply amount adjustment window in the second embodiment of the present invention.
FIG. 14 is a display example of an output condition reset window in the second embodiment of the present invention.
[Explanation of symbols]
1 Controller
2 Digital printing machine
12 RIP processing section
13 Correction converter
14 Halftone signal generator
15 Ink supply amount determination section
16 User interface section
17 memory
20 Control unit
60 recording section
80 printing department
90 Ink part
92 Flow valve
93 Opening adjustment motor
98 Ink Key
DGa dot gain correction curve
DGb dot gain correction curve
PA printing paper
PD page description data
PL printing version
RD raster data
RH correction raster data of high resolution
RHM composite correction raster data
RL Low-resolution correction raster data
SA ink supply data

Claims (15)

Ink amount adjustment including a printing plate on which an image is recorded according to image data representing a page, and the ink amount supplied to the printing plate can be independently adjusted for each of the divided areas divided into a plurality of areas. In a possible printing device,
Of the image data, partial image data corresponding to at least one of the divided areas is corrected with a first correction characteristic, and partial image data corresponding to another divided area is different from the first correction characteristic. Correction means for correcting with correction characteristics and generating corrected image data;
A means for determining the amount of ink to be supplied to each segmented area based on the corrected image data, wherein the ink supplied to each segmented area based on the portion of the corrected image data corresponding to each segmented area A determining means for determining the amount;
Recording means for recording an image on a printing plate based on the corrected image data;
Printing means for printing an image on a printing paper while supplying ink corresponding to the amount of ink for each divided area determined by the determining means to the printing plate;
Printing device with adjustable ink amount.   The recording means records a halftone dot image on a printing plate, and the printing means prints a halftone dot image on a printing paper, and the first and second correction characteristics are such that the halftone dot image is printed on a printing paper. The printing apparatus capable of adjusting the ink amount according to claim 1, wherein the printing apparatus has dot gain correction characteristics for correcting dot gain generated during printing. The correction means, for each of the divided areas, statistically processing a portion of the partial image data corresponding to the divided area, to determine a correction characteristic to be applied to the partial image data based on the result of the statistical processing, The printing apparatus capable of adjusting the ink amount according to claim 1 or 2, wherein the corrected image data is generated by performing correction based on the determined correction characteristic. The correction means includes
An overall correction means for generating overall correction data by correcting the entire image data with a second correction characteristic;
Partial correction means for correcting a portion of image data corresponding to at least one of the image data with the first correction characteristic to generate partial correction data;
Combining means for generating the corrected image data by overwriting the partial image data with respect to the whole correction data;
A printing apparatus capable of adjusting the ink amount according to claim 1 or 2. Ink quantity adjustment is possible with a printing plate on which images are recorded according to the image data representing the page, and the ink amount supplied to the printing plate can be adjusted independently for each divided area divided into a plurality of areas In a printing device
Correcting means for correcting the image data based on a first correction characteristic to generate first corrected image data;
Means for determining the amount of ink to be supplied to each of the divided areas based on the first corrected image data, wherein each of the divided areas is determined based on a portion of the first corrected image data corresponding to each of the divided areas; First determining means for determining the amount of ink to be supplied;
First recording means for recording an image of a printing plate based on the first corrected image data;
First printing means for printing an image on a printing paper while supplying ink of an ink amount of each divided area determined by the first determination means to the printing plate;
Change setting means for setting at least one division area as a change division area;
Partial correction means for partially correcting the image data corresponding to the changed section area based on a second correction characteristic different from the first correction characteristic to generate changed partial image data;
Second determining means for determining the amount of ink to be supplied to the changed section area based on the changed partial image data;
A portion corresponding to the changed section area of the first corrected image data is replaced with the changed partial image data to generate second corrected image data, and an image is recorded on a new printing plate based on the second corrected image data. A second recording means;
A second printing means for changing the ink amount of the change section area to the ink amount determined by the second determining means, and printing an image on a printing paper while supplying the ink;
Printing device with adjustable ink amount.   The first and second recording means record a halftone image on a printing plate, and the first and second printing means print a halftone image on a printing paper, wherein the first correction characteristic and the first correction characteristic 6. The printing apparatus according to claim 5, wherein the second correction characteristic is a dot gain correction characteristic for correcting a dot gain generated when a halftone image is printed on a printing paper. The image data is expressed in a page description language,
The printing apparatus further includes:
Raster conversion means for converting image data expressed in a page description language into raster format image data;
Storage means for storing the raster format image data;
With
The partial correction means further from said storage means reads the image data of a raster format of the changed segment areas and the ink amount adjustable printing according to claim 5 or 6, wherein performing correction on the image data that has been issued said read apparatus. A printing method in which an image is recorded on a printing plate according to image data representing a page, and printing is performed by independently adjusting the amount of ink supplied to each of the divided areas divided into a plurality of areas on the printing plate In
(A) The partial image data corresponding to at least one of the divided areas of the image data is corrected with the first correction characteristics, and the partial image data corresponding to the other divided areas is different from the first correction characteristics. Correcting with the second correction characteristics and generating corrected image data;
(B) Means for determining the amount of ink to be supplied to each segmented area based on the corrected image data, and supplying to each segmented area based on the portion of the corrected image data corresponding to each segmented area Determining the amount of ink to be produced;
(C) recording an image on a printing plate based on the corrected image data;
(D) a step of printing an image on a printing paper while supplying ink corresponding to the amount of ink for each divided region determined by the determining means to the printing plate;
Printing method.   The step (c) records a halftone image on a printing plate, and the step (d) prints a halftone image on a printing paper, and the first and second correction characteristics are: The printing method according to claim 8, wherein the printing method has dot gain correction characteristics for correcting a dot gain generated when printing on a printing paper. In the step (a), for each of the divided regions,
(A1) statistically processing a portion of the partial image data corresponding to the segmented area;
(A2) determining a correction characteristic to be applied to the partial image data based on the processing result of the step (a1);
(A3) correcting based on the determined correction characteristics to generate the corrected image data;
A printing method according to claim 8 or 9, further comprising: The step (a)
(A4) correcting the entire image data with a second correction characteristic to generate overall correction data;
(A5) correcting a portion of image data corresponding to at least one of the image data in the image data with a first correction characteristic to generate partial correction data;
(A6) generating the corrected image data by overwriting and synthesizing the partial image data with respect to the overall correction data;
A printing method according to claim 8 or 9. A printing method in which an image is recorded on a printing plate according to image data representing a page, and printing is performed by independently adjusting the amount of ink supplied to each of the divided areas divided into a plurality of areas on the printing plate In
(A) correcting the image data based on a first correction characteristic to generate first corrected image data;
(B) a step of determining the amount of ink to be supplied to each of the divided areas based on the first corrected image data, wherein each of the respective correction areas is based on a portion of the first corrected image data corresponding to each divided area. Determining the amount of ink supplied to the segmented area;
(C) recording a printing plate on the basis of the first corrected image data;
(D) a step of printing an image on a printing paper while supplying ink of an ink amount of each divided area determined by the first determining means to the printing plate;
(E) setting at least one segment area as a modified segment area;
(F) Partially correcting the image data corresponding to the change section area based on a second correction characteristic different from the first correction characteristic to generate changed partial image data;
(G) determining the amount of ink to be supplied to the changed section area based on the changed partial image data;
(H) The second corrected image data is generated by replacing a portion corresponding to the changed section area of the first corrected image data with the changed partial image data, and a new printing plate is formed based on the second corrected image data. An image recording step;
(I) changing the ink amount of the change section area to the ink amount determined in the step (g), and printing an image on a printing paper while supplying ink;
Printing method. The printing method further includes:
(J) The printing method according to claim 12, comprising a step of repeating and executing the steps (e) to (i). The steps (c) and (h) record a halftone image on a printing plate, and the steps (d) and (i) are steps of printing a halftone image on a printing paper, wherein the first correction characteristics The printing method according to claim 12 or 13, wherein the second correction characteristic is a dot gain correction characteristic for correcting a dot gain generated when a halftone image is printed on a printing paper. The image data is expressed in a page description language,
The printing method further includes:
(J) converting image data expressed in a page description language into image data in a raster format;
(K) storing the raster-format image data;
With
The step (f) further reads out the raster format image data of the change section area from the raster format image data stored in the step (k), and corrects the read image data. Item 15. The printing method according to any one of Items 12 to 14.

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