JP2009110352A - Image processor for image printing, image processing method and computer program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology for suppressing reduction of image quality of a print image in a printer performing multi-size dot printing. <P>SOLUTION: This image processor 300 for recording a plurality of kinds of ink dots having different size on a print medium to print the image has: a size parameter acquisition part acquiring a size parameter prescribing size of the print medium; and a print data generation part generating print data PD expressing a recording state of the plurality of kinds of the dots from ink volume data IAD expressing an ink volume recorded on the print medium. The print data generation part generates the print data PD such that a recording number has a different value according to the size parameter about a specific kind of dot among the plurality of kinds of the dots, to the same ink volume data IAD. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image processing technique for printing an image.

  Multi-size dot printing that forms (records) a plurality of ink dots of different sizes on a print medium in order to more accurately reproduce gradation in an image (print image) printed on a print medium such as printing paper. Done. When performing such multi-size dot printing, if the position (landing position) at which an ink dot having a size close to the pixel size defined by the print resolution (hereinafter also simply referred to as “print resolution”) is shifted, Banding or the like may occur in the printed image, and the image quality of the printed image may be reduced.

JP 2004-160913 A Japanese Patent Laid-Open No. 2003-118088 JP 2003-266700 A JP-A-2005-001202

  By the way, when printing an image using a large-format ink jet printer, there is a high possibility that the skew of the printing medium and the feeding accuracy may be lowered depending on the conveyance state of the printing medium. Therefore, in a large-format ink jet printer, there is a high possibility that the image quality of the printed image is deteriorated due to the skew of the print medium and the decrease in the feeding accuracy. This problem is conspicuous in large-format inkjet printers, but is not limited to large-format printers and is common to all inkjet printers. In addition, the problem is not limited to inkjet printers, but is common to various printers that perform multi-size dot printing.

  The present invention has been made to solve the above-described conventional problems, and an object of the present invention is to provide a technique for suppressing a deterioration in image quality of a printed image in a printer that performs multi-size dot printing.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

[Application Example 1]
An image processing apparatus for printing an image by recording a plurality of types of ink dots having different sizes on a print medium,
A size parameter acquisition unit that acquires a size parameter that defines the size of the print medium;
A print data generation unit that generates print data representing a recording state of the plurality of types of dots from ink amount data representing the amount of ink recorded on the print medium;
With
The print data generation unit may print the print data so that the number of recordings for a specific type of dots among the plurality of types of ink dots differs from each other according to the size parameter with respect to the same ink amount data. Generate
Image processing device.

  In the image processing apparatus according to the application example 1, print data in which the number of recorded dots of a specific type differs depending on the size parameter is generated for the same ink amount data. Generally, the conveyance state of the print medium varies depending on the size of the print medium. Therefore, the recording rate of a specific type of dot can be made more suitable in accordance with the size of the printing medium, so that it is possible to suppress a decrease in the printed image.

[Application Example 2]
An image processing apparatus according to Application Example 1,
The specific type of ink dot is an ink dot having a size closer to a pixel size defined by a print resolution than the size of an ink dot other than the specific type of ink dot among the plurality of types of ink dots,
When the size of the print medium is larger than a predetermined size, the print data generation unit has a larger number of recordings of the specific type of ink dots than when the size of the print medium is smaller than the predetermined size. Generating the print data so as to reduce,
Image processing device.

  Usually, the larger the size of the print medium, the greater the influence of skew and feed accuracy of the print medium. Therefore, when the size of the print medium is larger than a predetermined size, the print image when using a large print medium is reduced by reducing the number of recorded ink dots having a size close to the pixel size defined by the print resolution. The deterioration of image quality can be further suppressed.

[Application Example 3]
An image processing apparatus according to Application Example 1,
The specific type of ink dot is an ink dot having a size smaller than a predetermined size,
The print data generation unit is configured such that when the size of the print medium is smaller than a predetermined size, the number of recordings of the specific type of ink dots is larger than when the size of the print medium is larger than the predetermined size. Generating the print data so as to increase,
Image processing device.

  Usually, the smaller the size of the print medium, the more clearly the graininess of the printed image is visually recognized. Therefore, when the size of the print medium is smaller than the predetermined size, the number of ink dots that are smaller than the predetermined size is increased to further suppress the deterioration of the print image quality when using a small print medium. can do.

[Application Example 4]
An image processing apparatus according to any one of Application Examples 1 to 3,
The print data generation unit
A recording rate data generation unit that generates recording rate data from the ink amount data;
A data conversion unit for converting the recording rate data into the print data;
With
The recording rate data generation unit sets the maximum recording rate of the specific type of ink dots to different values according to the size parameter;
Image processing device.

  In Application Example 4, the maximum recording rate of a specific type of ink dot is set to a different value depending on the size parameter. Therefore, it becomes easier to make the number of recordings of a specific type of dot different according to the size parameter.

[Application Example 5]
An image processing apparatus according to Application Example 4,
The recording rate data generation unit
A first recording rate table showing a relationship between the ink amount and the recording rate of each of the plurality of types of ink dots;
A second recording rate table in which the maximum recording rate of the specific type of ink dots is different from the first recording rate table;
A recording rate table selection unit for selecting a recording rate table used for generating the recording rate data from the first and second recording rate tables based on the size parameter;
have,
Image processing device.

  In this application example, the recording rate table selection unit selects the first and second recording rate tables in which the maximum recording rates of the specific type of ink dots are different from each other on the basis of the size parameter. Can be set to different values according to the size parameter. Therefore, it becomes easier to set the maximum recording rate of a specific type of ink dots to different values according to the size parameter.

  Note that the present invention can be realized in various modes. For example, an image processing apparatus and an image processing method, an image printing apparatus using the image processing apparatus and the method, an image printing method and an image printing system, a computer program for realizing the functions of the apparatuses, the method, and the system, and the computer The present invention can be realized in the form of a recording medium recording the program, a data signal including the computer program and embodied in a carrier wave, and the like.

Next, embodiments of the present invention will be described in the following order based on examples.
A. First embodiment:
B. Modified example of recording rate table:
C. Second embodiment:
D. Third embodiment:
E. Variations:

A. First embodiment:
FIG. 1 is an explanatory diagram showing a schematic configuration of an image printing system to which the first embodiment is applied. The image printing system includes a printer 100 and a computer 200. The printer 100 is an ink jet printer that forms an image on the printing paper PTS by ejecting ink droplets onto the printing paper PTS. The printer 100 and the computer 200 are connected by a cable CV. The printer 100 discharges ink droplets onto the printing paper PTS based on the print data PD supplied from the computer 200 via the cable CV.

  A printer driver 300 is installed in the computer 200. The printer driver 300 is a module that generates print data PD based on image data. The print data PD generated by the printer driver 300 is a recording state of ink dots of three sizes of small, medium, and large (hereinafter simply referred to as “dots”) for each pixel on the main scanning line having the print resolution. Raster data representing is included. Note that the types of dots are not necessarily limited to these three types. In general, the number of types of dots can be any number greater than or equal to two.

  A program for realizing the functions of the printer driver 300 is supplied to the computer 200 in a form recorded on a computer-readable recording medium or included in a data signal embodied in a carrier wave. it can.

  In the first embodiment, the printer 100 as the image output device and the computer 200 as the image processing device are separate from each other. However, the function as the image processing device can be incorporated in the printer.

  FIG. 2 is a block diagram illustrating a functional configuration of the printer driver 300. The printer driver 300 includes an ink amount data generation unit 310, a printing condition input unit 320, a recording rate data generation unit 330, a halftone processing unit 340, and a rasterization processing unit 350.

  The ink amount data generation unit 310 performs color conversion processing on the image data IMD supplied to the printer driver 300 to generate ink amount data IAD. The ink amount data IAD is generated by, for example, referring to a color conversion lookup table (LUT) (not shown) by converting the RGB color component values of the image data IMD into CMYK color component values corresponding to the ink amounts. Done. The ink amount data IAD generated by the ink amount data generation unit 310 is supplied to the recording rate data generation unit 330.

  The printing condition input unit 320 accepts setting input of various printing conditions STG set in the printer driver 300. The set printing condition STG is supplied to the recording rate data generation unit 330. In the first embodiment, the printing paper size (paper size) among the printing conditions STG input to the printing condition input unit 320 is supplied to the recording rate data generation unit 330.

  The recording rate data generation unit 330 includes a recording rate table selection unit 332, a conversion processing execution unit 334, and two recording rate tables 336 and 338. The recording rate table selection unit 332 selects a recording rate table from the two recording rate tables 336 and 338 based on the printing condition STG input to the printing condition input unit 320. The conversion processing execution unit 334 refers to the selected recording rate table, converts the ink amount data IAD supplied from the ink amount data generation unit 310 into recording rate data representing the recording rates of small, medium, and large dots. Convert to RRD. Here, the recording rate refers to the rate at which dots are recorded in pixels within a certain area. The contents of the two recording rate tables 336 and 338 and the selection of the recording rate table by the recording rate table selecting unit 332 will be described later. The generated recording rate data RRD is supplied to the halftone processing unit 340.

  The halftone processing unit 340 generates dot arrangement data DPD representing a dot arrangement state from the recording rate data RRD by performing halftone processing such as dithering. The generated dot arrangement data DPD is rearranged in the main scanning direction by the rasterization processing unit 350, and raster data representing the dot formation state in the main scanning direction is generated. Print data PD including raster data is generated from the generated raster data.

  As described above, the generation of the print data PD from the ink amount data IAD is performed by the functions of the recording rate data generation unit 330, the halftone processing unit 340, and the rasterization processing unit 350. Therefore, the function of the “print data generation unit” that generates the print data PD from the ink amount data IAD is realized by three of the recording rate data generation unit 330, the halftone processing unit 340, and the rasterization processing unit 350. Yes. The conversion from the recording rate data RRD to the print data PD is performed by the halftone processing unit 340 and the rasterization processing unit 350. Therefore, the function as a “data conversion unit” for converting the recording rate data RRD to the print data PD is realized by two of the halftone processing unit 340 and the rasterization processing unit 350.

  The print data PD generated in this way is supplied from the printer driver 300 to the printer 100 via an interface (not shown) provided in the computer 200 (FIG. 1) and the cable CV. By ejecting ink onto the printing paper PTS according to the printing data PD supplied by the printer 100, an image represented by the image data IMD is formed on the printing paper PTS.

  FIG. 3 is an explanatory diagram showing the relationship between the ink amount in each of the two recording rate tables 336 and 338 and the recording rate of each of the small, medium, and large dots. 3A shows the relationship between the ink amount and the recording rate in the first recording rate table 336, and FIG. 3B shows the relationship between the ink amount and the recording rate in the second recording rate table 338. Show. In FIG. 3A and FIG. 3B, the solid line represents the recording rate of small dots with respect to the ink amount. The broken line represents the medium dot recording rate relative to the ink amount, and the alternate long and short dash line represents the large dot recording rate.

  As shown in FIG. 3A, in the first recording rate table 336, the maximum value (maximum recording rate) of the recording rate of small dots and medium dots is set to 60%. On the other hand, as shown in FIG. 3B, in the second recording rate table 338, the maximum recording rate of small dots and medium dots is set to 30%, which is lower than that of the first recording rate table 336. Therefore, when the second recording rate table 338 is used, the number of small dots and medium dots formed on the printing paper PTS is usually smaller than when the first recording rate table 336 is used.

  FIG. 4 is a flowchart showing the flow of print data generation processing by the printer driver 300. The print data generation process is performed by a CPU (not shown) of the computer 200 executing a program that implements the functions of the printer driver 300.

  In step S110, the recording rate data generation unit 330 acquires the printing condition STG set in the printing condition input unit 320. As described above, in the first embodiment, the recording rate data generation unit 330 acquires the paper size among the various printing conditions STG.

  In step S120, the ink amount data generation unit 310 acquires image data (RGB image data) IMD having RGB color component values. Next, in step S130, the ink amount data generation unit 310 converts the RGB color component values into CMYK color component values for the RGB image data IMD acquired in step S120.

  In step S140, the recording rate table selection unit 332 of the recording rate data generation unit 330 determines whether or not the paper size is A3 or less. If the paper size is A3 or less, control is transferred to step S150. In step S150, the recording rate table selection unit 332 selects the first recording rate table 336 having a high maximum recording rate for small and medium dots. On the other hand, if the paper size is larger than A3, the control moves to step S160. In step S160, the recording rate table selection unit 332 selects the second recording rate table 338 having a low maximum recording rate for small and medium dots.

  In step S170, the conversion processing execution unit 334 uses a recording rate table selected from the two recording rate tables 336 and 338, and a recording rate representing the recording rate of each dot having a small, medium, and large ink amount. Data RRD is generated. Specifically, the recording rate of each dot of small, medium, and large corresponding to the ink amount is specified. Then, recording rate data RRD representing the specified recording rate is generated.

  In step S180, the halftone processing unit 340 generates dot arrangement data DPD from the recording rate data RRD. In step S190, the rasterization processing unit 350 generates print data PD from the dot arrangement data DPD generated in step S180. As described above, the generated print data PD is supplied to the printer 100 (FIG. 1), and an image is formed on the print paper PTS.

  By the way, when an image is formed by the printer 100, if the arrangement of the printing paper PTS on which the image is formed is inclined with respect to the sub-scanning direction (that is, the conveyance direction of the printing paper PTS), May adversely affect the image formed (hereinafter also referred to as “printed image”).

  FIG. 5 is an explanatory diagram showing the influence of such a deviation (skew) of the printing paper PTS on the printed image. 5A and 5B show images (bands) formed by main scanning by driving the platen 110 and sequentially transporting the printing paper PTS in the transporting direction (paper feeding direction). It shows a state of being sequentially formed on the PTS.

  In the example of FIG. 5A, the printing paper PTS is fed obliquely with respect to the paper feeding direction. For this reason, as shown in FIG. 5A, the sides of the printing paper PTS in the main scanning direction are not parallel to the paper feed direction. Hereinafter, an angle formed between the left and right sides of the printing paper PTS and the paper feeding direction is referred to as a skew angle θs.

  The main scanning direction for forming the band is the axial direction of the platen 110, that is, the direction perpendicular to the paper feed direction. Therefore, in the example of FIG. 5A in which the skew angle θs is θ1 (> 0), the band BD1 indicated by hatching is formed obliquely with respect to the side of the printing paper PTS.

  When the band BD1 is formed on the printing paper PTS, the printing paper PTS is then conveyed in the paper feeding direction. Usually, the transport mechanism for the print paper PTS has a paper feed guide (not shown) that regulates the orientation of the print paper PTS in the paper feed direction. Therefore, when the inclined printing paper PTS is conveyed as shown in FIG. 5A, the printing paper PTS hits the paper feed guide and changes its direction.

  FIG. 5B shows a state in which the direction of the printing paper PTS has changed in this way. In the example of FIG. 5B, the printing paper PTS is inclined in the opposite direction to the case of FIG. Therefore, the skew angle θs is changed from θ1 in FIG. 5A to θ2 (<0).

  As described above, when the printing paper PTS on which the band BD1 is formed is transported and the band BD2 is formed on the transported printing paper PTS, the two bands BD1 and BD2 formed on the printing paper PTS are one of them. Will overlap and the other will leave.

  At this time, the width d in which the two bands BD1 and BD2 overlap and separate at both ends in the main scanning direction is the difference Δθs (= θ2) between the band width L and the skew angle θs when the two bands BD1 and BD2 are formed. −θ1) is expressed by the following formula (1).

d = L / 2 × sin (Δθs) ≈L / 2 × Δθs (1)

  Usually, the angle difference Δθs is sufficiently smaller than 1. Therefore, in the above equation (1), the width d can be treated as a value obtained by multiplying 1/2 of the band width L by the angle difference Δθs.

  As shown in Expression (1), the width d in which the two bands BD1 and BD2 are separated increases as the width L of these bands BD1 and BD2 increases. For this reason, as the size of the printing paper PTS increases, the accuracy of the formation positions of the bands BD1 and BD2 decreases. In the example of FIG. 5, a state in which the formation position accuracy of the bands BD <b> 1 and BD <b> 2 decreases due to skew in which the printing paper PTS is fed obliquely is generally shown, but in general, as the size of the printing paper PTS increases. There is a high possibility that the pitch of the dot row (dot row) along the main scanning line deviates from the printing resolution.

  FIG. 6 is an explanatory diagram showing a state in which small, medium, and large dots are formed on the printing paper. FIG. 6A shows a state in which the pitch of the dot row is maintained at the printing resolution P. On the other hand, in FIG. 6B, as shown in FIG. 5, the accuracy of the formation positions of the two bands BD1 and BD2 is lowered, and the pitch is wider than the printing resolution P in part between the dot rows. Is shown. In FIG. 6A and FIG. 6B, the black circles indicate the formed small, medium, and large dots. The alternate long and short dash line indicates the main scanning direction in which these dots are formed, that is, the direction of the dot row. A dotted line indicates an intermediate line of the dot row.

  In the example of FIG. 6A, the pitch of the dot row is maintained at the printing resolution P. Therefore, the small, medium, and large dots are arranged in the sub-scanning direction at the printing resolution P. As described above, the small, medium, and large dots are formed at equal intervals in the sub-scanning direction, so that an image formed by these dots is a good image without banding or the like.

  On the other hand, in the example of FIG. 6B, the pitch of the upper two dot rows is the print resolution P, whereas the pitch of the lower two dot rows is a pitch P ′ wider than the print resolution P. It has become. As described above, when the pitch of the dot row becomes wider than the printing resolution P, in an image formed by small dots and medium dots whose dot diameter (size) is close to the printing resolution P, there is a blank due to the spread of the pitch. It becomes easier to see and banding is more likely to occur. On the other hand, in the image formed with large dots, since the dot diameter is larger than the printing resolution P, the blank due to the widening of the pitch of the dot row is not visually recognized, and the occurrence of banding is suppressed.

  In the first embodiment, when the paper size is larger than A3, that is, when there is a high possibility that the pitch of the dot row is deviated from the printing resolution P, the second recording rate in which the recording rate of small dots and medium dots is low. Recording rate data RRD is generated using the table 338. Therefore, when print data PD is generated using the generated recording rate data RRD and an image is formed using the generated print data PD, it is possible to suppress the occurrence of banding due to a shift in the pitch of the dot rows.

  On the other hand, when the paper size is A3 or less, the shift of the pitch of the dot rows does not become so large. Further, when the paper size is small, the printed image is usually observed at a closer distance than when printed on a large printing paper. Therefore, in such a case, by using the first recording rate table 336 to increase the rate at which small and medium dots are formed, it is possible to suppress a decrease in graininess of the printed image.

  In the first embodiment, the recording rate table is selected based on the determination result of whether or not the paper size is larger than A3. However, the paper size serving as a determination criterion when selecting the recording rate table is as follows. It is appropriately changed according to the characteristics of the printer 100 (FIG. 1). For example, when the printer 100 is a printer that is unlikely to cause skew, the recording rate table may be selected based on the determination result of whether or not the paper size is larger than A2. On the other hand, when the printer 100 is a printer that easily causes skew, the recording rate table may be selected based on the determination result as to whether or not the paper size is larger than A4.

  In the first embodiment, the recording rate table is selected based on the paper size, but the recording rate table can be generally selected based on a parameter representing the size of the printing paper PTS. As such parameters, for example, the width and length of the printing paper PTS can be used.

B. Modified example of recording rate table:
In the first embodiment, when the paper size is larger than A3, as shown in FIG. 3B, both the maximum recording rate of small dots and the maximum recording rate of medium dots are set low. The recording rate table 338 is selected. However, depending on the relationship between the diameters of the small, medium, and large dots and the printing resolution P, the occurrence of banding can be suppressed by using a recording rate table different from the second recording rate table 338. .

  FIG. 7 is an explanatory diagram showing a modified example of such a recording rate table. FIG. 7A and FIG. 7B show the relationship between the ink amount in the recording rate table and the recording rate of each of small, medium, and large dots in the modified example. These recording rate tables differ from the second recording rate table 338 of FIG. 3B in that only one of the maximum recording rate of small dots and the maximum recording rate of medium dots is set low. ing.

  In the recording rate table of FIG. 7A, the maximum recording rate for small dots is set to 30%, and the maximum recording rate for medium dots is set to 60%. Similarly to the first embodiment, when the paper size is larger than A3, a recording rate table in which the maximum recording rate of small dots is set low is selected, and when the paper size is A3 or less, The first recording rate table 336 in which the maximum recording rate of small dots is set high is selected.

  As described above, by using the recording rate table shown in FIG. 7A, the number of small dots formed on the printing paper PTS is smaller than when the first recording rate table 336 is used. Thus, by reducing only the number of small dots formed, for example, when the small dot diameter is close to the print resolution P and the medium dot diameter is sufficiently larger than the print resolution P, the dot row The occurrence of banding due to the deviation of the pitch from the printing resolution P can be suppressed.

  In the example of FIG. 7B, the maximum recording rate for small dots is set to 60%, and the maximum recording rate for medium dots is set to 30%. When the size of the printing paper is larger than A3, a recording rate table in which the maximum recording rate of medium dots is set low is selected. When the size of the printing paper is A3 or less, the maximum of medium dots is selected. The first recording rate table 336 having a high recording rate is selected.

  As described above, by using the recording rate table shown in FIG. 7B, the number of medium dots formed on the printing paper is smaller than when the first recording rate table 336 is used. Thus, by reducing only the number of medium dots formed, for example, when the small dot diameter is sufficiently smaller than the print resolution P and the medium dot diameter is close to the print resolution P, the dot row The occurrence of banding due to the deviation of the pitch from the printing resolution P can be suppressed.

  Furthermore, for example, when the diameter of the large dots is close to the printing resolution P, a recording rate table that reduces the number of large dots formed can be used. In this case, the number of large dots formed may be reduced by increasing the maximum recording rate of at least one of small dots and medium dots. In addition, the number of large dots formed can be reduced by changing the degree of reduction in the recording rate of small dots and medium dots in areas with a large amount of ink without changing the maximum recording rate of small dots and medium dots. Also good.

C. Second embodiment:
FIG. 8 is a flowchart showing the flow of print data generation processing in the second embodiment. The print data generation process of the second embodiment is shown in FIG. 4 in that step S132a is added after step S130, and that two steps S110 and S140 are replaced with steps S110a and S140a, respectively. This is different from the print data generation process of the first embodiment shown. The other points are the same as in the first embodiment.

  In step S110a, the recording rate data generation unit 330 acquires a paper size and a printing paper type (paper type) among various printing conditions STG.

In step S132, the recording rate table selection unit 332 sets a reference size based on the paper type acquired in step S110a. As the reference size, a smaller reference size is set for a paper that is likely to cause skew, and a larger reference size is set for a paper that is less likely to cause skew. For example, the reference size is set as shown in Table 1 below.

  In step S140a, the recording rate table selection unit 332 determines whether the paper size is equal to or smaller than the reference size set in step S132. If the paper size is less than or equal to the reference size, control is transferred to step S150. On the other hand, if the paper size is larger than the reference size, control is transferred to step S160.

  Thus, in the second embodiment, the paper size is compared with the reference size set based on the type of printing paper. When the paper size is larger than the reference size, the occurrence of banding can be suppressed by reducing the rate at which small and medium dots are formed. On the other hand, when the paper size is smaller than the reference size, the decrease in graininess of the printed image can be suppressed by increasing the ratio of forming small and medium dots.

  In the second embodiment, the recording rate table is selected based on the paper type and the paper size. Therefore, it is preferable to the first embodiment in that a more appropriate recording rate table can be selected. On the other hand, the first embodiment is preferable to the second embodiment in that the processing in the recording rate table selection unit 332 can be simplified.

D. Third embodiment:
FIG. 9 is a block diagram illustrating a functional configuration of the printer driver 300b according to the third embodiment. In the printer driver 300b of the third embodiment, the printing condition STG is not supplied from the printing condition input unit 320 to the recording rate data generation unit 330b, and the recording rate data generation unit 330b has an image arrangement acquisition unit 331. 2 in that the printer driver 300 of the first embodiment shown in FIG. Other points are the same as in the first embodiment.

  FIG. 10 is a flowchart showing the flow of print data generation processing in the third embodiment. In the print data generation process of the third embodiment, step S110 is omitted, step S134 is added after step S130, and step S140 is replaced with step S140b. This is different from the print data generation process of the first embodiment shown in FIG. Other points are the same as in the first embodiment.

  In step S134, the image arrangement acquisition unit 331 acquires the print position (arrangement) of the image on the print paper PTS. The arrangement of the print image can be acquired by analyzing the ink amount data IAD and detecting a region where the ink amount is not 0 (not white), for example. However, the layout of the print image may be acquired by analyzing the image data IMD. Further, when the image data IMD includes arrangement data that specifies the print position of the image, it can be acquired based on the arrangement data.

  In step S140b, the recording rate table selection unit 332 determines whether or not the print image is arranged at the center of the printing paper PTS in the main scanning direction. Specifically, it is determined whether or not the print image is arranged near the center line of the print paper PTS along the sub-scanning direction. In the following description, unless otherwise specified, the “center” refers to the center in the main scanning direction, and the “center line” refers to the center line of the printing paper PTS along the sub-scanning direction. If the print image is arranged at the center of the print paper PTS, control is transferred to step S150. On the other hand, if the print image is not arranged at the center of the print paper PTS, control is transferred to step S160.

  Whether or not the print image is arranged at the center of the print paper PTS can be determined based on whether or not the print image is on the center line. However, the determination of whether or not it is arranged at the center can also be made by other methods. For example, the determination may be made based on whether or not the print image falls within a predetermined region including the center line, and based on the distance between the edge of the print image and the side of the print paper PTS in the main scanning direction. It is also possible to judge.

  FIG. 11 is an explanatory diagram showing an example of the arrangement of print images on the print paper PTS. FIG. 11A shows a state where the print image IPT1 is arranged at the center of the print paper PTS. FIG. 11B shows a state in which the print image IPT2 is arranged at a position from the right side of the print paper PTS. 11A and 11B, the center line CL indicates the center line of the printing paper PTS along the transport direction of the printing paper PTS.

  In the third embodiment, whether or not the print image is arranged at the center is determined based on whether or not the print image falls on the center line of the printing paper PTS. In the example of FIG. 11A, the print image IPT1 is on the center line CL. Therefore, in step S140 of FIG. 10, it is determined that the print image IPT1 is arranged at the center of the print paper PTS. On the other hand, in the example of FIG. 11B, the print image IPT2 does not cover the center line CL. Therefore, in step S140 of FIG. 10, it is determined that the print image IPT2 is not arranged at the center of the print paper PTS.

  As shown in FIG. 5, when there is a deviation of the printing paper PTS, the skew angle θs changes as the printing paper PTS is conveyed. However, even when the skew angle θs changes due to conveyance, the shift in the pitch of the dot rows is smaller at the center of the printing paper PTS than at both ends of the printing paper PTS. For this reason, when the print image is arranged at the center of the print paper PTS, the pitch deviation of the dot rows does not increase. On the other hand, when the print image is not arranged at the center of the printing paper PTS, as described above, the deviation of the pitch of the dot rows becomes large.

  In the third embodiment, the arrangement of the print image on the print paper PTS is acquired. If the print image is not arranged at the center of the printing paper PTS, the recording rate table 338 having a lower maximum recording rate of small / medium dots is selected, and the ratio of forming small / medium dots is low. It will be lost. Therefore, when the print image is not arranged at the center of the print paper PTS, the occurrence of banding due to the pitch deviation of the dot rows is suppressed. On the other hand, when the print image is arranged in the center portion of the print paper PTS, a decrease in the graininess of the print image is suppressed by increasing the ratio at which small and medium dots are formed.

  In the third embodiment, when the print image is not arranged at the center of the printing paper PTS, the recording rate table 338 having a lower maximum recording rate of small / medium dots is selected. For this reason, even when dots are formed during acceleration / deceleration for forming dots and the landing position is shifted in the main scanning direction, it is possible to suppress the deterioration of the image quality of the printed image due to the deviation of the landing position.

  As described above, in the third embodiment, the recording rate data is generated from the two recording rate tables 336 and 338 having different maximum recording rates of the small and medium dots based on the arrangement of the print image on the printing paper PTS. A recording rate table is selected. Therefore, it is possible to suppress the occurrence of banding when the print image is not arranged at the center of the print paper PTS, and to reduce the image quality of the print image when the print image is arranged at the center of the print paper PTS. It can be made better.

  In the third embodiment, the recording rate table is selected based on the layout of the print image in the main scanning direction. However, the recording rate table is selected based on the layout of the print image in the transport direction of the printing paper PTS. It is good also as what performs. Usually, the skew of the printing paper PTS tends to be larger at the end in the transport direction than at the center in the transport direction. Therefore, the first recording rate table 336 is selected when the print image is arranged at the center in the transport direction (sub-scanning direction), and the second when the print image is not arranged at the center in the transport direction. The recording rate table 338 is preferably selected.

  The recording rate table may be selected based on both the print image arrangement in the main scanning direction and the print image arrangement in the transport direction. In general, the recording rate table can be selected based on the arrangement of print images on the print paper PTS. In this case, the relationship between the layout of the print image and the selected recording rate table is appropriately changed according to the paper feed characteristics of the printer 100.

E. Variations:
In addition, this invention is not restricted to the said Example and embodiment, It can implement in a various aspect in the range which does not deviate from the summary, For example, the following deformation | transformation is also possible.

E1. Modification 1:
In the first and second embodiments, when the paper size is larger than a predetermined size, the recording rate table 338 having a lower maximum recording rate of small / medium dots is used. Accordingly, a recording rate table 338 in which the maximum recording rate of small / medium dots is lower may be used. For example, when the paper size is smaller than a predetermined size, the recording rate table 338 having a lower maximum recording rate of small / medium dots may be used. In this way, when the paper size is reduced, the contact area between the platen 110 and the printing paper PTS is reduced, and the paper feed accuracy is reduced. it can.

E2. Modification 2:
In each of the above embodiments, the third embodiment is applied to the printer driver 300b that is separate from the first and second embodiments. However, the third embodiment is combined with any one of the first and second embodiments. Is also possible. Specifically, when the paper size is larger than a predetermined size, the recording rate table selected according to the arrangement of the print image on the printing paper PTS is used, and the paper size is smaller than the predetermined size. May use a recording rate table 336 having a higher maximum recording rate of small and medium dots.

E3. Modification 3:
In each of the above embodiments, by selecting the recording rate table used to generate the recording rate data RRD (FIGS. 2 and 9) from the first and second recording rate tables 336 and 338, small / medium dot Although the maximum recording rate is changed, the maximum recording rate of small / medium dots may be set by other methods. For example, a recording rate table may be generated based on the maximum recording rate to be set, and the recording rate data RRD may be generated from the ink amount data IAD using the generated recording rate table.

E4. Modification 4:
In each of the above embodiments, the maximum recording rate of dots close to the printing resolution is changed according to the paper size and the arrangement of the print image. However, the dots for which the maximum recording rate is changed are not necessarily dots close to the printing resolution. Not necessary. For example, the dots whose maximum recording rate is to be changed may be dots smaller than a predetermined size. In general, the dots for which the maximum recording rate is to be changed are experimentally determined based on the print image quality when the paper size and the layout of the print image are changed.

E5. Modification 5:
In each of the embodiments described above, the ink amount data IAD (FIG. 2) has four CMYK color component values corresponding to the four types of CMYK ink used in the printer 100 (FIG. 1). In general, the ink amount data IAD is generated as data having a number of color component values corresponding to the type of ink used in the printer 100.

E6. Modification 6:
In each of the above embodiments, the present invention is applied to the printer driver 300 that generates the print data PD for the ink jet printer 100 (FIG. 1). However, the present invention performs multi-size dot printing in addition to the ink jet printer. As long as it is a printer, the present invention can also be applied to a printer driver that generates print data for other types of printers such as a laser printer. Further, the present invention can be applied to a facsimile apparatus and a copier as well as a printer as long as the apparatus includes an image processing apparatus corresponding to the printer driver 300.

1 is an explanatory diagram illustrating a schematic configuration of an image printing system to which a first embodiment is applied. FIG. 2 is a block diagram showing a functional configuration of a printer driver 300. FIG. FIG. 4 is an explanatory diagram showing the relationship between the ink amount in each of two recording rate tables 336 and 338 and the recording rate of small, medium and large dots. 5 is a flowchart showing a flow of print data generation processing by the printer driver 300. Explanatory drawing which shows the influence which a skew has on a printed image. Explanatory drawing which shows the state in which each dot of small, medium, and large was formed on the printing paper. Explanatory drawing which shows the modification of a recording rate table. 9 is a flowchart showing a flow of print data generation processing in the second embodiment. FIG. 9 is a block diagram illustrating a functional configuration of a printer driver 300b according to a third embodiment. 10 is a flowchart showing a flow of print data generation processing in the third embodiment. FIG. 3 is an explanatory diagram showing an example of arrangement of print images on a print paper PTS.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Printer 110 ... Platen 200 ... Computer 300, 300b ... Printer driver 310 ... Ink amount data generation part 320 ... Printing condition input part 330, 330b ... Recording rate data generation part 331 ... Image arrangement acquisition part 332 ... Recording ratio table selection part 334: Conversion processing execution unit 336, 338 ... Recording rate table 340 ... Halftone processing unit 350 ... Rasterization processing unit CV ... Cable PTS ... Printing paper

Claims (7)

An image processing apparatus for printing an image by recording a plurality of types of ink dots having different sizes on a print medium,
A size parameter acquisition unit that acquires a size parameter that defines the size of the print medium;
A print data generation unit that generates print data representing a recording state of the plurality of types of dots from ink amount data representing the amount of ink recorded on the print medium;
With
The print data generation unit may print the print data so that the number of recordings for a specific type of dots among the plurality of types of ink dots differs from each other according to the size parameter with respect to the same ink amount data. Generate
Image processing device. The image processing apparatus according to claim 1,
The specific type of ink dot is an ink dot having a size closer to a pixel size defined by a print resolution than the size of an ink dot other than the specific type of ink dot among the plurality of types of ink dots,
When the size of the print medium is larger than a predetermined size, the print data generation unit has a larger number of recordings of the specific type of ink dots than when the size of the print medium is smaller than the predetermined size. Generating the print data so as to reduce,
Image processing device. The image processing apparatus according to claim 1,
The specific type of ink dot is an ink dot having a size smaller than a predetermined size,
The print data generation unit is configured such that when the size of the print medium is smaller than a predetermined size, the number of recordings of the specific type of ink dots is larger than when the size of the print medium is larger than the predetermined size. Generating the print data so as to increase,
Image processing device. The image processing apparatus according to any one of claims 1 to 3,
The print data generation unit
A recording rate data generation unit that generates recording rate data from the ink amount data;
A data conversion unit for converting the recording rate data into the print data;
With
The recording rate data generation unit sets the maximum recording rate of the specific type of ink dots to different values according to the size parameter;
Image processing device. The image processing apparatus according to claim 4,
The recording rate data generation unit
A first recording rate table showing a relationship between the ink amount and the recording rate of each of the plurality of types of ink dots;
A second recording rate table in which the maximum recording rate of the specific type of ink dots is different from the first recording rate table;
A recording rate table selection unit for selecting a recording rate table used for generating the recording rate data from the first and second recording rate tables based on the size parameter;
have,
Image processing device. An image processing method for printing an image by recording a plurality of types of ink dots of different sizes on a print medium,
(A) obtaining a size parameter defining the size of the print medium;
(B) generating print data representing a recording state of the plurality of types of dots from ink amount data representing the amount of ink recorded on the print medium;
With
In the step (b), with respect to the same ink amount data, the printing is performed so that the number of recordings for a specific type of dots among the plurality of types of ink dots is different from each other according to the size parameter. Including the step of generating data,
Image processing method. A computer program for causing a computer to execute image processing for printing an image by recording a plurality of types of ink dots of different sizes on a print medium,
(A) a function of acquiring a size parameter that defines the size of the print medium;
(B) a function of generating print data representing a recording state of the plurality of types of dots from ink amount data representing the amount of ink recorded on the print medium;
To the computer,
The function (b) is configured so that, for the same ink amount data, the print data is set such that the number of recordings for a specific type of dots among the plurality of types of ink dots is different from each other according to the size parameter. Including the ability to generate
Computer program.

Images