JP2007038435A - Printer, printing program, printing method, apparatus for generating printing data, program for generating printing data, method for generating printing data, and recording medium with the program recorded - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a printer, a program and a printing method whereby the banding phenomenon caused by density irregularities is reduced, and also to provide an apparatus, a program and a method for generating printing data, and a recording medium. <P>SOLUTION: After correcting image data according to nozzle characteristics of a printing head 200, the printer of an inkjet system generates the printing data by adding a noise value of a predetermined amount to the corrected image data and making the data an N value. The density irregularities become inconspicuous because sizes of dots printed are dispersed. Deterioration of a printing image quality by the banding phenomenon is avoided accordingly. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a printing apparatus used for a facsimile apparatus, a copying machine, a printer apparatus for office automation equipment, and the like, and in particular, draws predetermined characters and images by ejecting fine particles of liquid ink onto printing paper (recording material). The present invention relates to a so-called inkjet printing apparatus, printing program, printing method, print data generation apparatus, print data generation program, print data generation method, and recording medium on which the program is recorded.

In the following, an ink jet printing apparatus (printer) will be described as an example.
A printer that employs such an ink jet method (hereinafter referred to as an “inkjet printer”) generally has a moving body called a carriage, which is integrally provided with an ink cartridge and a print head, on a printing paper in the paper feeding direction. By drawing (injecting) liquid ink particles in the form of dots from the nozzles of the print head while reciprocating in an orthogonal direction (width direction of the print paper), a predetermined character or image is drawn on the print paper. A desired printed matter is created. And by providing this carriage with four color (black, yellow, magenta, cyan) ink cartridges including black (black) and print heads for each color, not only monochrome printing but also full color printing combining each color (Furthermore, 6 colors, 7 colors, or 8 colors in which light cyan, light magenta, etc. are added to these colors are also put into practical use).

  In addition, in this type of ink jet printer in which printing is executed while the print head on the carriage is reciprocated in the direction orthogonal to the paper feed direction, the print head is moved several tens of times to cleanly print the entire page. Since it is necessary to reciprocate 100 times or more from the beginning, there is a disadvantage that it takes much printing time compared with other types of printing apparatuses, for example, laser printers using electrophotographic technology such as copying machines. . Such an ink jet printer is generally called a “multi-pass printer” or a “serial printer”.

  On the other hand, in an ink jet printer that does not use a carriage with a long print head having the same dimensions as the width of the printing paper, it is not necessary to move the printing head in the width direction of the printing paper. Therefore, high-speed printing similar to that of the laser printer is possible. In addition, since a carriage for mounting the print head and a drive system for moving the print head are not required, the printer housing can be reduced in size and weight, and the quietness can be greatly improved. Yes. Such an ink jet printer is generally called a “line head printer”.

  By the way, a print head indispensable for such an ink jet printer is formed by arranging fine nozzles having a diameter of about 10 to 70 μm in series at a constant interval or in multiple stages in the print direction. The amount of ink discharged from some nozzles may increase or decrease from a specified value due to an error, and the size of dots formed by the nozzles may differ from the target size.

As a result, the density of the print portion corresponding to the defective nozzle portion changes as compared with the print portion corresponding to the normal nozzle portion, so that it becomes conspicuous in a streak shape, and so-called “banding phenomenon” is called printing. Defects may occur and print quality may be significantly reduced.
That is, if the density of the print portion corresponding to the defective nozzle portion is smaller than the density of the adjacent normal nozzle, the portion becomes conspicuous in white stripes (when the printing paper is white). If the density of the corresponding printed part is larger than the density of the adjacent normal nozzle, that part becomes conspicuous in a dark streak shape.

  In particular, the banding phenomenon is more fixed than the case of the “multi-pass printer (serial printer)” as described above, and the print header is fixed (one-pass printing) and the number of nozzles is more than that of the multi-pass printer. This is more likely to occur in the case of the “line head type printer” that is much more common (in multi-pass printers, there is a technique that makes the white stripes inconspicuous by using the print head reciprocating many times).

Therefore, in order to prevent such poor printing due to density unevenness, research and development in the so-called hardware part such as improvement of print head manufacturing technology and design improvement has been eagerly advanced. It is difficult to provide a print head in which 100% “banding phenomenon” does not occur due to quality and technical aspects.
For this reason, for example, in the following Patent Documents 1 to 3 and the like, a test pattern is actually printed using a recording head in which “density unevenness” occurs, and this is read by a scanner or the like to obtain density unevenness from the actual density value. A correction table, a gradation correction table for each predetermined unit, a gradation correction table for an average nozzle, or the like is created, and gradation correction of image data is performed based on these tables to cope with density unevenness.
JP-A-5-92559 Japanese Patent Laid-Open No. 5-220977 Japanese Patent Laid-Open No. 10-138509

However, such a conventionally proposed method can eliminate some degree of density unevenness, but it is not sufficient.
Therefore, the present invention has been devised in order to effectively solve such a problem, and the object thereof is a novel printing apparatus that can eliminate or hardly make the banding phenomenon caused by density unevenness particularly inconspicuous. A printing program, a printing method, a printing data generation apparatus, a printing data generation program, a printing data generation method, and a recording medium on which the program is recorded are provided.

[Mode 1] In order to solve the above problems, a printing apparatus according to mode 1
Generated based on image data acquisition means for acquiring M (M ≧ 3) value image data, a print head having a plurality of nozzles capable of printing dots of different sizes, and characteristics of each nozzle of the print head Correction information storage means for storing correction information of the print head, and image data for correcting pixel values of the image data acquired by the image data acquisition means based on the correction information of the print head stored in the correction information storage means Correction means, image data N-value conversion means for converting the image data corrected by the image data correction means into N (M> N ≧ 2), and N-value conversion that is converted to N-value by the image data N-value conversion means Print data generating means for generating print data based on the data; and image data printing means for printing the print data generated by the print data generating means using the print head. ,
The image data N-value conversion means converts the image data corrected by the image data correction means into N (N ≧ 2) values after adding a predetermined noise value for each pixel of the image data. It is characterized by being.

  As a result, the input density value of the image data is corrected according to the actual output density value for each nozzle to eliminate the banding phenomenon due to a certain degree of density unevenness, and more noise is added. Since the banding phenomenon due to density unevenness is effectively eliminated, the banding phenomenon due to density unevenness is eliminated or hardly noticeable, and a high-quality printed matter can be obtained efficiently.

  Here, the “banding phenomenon” in the present embodiment refers to a printing defect in which “white streaks” or “dark streaks” are generated due to “density unevenness” (hereinafter referred to as “printing apparatus”). Form, "print program", "print method", "print data generation apparatus", "print data generation program", "print data generation method", and "the program is recorded" The same applies to the description relating to the “recording medium” and the best mode for carrying out the invention.

  “Density unevenness” means that dots of a size corresponding to the input density value (pixel value) are not formed as in other nozzles in which some nozzles are adjacent to each other. A phenomenon in which the concentration appears to change partially. If the dot size is smaller than the original size, the background of the printing paper will be exposed as much, so white streaks (if the printing paper is white) appear in that area. When the size is larger than the original size, the background of the printing paper is covered with dots and hidden accordingly, so the density of that part becomes darker and appears as “dark streaks” ( The following forms relating to “printing apparatus”, forms relating to “printing program”, forms relating to “printing method”, forms relating to “print data generating apparatus”, forms relating to “print data generating program”, forms relating to “print data generating method”, And the same in the description relating to the “recording medium on which the program is recorded”, the best mode for carrying out the invention, etc.)

  The “noise value” specifically refers to a numerical value that fluctuates the pixel value of each pixel, and includes a negative numerical value as well as a positive numerical value generated by a random number or the like (a form relating to the “printing apparatus” below) , A form related to “print program”, a form related to “print method”, a form related to “print data generation device”, a form related to “print data generation program”, a form related to “print data generation method”, and a record in which the program is recorded This is the same in the description of the form relating to “medium” and the best mode for carrying out the invention.

The “M value (M ≧ 3)” is a multi-value pixel value related to so-called luminance or density expressed as, for example, 8-bit 256 gradations, and “N value (M> “N ≧ 2)” is a process for classifying such M-value (multi-value) data into N types based on a certain threshold, and “dot size” In addition to the size (area) of the image itself, it is also a concept including not hitting dots (forms relating to “printing apparatus”, forms relating to “printing program”, forms relating to “printing method”, “print data”) Form relating to “Generator”, Form relating to “Print Data Generating Program”, Form relating to “Print Data Generating Method”, Form relating to “Recording Medium on which said Program is Recorded”, Best Mode for Carrying Out the Invention Same as is in the description).
[Mode 2] The printing apparatus of mode 2 is
In the printing apparatus according to the first aspect, the image data N-value conversion unit changes a noise value to be added according to a pixel value of the image data corrected by the image data correction unit. Is.
As a result, it is possible to effectively reduce the banding phenomenon while minimizing the deterioration of the original image quality of the image data.

[Mode 3] The printing apparatus of mode 3 is
In the printing apparatus according to aspect 1, when the pixel value of the image data corrected by the image data correction unit is a halftone, the image data N-value conversion unit adds a noise value to be added to the halftone pixel. This is characterized in that the noise value added to the pixels other than the halftone is increased.

  That is, the banding phenomenon due to density unevenness has a characteristic that it is particularly noticeable in the halftone area than in the high density area (shadow part) and the low density area (highlight part). Accordingly, the banding phenomenon can be effectively reduced by increasing the noise value added to the halftone pixels that are particularly noticeable as compared to the pixels in the shadow portion and the highlight portion as in this embodiment.

  In other words, the shadow area is less noticeable in the lower color of the printing paper, so the banding phenomenon is not noticeable because it is close to a so-called solid image, and if the noise is mixed in the highlight area, the image quality deteriorates. High quality prints can be obtained by reducing the amount.

[Mode 4] A printing apparatus according to mode 4
4. The error diffusion for diffusing an error generated when N (M> N ≧ 2) value is converted into an unprocessed pixel of the pixel data by the image data N-value conversion unit in the printing apparatus according to any one of forms 1 to 3. Means for subtracting the noise value added to the pixel from the error value and diffusing the error value after the subtraction when diffusing the error for each pixel to the unprocessed pixel. It is characterized by becoming.

  That is, in this embodiment, the error is effectively utilized by diffusing an error generated when N (M> N ≧ 2) is converted into an unprocessed pixel of the pixel data by the error diffusion unit. Can maintain high image quality. Further, by subtracting the noise value added to the pixel from the error value before error diffusion by the error diffusion means and then diffusing, it is possible to prevent the density change in that region due to the addition of the noise value. it can.

[Mode 5] A printing apparatus according to mode 5
5. The printing apparatus according to any one of forms 1 to 4, wherein the correction information storage unit is generated by a test pattern data generation unit that generates M (M ≧ 3) value test pattern data and the test pattern data generation unit. Test pattern data N-value conversion means for converting the test pattern data into N (M> N ≧ 2) values, and the test pattern data converted to N-value by the test pattern data N-value conversion means using the print head A test pattern printing means for printing, an output density detecting means for detecting the output density of the test pattern printed by the test pattern printing means, and the output density of the print head from the output density of the test pattern detected by the output density detecting means. Correction information generating means for generating correction information.

That is, as described above, the characteristics of the print head can be grasped at any time by acquiring the correction information stored in the correction information storage means, but the characteristics of the print head change greatly due to deterioration over time. Can be considered. Therefore, the test pattern data generation means, test pattern data N-value conversion means, test pattern printing means, output density detection means, and correction information generation means as in the present embodiment always reflect the latest print head state. Correction information can be generated and stored.
As a result, optimal correction processing can always be performed, so that the banding phenomenon can be reliably reduced.

[Mode 6] A printing apparatus according to mode 6 includes:
In the printing apparatus according to the fifth aspect, the test pattern data N-value conversion unit converts the test pattern data generated by the test pattern data generation unit into N (M> N ≧ 2) values before the test pattern data A predetermined noise value is added to each pixel of data, and then N (N ≧ 2) values are obtained.

In other words, in the present embodiment, noise is added to the test pattern data together with the addition of noise by the image data N-value conversion means.
Thus, by adding a certain amount of noise to the test pattern data, it is possible to reduce the N-value conversion characteristic on the image data side and generate correction information that is less dependent on the N-value conversion characteristic. The banding phenomenon can be effectively avoided and the amount of noise applied to the image data side can be reduced, so that the deterioration of image quality can be further reduced.

[Mode 7] A printing apparatus according to mode 7 includes:
In the printing apparatus according to mode 6, the test pattern data N-value conversion unit increases the noise value added for each pixel of the test pattern data more than the noise value added by the image data N-value conversion unit. It is characterized by being.

  In other words, accurate correction information cannot be generated unless the test pattern (printed image) printed by the test pattern printing unit is uniform throughout the entire region, regardless of its position, such as its upper and lower ends. Therefore, by increasing the noise value added for each pixel of the test pattern data as compared with the noise value added by the image data N-value conversion unit as in this embodiment, the N-value conversion characteristic is eliminated, and one nozzle It becomes possible to make the density average for each line in charge uniform.

[Mode 8] The print program of mode 8 is
The computer generates image data acquisition means for acquiring M (M ≧ 3) value image data, and the printing generated based on the characteristics of each nozzle of a print head having a plurality of nozzles capable of printing dots of different sizes Correction information storage means for storing the correction information of the head, and image data correction means for correcting the pixel value of the image data acquired by the image data acquisition means based on the correction information of the print head stored in the correction information storage means Image data corrected by the image data correction means is converted into N (M> N ≧ 2) value N-value conversion means, and the image data N-value conversion means is converted into N-valued data. Print data generation means for generating print data based on the image data printing means for printing the print data generated by the print data generation means using the print head; Together to function,
The image data N-value conversion means functions so as to convert the image data corrected by the image data correction means into N (N ≧ 2) values after adding a predetermined noise value for each pixel of the image data. It is characterized by this.

As a result, similar to the first embodiment, density unevenness is eliminated or hardly noticeable and the banding phenomenon is avoided, so that a high-quality printed matter can be obtained with certainty.
In addition, most printing devices on the market such as inkjet printers have a computer system including a central processing unit (CPU), a storage device (RAM, ROM), an input / output device, and the like. Since each means can be realized by software, it can be realized more economically and easily than a case where dedicated means is created to realize each means. Furthermore, it is possible to easily upgrade the version by modifying or improving the function by rewriting a part of the program.

[Mode 9] The print program of mode 9 is
The printing program according to the eighth aspect is characterized in that the image data N-value conversion unit changes a noise value to be added according to a pixel value of the image data corrected by the image data correction unit. Is.
As a result, the banding phenomenon can be effectively reduced while minimizing the deterioration of the original image quality of the image data as in the second mode.
Further, as in the case of the eighth aspect, since each of the above means can be realized by software using a computer system that is standard in most printing apparatuses currently on the market, dedicated hardware is created. Therefore, it can be realized economically and easily as compared with the case where each of the means is realized. Furthermore, it is possible to easily upgrade the version by modifying or improving the function by rewriting a part of the program.

[Mode 10] The print program of mode 10 is
In the printing program according to the eighth aspect, when the pixel value of the image data corrected by the image data correction unit is a halftone, the image data N-value conversion unit adds a noise value to be added to the halftone pixel. This is characterized in that the noise value added to the pixels other than the halftone is increased.

As a result, the banding phenomenon can be effectively reduced in the same manner as in the third aspect, and deterioration of the original image quality of the image data can be minimized.
Further, as in the case of the eighth aspect, since each of the above means can be realized by software using a computer system that is standard in most printing apparatuses currently on the market, dedicated hardware is created. Therefore, it can be realized economically and easily as compared with the case where each of the means is realized. Furthermore, it is possible to easily upgrade the version by modifying or improving the function by rewriting a part of the program.

[Mode 11] The print program of mode 11 is
In the printing program according to any one of Embodiments 8 to 10, error diffusion for diffusing an error generated when N (M> N ≧ 2) value is converted into an unprocessed pixel of the pixel data by the image data N-value conversion unit Means for subtracting the noise value added to the pixel from the error value and diffusing the error value after the subtraction when diffusing the error for each pixel to the unprocessed pixel. It is characterized by becoming.

As a result, the error generated during the N-value processing can be effectively used to maintain high image quality as in the fourth aspect, and the density change in the region due to the addition of the noise value can be prevented.
Further, as in the case of the eighth aspect, since each of the above means can be realized by software using a computer system that is standard in most printing apparatuses currently on the market, dedicated hardware is created. Therefore, it can be realized economically and easily as compared with the case where each of the means is realized. Furthermore, it is possible to easily upgrade the version by modifying or improving the function by rewriting a part of the program.

[Mode 12] The print program of mode 12 is
In the printing program according to any one of Embodiments 8 to 11, the correction information storage unit is generated by a test pattern data generation unit that generates M (M ≧ 3) value test pattern data and the test pattern data generation unit. Test pattern data N-value conversion means for converting the test pattern data into N (M> N ≧ 2) values, and the test pattern data converted to N-value by the test pattern data N-value conversion means using the print head A test pattern printing means for printing, an output density detecting means for detecting the output density of the test pattern printed by the test pattern printing means, and the output density of the print head from the output density of the test pattern detected by the output density detecting means. Correction information generating means for generating correction information.

As a result, similar to the fifth aspect, correction information reflecting the latest print head state can always be generated, stored and held.
Further, as in the case of the eighth aspect, since each of the above means can be realized by software using a computer system that is standard in most printing apparatuses currently on the market, dedicated hardware is created. Therefore, it can be realized economically and easily as compared with the case where each of the means is realized. Furthermore, it is possible to easily upgrade the version by modifying or improving the function by rewriting a part of the program.

[Mode 13] The print program of mode 13 is
In the printing program according to the twelfth aspect, the test pattern data N-value conversion unit converts the test pattern data generated by the test pattern data generation unit into N (M> N ≧ 2) values before the test pattern data A predetermined noise value is added to each pixel of data, and then N (N ≧ 2) values are obtained.

As a result, similar to the sixth aspect, the amount of noise applied to the image data side can be reduced, so that deterioration in image quality can be further reduced.
Further, as in the case of the eighth aspect, since each of the above means can be realized by software using a computer system that is standard in most printing apparatuses currently on the market, dedicated hardware is created. Therefore, it can be realized economically and easily as compared with the case where each of the means is realized. Furthermore, it is possible to easily upgrade the version by modifying or improving the function by rewriting a part of the program.

[Mode 14] The print program of mode 14 is
In the printing program according to the thirteenth aspect, the test pattern data N-value conversion unit increases the noise value added for each pixel of the test pattern data more than the noise value added by the image data N-value conversion unit. It is characterized by being.

As a result, the N-value conversion characteristic can be eliminated as in the seventh aspect, and the density average for each nozzle assigned line can be made uniform.
Further, as in the case of the eighth aspect, since each of the above means can be realized by software using a computer system that is standard in most printing apparatuses currently on the market, dedicated hardware is created. Therefore, it can be realized economically and easily as compared with the case where each of the means is realized. Furthermore, it is possible to easily upgrade the version by modifying or improving the function by rewriting a part of the program.

[Mode 15] The computer-readable recording medium of mode 15 is
It is a computer-readable recording medium which recorded the printing program in any one of form 8-13.
Accordingly, the printing program according to any one of the above embodiments 8 to 13 can be easily and easily transmitted to a user such as a user via a computer-readable storage medium such as a CD-ROM, a DVD-ROM, an FD, or a semiconductor chip. It can be reliably provided.

[Form 14] The printing method of form 14 is as follows:
Based on the image data acquisition step for acquiring M (M ≧ 3) value image data and the characteristics of each print head nozzle having a plurality of nozzles capable of printing dots of different sizes, the correction information of the print head is generated. A correction information generation step, an image data correction step for correcting the pixel value of the image data acquired in the image data acquisition step based on the correction information of the print head generated in the correction information generation step, and the image data correction Image data N-value conversion step that converts the image data corrected in the step into N (M> N ≧ 2) values, and print data is generated based on the N-value conversion data that is N-valued in the image data N-value conversion step. Print data generation step, and image data printing for printing the print data generated in the print data generation step using the print head. Includes a step, the,
In the image data N-value conversion step, the image data corrected in the image data correction step is converted into N (N ≧ 2) values after adding a predetermined noise value for each pixel of the image data. To do.
As a result, similar to the first embodiment, density unevenness is eliminated or hardly noticeable and the banding phenomenon is avoided, so that a high-quality printed matter can be obtained with certainty.

[Mode 15] The printing method of mode 15 is
15. The printing method according to claim 14, wherein in the image data N-value conversion step, a noise value to be added is changed according to a pixel value of the image data corrected in the image data correction step. Is.
As a result, the banding phenomenon can be effectively reduced while minimizing the deterioration of the original image quality of the image data as in the second mode.

[Mode 16] The printing method of mode 16 is
In the printing method according to the fourteenth aspect, when the pixel value of the image data corrected by the image data correction unit is a halftone, the image data N-value conversion step adds a noise value to be added to the halftone pixel. This is characterized in that the noise value added to the pixels other than the halftone is increased.
As a result, the banding phenomenon can be effectively reduced in the same manner as in the third aspect, and deterioration of the original image quality of the image data can be minimized.

[Mode 17] The printing method of mode 17 is
17. The printing method according to any one of Forms 14 to 16, wherein an error diffusion that diffuses an error generated when N (M> N ≧ 2) in the image data N-value conversion step to unprocessed pixels of the pixel data Means for subtracting the noise value added to the pixel from the error value and diffusing the error value after the subtraction when diffusing the error for each pixel to the unprocessed pixel. It is characterized by becoming.
As a result, the error generated during the N-value processing can be effectively used to maintain high image quality as in the fourth aspect, and the density change in the region due to the addition of the noise value can be prevented.

[Form 18] The printing method of form 18 includes:
18. The printing method according to any one of forms 14 to 17, wherein the correction information generation step is generated by a test pattern data generation step for generating M (M ≧ 3) value test pattern data and the test pattern data generation step. Test pattern data N-value conversion step for converting the test pattern data into N (M> N ≧ 2) values, and the test pattern data N-valued by the test pattern data N-value conversion means using the print head A test pattern printing step for printing, an output density detection step for detecting the output density of the test pattern printed in the test pattern printing step, and the output density of the test pattern from the output density of the test pattern detected in the output density detection step. A correction information generation step for generating correction information. It is intended.
As a result, similar to the fifth aspect, correction information reflecting the latest print head state can always be generated, stored and held.

[Form 19] The printing method of form 19 includes:
In the printing method according to Form 18, in the test pattern data N-value conversion step, before the test pattern data generated in the test pattern data generation step is converted into N (M> N ≧ 2) values, A predetermined noise value is added to each pixel of data, and then N (N ≧ 2) values are obtained.
As a result, similar to the sixth aspect, the amount of noise applied to the image data side can be reduced, so that deterioration in image quality can be further reduced.

[Mode 20] The printing method of mode 20 includes
In the printing method according to the nineteenth aspect, the test pattern data N-value conversion unit increases the noise value added for each pixel of the test pattern data more than the noise value added by the image data N-value conversion unit. It is characterized by.
As a result, the N-value conversion characteristic can be eliminated as in the seventh aspect, and the density average for each nozzle assigned line can be made uniform.

[Mode 21] A print data generation apparatus according to mode 21
Image data acquisition means for acquiring M (M ≧ 3) value image data, and correction of the print head generated based on the characteristics of each nozzle of the print head having a plurality of nozzles capable of printing dots of different sizes Correction information storage means for storing information, image data correction means for correcting pixel values of the image data acquired by the image data acquisition means based on the correction information of the print head stored in the correction information storage means, Image data N-value conversion means for converting the image data corrected by the image data correction means into N (M> N ≧ 2) values, and printing based on the N-value data converted to N-value by the image data N-value conversion means Printing data generation means for generating data,
The image data N-value conversion means converts the image data corrected by the image data correction means into N (N ≧ 2) values after adding a predetermined noise value for each pixel of the image data. It is characterized by being.

As a result, similar to the printing apparatus of the first embodiment, high-quality print data in which density unevenness is eliminated or hardly noticeable can be generated.
In addition, since it can be realized on software using a general-purpose computer system such as a personal computer, it is possible to exhibit excellent economic efficiency as compared with the case where it is realized by producing dedicated hardware.

[Mode 22] A print data generation apparatus according to mode 22
In the print data generation apparatus according to Form 21, the image data N-value conversion unit changes a noise value to be added according to a pixel value of the image data corrected by the image data correction unit. It is what.

As a result, it is possible to generate high-quality print data that avoids the banding phenomenon while minimizing the degradation of the original image quality of the image data as in the printing apparatus of the second aspect.
Further, since it can be realized on software using a general-purpose computer system such as a personal computer as in the form 21, it is possible to exhibit excellent economic efficiency as compared with the case where it is realized by producing dedicated hardware.

[Form 23] The print data generation apparatus of form 23 is
In the print data generation device according to Form 21, when the pixel value of the image data corrected by the image data correction unit is a halftone, the image data N-value conversion unit adds a noise value to the halftone pixel More than the noise value added to the pixels other than the halftone.

As a result, it is possible to generate print data in which the deterioration of the original image quality of the image data is minimized while effectively reducing the banding phenomenon as in the printing apparatus of the third aspect.
Further, since it can be realized on software using a general-purpose computer system such as a personal computer as in the form 21, it is possible to exhibit excellent economic efficiency as compared with the case where it is realized by producing dedicated hardware.

[Mode 24] The print data generation apparatus according to mode 24
24. The print data generation apparatus according to any one of forms 21 to 23, wherein an error generated when N (M> N ≧ 2) is converted into unprocessed pixels of the pixel data by the image data N-value conversion unit. The error diffusion unit further includes an error diffusion unit, and when the error for each pixel is diffused to an unprocessed pixel, the noise value added to the pixel is subtracted from the error value, and the error value after the subtraction is diffused. It is characterized by the above.

This makes it possible to maintain high image quality by effectively using the error generated during the N-value processing, as in the printing apparatus of the fourth aspect, and to prevent the density change in the region due to the addition of the noise value. Print data can be generated.
Further, since it can be realized on software using a general-purpose computer system such as a personal computer as in the form 21, it is possible to exhibit excellent economic efficiency as compared with the case where it is realized by producing dedicated hardware.

[Mode 25] A print data generation apparatus according to mode 25
25. The print data generation apparatus according to any one of forms 21 to 24, wherein the correction information storage unit includes a test pattern data generation unit that generates M (M ≧ 3) value test pattern data, and the test pattern data generation unit. The test pattern data generated in step N is converted into N (M> N ≧ 2) values, and the test pattern data converted into N values by the test pattern data N-value conversion unit is transferred to the print head. Test pattern printing means for printing using, output density detecting means for detecting the output density of the test pattern printed by the test pattern printing means, and printing from the output density of the test pattern detected by the output density detecting means Correction information generating means for generating correction information of the head.

As a result, the latest correction information reflecting the latest state of the print head can always be stored and held in the same manner as in the printing apparatus of the fifth aspect.
Further, since it can be realized on software using a general-purpose computer system such as a personal computer as in the form 21, it is possible to exhibit excellent economic efficiency as compared with the case where it is realized by producing dedicated hardware.

[Mode 26] The print data generation apparatus according to mode 26 is
In the print data generation device according to mode 25, the test pattern data N-value conversion unit converts the test pattern data generated by the test pattern data generation unit into N (M> N ≧ 2) values before A predetermined noise value is added to each pixel of the test pattern data, and then N (N ≧ 2) values are obtained.

As a result, the amount of noise applied to the image data side can be reduced in the same manner as in the printing apparatus of the sixth aspect, so that print data with less deterioration in image quality can be generated.
Further, since it can be realized on software using a general-purpose computer system such as a personal computer as in the form 21, it is possible to exhibit excellent economic efficiency as compared with the case where it is realized by producing dedicated hardware.

[Mode 27] A print data generation apparatus according to mode 27
In the print data generation device according to mode 26, the test pattern data N-value conversion unit adds a noise value added to each pixel of the test pattern data more than a noise value added by the image data N-value conversion unit. It is characterized by the fact that it is adapted.

As a result, the N-value conversion characteristic can be eliminated as in the seventh aspect, and print data capable of homogenizing the density average for each nozzle assigned line can be generated.
Further, since it can be realized on software using a general-purpose computer system such as a personal computer as in the form 21, it is possible to exhibit excellent economic efficiency as compared with the case where it is realized by producing dedicated hardware.

[Mode 28] The print data generation program of mode 28 is
The computer generates image data acquisition means for acquiring M (M ≧ 3) value image data, and the printing generated based on the characteristics of each nozzle of a print head having a plurality of nozzles capable of printing dots of different sizes Correction information storage means for storing the correction information of the head, and image data correction means for correcting the pixel value of the image data acquired by the image data acquisition means based on the correction information of the print head stored in the correction information storage means Image data corrected by the image data correction means is converted into N (M> N ≧ 2) value N-value conversion means, and the image data N-value conversion means is converted into N-valued data. And function as print data generation means for generating print data based on the
Before the image data N-value conversion means converts the image data corrected by the image data correction means into N (M> N ≧ 2) values, a predetermined noise value is added to each pixel of the image data. It is made to function so that it may be made into N (N> = 2) value.

As a result, similar to the printing apparatus of the first embodiment, high-quality print data in which density unevenness is eliminated or hardly noticeable can be generated.
In addition, since it can be realized on software using a general-purpose computer system such as a personal computer, it can exhibit excellent economic efficiency.

[Mode 29] The print data generation program of mode 29 is
In the print data generation program according to mode 28, the image data N-value conversion unit changes a noise value to be added according to a pixel value of the image data corrected by the image data correction unit. It is what.

As a result, it is possible to generate high-quality print data that avoids the banding phenomenon while minimizing the degradation of the original image quality of the image data as in the printing apparatus of the second aspect.
Moreover, since it can implement | achieve on software using general purpose computer systems, such as a personal computer, similarly to the form 21, the outstanding economical efficiency etc. can be exhibited.

[Mode 30] The print data generation program of mode 30 is
In the print data generation program according to mode 28, when the pixel value of the image data corrected by the image data correction unit is a halftone, the image data N-value conversion unit adds a noise value to the halftone pixel. More than the noise value added to the pixels other than the halftone.

As a result, it is possible to generate print data in which the deterioration of the original image quality of the image data is minimized while effectively reducing the banding phenomenon as in the printing apparatus of the third aspect.
Moreover, since it can implement | achieve on software using general purpose computer systems, such as a personal computer, similarly to the form 21, the outstanding economical efficiency etc. can be exhibited.

[Mode 31] The print data generation program of mode 31 is
In the print data generation program according to any one of forms 28 to 30, an error generated when N (M> N ≧ 2) value is converted by the image data N-value conversion unit to unprocessed pixels of the pixel data. The error diffusion unit further includes an error diffusion unit, and when the error for each pixel is diffused to an unprocessed pixel, the noise value added to the pixel is subtracted from the error value, and the error value after the subtraction is diffused. It is characterized by the above.

This makes it possible to maintain high image quality by effectively using the error generated during the N-value processing, as in the printing apparatus of the fourth aspect, and to prevent the density change in the region due to the addition of the noise value. Print data can be generated.
Moreover, since it can implement | achieve on software using general purpose computer systems, such as a personal computer, similarly to the form 21, the outstanding economical efficiency etc. can be exhibited.

[Mode 32] The print data generation program of mode 32 is
32. The print data generation program according to any one of forms 28 to 31, wherein the correction information storage unit includes a test pattern data generation unit that generates M (M ≧ 3) value test pattern data, and the test pattern data generation unit. The test pattern data generated in step N is converted into N (M> N ≧ 2) values, and the test pattern data converted into N values by the test pattern data N-value conversion unit is transferred to the print head. Test pattern printing means for printing using, output density detecting means for detecting the output density of the test pattern printed by the test pattern printing means, and printing from the output density of the test pattern detected by the output density detecting means Correction information generating means for generating correction information of the head.

As a result, the latest correction information reflecting the latest state of the print head can always be stored and held in the same manner as in the printing apparatus of the fifth aspect.
Moreover, since it can implement | achieve on software using general purpose computer systems, such as a personal computer, similarly to the form 21, the outstanding economical efficiency etc. can be exhibited.

[Mode 33] The print data generation program of mode 33 is
In the print data generation program according to the thirty-second aspect, the test pattern data N-value converting unit converts the test pattern data generated by the test pattern data generation unit into N (M> N ≧ 2) values before A predetermined noise value is added to each pixel of the test pattern data, and then N (N ≧ 2) values are obtained.

As a result, the amount of noise applied to the image data side can be reduced in the same manner as in the printing apparatus of the sixth aspect, so that print data with less deterioration in image quality can be generated.
Moreover, since it can implement | achieve on software using general purpose computer systems, such as a personal computer, similarly to the form 21, the outstanding economical efficiency etc. can be exhibited.

[Form 34] The print data generation program of form 34 is
In the print data generation program according to the thirty-third aspect, the test pattern data N-value conversion unit adds a noise value added to each pixel of the test pattern data more than a noise value added by the image data N-value conversion unit. It is characterized by the fact that it is adapted.

As a result, the N-value conversion characteristic can be eliminated as in the seventh aspect, and print data capable of homogenizing the density average for each nozzle assigned line can be generated.
Moreover, since it can implement | achieve on software using general purpose computer systems, such as a personal computer, similarly to the form 21, the outstanding economical efficiency etc. can be exhibited.

[Mode 35] The computer-readable recording medium of mode 35 is
It is a computer-readable recording medium which recorded the print data generation program in any one of form 28-34.
Accordingly, the printing program according to any one of the above embodiments 28 to 34 can be easily performed on a consumer such as a user via a computer-readable storage medium such as a CD-ROM, a DVD-ROM, an FD, or a semiconductor chip. It can be reliably provided.

[Mode 36] A print data generation method according to mode 36 includes:
Based on the image data acquisition step for acquiring M (M ≧ 3) value image data and the characteristics of each print head nozzle having a plurality of nozzles capable of printing dots of different sizes, the correction information of the print head is generated. A correction information generation step, an image data correction step for correcting the pixel value of the image data acquired in the image data acquisition step based on the correction information of the print head generated in the correction information generation step, and the image data correction Image data N-value conversion step that converts the image data corrected in the step into N (M> N ≧ 2) values, and print data is generated based on the N-value conversion data that is N-valued in the image data N-value conversion step. A print data generation step
In the image data N-value conversion step, the image data corrected in the image data correction step is converted into N (N ≧ 2) values after adding a predetermined noise value for each pixel of the image data. To do.
As a result, similar to the printing apparatus of the first embodiment, high-quality print data in which density unevenness is eliminated or hardly noticeable can be generated.

[Mode 37] A print data generation method according to mode 37 includes:
The print data generation method according to mode 36, wherein the image data N-value conversion step changes a noise value to be added according to a pixel value of the image data corrected in the image data correction step. It is what.
As a result, it is possible to generate high-quality print data that avoids the banding phenomenon while minimizing the degradation of the original image quality of the image data as in the printing apparatus of the second aspect.

[Mode 38] The print data generation method of mode 38 is
37. The print data generation method according to claim 36, wherein when the pixel value of the image data corrected by the image data correction unit is halftone, the image data N-value conversion step adds a noise value to the halftone pixel. More than the noise value added to the pixels other than the halftone.
As a result, it is possible to generate print data in which the deterioration of the original image quality of the image data is minimized while effectively reducing the banding phenomenon as in the printing apparatus of the third aspect.

[Mode 39] A print data generation method according to mode 39 includes:
39. The print data generation method according to any one of forms 36 to 38, wherein an error generated when N (M> N ≧ 2) is converted into an unprocessed pixel of the pixel data in the image data N-value conversion step. The error diffusion unit further includes an error diffusion unit, and when the error for each pixel is diffused to an unprocessed pixel, the noise value added to the pixel is subtracted from the error value, and the error value after the subtraction is diffused. It is characterized by the above.
This makes it possible to maintain high image quality by effectively using the error generated during the N-value processing, as in the printing apparatus of the fourth aspect, and to prevent the density change in the region due to the addition of the noise value. Print data can be generated.

[Form 40] A print data generation method according to form 40 includes:
40. In the print data generation method according to any one of forms 36 to 39, the correction information generation step includes a test pattern data generation step for generating M (M ≧ 3) value test pattern data, and the test pattern data generation step. A test pattern data N-value conversion step for converting the test pattern data generated in step N into N (M> N ≧ 2), and the test pattern data converted to N-value in the test pattern data N-value conversion step to the print head. A test pattern printing step printed using, an output density detecting step for detecting an output density of the test pattern printed in the test pattern printing step, and the printing from the output density of the test pattern detected in the output density detecting step A correction information generating step for generating head correction information. And it is characterized in and.
As a result, the latest correction information reflecting the latest state of the print head can always be stored and held in the same manner as in the printing apparatus of the fifth aspect.

[Form 41] A print data generation method according to form 41 includes:
In the print data generation method according to Form 40, the test pattern data N-value conversion step may include the test pattern data generated before the test pattern data generation step before N (M> N ≧ 2). A predetermined noise value is added to each pixel of the test pattern data, and then N (N ≧ 2) values are obtained.
As a result, the amount of noise applied to the image data side can be reduced in the same manner as in the printing apparatus of the sixth aspect, so that print data with less deterioration in image quality can be generated.

[Form 42] A print data generation method according to form 42 includes:
42. In the print data generation method according to mode 41, the test pattern data N-value conversion unit adds a noise value added to each pixel of the test pattern data more than a noise value added by the image data N-value conversion unit. It is characterized by doing.
As a result, the N-value conversion characteristic can be eliminated as in the seventh aspect, and print data capable of homogenizing the density average for each nozzle assigned line can be generated.

Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the accompanying drawings.
1 to 16 show a printing apparatus 100, a printing program, a printing method, a printing data generation apparatus, a printing data generation program, a printing data generation method, and a computer-readable recording medium on which these programs are recorded. This embodiment is shown.

FIG. 1 is a functional block diagram showing an embodiment of a printing apparatus 100 according to the present invention.
As illustrated, the printing apparatus 100 includes an image data acquisition unit 10 that acquires multi-value image data, a print head 200 that includes a plurality of nozzles that can print dots of different sizes, and nozzles of the print head 200. The correction information storage means 12 for storing the correction information of the print head 200 generated based on the characteristics of each, and the image data acquisition means 10 based on the correction information of the print head 200 stored in the correction information storage means. Image data correction means 12 for correcting the pixel value of the acquired image data, image data N-value conversion means 14 for converting the image data corrected by the image data correction means 12 into N values for each pixel, and the image data N value An error diffusing means 16 for diffusing an error generated when the N-value is converted into an N-value by the converting means 14 to an unprocessed pixel of the pixel data; 6, print data generation means 18 for generating print data based on the N-valued data that has been N-valued while being error-diffused, and the print data generated by the print data generation means 18 using the print head 200. It is mainly composed of image data printing means 20 for printing.

First, the print head 200 applied to the present invention will be described.
FIG. 2 is a partially enlarged bottom view showing the structure of the print head 200.
As shown in the figure, this print head 200 has a long structure extending in the paper width direction of printing paper used in a so-called line head type printer, and has a plurality of nozzles N for discharging black (K) ink exclusively. (18 in the figure) A plurality of black nozzle modules 50 arranged in a straight line in the main scanning direction and a plurality of nozzles N that discharge yellow (Y) ink exclusively are arranged in a straight line in the main scanning direction. A yellow nozzle module 52, a plurality of nozzles N that eject magenta (M) ink exclusively, and a magenta nozzle module 54 that is also arranged linearly in the main scanning direction, and a nozzle that ejects cyan (M) ink exclusively Four nozzle modules 50, 52, 54 such as a cyan nozzle module 56 in which a plurality of Ns are arranged in a straight line in the main scanning direction. 56 which are arranged integrally so as to overlap in the printing direction (paper feed direction). In the case of a print head intended for monochrome, only a black (K) nozzle module, and in the case of a print head targeting a high-quality image, a light magenta module that exclusively ejects light magenta (LM) ink. There are also 6-color and 7-color types, including a light cyan module that discharges light cyan (LC) ink exclusively.

  Each of the nozzles N1, N2, N3... Is supplied with ink supplied into an ink chamber (not shown) provided for each nozzle by a piezoelectric element such as a piezo actuator (not shown) provided for each ink chamber. By ejecting from the nozzles N1, N2, N3..., Circular dots are printed on the white printing paper (ink landing), and further, the voltage applied to the piezoelectric element is controlled in multiple stages from the ink chamber. .., So that dots of different sizes can be printed for each nozzle N1, N2, N3... (In this embodiment, as described later, 8 including “no dot” is included). Pattern (size) dots can be printed).

Further, in the print head 200 having such a structure, the ink is supplied in a prescribed amount due to variations in the size of the nozzle holes of the nozzles N1, N2, N3. May not be discharged.
For example, in the case of the print head 200 as shown in FIG. 3, the nozzles N <b> 6 to N <b> 11 are controlled to have the same ink discharge amount (same dot size), but the nozzle N <b> 7 has the nozzle N <b> 6 and the like. A larger amount of ink is ejected than the normal nozzle ejection amount (large ejection amount), and conversely, the nozzle N10 may have an insufficient ink ejection amount compared to the normal nozzle ejection amount ( Large discharge volume).

  When printing is performed using such a print head 200, that is, dots are continuously printed, as shown in FIG. 4, the size of the dot to be printed at a nozzle having a discharge amount larger than a specified value (large discharge amount), as shown in FIG. However, the nozzle size is larger than the target dot size, and the nozzle size to be printed is smaller than the target dot size in a nozzle having a discharge amount larger than a specified value (large discharge amount).

  As a result, even though the print head 200 is controlled to print the dot pattern as shown in FIG. 5, the dot pattern as shown in FIG. 6 is printed, and the dot line corresponding to the nozzle N7 has a dark streak. Or a background (white color) appears in the dot line portion corresponding to the nozzle N10, and this becomes a white stripe and becomes conspicuous.

Note that the dot pattern in FIG. 5 uses only one type of dot for ease of explanation, but a plurality of size dots or multiple colors like an actual color or monochrome printed matter. Needless to say, the same inconvenience occurs even in the case of a dot pattern in which the dots are mixed.
3 and FIG. 6, the example in which the variation in the ink discharge amount occurs randomly has been described. Generally, such a variation in the ink discharge amount occurs in a nozzle or the like located at the head end portion or the central portion side. The nozzle on the head end side ejects a specified amount or more of ink and prints a dot of a predetermined size or more, and the nozzle on the head center side discharges less than a specified amount of ink to meet the predetermined size. There is a tendency that no dots are easily printed. For example, in a pattern in which dots of eight different sizes including “no dot” are divided, the nozzle at the head end portion is 1 in comparison with the normal nozzle in comparison with the dot size formed in each normal nozzle. Dots that are larger by 2 sizes are formed, and the nozzles on the center side of the head tend to form dots that are 1 to 2 sizes smaller than normal nozzles.

  Further, the characteristics of the print head 200 are fixed to some extent in the manufacturing stage, and it is considered that it is relatively rare to change after manufacturing except for ejection failure due to ink clogging or the like. In addition, it is known that each nozzle changes due to various factors such as a change in ink viscosity due to deterioration with time, a change in nozzle hole diameter, or a change in operation of a piezoelectric element.

  Next, the image data acquisition means 10 sends multi-valued image data for printing sent from a printing instruction device (not shown) such as a personal computer (PC) or a printer server connected to the printing device 100 to the network. Etc., or a function to read and acquire directly from an image (data) reading device such as a scanner or a CD-ROM drive (not shown), and to obtain a multi-valued color image If the data is multi-value RGB data, for example, image data in which the gradation (luminance value) for each color (R, G, B) per pixel is represented by 8 bits and 256 gradations (0 to 255), A function for converting this into multi-value CMYK (for four colors) data corresponding to each ink of the print head 200 is also exhibited at the same time. .

Next, the image data correction unit 12 provides a function of correcting each pixel value of the multivalued image data acquired by the image data acquisition unit 10 according to the nozzle characteristics of the print head 200.
That is, the image data correction unit 12 is a multi-valued image acquired by the image data acquisition unit 10 for each pixel corresponding to each nozzle based on the input density correction table 300 stored and stored in the correction information storage unit 30. A function for reducing the density unevenness phenomenon as described above by correcting each pixel value of the data is provided.

FIG. 7 shows an example of this input density correction table 300, and FIG. 8 shows the input of four nozzles of nozzle numbers 1 to 4 among the nozzles recorded in this input density correction table 300. The relationship between a luminance value and an output luminance value (measured luminance average) is shown.
In the example of FIG. 8, it can be seen that the nozzles with nozzle numbers 1, 3, and 4 exhibit the same nozzle characteristics, but the nozzle with nozzle number 2 has a higher input luminance value than other nozzles. It can be seen that the output density value is slightly high. This indicates that when nozzle numbers 1, 3, and 4 are assumed to be normal nozzles, the nozzle of nozzle number 2 tends to eject ink slightly less than these normal nozzles.

  Therefore, the image data correction unit 12 detects the pixel of the image data corresponding to the nozzles of nozzle numbers 1, 3, and 4, and adds a predetermined pixel value to the original pixel value for the pixel value. Therefore, the pixel value of the pixel corresponding to the nozzle of nozzle number 2 is more than the pixel value added to the pixels corresponding to the nozzles of nozzle numbers 1, 3, and 4. A larger number of pixels are added to correct the pixel value. Although not shown, for pixel values for nozzles with a larger ink discharge amount than normal, a pixel value smaller than the pixel value to be added normally is added to correct the pixel value.

FIG. 9 schematically shows a specific example of such pixel value correction processing.
For example, in order to obtain a measured luminance (or density) of “70” as an average value of measured luminance (or density) in an actual printed matter, a pixel value “60” is obtained for a pixel corresponding to the nozzle of nozzle number L. The pixel value is corrected to “105” obtained by adding the pixel value “55” to “105”, and in the case of the pixel corresponding to the nozzle of the nozzle number M, the pixel value “70” is added to the pixel value “60”. 130 ”, and in the case of the pixel corresponding to the nozzle of nozzle number M, the pixel value is corrected to“ 145 ”obtained by adding the pixel value“ 85 ”to the pixel value“ 60 ”( The measured luminance (or density) of the measured luminance (or density) average value “70” can be obtained by conversion.

  Here, correction information (input density correction table 300) used for image correction by the image data correction unit 12 includes test pattern data generation unit 32 for generating multi-value test pattern data, as shown in FIG. Test pattern data N-value conversion means 34 for converting the test pattern data generated by the test pattern data generation means 32 to N-value, and the test pattern data converted to N-value by the test pattern data N-value conversion means 34 for printing Test pattern printing means 36 for printing using the head 200, output density detection means 38 for detecting the output density of the test pattern printed by the test pattern printing means 36, and the test pattern detected by the output density detection means Correction information generating means 300 for generating correction information of the print head from the output density of Thus it is adapted to be appropriately updated in formation and date.

  That is, first, the test pattern data generating means 32 has, for example, eight gradations (brightness “0”, “36”, “73”, “109”, “146”) whose luminance changes stepwise as shown in FIG. , “182”, “219”, “255”), the test pattern data 500 is generated, and then the dot / gradation conversion as shown in FIG. The test pattern data 500 is converted into N-values in accordance with a table 400 (described later in detail), and N-valued data is generated.

Thereafter, print data obtained by converting the N-valued data of the test pattern into a dot pattern according to a dot / gradation conversion table 400 (detailed later) as shown in FIG. The test pattern printing means 36 using the printing function 100 prints the test pattern print data to generate a test pattern printed matter.
Then, the printed matter of this test pattern is optically read by output density detecting means 38 such as a scanner having a performance higher than the number of pixels, and the output density of the dot line corresponding to each nozzle is detected, Based on the detection result, the correction information generation unit 300 generates the input density correction table 300 as described above.

  Therefore, if such a series of processes for generating the input density correction table 300 is executed not only when the target print head is specified or replaced, but also periodically or as needed, the time will be temporarily reduced. Even when the nozzle characteristics of the print head 200 change due to deterioration or the like, it is possible to always create a highly accurate input density correction table 300 that accurately reflects the state of the print head 200 at that time, and hold and provide this. .

Next, the image data N-value conversion means 14 provides a function of generating N-value image data by converting the multi-value image data corrected by the image data correction means 12 into N (M> N ≧ 2) values. However, in the N-value conversion, a predetermined noise value is added to each pixel of the image data in advance, and then N (N ≧ 2) value is set.
Here, the noise value addition processing will be described in detail later. The image data N-value conversion means 14 is a reference noise for each pixel of the multivalued image data corrected by the image data correction means 12. (Pixel value: + N to -N) is added at random, and an N value using a predetermined threshold value for each pixel according to the pixel value (luminance or density value) of each pixel of the image data after the noise addition. It has come to become. For example, the pixel value (luminance or density value) of each pixel of the image data after adding noise is represented by 8 bits and 256 gradations, and when this is converted to 8 values with gradations: N = 8, As shown in the right column of the 11 dot / gradation conversion table 400, the pixel values of the respective pixels are classified into eight using seven threshold values for N-value conversion.

The right column of the dot / gradation conversion table 400 in FIG. 11 shows the relationship between the threshold value for N-value conversion and each pixel value when multi-valued pixel values are converted to eight values with gradation: N = 7. Is.
That is, according to the dot / gradation conversion table 400, when the pixel value (luminance value or density value) of each pixel of the multivalued image data is expressed by 8 bits (0 to 255), “233 ( “First threshold)”, “191 (second threshold)”, “159 (third threshold)”, “128 (fourth threshold)”, “96 (fifth threshold)”, “64 (sixth threshold)” , “32 (seventh threshold value)” and seven N-value thresholds, and when the pixel value is “223 or more”, N = 1 (luminance “255”, density “0”), and the pixel value “ 191 to 222 ”, N = 2 (luminance“ 219 ”, density“ 36 ”), and when the pixel value is“ 159 to 190 ”, N = 3 (luminance“ 182 ”, density“ 73 ”), When the pixel value is “128 to 158”, N = 4 (luminance “146”, density “109”), and the pixel value is “96”. 127 = N = 5 (luminance “109”, density “146”), and pixel value “64-95”, N = 6 (luminance “73”, density “182”), pixel value Is “32 to 63”, N = 7 (luminance “36”, density “219”), and when the pixel value is “31 or less”, N = 8 (luminance “0”, density “255”). As shown in FIG.

  Next, the specific example of the error diffusing means 16 will be described in detail later. When diffusing an error for each pixel generated in such N-value conversion processing into unprocessed pixels, the error diffusion means 16 draws its attention from the error value. A function of subtracting the noise value added to the pixel and diffusing the error value after the subtraction into an unprocessed pixel according to an error diffusion matrix such as the Floyd & Steinberg type shown in FIG. 12 is provided.

Then, the print data generation unit 18 sets a corresponding dot for each pixel of the N-valued data that has been subjected to the error diffusion processing in this way, and can be used in the inkjet printing unit 20 for printing. Provides the ability to generate data.
The left column of the dot / gradation conversion table 400 in FIG. 11 is a reference diagram showing the relationship between the pixel value of each pixel of the N-ary data and the dot size performed by the print data generation means 18.

  In the example shown in the figure, when “gradation: N = 8” is made eight-valued and “luminance value” is selected as the pixel value, the dot number when “N = 1” is “0” and the dot size is The dot number in the case of “no dot (no dot printed)” and “N = 2” is “1”, the dot size is the smallest dot area, and the dot number in the case of “N = 3” is “ 2 ”, the dot size is the second largest. The dot number for “N = 4” is “3” and the dot size is the third largest. The dot number for “N = 5” is “4” and the dot size is the fourth. It is getting bigger. Further, when “N = 6”, the dot number is “5” and the dot size is the fifth largest, and when “N = 7”, the dot number is “6” and the dot size is the sixth. It is getting bigger. When “N = 8”, the dot number is “7”, the dot size is the largest, and each dot is converted.

When a “density value” is used as the pixel value, each pixel value is converted into a dot having a reverse relationship to the “density value”. Also, the relationship between the dot size and the ink discharge amount shown in FIG. 4 corresponds to the dot size shown in the left column of the dot / tone conversion table 400 of FIG.
Next, the printing unit 20 dot-injects ink from the nozzle modules 50, 52, 54 and 56 formed on the print head 200 while moving one or both of the print medium (paper) and the print head 200, respectively. In addition to the print head 200 described above, the print head 200 is moved over the print medium in order to form a predetermined image consisting of a large number of dots on the print medium. Print head feed mechanism (not shown) that reciprocates in the width direction (multi-pass type), paper feed mechanism (not shown) for moving the print medium, and control of ink ejection of the print head 200 based on the print data. It is composed of known components such as a print controller mechanism (not shown).

  Here, the printing apparatus 100 includes various controls for printing, image data acquisition means 10, image data correction means 12, image data N-value conversion means 14, error diffusion means 16, print data generation means 18, and image data printing. A computer system for realizing the means 20 and the like with software (computer program) is provided. As shown in FIG. 10, the hardware configuration is a central processing unit (CPU) that performs various controls and arithmetic processing. A PCI (Peripheral Component) between the Processing Unit 60, a RAM (Random Access Memory) 62 constituting a main storage device (Main Storage), and a ROM (Read Only Memory) 64 which is a read-only storage device. It is connected by various internal / external buses 68 such as a t interconnect (BUS) bus or an ISA (Industrial Standard Architecture) bus, etc. A network for communicating with a storage device (Secondary Storage) 70, an output device 72 such as a printing means 20, a CRT, and an LCD monitor, an input device 74 such as an operation panel, a mouse, a keyboard, and a scanner, and a print instruction device (not shown). L or the like is connected.

  When the power is turned on, a system program such as BIOS stored in the ROM 64 or the like is stored in various dedicated computer programs stored in the ROM 64 in advance, or in a CD-ROM, DVD-ROM, flexible disk (FD), or the like. Various dedicated computer programs installed in the storage device 70 via the medium or the communication network L such as the Internet are similarly loaded into the RAM 62, and the CPU 60 performs various operations according to instructions described in the program loaded in the RAM 62. Each function of each means as described above can be realized on software by performing predetermined control and arithmetic processing by making full use of resources.

Next, an example of the flow of printing processing using the printing apparatus 100 having the above configuration will be described with reference mainly to the flowcharts of FIGS.
14 is an example of the overall flow of printing processing by the printing apparatus 100 according to the present invention, and the flowchart of FIG. 15 is an example of the flow of generation processing of correction information used in the image data correction processing. Is shown respectively. Further, the flowchart of FIG. 16 shows an example of the flow of noise addition N-value conversion processing by the image data N-value conversion means 14.

  First, as shown in the flowchart of FIG. 14, when the printing apparatus 100 has finished a predetermined initial operation for printing processing after the power is turned on, in the first step S100, a printing instruction (not shown) such as a personal computer is displayed. If a terminal is connected, it is monitored whether there is an explicit print instruction from the print instruction terminal, and it is determined that this print instruction and multi-value image data to be processed have been sent (Yes) Shifts to the next step S102 to acquire (read) the image data, and if the image data is color image data composed of RBG, the color image data corresponds to each ink color of the print head 200. As described above, the CMYK color conversion process is executed.

  Next, the process proceeds to step S104, and an input density correction table 300 created corresponding to the nozzle characteristics of the print head 200 as shown in FIG. 7 is read, and based on this input density correction table 300, as described above. After correcting the pixel value of each pixel of the image data, the process proceeds to the next step S106 to add a predetermined noise value to the corrected image data to make an N value, and then the process proceeds to the next step S108. Then, print data is generated, and finally printing is executed based on the print data in step S110.

The flowchart of FIG. 15 shows an example of the flow of a correction information generation process used in the image data correction process in step S104.
First, multi-value test pattern data as shown in FIG. 13 is generated in the first step S200, and then in the next step S202, the test pattern data is converted into four values to generate N-value data. In step S204, the N-valued data is converted into print data, and the test pattern is actually printed on the print medium using the print head 200.

  Thereafter, the process proceeds to the next step S206, where the printed matter of the test pattern is optically read by a scanner or the like to detect the output density of dots corresponding to each nozzle, and correction information (input density correction table) is based on the detection result. 300), and in the last step S210, the correction information is stored in a storage device such as an HDD or a RAM, thereby completing the correction information generation process.

Next, the flowchart of FIG. 16 shows a specific example of the flow of the noise-added N-ary process in step S106 of the flow of FIG.
First, in the first step S300, the basic maximum noise amount to be added to each pixel of the corrected image data is set, and then the first target pixel to be processed in the next step S304 is passed through the next step S302. If it is determined, the process proceeds to the next step S306, the noise value to be added to the target pixel is determined by a random number, and the noise value determined in the next step S308 is added (added) to the target pixel. To do.

  For example, if the pixel value of each pixel of the corrected image data is represented by 8 bits and 256 gradations, and the basic maximum noise amount is set to “± 30” in the first step S300, the pixel of interest When the pixel value of “100” is “100”, the added noise value is in the range of “+30 to −30”. Therefore, the pixel value of the target pixel is in the range of “70” to “130”. It is converted into such a pixel value. If the pixel value is changed from “100” to “70” by adding such a noise value, the N value is changed from “5” to “6” according to the dot / gradation conversion table 400 of FIG. If the pixel value is changed from “100” to “130”, the N value is changed from “5” to “4”.

  If the N-value conversion of the target pixel is completed in this way, the process proceeds to the next step S312 and the noise value is subtracted from the error generated by the N-value conversion, and then the process proceeds to the next step S314. The error after the subtraction is distributed to the unprocessed pixels around the target pixel according to the error diffusion matrix as shown in FIG. 12, and then the process proceeds to the next step S316 to move the target pixel to be processed. Returning to step S302, the same process is executed for all or any target pixel, and the noise-added N-value conversion process ends.

As described above, the present invention not only corrects image data based on correction information related to the nozzle characteristics of the print head 200 but also adds a noise value to the corrected image data and then performs N-value processing. Since this is executed, the dot size changes so as to increase or decrease appropriately compared to the original dot size.
As a result, even if the nozzle is a defective nozzle with an abnormal discharge amount, and even if the density unevenness cannot be sufficiently solved only by the pixel value correction as described above, all the dots of the peripheral pixels including the target pixel are all Alternatively, it is possible to effectively eliminate banding phenomenon and density unevenness such as dark stripes and white stripes that occur in a part of the dot when the dot size changes from the original size.

In addition, when performing error diffusion, the noise value added previously is subtracted from the error, and the error after subtraction is distributed to the unprocessed pixels. The accompanying density change can also be eliminated in units of the target pixel.
The print head 200 in the present embodiment corresponds to the print head in the printing apparatus such as the first form of means for solving the above-described problem, and the image data acquisition means 10, the image data correction means 12, and the image data N value. Means 14, error diffusion means 16, print data generation means 18, image data printing means 20, and correction information storage means 30 are image data acquisition means, image data in a printing apparatus such as Form 1 of means for solving the problem. It corresponds to a correction unit, an image data N-ary unit, an error diffusion unit, a print data generation unit, and an image data printing unit.

  Further, the test pattern data generation means 32, the test pattern data N-value conversion means 34, the test pattern printing means 36, and the output density detection means 38 in the present embodiment are printed in the form 5 of means for solving the above-mentioned problems. Corresponding to test pattern data generation means, test pattern data N-value conversion means, test pattern printing means, and output density detection means in the apparatus, the input density correction table 300 is a print of form 5 of means for solving the above-mentioned problems. This corresponds to correction information generating means in the apparatus.

Further, in the present invention and each of the embodiments described above, as the size of dots to be divided by the print head 200, as shown in FIG. 11, eight patterns including “no dot” are used. Is not limited to this, and it is sufficient that there are at least two patterns other than “no dot”, and it is preferable that the number of patterns is larger.
Further, the present invention is characterized in that a predetermined noise value is added to the image data corrected according to the nozzle characteristics, with almost no modification to the existing print head 200 and the image data printing means 20 itself. Since the N-value conversion processing is performed, it is not necessary to prepare a special print head 200 or printing means 20, and the existing inkjet print head 200 or printing means 20 (printer) is used as it is. It is possible to do.

Accordingly, if the print head 200, the printing means 20, and the like are separated from the printing apparatus 100 of the present invention, the function can be realized by a general-purpose information processing apparatus (print data generation apparatus) such as a personal computer or a print data generation program. It becomes.
Needless to say, the printing apparatus 100 according to the present invention is not limited to a form in which all of the functions are accommodated in a single housing, and an error from a part of the functions, for example, the image data acquisition unit 10. The configuration may be such that the functions up to the diffusing unit 16 are realized on the personal computer side, and the functions are physically divided so that the print data generating unit 18 and the image data printing unit 20 are realized on the existing printer side.

  FIG. 22 shows the minimum configuration of the printing apparatus 100 of the present invention. At least the image data acquisition means 10, the image data correction means 12, the image data N-value conversion means 14, the print data generation means 18, If the image data printing unit 20 and the correction information storage unit 30 are provided, the test pattern data generation unit 32, the test pattern data N-value conversion unit 34, and the test pattern for generating the error diffusion unit 16 and the input density correction table 300 are provided. The printing unit 36 and the output density detection unit 38 can be omitted.

The printing apparatus 100 of the present invention can be applied not only to a line head type ink jet printer but also to a multi-pass type ink jet printer (serial printer).
FIG. 23 shows respective printing methods by the line head type ink jet printer and the multi-pass type ink jet printer.
As shown in FIG. 3A, when the width direction of the rectangular printing paper P is the main scanning direction of the image data and the longitudinal direction is the sub-scanning direction of the image data, the line head type inkjet printer As shown in (B), the print head 200 has a length corresponding to the paper width of the printing paper S, the printing head 200 is fixed, and the printing paper S is sub-scanned with respect to the printing head 200. By moving in the direction, printing is completed in a so-called one pass (operation). Note that it is also possible to perform printing while fixing the printing paper S and moving the print head 200 side in the sub-scanning direction, or moving both in the opposite direction, as in a so-called flatbed scanner. . On the other hand, in the multi-pass type ink jet printer, as shown in FIG. 5C, the print head 200, which is much shorter than the paper width, is positioned in the direction perpendicular to the main scanning direction. Printing is executed by moving the printing paper S in the sub-scanning direction by a predetermined pitch while reciprocating in the main scanning direction many times. Therefore, the latter multi-pass type ink jet printer has a drawback that it takes longer printing time than the former line head type ink jet printer, but the number of nozzles to be corrected greatly increases. Correction processing can be greatly reduced.

In this embodiment, an ink jet printer that performs printing by ejecting ink in dots has been described as an example. However, the present invention is another printing apparatus that uses a print head in which printing mechanisms are arranged in a line. For example, the present invention is also applicable to a thermal head printer called a thermal transfer printer or a thermal printer.
In FIG. 2, each nozzle module 50, 52, 54, 56 provided for each color of the print head 200 has a form in which the nozzles N are continuous in a straight line in the longitudinal direction of the print head 200. 24, each of these nozzle modules 50, 52, 54, 56 is composed of a plurality of short nozzle units 50a, 50b,... 50n, which are arranged before and after the print head 200 in the moving direction. You may comprise as follows. In particular, if each nozzle nozzle module 50, 52, 54, 56 is configured with a plurality of short nozzle units 50a, 50b,..., 50n as compared with a case where the nozzle units are configured integrally with a long nozzle unit. Yield is greatly improved.

  Each means for realizing the printing apparatus 100 of the present invention described above can be realized on software using a computer system incorporated in most existing printing apparatuses. In addition to being stored in a semiconductor ROM in advance in a product or distributed via a network such as the Internet, a computer-readable recording medium R such as a CD-ROM, DVD-ROM, or FD as shown in FIG. It is possible to easily provide it to a desired user or the like.

Next, a second embodiment relating to a printing apparatus 100, a printing program, a printing method, a printing data generation apparatus, a printing data generation program, a printing data generation method, and a computer-readable recording medium recording these programs according to the present invention. Will be explained.
FIG. 17 and FIG. 18 show an example of the second embodiment of the present invention, and this embodiment shows a modification of the noise addition N-value conversion processing of the first embodiment. It is a thing.

FIG. 17 is a flowchart showing an example of the flow of noise addition N-ary processing according to the present embodiment.
As shown in the figure, in the first step S400, the basic threshold fluctuation amount is set, and then the next step S402 is followed to the third step S404 to determine the target pixel to be processed first, and the basic step The threshold fluctuation amount is determined based on a random number.

For example, as in the first embodiment, the pixel value of each pixel of the corrected image data is represented by 8 bits and 256 gradations. In the first step S400, the basic threshold maximum variation is “ Assuming that ± 20 is set, each N-value threshold value varies within the range of “+20 to −20” with respect to the original threshold value.
If the basic threshold fluctuation amount is determined in this way, the process proceeds to the next step S408, and the noise value determined in the same manner as in the first embodiment is added to the target pixel. The process proceeds to the next step S410, and the target pixel is converted to N-value using the threshold for N-value conversion in which each threshold value is changed based on the basic threshold value change amount.

FIG. 18 shows an example of the dot / gradation conversion table 400 in which the threshold values for N-value conversion are changed in this way. The normal seven N-value threshold values “223” and “191” are shown. , “159”, “128”, “96”, “64”, “32” are “240”, “199”, “141”, “133”, “91”, “49”, “19”, respectively. Have fluctuated.
Therefore, for example, when the pixel value of the target pixel is “50”, the normal N threshold value is converted to the N value “7” and the second largest dot (dot number 6) is assigned. However, the converted new threshold value is converted to the N value “6” and the third largest dot (dot number 5) is assigned. If the pixel value of the target pixel is “150”, the normal N-value threshold is converted to the N value “4” and the third smallest dot (dot number 3) is assigned. However, the converted new threshold value is converted to the N value “3” and the second smallest dot (dot number 2) is assigned.

  After that, when the N-value conversion of the target pixel is completed in this way, the noise value is calculated from the error generated by the N-value conversion in the next step S412 in the same manner as in the first embodiment. In step S414, the error after the subtraction is distributed to the unprocessed pixels around the target pixel, and then the target pixel to be processed is moved to the next step S416, and the process returns to step S402. The N-value conversion process is completed by executing the same process on the or any target pixel.

  As described above, in the present embodiment, in addition to adding a noise value to the corrected image data, the N-value conversion process is performed using a value obtained by changing the N-value conversion threshold value as compared with the normal case. As a result, in addition to the dot size variation effect due to the addition of noise values, the dot size after N-level variation also varies, so the banding and density unevenness reduction effects that are equal to or greater than those in the first embodiment are reduced. Can be achieved.

In the N-value conversion process of FIG. 17, the noise value addition process in step S408 is not necessarily required. Therefore, in some cases, the same effect can be expected even if the noise value addition process in step S408 is omitted.
Next, a third embodiment relating to a printing apparatus 100, a printing program, a printing method, a printing data generation apparatus, a printing data generation program, a printing data generation method, and a computer-readable recording medium on which these programs are recorded, according to the present invention. Will be explained.

FIGS. 19 to 21 show an example of the third embodiment of the present invention. This embodiment relates to the noise addition N-value conversion processing of the first and second embodiments. This modification is shown.
FIG. 19 is a flowchart showing an example of the flow of noise addition N-ary processing according to the present embodiment.

As shown in the figure, in the first step S500, the basic noise amount is set in the same manner as in the first embodiment, and then the process proceeds to the next step S502 to obtain the noise addition amount table 600 describing the noise addition amount. (Read).
FIG. 20 shows an example of the noise addition amount table 600 acquired in step S502, and shows the relationship between the additional noise amount and the normalized noise addition index with respect to the pixel value of the target pixel. Rather than adding all of the maximum noise values determined in step S500, the noise addition amount is varied from “0” in the range of the maximum noise value determined in the first step according to the pixel value. It is stipulated in.

  That is, as shown in FIG. 21, a so-called “highlight” region with a high luminance value, which is a neighborhood region where the pixel value is “0”, or a so-called “low highlight” region where the pixel value is a neighborhood region where the pixel value is “255”. In the “shadow” area, banding and uneven density phenomenon are inconspicuous, so only a part of the determined maximum noise value is added instead of all of the determined maximum noise values. Conversely, the banding phenomenon and uneven density phenomenon are most noticeable. In the halftone region (the vicinity region where the pixel value is “127”), it is defined that a noise value of 100% of the maximum noise value or a value close thereto is added.

Therefore, when the noise addition amount table 600 describing the noise addition amount is acquired in step S502, the process proceeds to the fourth step S506 through the next step S504, and the target pixel to be processed first is determined. Thus, in the next step S508, the pixel value (luminance value) of the target pixel is detected.
If the pixel value (luminance value) of the target pixel to be processed is detected in this way, the process proceeds to the next step S510, the noise addition amount table 600 is referred to, and its normalized noise addition index and its The amount of noise to be added is determined based on the pixel value of the target pixel. Specifically, the percentage of the maximum value “1” of the normalization noise addition index corresponding to the intersection of the vertical line corresponding to the pixel value of the target pixel and the normalization noise addition index line is calculated, and the ratio (% ) Is multiplied by the basic noise amount, the noise amount to be added can be easily determined.

  When the amount of noise to be added to the target pixel is determined in this way, the process proceeds to the next step S512, and the noise value determined in the same manner as in the above embodiment is added to the target pixel. To the next step S514, the pixel of interest is converted to an N-value, and in the next step S516, the noise value is subtracted from the error generated by the N-value conversion. After the distribution to the unprocessed pixels, the target pixel to be processed in the next step S518 is moved to the next, and the process returns to step S504, and the same process is performed on all or arbitrary target pixels to obtain the N value. Processing ends.

  As described above, in this embodiment, since the amount of noise to be added is changed according to the pixel value, the amount of noise to be added is reduced for a highlight portion or a shadow portion where banding phenomenon is not noticeable. Since the amount of noise added to the intermediate gradation portion where the banding phenomenon is conspicuous is increased, it is possible to efficiently avoid the banding phenomenon and the density unevenness phenomenon.

  In the first to third embodiments, a predetermined amount of noise value is added to the corrected image data by the image data N-value conversion means 14, but the image data N In addition to the addition of noise by the valuation means 14, the test pattern data N-value conversion means 34 of the correction information storage means 30 similarly adds a predetermined amount of noise to the test pattern data and then N-values it. This makes it possible to obtain accurate input / output density correction information.

That is, when generating input / output density correction information from a test pattern, it is important to obtain a measured luminance average value of an ideal dot print position corresponding to a desired nozzle number from a test pattern print image.
Therefore, ideal dot printing corresponding to the nozzle number of each tone of the test pattern is achieved by relatively increasing the N-value noise addition amount of the test pattern data, reducing the N-value characteristics, and improving the dot dispersibility. Since the average measured luminance value of the position can be made uniform, accurate input / output density correction information can be obtained.

1 is a functional block diagram illustrating an embodiment of a printing apparatus according to the present invention. It is a partial enlarged bottom view which shows the structure of a print head. FIG. 6 is a schematic diagram illustrating a variation phenomenon of ink discharge amounts from nozzles of a print head. It is explanatory drawing which shows the relationship between the variation of an ink discharge amount, and a printing dot. FIG. 6 is an explanatory diagram illustrating an example of an ideal dot pattern printed by a print head having no variation in ink discharge amount. It is explanatory drawing which shows an example of the dot pattern printed with the print head with which the amount of ink discharge varies. It is a figure which shows an example of an input density correction table. It is a graph which shows the relationship between the input brightness produced based on the input density correction table, and the measured brightness average. It is a schematic diagram which shows an example of the correction process of a correction process target pixel. It is a block diagram which shows the hardware constitutions of the computer system which implement | achieves the printing apparatus which concerns on this invention. It is a figure which shows an example of the dot value / gradation conversion table which showed the relationship between the pixel value referred at the time of N value-ized process, N value, and the N value and dot size. It is a figure which shows an example of an error diffusion matrix. It is a schematic diagram which shows test pattern data. It is a flowchart figure which shows an example of the whole flow of the printing process by the printing apparatus which concerns on this invention. It is a flowchart figure which shows an example of the flow of the production | generation process of the correction information utilized by an image data correction process. It is a flowchart figure which shows an example of the flow of the noise addition N-value-ized process by an image data N-value-ized means. It is the flowchart figure which showed an example of the flow of the noise addition N-value-izing process which concerns on 2nd Embodiment. It is a figure which shows the other example of the dot and gradation conversion table which showed the relationship between the pixel value and N value which are referred in the case of N-value conversion processing, and the N value and dot size. It is the flowchart figure which showed an example of the flow of the noise addition N-value-izing process which concerns on 3rd Embodiment. It is a figure which shows an example of the noise addition amount table used with the noise addition N-value-izing process which concerns on 3rd Embodiment. It is explanatory drawing which outlined the relationship between a density | concentration area | region and noise addition amount. FIG. 2 is a functional block diagram illustrating a minimum configuration of a printing apparatus according to the present invention. It is explanatory drawing which shows the difference in the printing system by a multipass type | mold inkjet printer and a line head type inkjet printer. It is a conceptual diagram which shows the other example of the structure of a print head. It is a conceptual diagram which shows an example of the computer-readable recording medium which recorded the program which concerns on this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 100 ... Printing apparatus, 200 ... Print head, 300 ... Input density correction table, 400 ... Dot / tone conversion table, 500 ... Test pattern data, 600 ... Noise addition amount table, 10 ... Image data acquisition means, 12 ... Image data Correction means, 14 ... Image data N-value conversion means, 16 ... Error diffusion means, 18 ... Print data generation means, 20 ... Image data printing means, 30 ... Correction information storage means, 32 ... Test pattern data generation means, 34 ... Test Pattern data N-value conversion means 36... Test pattern printing means 38... Output density detection means 50... Black nozzle module 52 52 yellow nozzle module 54 54 magenta nozzle module 56 ... cyan nozzle module 60 ... CPU 62 ... RAM, 64 ... ROM, 66 ... interface, 70 ... Device, 72 ... output device, 74 ... input apparatus, N ... nozzle, R ... recording medium.

Claims (14)

Image data acquisition means for acquiring image data of M (M ≧ 3) values;
A print head with multiple nozzles capable of printing dots of different sizes;
Correction information storage means for storing correction information of the print head generated based on the characteristics of each nozzle of the print head;
Image data correction means for correcting the pixel value of the image data acquired by the image data acquisition means based on the correction information of the print head stored in the correction information storage means;
Image data N-value conversion means for converting the image data corrected by the image data correction means into N (M> N ≧ 2) values;
Print data generating means for generating print data based on the N-valued data that has been N-valued by the image data N-value converting means;
Image data printing means for printing the print data generated by the print data generation means using the print head,
The image data N-value conversion means converts the image data corrected by the image data correction means into N (N ≧ 2) values after adding a predetermined noise value for each pixel of the image data. A printing apparatus. The printing apparatus according to claim 1,
The printing apparatus according to claim 1, wherein the image data N-value conversion unit changes a noise value to be added according to a pixel value of the image data corrected by the image data correction unit. The printing apparatus according to claim 1,
When the pixel value of the image data corrected by the image data correction unit is a halftone, the image data N-value conversion unit adds a noise value added to the halftone pixel to a pixel other than the halftone A printing device characterized in that the value is larger than the value. The printing apparatus according to any one of claims 1 to 3,
Error diffusion means for diffusing an error generated when N (M> N ≧ 2) is converted into N (M> N ≧ 2) values by the image data N-value conversion means to the unprocessed pixels of the pixel data;
The error diffusion means subtracts the noise value added to the pixel from the error value when diffusing the error for each pixel to the unprocessed pixel, and diffuses the error value after the subtraction. A printing apparatus characterized by that. The printing apparatus according to any one of claims 1 to 4,
The correction information storage means includes
Test pattern data generating means for generating test pattern data of M (M ≧ 3) values;
Test pattern data N-value conversion means for converting the test pattern data generated by the test pattern data generation means into N (M> N ≧ 2) values;
Test pattern printing means for printing the test pattern data N-valued by the test pattern data N-value making means using the print head;
Output density detecting means for detecting the output density of the test pattern printed by the test pattern printing means;
A printing apparatus comprising: correction information generating means for generating correction information of the print head from the output density of the test pattern detected by the output density detecting means. The printing apparatus according to claim 5, wherein
The test pattern data N-value conversion unit converts a predetermined noise value for each pixel of the test pattern data before converting the test pattern data generated by the test pattern data generation unit to N (M> N ≧ 2). The printing apparatus is characterized in that N (N ≧ 2) values are added after adding. The printing apparatus according to claim 6.
The test pattern data N-value conversion means is configured to increase the noise value added for each pixel of the test pattern data more than the noise value added by the image data N-value conversion means. Printing device. Computer
Image data acquisition means for acquiring image data of M (M ≧ 3) values;
Correction information storage means for storing correction information of the print head generated based on the characteristics of each nozzle of the print head provided with a plurality of nozzles capable of printing dots of different sizes;
Image data correction means for correcting the pixel value of the image data acquired by the image data acquisition means based on the correction information of the print head stored in the correction information storage means;
Image data N-value conversion means for converting the image data corrected by the image data correction means into N (M> N ≧ 2) values;
Print data generating means for generating print data based on the N-valued data that has been N-valued by the image data N-value converting means;
The print data generated by the print data generating unit functions as an image data printing unit that prints using the print head, and
The image data N-value conversion means functions so as to convert the image data corrected by the image data correction means into N (N ≧ 2) values after adding a predetermined noise value for each pixel of the image data. A printing program characterized by that.   A computer-readable recording medium on which the printing program according to claim 8 is recorded. An image data acquisition step of acquiring M (M ≧ 3) value image data;
A correction information generation step for generating correction information of the print head based on the characteristics of each nozzle of the print head provided with a plurality of nozzles capable of printing dots of different sizes;
An image data correction step for correcting the pixel value of the image data acquired in the image data acquisition step based on the correction information of the print head generated in the correction information generation step;
An image data N-value conversion step for converting the image data corrected in the image data correction step into N (M> N ≧ 2) values;
A print data generation step for generating print data based on the N-value data converted into the N-value in the image data N-value conversion step;
An image data printing step for printing the print data generated in the print data generation step using the print head,
In the image data N-value conversion step, the image data corrected in the image data correction step is converted into N (N ≧ 2) values after adding a predetermined noise value for each pixel of the image data. How to print. Image data acquisition means for acquiring image data of M (M ≧ 3) values;
Correction information storage means for storing correction information of the print head generated based on the characteristics of each nozzle of the print head provided with a plurality of nozzles capable of printing dots of different sizes;
Image data correction means for correcting the pixel value of the image data acquired by the image data acquisition means based on the correction information of the print head stored in the correction information storage means;
Image data N-value conversion means for converting the image data corrected by the image data correction means into N (M> N ≧ 2) values;
Print data generation means for generating print data based on the N-valued data that has been N-valued by the image data N-value conversion means;
The image data N-value conversion means converts the image data corrected by the image data correction means into N (N ≧ 2) values after adding a predetermined noise value for each pixel of the image data. A print data generation apparatus characterized by comprising: Computer
Image data acquisition means for acquiring image data of M (M ≧ 3) values;
Correction information storage means for storing correction information of the print head generated based on the characteristics of each nozzle of the print head provided with a plurality of nozzles capable of printing dots of different sizes;
Image data correction means for correcting the pixel value of the image data acquired by the image data acquisition means based on the correction information of the print head stored in the correction information storage means;
Image data N-value conversion means for converting the image data corrected by the image data correction means into N (M> N ≧ 2) values;
While functioning as print data generation means for generating print data based on the N-valued data that has been N-valued by the image data N-value conversion means,
The image data N-value conversion means functions so as to convert the image data corrected by the image data correction means into N (N ≧ 2) values after adding a predetermined noise value for each pixel of the image data. A print data generation program.   A computer-readable recording medium on which the print data generation program according to claim 12 is recorded. An image data acquisition step of acquiring M (M ≧ 3) value image data;
A correction information generation step for generating correction information of the print head based on the characteristics of each nozzle of the print head provided with a plurality of nozzles capable of printing dots of different sizes;
An image data correction step for correcting the pixel value of the image data acquired in the image data acquisition step based on the correction information of the print head generated in the correction information generation step;
An image data N-value conversion step for converting the image data corrected in the image data correction step into N (M> N ≧ 2) values;
A print data generation step for generating print data based on the N-value data converted into the N-value in the image data N-value conversion step,
In the image data N-value conversion step, the image data corrected in the image data correction step is converted into N (N ≧ 2) values after adding a predetermined noise value for each pixel of the image data. How to print.

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