JP2006231915A - Printer, printing program, printing method, image processor, image processing program, image processing method, and recording medium with program recorded - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide novel apparatus, program and method for printing whereby white streaks generated by the dot omission phenomenon can be solved, and to provide an apparatus, a program and a method for image processing, etc. <P>SOLUTION: The printer of an inkjet system using a printing head with a plurality of nozzles specifies a deficient pixel from characteristic information of the printing head and image data, corrects a pixel value after distributing the pixel value of the deficient pixel to the nearby pixels, processes the corrected image data to N-value data processing to generate printing data, and carries out printing. Thus, the white streak phenomenon generated by the dot omission phenomenon can be solved or made almost inconspicuous. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a printing apparatus, a printing apparatus control program, and a printing apparatus control method used for a facsimile apparatus, a copying machine, a printing apparatus for office automation equipment, and the like. ) A printing apparatus, a printing program, a printing method, an image processing apparatus, an image processing program, and an image processing method, which are suitable for performing a so-called ink jet printing process in which predetermined characters and images are drawn And a recording medium on which the program is recorded.

The following describes a printing apparatus, particularly a printer that employs an inkjet method (hereinafter referred to as an “inkjet printer”).
Ink jet printers are generally inexpensive and can easily obtain high-quality color prints, and are widely used not only in offices but also in general users with the spread of personal computers and digital cameras.

  In such an ink jet printer, a moving body called a carriage or the like in which an ink cartridge and a print head are integrated is generally placed on a print medium (paper) in a direction perpendicular to the paper feed direction. By ejecting (injecting) liquid ink particles in the form of dots from the nozzles of the print head while reciprocating, predetermined characters and images are drawn on the print medium to create a desired printed matter. The carriage is equipped with ink cartridges of four colors (black, yellow, magenta, cyan) including black (black) and a print head for each color, so that not only monochrome printing but also full-color printing combining each color is possible. (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 a direction perpendicular to the paper feed direction, several tens of print heads are used to cleanly print the entire page. Since it is necessary to reciprocate more than 100 times from the first time, there is a disadvantage that it takes much longer printing time than other types of printing apparatuses, for example, laser printers using electrophotographic technology such as copying machines. is there.

  On the other hand, in an inkjet printer of a type in which a long print head having the same (or long) dimension as the width of the print paper is used and a carriage is not used, it is not necessary to move the print head in the width direction of the print paper. Since printing can be performed by so-called one scanning (one pass), high-speed printing is possible as in the case of the laser printer. In addition, since a carriage for mounting the print head and a drive system for moving the print head are not required, the printer casing can be reduced in size and weight, and the quietness can be greatly improved. Yes. The former inkjet printer is generally called a “multi-pass printer”, and the latter inkjet printer is generally called a “line head printer” or a “serial printer”.

  By the way, a print head indispensable for such an ink jet printer has fine nozzles having a diameter of about 10 to 70 μm arranged in one row at a predetermined interval or in a plurality of rows in a direction perpendicular to the nozzle arrangement direction. Therefore, due to manufacturing errors, the ink ejection direction of some nozzles may be tilted, or the position of the nozzles may be shifted from the ideal position. There may be a so-called “flight curve phenomenon” in which the position deviates from the ideal position. In addition, there are inks whose ink amount is greatly increased or decreased as compared with the ideal amount, as the variation is large due to the dispersion characteristics of the nozzles.

  As a result, a printing defect referred to as a so-called “banding phenomenon” may occur in a portion printed using the defective nozzle, and the print quality may be significantly reduced. In other words, when the “flight bend” phenomenon occurs, the distance between the dots ejected by the adjacent nozzles becomes non-uniform, and the portion where the distance between adjacent dots is longer than normal is indicated by “white streaks (if the printing paper is white) ) ”Occurs, and“ dark streaks ”occur in a portion where the distance between adjacent dots is shorter than normal. Even when the ink amount is not ideal, a dark streak occurs in a nozzle portion where the ink amount is large, and a white streak occurs in a portion where the ink amount decreases.

  In particular, the banding phenomenon is more likely to occur in the “line head type printer” in which the print head or print medium is fixed (one pass printing) than in the case of the “multi-pass type printer” (serial printer) as described above. (In multi-pass printers, there is a technique that makes banding inconspicuous by using the print head reciprocating many times).

Therefore, in order to prevent a kind of printing defects due to such "banding phenomenon", research and development in the so-called hardware part, such as improvement of print head manufacturing technology and design improvement, has been earnestly advanced. It is difficult to provide a print head in which 100% “banding phenomenon” does not occur due to manufacturing costs, technical aspects, and the like.
Therefore, in addition to the improvement in the hardware part as described above, a technology that reduces such “banding phenomenon” using a so-called software method such as printing control as described below is used in combination. Has been.

For example, in Patent Documents 1 and 2 shown below, pixel values of pixels corresponding to missing dots are distributed to the neighboring pixels, and the pixel values of the neighboring pixels are changed, thereby preventing printing defects such as “dot missing phenomenon”. I try to reduce it.
Further, in Patent Document 3 shown below, the pixel value of a pixel corresponding to a missing dot is diffused to surrounding pixels by an intermediate gradation method such as an error diffusion method, thereby reducing printing defects such as a “missing dot phenomenon”. Like to do.
JP 2004-58284 A JP 2002-29074 A JP-A-5-30361

However, in the method of changing the pixel value of a neighboring pixel by assigning the pixel value of a pixel that is simply missing a dot to the neighboring pixels as in Patent Documents 1 and 2, the pixel value of the sorting destination pixel is saturated. Because it is designed to cover with other colors, it is possible that the corresponding color will change.
On the other hand, in the method using error diffusion processing such as Patent Document 3 described above, all of the generated pixel values are distributed to the pixels downstream in the scanning direction of the missing dot pixels. There is a risk that the pixel value of will change greatly, and the corresponding gradation will change greatly from other parts.

Therefore, the present invention has been devised in order to effectively solve such problems, and a purpose thereof is to provide a novel printing apparatus and printing that can eliminate white stripes caused by missing dots or make them almost inconspicuous. A program, a printing method, an image processing apparatus, an image processing program, an image processing method, and a recording medium on which the program is recorded are provided.
Another object of the present invention is to provide a novel printing apparatus, printing program, printing method and image processing apparatus, image processing program, image processing method, and program that can faithfully reproduce an original image with respect to pixel values such as density (luminance). Is provided.

[Mode 1] In order to solve the above problem, a printing apparatus according to mode 1
Image data storage means for storing image data of M values (M ≧ 3);
A print head having a plurality of nozzles for printing dots;
Print head characteristic information storage means for storing print head characteristic information indicating the characteristics of the nozzles of the print head;
A defective pixel specifying means for specifying a defective pixel from the image data based on the print head characteristic information stored in the print head characteristic information storage means;
Pixel value correcting means for distributing the pixel value of the defective pixel specified by the defective pixel specifying means to pixels near the defective pixel;
N-valued data generating means for generating N-value (M> N ≧ 2) image data based on the image data corrected by the pixel value correcting means;
Print data generating means for generating print data based on N-value image data generated by the N-valued data generating means;
And printing means for executing printing using the print head based on the print data generated by the print data generation means.

  As a result, as described later, the pixel value of the defective pixel is distributed to the neighboring pixels and the pixel value of the image data is corrected, so that the dot size of the pixel near the defective pixel is changed to the original dot size (dot Therefore, “white streaks” generated by the so-called dot drop phenomenon can be effectively eliminated or made almost inconspicuous.

  Here, “pixel value” generally indicates “brightness” that is an index of brightness, and “density value” that is an index of color density, but in this embodiment, mainly “density” Value ”(forms relating to“ printing apparatus ”,“ printing program ”,“ printing method ”,“ image processing apparatus ”,“ image processing program ”,“ image processing ”below) This is the same in the description of the form relating to the “method”, the form relating to the “recording medium on which the program is recorded”, the best mode for carrying out the invention, and the like.

  The “M value (M ≧ 3)” is a so-called multi-value pixel value related to so-called luminance or density, which is expressed as, for example, 8-bit 256 gradation, and “N value ( “M> N ≧ 2)”, which will be described in detail later, is a process of classifying such M-value (multi-value) data into N types based on a certain threshold value. In addition to the so-called “binary” in which a dot is hit or not, a concept that includes changing the dot size in several stages according to the size of the pixel value. Examples of the N types of classification processing include known halftone processing. (Forms relating to “printing apparatus”, forms relating to “printing program”, aspects relating to “printing method”, aspects relating to “image processing apparatus”, aspects relating to “image processing program”, aspects relating to “image processing method”, and “ This is the same in the description relating to the “recording medium on which the program is recorded”, the best mode for carrying out the invention, and the like).

  The reason why the value of “N” is set to (N ≧ 2) is that it is necessary to at least define binarization regarding whether or not dots are hit in order to generate print data. (Forms relating to “printing device”, “printing program”, “printing method”, “image processing device”, “image processing program”, “image processing method”, In addition, the same applies to the description relating to the “recording medium on which the program is recorded” and the column of the best mode for carrying out the invention.

  Further, the “neighboring pixel” means, for example, when the print resolution is 720 [dpi] (the distance between dots is about 35 [μm]), above or below the target pixel continuous with the target pixel (dot) or The left and right are about 2 to 4 pixels (dots). The number of pixels in the vicinity differs depending on the resolution (the following forms related to “printing apparatus”, forms related to “printing program”, forms related to “printing method”, forms related to “image processing apparatus”, “image processing” The same applies to the description relating to the "program", the "image processing method", the "recording medium on which the program is recorded", the best mode for carrying out the invention, and the like.

  “Dot” refers to a single region formed by ink ejected from one or more nozzles landing on a print medium. Further, “dots” are not “zero” in area, and of course have a certain size (area), and there are a plurality of types for each size. However, dots formed by ejecting ink are not always perfect circles. For example, when dots are formed in a shape other than a perfect circle such as an ellipse, the average diameter is treated as the dot diameter, or the area equal to the area of the dots formed by ejecting a certain amount of ink is used. In some cases, a perfect circle equivalent dot is assumed and the diameter of the equivalent dot is treated as the dot diameter. In addition, for example, a method for hitting dots having different densities includes a method of hitting dots having the same dot size and different densities, a method of hitting dots having the same density and different sizes, and ejection of ink having the same density. It is possible to consider a method in which the amount of dots is different and the density is varied by overstrike. In addition, when one ink droplet ejected from one nozzle is separated and landed, it is considered as one dot, but two nozzles or two or more formed from one nozzle around the time. If two dots are attached, it is assumed that two dots are formed (the following forms relating to “printing apparatus”, forms relating to “printing program”, forms relating to “printing method”, “image processing apparatus”) This is the same in the description of the form relating to "the image processing program", the form relating to the "image processing method", the form relating to the "recording medium on which the program is recorded", the best mode for carrying out the invention, and the like. ).

  The “image data storage means” stores image data input from an optical print result reading means such as a scanner means, or image data input from an external device via a network such as a LAN or WAN. Or image data recorded on a recording medium such as a CD-ROM or DVD-ROM input via a driving device such as a CD drive or DVD drive of the printing apparatus (refer to the following “ The same applies to the description of the form relating to “printing apparatus”, the form relating to “image processing apparatus”, and the column of the best mode for carrying out the invention.

  The “print head characteristic information storage means” stores the print head characteristic information by any means at any time, and may store the print head characteristic information in advance. Instead of storing the characteristic information in advance, the print head characteristic information may be stored by an external input or the like during the operation of the printing apparatus. For example, before the printing apparatus at the time of shipment from the factory is sold as a product, dot formation of each nozzle constituting the print head is performed from the print result by the print head using an optical print result reading means such as a scanner means. Inspect the positional deviation amount, etc., and store the inspection result in advance, or when using the printing apparatus, inspect the deviation amount of the dot formation position of each nozzle constituting the print head in the same way as at the time of factory shipment. Any timing may be used as long as the print head characteristic information can be stored when the product is used, such as storing the inspection result. In addition, in order to cope with the case where the characteristics of the print head change after use of the printing apparatus, the print result by the print head is used regularly or at a predetermined time using an optical print result reading means such as a scanner means. The print head characteristic information may be updated, for example, by inspecting the print position deviation amount of the print head and storing the result of the inspection together with data at the time of factory shipment or overwriting the data. (This is the same in the description of the form relating to the “printing apparatus”, the form relating to the “image processing apparatus”, and the section of the best mode for carrying out the invention).

  In addition, the “missing pixel” refers to a pixel corresponding to a missing nozzle in which no dot is formed due to a defect in the print head (a form relating to a “printing apparatus” below, a form relating to a “printing program”, “ Form relating to “printing method”, form relating to “image processing apparatus”, form relating to “image processing program”, form relating to “image processing method”, form relating to “recording medium on which said program is recorded”, best for carrying out the invention This is the same in the description of the column of the form.

  In addition, “white streaks” means that a phenomenon in which the distance between adjacent dots becomes larger than a predetermined distance due to the “dot missing phenomenon” continuously occurs in the direction perpendicular to the nozzle arrangement direction, and the background of the print medium A portion (area) in which colors are conspicuous in stripes (forms relating to “printing apparatus”, forms relating to “printing program”, forms relating to “printing method”, forms relating to “image processing apparatus”, “ The same applies to the description relating to the “image processing program”, the “image processing method”, the “recording medium on which the program is recorded”, the best mode for carrying out the invention, and the like.

[Mode 2] The printing apparatus of mode 2
In the printing apparatus according to the first aspect, the pixel value correcting unit distributes the pixel value of the defective pixel to the pixel having the closest distance from the defective pixel, and the pixel value after distribution of the pixel having the closest distance When the value exceeds a predetermined range, the remaining pixel value is distributed to the pixel having the next closest distance from the pixel having the shortest distance from the defective pixel.

  As a result, the pixel value of the pixel closest to the defective pixel is changed, so that the white stripe generated in the defective pixel portion can be effectively eliminated or made almost inconspicuous. That is, when this pixel value is a density value, the density of the pixel closest to the defective pixel increases and the dot size increases, so that the area of the defective pixel is covered by the increased dot. As a result, the area of white stripes is reduced and the white stripes are eliminated or hardly noticeable.

  Here, the “distance” indicates a distance between pixels of the image data, and is different from a physical distance. When one pixel is regarded as one point, the distance between each pixel can be calculated by the Euclidean distance, the city block distance, the chess board distance, and the like (forms relating to the “printing apparatus” below, “ A form relating to “print program”, a form relating to “printing method”, a form relating to “image processing apparatus”, a form relating to “image processing program”, a form relating to “image processing method”, and a form relating to “recording medium on which the program is recorded”, The same applies to the description of the best mode column for carrying out the invention).

  The “predetermined range” is a range of values where the pixel value does not saturate. If the pixel value exceeds this range, the pixel value is saturated (displayed even if the value further increases). (The result does not change). For example, if the maximum gradation that can be displayed by the display device is 8 bits, an image having a density value of “256” or higher cannot be displayed (represented). Therefore, the density value is “256” or higher. This image can be expressed only by an image having a density value of “255”, no matter how much the value is further increased. Thus, a pixel having a density value exceeding the maximum displayable gradation of the display device is referred to as a saturated pixel (hereinafter referred to as “printing device”, “printing program”, and “printing method” , A form relating to “image processing apparatus”, a form relating to “image processing program”, a form relating to “image processing method”, a form relating to “recording medium on which the program is recorded”, a column of the best mode for carrying out the invention, etc. The same in the description).

[Mode 3] The printing apparatus of mode 3
In the printing apparatus according to aspect 2, when the pixel value after distribution of the pixel closest to the defective pixel exceeds a predetermined range, the pixel value correction unit is configured to exceed the predetermined range. The pixel values are distributed in order from the pixel having the closest distance from the defective pixel other than the pixel closest to the defective pixel so that the pixel value after distribution of each pixel does not exceed the predetermined range. It is characterized by this.

As a result, the pixel value changes preferentially from the shortest distance from the defective pixel, so that white streaks generated in the defective pixel portion can be effectively eliminated or made almost inconspicuous. That is, when this pixel value is a density value, the closer the distance from the missing pixel, the higher the density of the pixel and the larger the dot size, so that the area of the missing pixel is covered by the larger dot. As a result, the area of white stripes is reduced and the white stripes are eliminated or hardly noticeable.
Further, even when the pixel value of the first distribution destination pixel is saturated, all of the pixel values of the defective pixel can be distributed in order from the nearest pixel of the neighboring pixels, so the density (luminance) The average pixel value such as is the same as the original image, and the original image can be reproduced faithfully.

[Form 4] The printing apparatus of form 4
In the printing apparatus according to Mode 2 or 3, when there are a plurality of pixels to which the pixel value of the defective pixel is distributed, the pixel value correction unit distributes the pixel value evenly to each of these pixels. It is characterized by being.
As a result, the pixel values of the pixels in the vicinity of the defective pixel change uniformly, so that white stripes can be more effectively eliminated or made almost inconspicuous.

[Form 5] The printing apparatus of form 5 is
5. The printing apparatus according to any one of forms 1 to 4, wherein the pixel value correcting unit positions a pixel to which a pixel value of the defective pixel is distributed in a nozzle array direction of the print head with respect to the defective pixel. It is characterized by selecting from a plurality of pixels.
This simplifies pixel value correction processing compared to a method in which pixel values are distributed to pixels in a direction different from the nozzle arrangement direction of the print head. Value correction processing can be realized.

[Mode 6] A printing apparatus according to mode 6 includes:
In the printing apparatus according to any one of Embodiments 1 to 5, the N-value data generation unit generates N-value (M> N ≧ 2) image data based on the image data corrected by the pixel value correction unit. When generating, an error diffusion method is used.
As a result, in addition to the effects described in the first to fifth aspects, an error generated when the N value of each pixel is converted can be effectively used, so that a high-quality printed matter that faithfully represents the intermediate gradation can be obtained with certainty. it can.

  Here, “error diffusion processing” is the same as that normally used in the field of image processing, and an error caused by binarization processing of a certain pixel is assigned to surrounding pixels according to a predetermined error diffusion matrix. In the subsequent processing, this refers to processing for minimizing the error as a whole by taking the influence into consideration. That is, if the density value of a pixel is larger than the intermediate value of half the number of gradations of the image, it is classified as black, and if it is smaller, it is classified as white, and then an error between the density value before classification and the density value after processing is appropriately This is a method of distributing and adjusting to surrounding pixels at a ratio (forms relating to “printing device”, “printing program”, “printing method”, “image processing device”, “image processing program” below) The same applies to the description relating to "the image processing method", the aspect relating to the "recording medium on which the program is recorded", and the best mode for carrying out the invention.

[Mode 7] A printing apparatus according to mode 7 includes:
In the printing apparatus according to the sixth aspect, the N-valued data generation unit, when the error diffusion destination pixel is a defective pixel specified by the defective pixel specifying unit, generates an error diffused to the defective pixel. It is characterized by being distributed to the pixels in the vicinity of the pixels.
As a result, the error is not diffused to the defective pixel, and the error can be effectively utilized.

[Mode 8] A printing apparatus according to mode 8
The printing apparatus according to any one of Forms 1 to 7, wherein the print head characteristic information includes information indicating whether or not the nozzles can eject ink.
As a result, it is possible to easily identify the nozzle that cannot eject the ink that causes the white streaks, and thus it is possible to easily identify the defective pixel.

  Here, the information indicating whether or not ink can be ejected is information indicating whether or not ink can be ejected. The ink ejection state of the nozzles can be detected by, for example, a CCD sensor provided in the printing apparatus, and based on the detection result, it can be determined whether each nozzle can eject ink. Further, it may be determined that ink cannot be ejected even if the amount of ink ejected is so small that it can be regarded as equivalent to a state where it cannot be ejected (for example, the amount of ejecting that generates the “white streaks”).

[Mode 9] A printing apparatus according to mode 9
In the printing apparatus according to any one of Forms 1 to 8, the print head can be printed by one scan because the nozzles are continuously arranged over a wider range than the mounting area of the print medium. It is a characteristic print head.
As a result, as described above, the “white streaks” caused by the banding phenomenon that is particularly likely to occur when using a line head type print head that completes printing in one scan (one pass) is eliminated or made almost inconspicuous. Can do.

  Here, “one-scan printing” means that for one line in the paper feed direction (head movement direction) to be printed by each nozzle, the line is printed only by the responsible nozzle, and the assigned nozzle is once When it passes, it means that the printing of the line is finished (the following “print program” form, “print method” form, “image processing apparatus” form, “image processing program” form, “image” This is the same in the description of the form relating to the “processing method”, the form relating to the “recording medium on which the program is recorded”, the best mode for carrying out the invention, and the like.

[Mode 10] A printing apparatus according to mode 10 includes:
The printing apparatus according to any one of Embodiments 1 to 8, wherein the print head is a print head that performs printing while reciprocating in a direction orthogonal to a paper feed direction of the print medium. It is.
The dot drop phenomenon described above is conspicuous in the case of a line head type print head, but also occurs in the case of a multi-pass type print head. Therefore, if the printing method according to any one of the first to eighth embodiments is applied to a multi-pass type print head, “white streaks” due to a dot missing phenomenon that occurs in the multi-pass type print head can be surely eliminated. Or it can be made almost inconspicuous.

  Further, in the case of a multi-pass type print head, it is possible to avoid the banding phenomenon as described above by taking measures such as repeating scanning of the print head. If it is applied, it is not necessary to scan the same portion over and over again, so that higher-speed printing can be realized.

[Form 11] The print program of form 11 is
Identifying a defective pixel from the image data of M value (M ≧ 3) based on print head characteristic information indicating the characteristics of the nozzle of a print head having a plurality of nozzles for printing dots Means,
Pixel value correcting means for distributing the pixel value of the defective pixel specified by the defective pixel specifying means to pixels near the defective pixel;
N-valued data generating means for generating N-value (M> N ≧ 2) image data based on the image data corrected by the pixel value correcting means;
Print data generating means for generating print data based on N-value image data generated by the N-valued data generating means;
Based on the printing data generated by the print data generating means, the printing data is made to function as a printing means for executing printing using the print head.

As a result, the pixel value of the pixel in the vicinity of the defective pixel is changed and the dot size is changed as in the first mode, so that “white streaks” can be eliminated or hardly noticeable.
Further, as in the case of the mode 2, since all the pixel values of the defective pixel are distributed to the neighboring pixels, the average pixel value is the same as that of the original image, and the original image can be faithfully reproduced. . In addition, most printing apparatuses on the market such as inkjet printers are equipped with 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 12] The printing program of mode 12 is
In the printing program according to mode 11, the pixel value correcting unit distributes the pixel value of the defective pixel to the pixel having the closest distance from the defective pixel, and the pixel value after distribution of the pixel having the closest distance When the value exceeds a predetermined range, the remaining pixel value is distributed to the pixel having the next closest distance from the pixel having the shortest distance from the defective pixel.

  As a result, the same effect as in the second aspect can be obtained, and since it can be realized by software as in the case of the eleventh aspect, it is more economical and easier than when dedicated hardware is created to realize each of the above means. Can be realized. Furthermore, it is possible to easily upgrade the version by modifying or improving the function by rewriting a part of the program.

[Form 13] The print program of form 13 is
In the printing program according to the twelfth aspect, when the pixel value after distribution of the pixel closest to the defective pixel exceeds a predetermined range, the pixel value correction unit is configured to exceed the predetermined range. The pixel values are distributed in order from the pixel having the closest distance from the defective pixel other than the pixel closest to the defective pixel so that the pixel value after distribution of each pixel does not exceed the predetermined range. It is characterized by this.

  As a result, the same effect as in the third aspect can be obtained, and since it can be realized by software as in the case of the eleventh aspect, it is more economical and easier than the case where the above-mentioned means are realized by creating dedicated hardware. Can be realized. Furthermore, it is possible to easily upgrade the version by modifying or improving the function by rewriting a part of the program.

[Form 14] The print program of form 14 is
In the printing program according to mode 12 or 13, when there are a plurality of pixels to which the pixel value of the defective pixel is distributed, the pixel value correcting unit distributes the pixel value evenly to each of these pixels. It is characterized by being.
As a result, the same effect as in the fourth aspect can be obtained, and since it can be realized by software as in the case of the eleventh aspect, it is more economical and easier than when dedicated hardware is created and each of the above means is realized. Can be realized. Furthermore, it is possible to easily upgrade the version by modifying or improving the function by rewriting a part of the program.

[Form 15] The print program of form 15 is
In the printing program according to any one of Forms 11 to 14, the pixel value correcting unit positions a pixel to which the pixel value of the defective pixel is distributed in the nozzle array direction of the print head with respect to the defective pixel. It is characterized by selecting from a plurality of pixels.

  As a result, the same effect as that of the fifth aspect can be obtained, and since it can be realized by software as in the case of the eleventh aspect, it is more economical and easier than the case where the respective means are realized by creating dedicated hardware. Can be realized. Furthermore, it is possible to easily upgrade the version by modifying or improving the function by rewriting a part of the program.

[Mode 16] The print program of mode 16 is
In the printing program according to any one of Embodiments 11 to 15, the N-value data generation unit generates N-value (M> N ≧ 2) image data based on the image data corrected by the pixel value correction unit. When generating, an error diffusion method is used.

  As a result, the same effect as in the sixth aspect can be obtained, and since it can be realized by software as in the case of the eleventh aspect, it is economical and easy as compared with the case where the respective means are realized by creating dedicated hardware. Can be realized. Furthermore, it is possible to easily upgrade the version by modifying or improving the function by rewriting a part of the program.

[Mode 17] The print program of mode 17 is
In the printing program according to mode 16, when the error diffusion destination pixel is a defective pixel specified by the defective pixel specifying unit, the N-valued data generation unit generates an error diffused to the defective pixel. It is characterized by being distributed to the pixels in the vicinity of the pixels.

  As a result, the same effect as in the seventh aspect can be obtained, and since it can be realized by software as in the case of the eleventh aspect, it is more economical and easier than the case where the respective means are realized by creating dedicated hardware. Can be realized. Furthermore, it is possible to easily upgrade the version by modifying or improving the function by rewriting a part of the program.

[Form 18] The print program of form 18 is
In the printing program according to any one of Embodiments 11 to 17, the print head characteristic information includes information indicating whether or not the nozzles can eject ink.
As a result, the same effect as in the eighth aspect can be obtained, and since it can be realized by software as in the case of the eleventh aspect, it is more economical and easier than the case where the respective means are realized by creating dedicated hardware. Can be realized. Furthermore, it is possible to easily upgrade the version by modifying or improving the function by rewriting a part of the program.

[Embodiment 19] The computer-readable recording medium of Embodiment 19 is
A computer-readable recording medium on which the printing program according to any one of forms 11 to 18 is recorded.
Accordingly, the printing program according to any one of the above embodiments 11 to 18 can be easily provided to users such as users via a computer-readable storage medium such as a CD-ROM, DVD-ROM, FD, or semiconductor chip. And can be provided reliably.

[Mode 20] The printing method of mode 20 includes:
A defective pixel specifying step of specifying a defective pixel from image data of M values (M ≧ 3) based on print head characteristic information indicating the characteristics of the nozzle of a print head provided with a plurality of nozzles for printing dots;
A pixel value correcting step for distributing the pixel value of the defective pixel specified in the defective pixel specifying step to pixels in the vicinity of the defective pixel;
An N-valued data generation step for generating N-value (M> N ≧ 2) image data based on the image data corrected in the pixel value correction step;
A print data generation step for generating print data based on the N-value image data generated in the N-value data generation step;
And a printing step of executing printing using the print head based on the printing data generated in the printing data generation step.
As a result, the pixel value of the pixel in the vicinity of the defective pixel is changed and the dot size is changed as in the first mode, so that “white streaks” can be eliminated or hardly noticeable.

[Form 21] The printing method of form 21 is
The printing method according to aspect 20, wherein the pixel value correcting step distributes the pixel value of the defective pixel to the pixel having the closest distance from the defective pixel, and the pixel value after distribution of the pixel having the closest distance When the value exceeds a predetermined range, the remaining pixel value is distributed to the pixel closest to the next pixel after the pixel closest to the defective pixel.

  As a result, the pixel value of the pixel having the closest distance from the defective pixel changes in the same way as in the second aspect, so that the white stripe generated in the defective pixel portion can be effectively eliminated or made almost inconspicuous. Further, since all of the pixel values of the defective pixels are distributed to the nearest pixels, the average pixel value is the same as that of the original image, and the original image can be faithfully reproduced.

[Form 22] The printing method of form 22 is
In the printing method of form 21, in the pixel value correction step, when the pixel value after distribution of the pixel closest to the defective pixel exceeds a predetermined range, the pixel value corresponding to the predetermined range is exceeded. Are distributed in order from the pixel having the closest distance from the defective pixel other than the pixel having the closest distance from the defective pixel so that the pixel value after distribution of each pixel does not exceed the predetermined range. It is a feature.

  As a result, the pixel value changes preferentially from the side closer to the defective pixel as in the third mode, so that the white stripe generated in the defective pixel portion is effectively eliminated or made almost inconspicuous. Can do. In addition, since all the pixel values of the defective pixel are distributed to the neighboring pixels, the average pixel value is the same as that of the original image, and the original image can be faithfully reproduced.

[Form 23] The printing method of form 23 is
23. In the printing method according to mode 21 or 22, when there are a plurality of pixels to which the pixel value of the defective pixel is distributed, the pixel value correcting step distributes the pixel value evenly to each of these pixels. It is characterized by.
As a result, the pixel values of the pixels in the vicinity of the defective pixel change equally as in the fourth aspect, so that the white stripe can be more effectively eliminated or made hardly noticeable.

[Form 24] The printing method of form 24 includes:
In the printing method according to any one of forms 20 to 23, in the pixel value correction step, a pixel to which a pixel value of the defective pixel is distributed is positioned with respect to the defective pixel in a nozzle array direction of the print head. It is characterized by selecting from a plurality of pixels.
As a result, the pixel value correction process is simplified as compared with the method of distributing the pixel value to the pixels in the direction different from the nozzle arrangement direction of the print head as in the fifth aspect, so that the amount of information processing is greatly reduced. Thus, high-speed pixel value correction processing can be realized.

[Form 25] The printing method of form 25 is
25. The printing method according to any one of forms 20 to 24, wherein the N-valued data generating step generates N-value (M> N ≧ 2) image data based on the image data corrected by the pixel value correcting unit. In this case, an error diffusion method is used.
As a result, as in the case of the sixth aspect, an error generated when the N value of each pixel is converted can be effectively used, so that a printed matter with higher image quality can be provided.

[Form 26] The printing method of form 26 is
In the printing method according to mode 25, in the N-valued data generation step, when the error diffusion destination pixel is a defective pixel specified by the defective pixel specifying unit, an error diffused to the defective pixel is determined as the defective pixel. This is characterized by distributing to pixels in the vicinity of the pixel.
As a result, as in the case of the seventh aspect, the error is not diffused to the defective pixel, so that the error can be effectively used.

[Form 27] The printing method of form 27 is
27. The printing method according to any one of forms 20 to 26, wherein the print head characteristic information includes information indicating whether or not the nozzles can eject ink.
As a result, the defective pixel can be easily identified as in the eighth embodiment.

[Mode 28] An image processing apparatus according to mode 28
Image data storage means for storing image data of M value (M ≧ 2);
Print head characteristic information storage means for storing print head characteristic information indicating characteristics of the nozzle of a print head provided with a plurality of nozzles for printing dots;
A defective pixel specifying means for specifying a defective pixel from the image data based on the print head characteristic information stored in the print head characteristic information storage means;
And a pixel value correcting unit that distributes the pixel value of the defective pixel specified by the defective pixel specifying unit to pixels in the vicinity of the defective pixel.
As a result, the same effect as in the first aspect can be obtained, and each means can be realized on software, and thus can be realized by an information processing apparatus such as a general-purpose personal computer.

[Mode 29] An image processing apparatus according to mode 29
29. The image processing apparatus according to aspect 28, wherein the pixel value correcting unit distributes the pixel value of the defective pixel to the pixel having the closest distance from the defective pixel, and the pixel after distribution of the pixel having the closest distance When the value exceeds a predetermined range, the remaining pixel value is distributed to the pixel closest to the next pixel after the pixel closest to the defective pixel. .
As a result, the same effect as in the second embodiment can be obtained, and the pixel value correcting means can be realized on software as in the twenty-eighth embodiment, and therefore can be realized by an information processing apparatus such as a general-purpose personal computer.

[Mode 30] An image processing apparatus according to mode 30
In the image processing device according to mode 29, when the pixel value after distribution of the pixel closest to the defective pixel exceeds a predetermined range, the pixel value correction unit is configured to exceed the predetermined range. Are distributed in order from the pixel closest to the defective pixel other than the pixel closest to the defective pixel, and the pixel value after distribution of each pixel does not exceed the predetermined range. It is characterized by doing.
As a result, the same effect as in the third aspect can be obtained, and since the pixel value correcting means can be realized on software as in the twenty-eighth aspect, it can be realized by an information processing apparatus such as a general-purpose personal computer.

[Mode 31] An image processing apparatus according to mode 31
In the image processing device according to mode 29 or 30, when there are a plurality of distribution destination pixels selected in accordance with the distance from the defective pixel, the pixel value correction unit performs the pixel value for each of these pixels. Are distributed evenly.
As a result, the same effect as in the fourth aspect can be obtained, and the pixel value correcting means can be realized on software as in the twenty-eighth aspect, so that it can be realized by an information processing apparatus such as a general-purpose personal computer.

[Mode 32] An image processing apparatus according to mode 32
32. The image processing apparatus according to any one of Forms 28 to 31, wherein the pixel value correcting unit positions a pixel to which a pixel value of the defective pixel is distributed in a nozzle array direction of the print head with respect to the defective pixel. It is characterized by selecting from a plurality of pixels.
As a result, the same effect as in the fifth aspect can be obtained, and the pixel value correcting means can be realized on software as in the twenty-eighth aspect, and therefore can be realized by an information processing apparatus such as a general-purpose personal computer.

[Mode 33] An image processing apparatus according to mode 33
33. The image processing apparatus according to any one of Forms 28 to 32, wherein the print head characteristic information includes information indicating whether ink is ejected from the nozzles.
As a result, the same effects as in the eighth embodiment can be obtained, and the pixel value correcting means can be realized on software as in the twenty-eighth embodiment, and therefore can be realized by an information processing apparatus such as a general-purpose personal computer.

[Form 34] The image processing program of form 34 is
A defective pixel specifying means for specifying a defective pixel from M value (M ≧ 2) image data based on print head characteristic information indicating characteristics of the nozzle of a print head having a plurality of nozzles for printing dots; ,
The pixel value correcting unit distributes the pixel value of the defective pixel specified by the defective pixel specifying unit to the pixels in the vicinity of the defective pixel.

  As a result, the same effects as in the first aspect can be obtained, and each means can be realized by software using a general-purpose computer system such as a personal computer (PC). Compared with the case of realizing, it can be realized economically and easily. Furthermore, it is possible to easily upgrade the version by modifying or improving the function by rewriting a part of the program.

[Mode 35] The image processing program of mode 35 is
In the image processing program according to mode 34, the pixel value correcting unit distributes the pixel value of the defective pixel to the pixel having the closest distance from the defective pixel, and the pixel after distribution of the pixel having the closest distance When the value exceeds a predetermined range, the remaining pixel value is distributed to the pixel closest to the next pixel after the pixel closest to the defective pixel. .

  As a result, the same effects as those of the form 2 can be obtained, and, as in the form 34, each means can be realized by software using a general-purpose computer system such as a personal computer (PC). Compared to the case of creating and realizing each of the above means, it can be realized economically and easily. Furthermore, it is possible to easily upgrade the version by modifying or improving the function by rewriting a part of the program.

[Mode 36] The image processing program of mode 36 is
In the image processing program according to form 35, when the pixel value after distribution of the pixel closest to the defective pixel exceeds a predetermined range, the pixel value correction unit is configured to exceed the predetermined range. Are distributed in order from the pixel closest to the defective pixel other than the pixel closest to the defective pixel, and the pixel value after distribution of each pixel does not exceed the predetermined range. It is characterized by doing.

  As a result, the same effect as in the third aspect can be obtained, and, as in the thirty-fourth aspect, each means can be realized by software using a general-purpose computer system such as a personal computer (PC). Compared to the case of creating and realizing each of the above means, it can be realized economically and easily. Furthermore, it is possible to easily upgrade the version by modifying or improving the function by rewriting a part of the program.

[Form 37] The image processing program of form 37 is
37. In the image processing program according to form 35 or 36, when there are a plurality of distribution destination pixels selected in accordance with the distance from the defective pixel, the pixel value correction unit performs the pixel value for each of these pixels. Are distributed evenly. As a result, the same effects as those of the form 4 can be obtained. Similarly to the form 34, each means can be realized by software using a general-purpose computer system such as a personal computer (PC). Compared to the case of creating and realizing each of the above means, it can be realized economically and easily. Furthermore, it is possible to easily upgrade the version by modifying or improving the function by rewriting a part of the program.

[Mode 38] The image processing program of mode 38 is
In the image processing program according to any one of forms 34 to 37, the pixel value correcting unit positions a pixel to which the pixel value of the defective pixel is distributed in the nozzle array direction of the print head with respect to the defective pixel. It is characterized by selecting from a plurality of pixels.

  As a result, the same effects as in the fifth aspect can be obtained. Similarly to the thirty-fourth aspect, each means can be realized by software using a general-purpose computer system such as a personal computer (PC). Compared to the case of creating and realizing each of the above means, it can be realized economically and easily. Furthermore, it is possible to easily upgrade the version by modifying or improving the function by rewriting a part of the program.

[Embodiment 39] The image processing program of embodiment 39 is
In the image processing program according to any one of forms 34 to 38, the print head characteristic information includes information indicating whether or not the nozzles can eject ink.
As a result, the same effects as those of the eighth embodiment can be obtained. Similarly to the thirty-fourth embodiment, each means can be realized by software using a general-purpose computer system such as a personal computer (PC). Compared to the case of creating and realizing each of the above means, it can be realized economically and easily. Furthermore, it is possible to easily upgrade the version by modifying or improving the function by rewriting a part of the program.

[Mode 40] The computer-readable recording medium of mode 40 is
A computer-readable recording medium on which the image processing program according to any one of forms 34 to 39 is recorded.
As a result, the image processing program according to any one of the above-described forms 34 to 39 is transmitted to a user such as a user via a computer-readable storage medium such as a CD-ROM, DVD-ROM, FD, or semiconductor chip. It can be provided easily and reliably.

[Form 41] An image processing method of form 41 includes:
A defective pixel specifying step of specifying a defective pixel from M value (M ≧ 2) image data based on print head characteristic information indicating characteristics of the nozzle of a print head having a plurality of nozzles for printing dots;
And a pixel value correcting step for distributing the pixel value of the defective pixel specified in the defective pixel specifying step to pixels in the vicinity of the defective pixel.
As a result, the same effects as those of the first embodiment can be obtained, and a hardware configuration such as a print head is not required, and therefore, it can be realized only by software using a general-purpose computer system such as a personal computer.

[Form 42] An image processing method according to form 42 includes:
42. In the image processing method according to aspect 41, the pixel value correcting step distributes the pixel value of the defective pixel to the pixel having the closest distance from the defective pixel, and the pixel after distribution of the pixel having the closest distance When the value exceeds a predetermined range, the remaining pixel value is distributed to the pixel closest to the next pixel after the pixel closest to the defective pixel.
As a result, the same effects as those of the second embodiment can be obtained and a hardware configuration such as a print head is not required as in the case of the fourth embodiment. Therefore, it can be realized only by software using a general-purpose computer system such as a personal computer.

[Form 43] An image processing method according to form 43 includes:
In the image processing method according to aspect 42, when the pixel value after distribution of the pixel closest to the defective pixel exceeds a predetermined range, the pixel value correction step includes an amount exceeding the predetermined range. Are distributed in order from the pixel closest to the defective pixel other than the pixel closest to the defective pixel, and the pixel value after distribution of each pixel does not exceed the predetermined range. It is characterized by doing.
As a result, the same effects as those of the third embodiment can be obtained, and since a hardware configuration such as a print head is not required as in the fourth embodiment, it can be realized only by software using a general-purpose computer system such as a personal computer.

[Form 44] An image processing method according to form 44 includes:
In the image processing method according to form 42 or 43, when there are a plurality of distribution destination pixels selected in accordance with the distance from the defective pixel, the pixel value correction step performs the pixel value for each of these pixels. Are distributed evenly. As a result, the same effect as in the fourth aspect can be obtained, and similarly to the fourth aspect, a hardware configuration such as a print head is not required. Therefore, it can be realized only by software using a general-purpose computer system such as a personal computer.

[Form 45] An image processing method according to form 45 includes:
45. The image processing method according to any one of forms 41 to 44, wherein the pixel value correction step positions a pixel to which a pixel value of the defective pixel is distributed in a nozzle array direction of the print head with respect to the defective pixel. It is characterized by selecting from a plurality of pixels.
As a result, the same effect as in the fifth aspect can be obtained, and since a hardware configuration such as a print head is not required as in the fourth aspect, it can be realized only by software using a general-purpose computer system such as a personal computer.

[Form 46] An image processing method according to form 46 includes:
46. The image processing method according to any one of forms 41 to 45, wherein the print head characteristic information includes information indicating whether or not the nozzles can eject ink.
As a result, the same effects as those of the eighth embodiment can be obtained, and since a hardware configuration such as a print head is not required similarly to the fourth embodiment, it can be realized only by software using a general-purpose computer system such as a personal computer.

Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the accompanying drawings.
1 to 35 show a printing apparatus 100, a printing program, a printing method, an image processing apparatus, an image processing program, an image processing method, and a computer-readable recording medium according to a first embodiment of the invention. It is.
FIG. 1 is a functional block diagram showing an embodiment of a printing apparatus 100 according to the present invention.

  As shown in the figure, the printing apparatus 100 acquires a print head 200 having a plurality of nozzles, a print head characteristic acquisition unit 10 that acquires characteristics of the print head 200, and multi-value image data to be used for printing. The defective pixel is identified from the image data based on the print data characteristic information indicating the characteristics of the nozzles of the print head 200 acquired by the print data characteristic acquisition means 10 and the image data acquisition means 12 for storing the image data. And a pixel value correcting unit 16 that distributes the pixel value of the defective pixel specified by the defective pixel specifying unit 14 to pixels near the defective pixel to correct the pixel value of the image data, N-valued data generating means 18 for generating N-valued image data by converting the image data corrected by the pixel value correcting means 16 into N-values; Print data generation means 20 for generating print data based on the N-value image data generated by the means 18, and ink jet printing for executing printing based on the print data generated by the print data generation means 20 The means 22 is mainly composed of.

First, the print head 200 applied to the present invention will be described.
FIG. 3 is a partially enlarged bottom view showing the structure of the print head 200, and FIG. 4 is a partially enlarged side view thereof.
As shown in FIG. 3, the print head 200 includes a black nozzle module in which a plurality of nozzles N (18 in the figure) that exclusively discharge black (K) ink are linearly arranged in the nozzle arrangement direction. 50, and a plurality of nozzles N that also discharge yellow (Y) ink exclusively, and a yellow nozzle module 52 that is linearly arranged in the nozzle arrangement direction, and a plurality of nozzles that also discharge magenta (M) ink exclusively. The magenta nozzle module 54 in which the nozzles N are linearly arranged in the nozzle arrangement direction and the cyan nozzle in which a plurality of nozzles N that specifically discharge cyan (M) ink are arranged linearly in the nozzle arrangement direction The configuration includes four nozzle modules 50, 52, 54 and 56 such as the nozzle module 56. As shown in FIG. 3, the nozzle modules 50, 52, 54, and 54 are arranged so that the nozzles N of the same number in these four nozzle modules are aligned in the printing direction (perpendicular to the nozzle arrangement direction). 56 are integrally arranged. Accordingly, the plurality of nozzles N constituting each nozzle module are arranged linearly in the nozzle arrangement direction, and the nozzles N of the same number in the four nozzle modules are arranged linearly in the printing direction.

  Further, the print head 200 having such a structure is provided with a piezo (not shown) provided for each of the ink chambers. The ink supplied into the ink chamber (not shown) provided for each of the nozzles N1, N2, N3. By ejecting from each nozzle N1, N2, N3... By a piezoelectric element such as a piezo actuator, circular dots are printed on white printing paper, and the voltage applied to this piezoelectric element is multistage. By controlling the amount of ink discharged from the ink chamber, dots of different sizes can be printed for each nozzle N1, N2, N3. There are also cases where a single dot is formed by applying a voltage to the nozzles in two stages in a short time series in a time series and combining two ejections on the printing paper. In this case, by utilizing the fact that the ejection speed varies depending on the size of the dots, by ejecting the large dots following the small dots, the ink is landed at substantially the same position on the paper surface to form one larger dot. It is possible. FIG. 4 shows, for example, a black nozzle module 50, which is one of these four nozzle modules 50, 52, 54, and 56, from the side, and the sixth nozzle N6 from the left is a so-called dot. This indicates a state in which no ink is ejected from the nozzle N6 due to a dropout phenomenon.

  Therefore, when printing is performed using the black nozzle module 50, as shown in FIG. 5, in the state where no dot missing has occurred, all the dots are printed at the specified printing position (ideal). As shown in FIG. 6, for example, when the sixth nozzle N6 from the left has an ejection failure, the dot of the pixel corresponding to the portion that the nozzle N6 is responsible for is not formed at all and the defect is lost. As a result, white streaks extending in a direction perpendicular to the nozzle arrangement direction are generated in the portion.

  Next, the print head characteristic acquisition means 10 provides a function for acquiring the characteristics of the nozzles constituting the print head 200. More specifically, as shown in FIG. Specifically, whether or not a dot missing phenomenon has occurred in the constituent nozzles, and if a dot missing phenomenon has occurred, which abnormal nozzle N has caused the dot missing phenomenon is specifically described. The function to acquire and specify is to be demonstrated.

  That is, as shown in FIG. 1, the print head characteristic acquisition unit 10 is further provided with a print head characteristic information storage unit 24 or a print head characteristic detection unit 26. The print head characteristic information storage unit 24 stores the print head characteristic information in advance. The print head characteristic information indicating the characteristics of the nozzles constituting the print head 200 is read, or the print head characteristics indicating the characteristics of the nozzles constituting the print head 200 detected by the print head characteristic detection unit 26 are read out. By reading the information, the print head characteristic information can be easily acquired at a necessary time.

  Here, the print head characteristic information storage unit 24 reads, for example, a print head characteristic test result written at the time of manufacture of the print head 200 or when incorporated in the printing apparatus 100 (printing means 22). The print head characteristic detector 26 is composed of a free ROM, RAM and the like, and the print head characteristic detection unit 26 periodically or in order to cope with a change in the characteristics of the nozzles constituting the print head 200 after use. The characteristics of the nozzles constituting the print head 200 are inspected from the print results by the print head 200 using an optical print result reading means such as a scanner means at a time, and the inspection results are stored in the print head characteristic information storage unit 24. This data is saved with or overwritten on the data. It should be noted that the characteristics of the nozzles constituting the print head 200, that is, ejection failures due to ink clogging, etc. occur relatively frequently even after production, so that the contents of the characteristics can be updated as needed.

FIG. 7 shows an example of a table 300A in which information about a missing nozzle causing a missing dot (discharge failure) among the print head characteristic information acquired by the print head characteristic acquiring unit 10 is shown.
In the illustrated example, the number of nozzles of one nozzle module constituting the print head 200 is “180”, a unique nozzle number is assigned to each nozzle, and the discharge state of each nozzle is set to “0”. And “1”. A state where a discharge failure has occurred is indicated by “0”, and a good state where no discharge failure has occurred is indicated by “1”. In the example of the table 300A, the state of the nozzle number “N10” is “0”, which indicates that the nozzle of the nozzle number “N10” is a defective ejection nozzle.

  Next, the image data acquisition means 12 receives multi-valued color image data for printing sent from a print instruction apparatus such as a personal computer (PC) or a printer server (not shown) connected to the printing apparatus 100 via a network or the like. Acquired and stored in a storage device 70 or RAM 62 described later, or directly read and acquired from an image (data) reading device such as a scanner or a CD-ROM drive (not shown). A function of storing in the RAM 62 is provided.

The acquired multi-value color image data is multi-value RGB data, for example, an image in which the gradation (luminance value) for each color (R, G, B) per pixel is expressed by 8 bits (0 to 255). In the case of data, the color conversion process is further performed, and the function of converting the data into multivalued CMYK (in the case of four colors) data corresponding to each ink of the print head 200 is also exhibited.
Next, the defective pixel specifying unit 14 determines whether the dot data from the image data acquired by the image data acquisition unit 12 based on the print head characteristic information of the print head 200 acquired by the print head characteristic acquisition unit 10. A function for specifying a so-called defective pixel, which is a pixel corresponding to a defective nozzle in which no is formed, is provided.

  For example, in the example of FIGS. 5 and 6, among the plurality of nozzles N constituting the print head 200, the nozzle N <b> 6 is a defective nozzle that has caused an ejection failure. Each pixel corresponding to a dot (6A, 6B, 6C, 6D, 6F, 6G, 6H, 6J, 6K,...) To be formed is specified as a defective pixel. In addition, since such a defective pixel corresponds to a pixel row corresponding to a nozzle causing ejection failure, in most cases, it occurs continuously in a line state in a direction perpendicular to the nozzle arrangement direction. is there.

  The pixel value correcting unit 16 will be described in detail later with reference to some flowcharts. The pixel value of the defective pixel specified by the defective pixel specifying unit 14 is distributed to neighboring pixels by distributing the pixel value of the pixel of the image data. A function to correct the value is provided. For example, in the case of FIGS. 5 and 6, the original pixels of the respective pixels corresponding to the dots (6A, 6B, 6C, 6D, 6F, 6G, 6H, 6J, 6K,...) To be formed by the defective nozzle N6. The value is distributed to one or more pixels in the vicinity (nozzle arrangement direction) excluding the direction perpendicular to the nozzle arrangement direction according to a predetermined algorithm.

Next, the N-valued data generating means 18 provides a function of generating N-value image data by converting the image data corrected by the pixel value correcting means 16 into N-values.
For example, the pixel value (density or luminance) of each pixel of the image data corrected by the pixel value correcting unit 16 is specified by 8 bits (0 to 256 gradations), and is converted into a quaternary value. In this case, the pixel value of each pixel is classified into four gradations using three threshold values.

The right column of the dot / gradation conversion table 300B in FIG. 8 shows the relationship between the threshold value and each pixel value when the multi-valued pixel value is converted into four values.
That is, according to this dot / conversion table 300B, when the pixel value (density value) of each pixel of multi-valued image data is specified by 8 bits and 256 gradations (0 to 255), “42 (No. 3 threshold values such as “1 threshold value”, “126 (second threshold value)”, and “210 (third threshold value)”. When the pixel value is “0 to 42”, the gradation value is 1 (density “0”). ], When the pixel value is “43 to 126”, the gradation value is 2 (density “84”), and when the pixel value is “127 to 210”, the gradation value is 3 (density “168”). When the pixel value is “211 to 255”, the gradation value is 4 (density “255”) and is converted into four values.

The print data generation unit 20 sets a corresponding dot for each pixel of the N-valued data that has been N-valued for each pixel in this way, and is used in the inkjet type printing unit 22. A function to generate data for use is provided.
The left column of the dot / gradation conversion table 300B in FIG. 8 is a reference diagram showing the relationship between the gradation value of each pixel of the N-ary data and the dot size performed by the print data generation means 20.

  In the example in the figure, the dot size for the gradation value “1” relating to the density value is “no dot”, and the dot size for the gradation value “2” is “small dot” with a small dot area, gradation The dot size for the value “3” is converted to “medium dot” slightly larger than the small dot, and the dot size for the gradation value “4” is converted to “large dot” with a large dot area. It has become. When a “brightness value” is used as the pixel value, each pixel value is converted into a dot having a reverse relationship to the “density value”.

  The printing unit 22 ejects ink in the form of dots 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) S and the print head 200, respectively. In addition to the above-described print head 200, the print head 200 is formed on the print medium S with its width in addition to the above-described print head 200. A print head feed mechanism (not shown) that reciprocates in the direction (in the case of the multi-pass type), a paper feed mechanism (not shown) for moving the print medium S, and the ink ejection of the print head 200 are controlled 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 and print head characteristic acquisition means 10, the image data acquisition means 12, missing pixel identification means 14, pixel value correction means 16, N-valued data generation 18, printing A computer system for realizing each function such as the data generation unit 20 and the printing unit 22 on software is provided, and the hardware configuration thereof is a central processing unit that performs various controls and arithmetic processing as shown in FIG. Between a CPU (Central Processing Unit) 60 that is a processing device, a RAM (Random Access Memory) 62 that constitutes a main storage device (Main Storage), and a ROM (Read Only Memory) 64 that is a read-only storage device. PCI (Peripheral Compon It is connected by various internal / external buses 68 such as an ent 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 22, CRT, and LCD monitor, an input device 74 such as an operation panel, mouse, keyboard, scanner, and a print instruction device (not shown). L and the like are 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 making full use of resources and performing predetermined control and arithmetic processing.

Next, an example of the flow of processing such as printing processing and pixel value correction processing using the printing apparatus 100 configured as described above will be described with reference mainly to the flowcharts of FIGS.
As described above, the print head 200 for printing dots is generally capable of printing dots of a plurality of types of colors such as four colors and six colors almost simultaneously, but the following example shows the explanation. In order to facilitate the explanation, it is assumed that any dot is printed by the print head 200 of any one color (monochrome) (monochrome image).

First, the flowchart of FIG. 9 shows the flow of the entire printing process of the printing apparatus 100.
As shown in the figure, first, after a predetermined initial operation for printing processing is completed after the power is turned on, the printing apparatus 100 proceeds to the first step S100, and a printing instruction terminal such as a personal computer is connected. If yes, the image data acquisition unit 12 monitors whether there is an explicit print instruction from the print instruction terminal, and if it is determined that there is a print instruction (Yes), the process proceeds to the next step S102 Then, it is determined whether multi-value (for example, 8-bit 256 gradation) image data (hereinafter simply referred to as image data) to be printed has been sent from the print instruction terminal together with the print instruction.

As a result, for example, when it is determined that the image data has not been sent even after a predetermined time (No), the processing ends as it is, but when it is determined that the image data has been sent within the predetermined time ( Yes), the process proceeds to the next step 104, and print head characteristic information of the target print head 200 is acquired from the print head characteristic acquisition unit 10.
At this time, when the image data acquired by the image data acquisition means 12 is multi-value RGB data, as described above, this is converted to multi-value CMYK data corresponding to the ink used based on a predetermined conversion algorithm. After conversion, the multivalued CMYK data is processed as image data.

  Next, when the image data to be processed and the print head characteristic information of the print head 200 are acquired in this way, the process proceeds to the next step S106 and the defective pixel specifying means 14 performs printing of the print head 200. Based on the head characteristic information, a process of identifying a defective pixel in which a dot of a predetermined size is to be originally formed from each pixel constituting the image data is performed. That is, as described above, out of a large number of nozzles constituting the print head 200, the pixels corresponding to the dots to be formed by the nozzles causing the ejection failure are specified as the defective pixels.

Then, if a defective pixel where a dot of a predetermined size is to be originally formed is specified from the image data to be processed in this way, the process proceeds to the next step S108 and the pixel value correcting means 16 performs the determination. A process of correcting the pixel value of the image data to be processed by distributing the pixel value of the defective pixel to the pixels in the vicinity thereof is executed.
10 to 13 are flowcharts showing an example of the flow of pixel value correction processing of image data by the pixel value correction means 16 in step S108.

First, FIG. 10 shows an example of a flow of processing for specifying a defective pixel corresponding to a defective ejection nozzle and distributing a pixel value (luminance value or density value) of the specified pixel.
As shown in the drawing, in the first step S200 and step S202, it is determined whether or not there is a pixel to be processed in the Y coordinate (nozzle arrangement direction) and the X coordinate (perpendicular to the nozzle arrangement direction). When it is determined that there is also (Yes), the process proceeds to step S204 to determine whether or not the pixel is a pixel corresponding to the ejection failure nozzle, that is, a defective pixel.

  As a result of the determination process, when it is determined that the pixel is not a defective pixel (No), the process returns to step S202. However, when it is determined that the pixel is a defective pixel (Yes), the process proceeds to the next step S206 and the process proceeds to step S202. After obtaining the pixel (i, j) and its pixel value V, the process proceeds to the next step S208, and processing for distributing the pixel value V to the neighboring pixels excluding other defective pixels is performed. In the flow of FIG. 10, it is determined whether each pixel is a defective pixel. However, in the case of a line head type print head 200 described in detail later, as shown in FIG. The processing flow may limit the variable for controlling the arrangement direction) to defective ejection nozzle lines (step S201 and step S203 in FIG. 11).

FIG. 12 shows an example of the processing flow for determining the distribution destination of pixel values in step S208 of the flow of FIG.
First, in the first step S300 to the third step S304, pixel value variable initialization (dens is received from the caller) processing, longest distance control variable initialization (D = 1) processing, and shortest distance control variable, respectively. After performing the initialization (d = 0) processing, the process proceeds to step S306, which is the fourth processing, and the distribution destination of the pixel value V of a predetermined defective pixel (hereinafter referred to as “target pixel” as appropriate) to be processed Search for pixels.

  That is, in this step S306, as the condition of the distribution destination pixel (m, n), (1) the pixel is within the range of the pixel (i ± D, j ± D), and (2) the distance from the target pixel. All conditions such that (1) is less than or equal to “D”, (3) the distance is greater than “d”, and (4) the pixel value can be distributed to the distribution destination pixel (m, n). The nearest pixel that satisfies is searched. When a plurality of equidistant pixels are found as a result of this search, the plurality of pixels are searched simultaneously as a pixel group of distribution destination candidates.

  Then, in the next step 308, it is determined whether or not a distribution candidate pixel has been found. When it is determined that the distribution candidate pixel has not been found (No), the process proceeds to step S318, but when it has been determined that a distribution candidate pixel has been found. (Yes) shifts to the next step S310 and distributes the pixel value (dens) of the target pixel that is the processing target pixel to the distribution candidate pixel.

  Thereafter, the process proceeds to the next step S312. In step S310, it is determined whether or not all pixel values of the target pixel have been distributed. When it is determined that all pixel values have been distributed (Yes), the processing is performed as it is. When it is determined that all pixel values have not been distributed (Yes), that is, when it is determined that there are still residual pixel values, the process proceeds to step S314 and the remaining pixel values are set. While calculating (original pixel value (dens) −distribution destination pixel value (dens ′)), the process proceeds to the next step S316, and the shortest distance control variable “d” from the target pixel is set to the pixel (i, j). And the distance between the pixels (m, n) and the pixel to which the residual pixel value is distributed is searched again, and the same processing is repeated until all the residual pixel values are exhausted.

On the other hand, in step S308, when a distribution destination pixel that satisfies all the conditions of the previous step S306 is not found (No), the process proceeds to step S318, where the longest distance control variable “D” is increased by “1” and the distribution destination is increased. The pixel is searched again, and the same processing is repeated until a pixel that satisfies all the conditions in step S306 is found.
FIG. 13 shows an example of the pixel value distribution processing after the distribution candidate pixel is found in step S310. First, in the first step S400, after equidistant candidate pixels are set as a candidate pixel group, the next In step S402, the pixel values are evenly distributed to the candidate pixel group (when a plurality of equidistant pixels are found). As a result, in the next step S404, it is determined whether or not the pixel value of each pixel in the pixel group having the shortest distance from the target pixel in the distribution candidate pixel group is saturated. (No) terminates the processing assuming that all pixel values have been distributed, but when it is determined that all pixel values of the pixels of the distribution candidate pixel group are saturated (Yes), The process proceeds to the next step S406, and it is further determined whether or not the pixel values of all candidate pixels are saturated.

  As a result of this determination processing, when it is determined that the pixel values of all the distribution destination candidate pixel groups are not saturated (No), no residual pixel value exists, that is, all pixel values are distributed. It is determined that the pixel value distribution process is finished, but when it is determined that the pixel values of all the pixel value candidate pixels are saturated (Yes), it is determined that there is a residual pixel value. The process proceeds to the next step S408 to reset the total saturation amount to the residual pixel value, and then the process proceeds to the next step S410 to reset the unsaturated pixels to the candidate pixel group, and the process returns to step 402 and the same. The process will be repeated.

14 and 15 show a ¼ portion of the Euclidean distance matrix centered on the target pixel to be processed. Each square corresponds to each pixel of the original image, and the numerical value in the square represents the Euclidean distance from the target pixel (0.0) on the upper left in the figure to each pixel.
As shown in FIG. 14, in step S308, when “D = 1”, the first neighboring pixel that is found as a distribution destination candidate for the pixel value of the target pixel (0.0) is the pixel with the distance “1.0”. However, if the process proceeds to “No” in step S312, the residual pixel value that could not be distributed to dens is set in step S314, and “d” is set to “1.0” in step S316. The process returns to step S308.

Next, in step S308, the process proceeds to the “No” side, and the loop of “D = 1” ends, and then the process proceeds to the loop of “D = 2” as shown in FIG.
As shown in FIG. 15, in step S308, when “D = 2”, the first neighboring pixel found as a distribution destination candidate for the pixel value of the target pixel (0.0) is the distance “1.4”. Although the pixel is “2.0”, the pixel having the distance “1.0” is ignored by the condition (3) in step S308. First, in step S308, as the first pixel value distribution destination candidate pixel, the nearest pixel with a distance of “1.4” is selected, and the residual pixel value is distributed to the pixel. If the pixel value of the distribution destination pixel is saturated and there is still a residual pixel value, the process proceeds to step S312, step S314, and step S316 in the same manner as described above, and “d = 1.4” is set. Next, the pixel with the distance “2.0” becomes the next distribution destination candidate. If a residual pixel value is generated even at a pixel of distance “2.0”, the process continues to the next loop until all residual pixel values disappear, such as “D = 3, 4,...”.

FIG. 16A shows the priorities of the distribution destination pixels of the target pixel (missing pixel) that is the pixel value distribution target by the above-described distribution processing flow.
That is, first, in order to distribute the pixel value of the target pixel (missing pixel) to the neighboring pixels, the neighboring pixels “1” and “1” that are the shortest (nearest) from the target pixel are first selected. Thus, the pixels are equally distributed to the neighboring pixels “1” and “1”.

As a result, when all the pixel values have been distributed to the neighboring pixels “1” and “1”, the pixel value distribution processing for the target pixel is terminated at that time, but the neighboring pixel “1”, If all of “1” are saturated and a residual pixel value is generated, then the neighboring pixels “2”, “2”, “2”, “2” having the shortest distance to the target pixel are Residual pixel values are evenly distributed.
Similarly, if all the residual pixel values are distributed to the neighboring pixels “2”, “2”, “2”, “2” as a result of this distribution processing, the pixel of the target pixel at that time The value distribution process ends. If all neighboring pixels “2”, “2”, “2”, “2” are saturated and the remaining pixel value remains, the next pixel of interest On the other hand, neighboring pixels “3”, “3” → “4”, “4”, “4”, “4”, “4”, “4”, “4”, “4” → “5” with a short distance. , “5”..., The remaining pixel values are sequentially distributed until it becomes zero.

Note that, unlike the case of FIG. 16A, FIG. 16B shows a simple distribution mask in which only pixels in the nozzle array direction are selected as distribution destination candidate pixels.
Then, when such pixel value correction processing is completed, the process returns to FIG. 9 and proceeds to the next step S110 where the image data corrected by the N-value data generation means 18 is converted into N-values. Print data is generated by assigning dots corresponding to the respective pixel values of the N-valued data by the print data generation means 20, and print processing is executed based on the print data by the print means 22. Thus, the printing process by the printing apparatus 100 of the present invention is finished.

FIG. 17A shows a multi-tone original image (20 × 20 (Pixel)) that is an image of a so-called black hole in which the density in the central part is high and the density gradually decreases toward the peripheral part. The pixel value of each pixel is represented by 8 bits and 256 gradations.
FIG. 17B is a quaternary image in which the multi-gradation original image shown in FIG. 17A is quaternized and expressed in four gradations, and FIG. FIG. 17 shows a state in which pixels located in the center portion of the quaternary image shown in FIG. 17B are missing as they are in a vertical line.

Thus, in an image obtained by converting the original image into N-values as it is, even if one missing dot (one line) occurs particularly in a high density portion, white streaks are noticeable, and the image quality is significantly deteriorated. become.
On the other hand, FIG. 18A shows that when pixels located in the center portion of the image are missing in the vertical direction as they are, the pixel values of the missing pixels are distributed only to the pixels on both sides, respectively. FIG. 18B shows a state in which the pixel values of the image data are corrected, and FIG. 18B is an image obtained by converting the original image of FIG. .

  In this way, in an image in which the pixel value of the defective pixel is distributed only to the pixels on both sides thereof and the pixel value of the image data of the original image is corrected, the density of the pixels on both sides of the defective pixel (line) 17 is darker than that in FIG. 17A, and it is remarkable that the pixel value has changed greatly due to the distribution processing of the pixel value, but the average luminance of all the pixels is “155.6”. The average brightness “153.1” of the original image shown in FIG.

This is because when the pixel values of some of the pixels at the distribution destination are saturated, the remaining pixel values that could not be distributed are discarded as they are.
On the other hand, FIG. 19A shows a simplified pixel value as shown in FIG. 16B when the pixels located at the center of the image are missing in the vertical direction as in FIG. Using the distribution mask, the pixel values of the defective pixels are not only distributed to the pixels on both sides, but when the pixel values of the pixels on both sides are saturated, the pixel values of the original image are further distributed in order to the neighboring pixels. FIG. 19B shows a state in which the pixel value of the image data is corrected, and FIG. 19B is an image obtained by converting the original image in FIG. .

  Thus, in an image in which the pixel value of the missing pixel is distributed not only to the pixels on both sides but also to the neighboring pixels in order and the pixel value of the image data of the original image is corrected, Not only the density of the pixels on both sides of the defective pixel (line), but also the density of the pixels in the vicinity thereof are changed darker than in FIG. 17A, and the average luminance of all the pixels is also “153.1”. Thus, the average brightness “153.1” of the original image shown in FIG.

This is a result of distributing the pixel value of the defective pixel to the pixel value of the neighboring pixel, and distributing all of the residual pixel values generated when the pixel value of the pixel is saturated to the neighboring pixels. It can also be seen from the fact that the size of the high density region is larger than that in the case of FIG.
Accordingly, in the subsequent print data generation processing, if dots are assigned to each pixel of the N-valued image (data) as shown in FIG. 18B, the dot size of the pixel near the white stripe is the dot size of the original image. As a result, the white streak portion is filled with the large dots, which eliminates the white streak particularly in the high-density portion at the center of the image, or makes it hardly noticeable, thereby avoiding deterioration of the image quality. .

In addition, since the present invention distributes all of the pixel values of the defective pixel to the effective pixels in the vicinity thereof, the average pixel value and all pixel values are the same as the average pixel value and all pixel values of the original image. Therefore, the original image can be expressed faithfully.
It should be noted that the difference in average luminance (0...) Between FIG. 18 (b) and FIG. 19 (b) is compared to the difference in average luminance (“2.5”) between FIG. 18 (a) and FIG. 19 (a). The reason 5) is small is due to rounding errors in N-value conversion, and when N-value conversion is performed with a small image of 20 × 20 as in the example, it may happen that the influence of rounding errors is greatly affected by chance.

  20 (a) to 20 (c), 21 (a), 21 (b), 22 (a), and 22 (b) are respectively the same as FIGS. 17 (a) to 17 (c) and 18 (a). , (B), and FIGS. 19 (a) and 19 (b), a pattern in which the brightness of each pixel is opposite, that is, the density of the central part is low, and the density gradually increases toward the peripheral part, so-called white This pattern is an image of a hole, and even in such a pattern, white streaks that are conspicuous particularly in a portion having a high density in the peripheral portion can be eliminated or made almost inconspicuous.

Further, there is a certain difference (0.2) between the average luminance (109.5) of the original image shown in FIG. 20 (a) and the average luminance (109.7) of the image shown in FIG. On the other hand, the average luminance (109.5) of the image shown in FIG. 22A according to the present invention is the same as the average luminance of the original image shown in FIG. 20A, and faithfully represents the original image. be able to.
23 to 32 show the pixel values (luminance) corresponding to the image shown in FIG. 17 and the like described above, FIG. 23 shows FIG. 17 (a), and FIG. 24 shows FIG. b), FIG. 25 in FIG. 18 (a), FIG. 27 in FIG. 19 (a), FIG. 28 in FIG. 20 (a), and FIG. 30 corresponds to FIG. 20C, FIG. 31 corresponds to FIG. 21A, and FIG. 32 corresponds to FIG. 22A.

That is, as shown in FIG. 23, the pixel value (luminance) of each pixel of the original image is expressed in 256 gradations within the range of “0” to “255”, whereas 4 in FIG. The pixel value (luminance) of each pixel of the digitized image is expressed by four gradations of “0”, “85”, “170”, and “255”.
Then, as shown in FIG. 25, when a missing dot occurs in the central portion of such an original image and white stripes occur in a vertical line, the pixel values of the pixels corresponding to the white stripes are all “255”. Nevertheless, since the pixel values on both sides are not changed at all, the white streaks are particularly noticeable in the central portion of the image having a high density value (low luminance value).

  For this reason, as shown in FIG. 26, by distributing the pixel values of the defective pixels only to the pixel value correction lines on both sides thereof, only the pixel values on both sides of the white streak change greatly, and the N-valued image is also white streak. The pixel value is saturated, but the pixel value is saturated only in the central part of the pixel value correction line on both sides of the defective pixel, and the pixel value of the pixel in the next line changes completely. The saturated residual pixel value is discarded as it is. As a result, the average pixel value of the image changes compared to the average pixel value of the original image, and the original image cannot be faithfully reproduced.

  On the other hand, in FIG. 27, when the pixel value correction lines on both sides of the defective pixel are saturated, the residual pixel values are sequentially distributed to the adjacent pixels. In addition, the pixel values of one to three neighboring pixels with respect to the pixels on the pixel value correction line also change. As a result, the average pixel value of the image is the same as the average pixel value of the original image, so that the original image can be faithfully reproduced even if the white stripe phenomenon occurs.

  Similarly, in the images of FIGS. 28 to 30, the pixel value in the vicinity of the white streak is not changed at all, so that the white streak portion becomes conspicuous. However, as shown in FIGS. By distributing the pixel value of the pixel corresponding to 1 to the pixels in the vicinity of the white stripe and correcting the pixel value, the N-valued image also changes to one in which the white stripe is eliminated or hardly noticeable, and the original image and Since the average pixel values are the same, the original image can be faithfully reproduced.

Here, as described above, the technique of dividing the dot size in a single printed material is a conventionally known technology, and particularly used in obtaining a printed material that achieves a high balance between printing speed and print image quality. It is. In other words, high image quality can be obtained by reducing the dot size, while reducing the dot size requires high performance in machine accuracy,
In order to form a solid image with small dots, it is necessary to strike many dots. Therefore, the printing speed and the image quality are realized with a high balance by using a dot size sorting technique such as reducing the dot size for a high-detail image portion and increasing the dot size for a solid image portion.

As a technical method for realizing the dot size sorting in this way, for example, in the case of a method using a piezo element in the print head, the voltage applied to the piezo element is changed to eject ink. It can be easily realized by controlling the amount.
Also, as shown in FIG. 8, the sizes of dots that can be divided by the present invention and the normal print head 200 include four patterns of “large dots”, “medium dots”, “small dots”, and “no dots”. The area ratio is also, for example, when a dot of size “small” is “1”, “medium” dots are “2 (times)”, and “large” dots are “3 (times)”. However, the type of dot size is not limited to this, and it is sufficient that there are at least two patterns other than “no dot”.

Further, in this N-value processing, if a known halftoning technique such as error diffusion processing or dithering is used in combination, a further excellent banding avoidance effect can be obtained.
Further, the print head 200 and the print head characteristic information storage unit 24 in the present embodiment correspond to the print head and the print head characteristic information storage unit in the printing apparatus, such as the form 1 of the means column for solving the invention. The image data acquisition unit 12 corresponds to the image data storage unit in the printing apparatus of the first embodiment. Further, the defective pixel specifying unit 14 corresponds to the defective pixel specifying unit in the printing apparatus of the first form, and the pixel value correcting unit 16 corresponds to the pixel value correcting unit of the printing apparatus of the first form. The N-value data generation unit 18, the print data generation unit 20, and the printing unit 22 correspond to the N-value data generation unit, the print data generation unit, and the printing unit in the printing apparatus of the first embodiment. .

  In addition, the present invention is characterized in that the image data is converted into print data in accordance with the print head characteristics with little modification to the existing print head 200 and the printing means 22 itself. In addition, it is not necessary to prepare a dedicated one as the printing unit 22, and it is possible to use the existing inkjet print head 200 and the printing unit 22 (printer) as they are.

Therefore, if the print head 200 and the printing unit 22 are separated from the printing apparatus 100 of the present invention, the function can be realized only by a general-purpose information processing apparatus (image processing apparatus) such as a personal computer.
Further, if the N-valued data means 18 is also realized by another information processing apparatus and is in charge of pixel value correction as an image processing apparatus, the processing load on one information processing apparatus is reduced and higher speed is achieved. In addition, the pixel value correction process can be realized.

  Further, 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. If a line head type ink jet printer is used, dot missing has occurred. However, it is possible to obtain a high-quality printed matter with almost no noticeable white streaks in one pass, and a multi-pass inkjet printer can reduce the number of reciprocating operations, enabling faster printing than before. It becomes. For example, when a desired image quality can be realized by one printing, the printing time can be shortened to 1 / K as compared with the case where printing is performed by K reciprocating printing.

FIGS. 33A to 33C show respective printing methods using a line head type ink jet printer and a multi-pass type ink jet printer.
As shown in FIG. 6A, when the illustrated image is printed on a rectangular printing paper S, as shown in FIG. 5B, the width direction of the printing paper S is the nozzle arrangement direction of the image data, When the longitudinal direction is a direction perpendicular to the nozzle arrangement direction of the image data, in the line head type ink jet printer, the print head 200 has a length corresponding to the paper width of the print paper S. Is fixed, and the printing paper S is moved in a direction perpendicular to the nozzle arrangement direction with respect to the print head 200, so that printing is completed in one pass (operation). The printing paper S is fixed as in a so-called flatbed scanner, and printing is performed while the print head 200 side is moved in the direction perpendicular to the nozzle arrangement direction, or both are moved in opposite directions. It is also possible. On the other hand, in the multi-pass type ink jet printer, as shown in FIG. 3C, the longitudinal direction of the printing paper S is the nozzle arrangement direction of the image data, and the width direction is perpendicular to the nozzle arrangement direction of the image data. In this case, the print head 200, which is much shorter than the length of the paper width, is positioned in the nozzle arrangement direction, and the print paper S is moved to the predetermined direction while being reciprocated many times in the direction perpendicular to the nozzle arrangement direction. Printing is executed by moving the nozzles in the nozzle arrangement direction by pitch. 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 print head 200 can be repeatedly positioned at an arbitrary position. Among the banding phenomenon as described above, it is possible to cope to some extent with respect to the reduction of the white streak phenomenon.

In the first and second embodiments, an ink jet printer that performs printing by ejecting ink in dots has been described as an example. However, the present invention provides a print head in which the printing mechanisms are arranged in a line. The present invention can also be applied to other printing apparatuses used, for example, thermal head printers called thermal transfer printers or thermal printers.
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. 3, 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 linearly continuous in the longitudinal direction of the print head 200. 34, 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 movement direction of the print head 200. You may comprise as follows. In particular, if each of the nozzle modules 50, 52, 54, 56 is configured with a plurality of short nozzle units 50a, 50b,... 50n, the yield is significantly higher than that of a long nozzle unit. improves.

  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.

  Until now, a plurality of nozzles are linearly arranged in the same direction as the width direction of the rectangular print paper, the width direction is the “nozzle arrangement direction”, and the longitudinal direction of the rectangular print paper is the “nozzle” A line head type print head that is “perpendicular to the arrangement direction”, a plurality of nozzles are arranged in the same direction as the longitudinal direction, the longitudinal direction is the “nozzle arrangement direction”, and the width direction of the rectangular printing paper is For print heads with a configuration in which the “nozzle alignment direction” and the “printing direction (paper transport direction)” are perpendicular or nearly perpendicular, such as a short multi-pass print head that is “perpendicular to the nozzle arrangement direction” As described above, the present invention is not limited to this, and there are other print heads such as a print head in which a plurality of short nozzle modules are arranged, a print head in which the “nozzle arrangement direction” and the “print direction” are not perpendicular or almost perpendicular to each other. That.

Hereinafter, several configuration examples of the line head type print head and the multi-pass type print head will be described with reference to FIGS. Here, FIGS. 36A to 36D are diagrams showing a configuration example of a print head of a line head type printer. FIGS. 37A to 37D are diagrams showing a configuration example of a print head of a multi-pass printer.
First, a configuration example of a line head type print head will be described.

  In the configuration example of FIG. 36A, the plurality of nozzles used in the first and second embodiments are arranged linearly in the same direction as the width direction of the rectangular printing paper S, and the width direction Is a long print head in which the longitudinal direction of the printing paper S is “perpendicular to the nozzle arrangement direction” (length equal to the width direction or longer than the width direction). In the case of this configuration example, the “perpendicular direction to the nozzle arrangement direction” and the “printing direction (paper transport direction)” are the same direction. That is, the “nozzle arrangement direction” and the “printing direction” are vertical (or almost vertical). On the other hand, in the configuration example of FIG. 36B, the “nozzle arrangement direction” and the width direction of the printing paper S are not the same direction, and a plurality of nozzles are arranged obliquely with respect to the width direction. Print head. In this configuration example, the “perpendicular direction to the nozzle arrangement direction” and the “printing direction” are not the same direction, and the “direction in which each nozzle continuously prints” is the “printing direction”. That is, the “nozzle arrangement direction” and the “printing direction (paper transport direction)” are not vertical (or almost vertical). Therefore, the longitudinal direction of the printing paper S is “the direction in which each nozzle prints continuously”, and the width direction of the printing paper S is not in the “nozzle arrangement direction”, but in the “direction in which each nozzle prints continuously”. "Vertical direction". As described above, it is known that a high-resolution image can be obtained if the nozzle arrangement direction is inclined with respect to the width direction perpendicular to the print direction.

  In the configuration example of FIG. 36C, a plurality of short nozzle modules in which a plurality of nozzles are linearly arranged in the same direction as the width direction of the rectangular printing paper S are arranged alternately in the width direction instead of a straight line. This is a print head having a provided configuration. This configuration example is a configuration in which a single nozzle module is divided into a plurality of nozzle modules, and is the same configuration as the configuration example of FIG. 36A. Therefore, the “nozzle arrangement direction” is the width direction of the printing paper S, The “perpendicular direction to the nozzle arrangement direction” is the longitudinal direction of the printing paper S and the “printing direction”. On the other hand, the configuration example in FIG. 36D is a print head having a configuration in which a plurality of nozzles are arranged obliquely with respect to the width direction of the print paper S, similarly to the configuration example in FIG. However, in the configuration example in FIG. 36D, a plurality of short nozzle modules in which a plurality of nozzles are arranged in an oblique direction are arranged in the width direction of the printing paper S in an oblique state with respect to the width direction. It has become. This configuration example is a configuration in which a single nozzle module is divided into a plurality of nozzle modules, and is the same configuration as the configuration example of FIG. 36B. Therefore, the longitudinal direction of the printing paper S is “each nozzle is continuous. And the width direction of the printing paper S is “perpendicular to the direction in which each nozzle prints continuously”.

Next, a configuration example of a multi-pass type print head will be described.
In the configuration example of FIG. 37A, a plurality of nozzles are arranged in the same direction as the longitudinal direction of the rectangular print paper S, the longitudinal direction is “nozzle arrangement direction”, and the width direction of the print paper S is “nozzle arrangement”. This is a short print head having a “perpendicular direction to the direction”. In the case of this configuration example, the “perpendicular direction to the nozzle arrangement direction” and the “printing direction (paper transport direction)” are the same direction. That is, the “nozzle arrangement direction” and the “printing direction” are vertical (or almost vertical). Further, the traveling direction of the print head reciprocates with respect to the width direction of the print paper S as shown in FIG. On the other hand, in the configuration example of FIG. 37B, the “nozzle arrangement direction” and the longitudinal direction of the printing paper S are not the same direction, but a short configuration in which a plurality of nozzles are arranged obliquely with respect to the longitudinal direction. Print head. In this configuration example, the “perpendicular direction to the nozzle arrangement direction” and the “printing direction” are not the same direction, and the “direction in which each nozzle continuously prints” is the “printing direction”. That is, the “nozzle arrangement direction” and the “printing direction (paper transport direction)” are not vertical (or almost vertical). Accordingly, the width direction of the printing paper S is not the “nozzle arrangement direction”, but “the direction in which each nozzle prints continuously”, and the longitudinal direction of the printing paper S is “the direction in which each nozzle prints continuously”. “Vertical direction”. As described above, it is known that a high-resolution image can be obtained if the nozzle arrangement direction is inclined with respect to the longitudinal direction which is perpendicular to the printing direction.

  In the configuration example of FIG. 37 (c), a plurality of short nozzle modules in which a plurality of nozzles are linearly arranged in the same direction as the longitudinal direction of the rectangular printing paper S are arranged alternately in the width direction instead of in a straight line. This is a short print head having a provided configuration. This configuration example is a configuration in which a single nozzle module is divided into a plurality of nozzle modules, and is the same configuration as the configuration example of FIG. 37A, so that the “nozzle arrangement direction” is the width direction of the printing paper S, The “perpendicular direction to the nozzle arrangement direction” is the longitudinal direction of the printing paper S and the “printing direction”. On the other hand, the configuration example of FIG. 37D is a short print head having a configuration in which a plurality of nozzles are arranged obliquely with respect to the longitudinal direction of the printing paper S, similarly to the configuration example of FIG. is there. However, in the configuration example of FIG. 37 (d), a configuration in which a plurality of shorter nozzle modules in which a plurality of nozzles are arranged in an oblique direction is arranged in the longitudinal direction of the printing paper S in an oblique state with respect to the longitudinal direction. It has become. In this configuration example, a single nozzle module is divided into a plurality of nozzle modules, and the configuration is the same as the configuration example in FIG. 37B. And the longitudinal direction of the printing paper S is “perpendicular to the direction in which each nozzle prints continuously”.

  Like the line head type print head shown in FIGS. 36A and 36C described above and the multipass type print head shown in FIGS. 37A and 37C described above, the “nozzle arrangement direction” ”And“ printing direction ”are not only print heads configured to be vertical, but also the line head type print head shown in FIGS. 36B and 36D described above and FIGS. 37B and 37B described above. The present invention can also be applied to a print head having a configuration in which the “nozzle arrangement direction” and the “print direction” are not perpendicular to each other, such as the multi-pass print head shown in d).

1 is a functional block diagram illustrating an embodiment of a printing apparatus according to the present invention. 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. FIG. 4 is a partially enlarged bottom view showing the structure of the print head according to the present invention. It is a partial enlarged side view showing the structure of the print head according to the present invention. It is a conceptual diagram which shows an example of the ideal dot pattern in which a dot missing phenomenon does not occur. It is a conceptual diagram which shows an example of the dot pattern formed by one dot missing phenomenon. 6 is a print head characteristic information table showing an example of print head characteristic information related to missing dots. It is a figure which shows an example of the relationship between a multi-value pixel value and a gradation value, and the relationship between a gradation value and dot size. FIG. 5 is a flowchart illustrating an example of a process flow in the printing apparatus according to the present invention. It is a flowchart figure which shows an example of the flow of a pixel value distribution process. It is a flowchart figure which shows the other example of the flow of a pixel value distribution process. It is a flowchart figure which shows an example of the flow for determining the pixel group of a pixel value distribution destination. It is a flowchart figure which shows the specific example of a pixel value distribution process. A quarter portion of the Euclidean distance (D = 1) matrix centered on the pixel of interest is shown. A quarter portion of the Euclidean distance (D = 2) matrix centered on the pixel of interest is shown. It is a figure which shows the distribution policy regarding the pixel value of an attention pixel. It is a figure which shows the state of the original image which imaged the black hole. It is a figure which shows the state of the image which performed the conventional pixel value correction process with respect to the image of FIG. It is a figure which shows the state of the image which implemented the pixel value correction process which concerns on this invention with respect to the image of FIG. It is a figure which shows the state of the original image which carried out the white hole image. It is a figure which shows the state of the image which performed the conventional pixel value correction process with respect to the image of FIG. It is a figure which shows the state of the image which implemented the pixel value correction process which concerns on this invention with respect to the image of FIG. It is the figure which showed the relationship between each pixel and pixel value of the image shown to Fig.17 (a). It is the figure which showed the relationship between each pixel and pixel value of the image shown in FIG.17 (b). It is the figure which showed the relationship between each pixel and pixel value of the image shown in FIG.17 (c). It is the figure which showed the relationship between each pixel and pixel value of the image shown to Fig.18 (a). It is the figure which showed the relationship between each pixel and pixel value of the image shown to Fig.19 (a). It is the figure which showed the relationship between each pixel and pixel value of the image shown to Fig.20 (a). It is the figure which showed the relationship between each pixel and pixel value of the image shown in FIG.20 (b). It is the figure which showed the relationship between each pixel and pixel value of the image shown in FIG.20 (c). It is the figure which showed the relationship between each pixel and pixel value of the image shown to Fig.21 (a). It is the figure which showed the relationship between each pixel and pixel value of the image shown to Fig.22 (a). 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. (A)-(d) is a figure which shows the structural example of the print head of a line head type printer. (A)-(d) is a figure which shows the structural example of the print head of a multipass printer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Printing apparatus, 200 ... Print head, 300A ... Print head characteristic information recording table, 300B ... Dot / tone conversion table, 10 ... Print head characteristic acquisition means, 12 ... Image data acquisition means, 14 ... Missing pixel specifying means, 16 ... Pixel value correcting means, 18 ... N-valued data generating means, 20 ... Print data generating means, 22 ... Printing means, 24 ... Print head characteristic information storage section, 26 ... Print head characteristic detecting section, 60 ... CPU, 62 ... RAM, 64 ... ROM, 66 ... interface, 70 ... storage device, 72 ... output device, 74 ... input device, 50 ... black nozzle module, 52 ... yellow nozzle module, 54 ... magenta nozzle module, 56 ... cyan nozzle module, P ... pixel, S ... print medium (paper), N ... nozzle, R ... recording medium

Claims (17)

Image data storage means for storing image data of M values (M ≧ 3);
A print head having a plurality of nozzles for printing dots;
Print head characteristic information storage means for storing print head characteristic information indicating the characteristics of the nozzles of the print head;
A defective pixel specifying means for specifying a defective pixel from the image data based on the print head characteristic information stored in the print head characteristic information storage means;
Pixel value correcting means for distributing the pixel value of the defective pixel specified by the defective pixel specifying means to pixels near the defective pixel;
N-valued data generating means for generating N-value (M> N ≧ 2) image data based on the image data corrected by the pixel value correcting means;
Print data generating means for generating print data based on N-value image data generated by the N-valued data generating means;
A printing apparatus comprising: a printing unit that executes printing using the print head based on the printing data generated by the print data generation unit. The printing apparatus according to claim 1,
The pixel value correcting means distributes the pixel value of the defective pixel to the pixel having the closest distance from the defective pixel, and when the pixel value after distribution of the pixel having the closest distance exceeds a predetermined range The printing apparatus is characterized in that the remaining pixel values are distributed to the pixel closest to the next pixel after the pixel closest to the defective pixel. The printing apparatus according to claim 2,
When the pixel value after the distribution of the pixel closest to the defective pixel exceeds a predetermined range, the pixel value correction unit determines the pixel value exceeding the predetermined range from the defective pixel most. A printing apparatus that distributes in order from a pixel having a shorter distance from the defective pixel other than a pixel having a short distance so that a pixel value after distribution of each pixel does not exceed the predetermined range. The printing apparatus according to claim 2 or 3,
When there are a plurality of pixels to which the pixel value of the defective pixel is distributed, the pixel value correcting unit distributes the pixel value evenly to each of these pixels. . The printing apparatus according to any one of claims 1 to 4,
The pixel value correcting means selects a pixel to which the pixel value of the defective pixel is distributed from a plurality of pixels located in the nozzle array direction of the print head with respect to the defective pixel. A printing apparatus characterized by the above. The printing apparatus according to any one of claims 1 to 5,
The N-valued data generating means uses an error diffusion method when generating image data of N values (M> N ≧ 2) based on the image data corrected by the pixel value correcting means. A printing apparatus characterized by that. The printing apparatus according to claim 6.
When the error diffusion destination pixel is a defective pixel specified by the defective pixel specifying unit, the N-value data generation unit distributes an error diffused to the defective pixel to pixels near the defective pixel. A printing apparatus characterized by comprising: The printing apparatus according to any one of claims 1 to 7,
The printing apparatus, wherein the print head characteristic information includes information indicating whether ink is ejected from the nozzles. The printing apparatus according to any one of claims 1 to 8,
The printing apparatus according to claim 1, wherein the print head is a print head in which the nozzles are continuously arranged over a range wider than a mounting area of the print medium and can be printed by one scan. The printing apparatus according to any one of claims 1 to 8,
The printing apparatus, wherein the print head is a print head that performs printing while reciprocating in a direction orthogonal to a paper feeding direction of the print medium. Computer
A defective pixel specifying means for specifying a defective pixel from image data of M values (M ≧ 3) based on print head characteristic information indicating characteristics of the nozzle of a print head provided with a plurality of nozzles for printing dots;
Pixel value correcting means for distributing the pixel value of the defective pixel specified by the defective pixel specifying means to pixels near the defective pixel;
N-valued data generating means for generating N-value (M> N ≧ 2) image data based on the image data corrected by the pixel value correcting means;
Print data generating means for generating print data based on N-value image data generated by the N-valued data generating means;
A printing program that functions as a printing unit that executes printing using the print head based on printing data generated by the print data generation unit.   The computer-readable recording medium which recorded the printing program of Claim 11. A defective pixel specifying step of specifying a defective pixel from image data of M values (M ≧ 3) based on print head characteristic information indicating the characteristics of the nozzle of a print head provided with a plurality of nozzles for printing dots;
A pixel value correcting step for distributing the pixel value of the defective pixel specified in the defective pixel specifying step to pixels in the vicinity of the defective pixel;
An N-valued data generation step for generating N-value (M> N ≧ 2) image data based on the image data corrected in the pixel value correction step;
A print data generation step for generating print data based on the N-value image data generated in the N-value data generation step;
And a printing step of performing printing using the print head based on the printing data generated in the printing data generation step. Image data storage means for storing image data of M value (M ≧ 2);
Print head characteristic information storage means for storing print head characteristic information indicating characteristics of the nozzle of a print head provided with a plurality of nozzles for printing dots;
A defective pixel specifying means for specifying a defective pixel from the image data based on the print head characteristic information stored in the print head characteristic information storage means;
An image processing apparatus comprising: a pixel value correcting unit that distributes a pixel value of a defective pixel specified by the defective pixel specifying unit to pixels near the defective pixel. Computer
A defective pixel specifying means for specifying a defective pixel from M value (M ≧ 2) image data based on print head characteristic information indicating characteristics of the nozzle of a print head having a plurality of nozzles for printing dots;
An image processing program that functions as a pixel value correcting unit that distributes a pixel value of a defective pixel specified by the defective pixel specifying unit to pixels near the defective pixel.   A computer-readable recording medium on which the image processing program according to claim 15 is recorded. A defective pixel specifying step of specifying a defective pixel from M value (M ≧ 2) image data based on print head characteristic information indicating characteristics of the nozzle of a print head having a plurality of nozzles for printing dots;
And a pixel value correcting step for distributing the pixel value of the defective pixel specified in the defective pixel specifying step to pixels in the vicinity of the defective pixel.

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