JP2006212792A - Printer, printing program, printing method, image processor, image processing program, image processing method, and recording medium with the program recorded - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a printer which can reduce the banding phenomenon brought about by flight deflection, and to provide a printing program, a printing method, an image processor, an image processing program, an image processing method and a recording medium with the program recorded. <P>SOLUTION: The printer of an inkjet system divides image data to an intermediate tone region and the other region, makes the intermediate tone region to be a low resolution, and also changes a size of dots which cause the flight deflection in the intermediate tone region. The printer is equipped with a printing head 200 which prints dots of different sizes; a flight deflection information acquiring means 10 which acquires flight deflection information of the printing head; a printing data generating means 20 which generates printing data with dots corresponding to each pixel of the N-value image data (2≤N) set therein; a dot size changing means 22 which changes sizes of the dots that cause the flight deflection phenomenon determined on the basis of the flight deflection information of the printing head 200 that is acquired by the flight deflection information acquiring means 10, and of dots near the dots among dots of the printing data generated by the printing data generating means 20; and a printing means 24 which carries out printing on the basis of the printing data with the dot sizes changed by the dot size changing means 22. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a printing apparatus such as a facsimile machine, a copying machine, or a printer for office automation equipment, and in particular, draws a predetermined character or image by ejecting fine particles of liquid ink of a plurality of colors onto a printing paper (recording material). The present invention relates to a so-called inkjet printing apparatus, printing program, printing method and image processing apparatus, image processing program, image processing method, and recording medium on which the program is recorded.

Printers that employ such an ink jet method (hereinafter referred to as “inkjet printers”) are generally inexpensive and can easily obtain high-quality color prints, so with the spread of personal computers and digital cameras, It has become widespread for general users.
In general, such an ink jet printer has a print head in which a moving body called a carriage, which is integrally provided with an ink cartridge and a print head, reciprocates on the print medium (paper) in the right and left directions in the paper feed direction. By ejecting (injecting) liquid ink particles from the nozzles in the form of dots, predetermined characters and images are drawn on the printing paper to create a desired printed matter. The carriage is equipped with four color (yellow, magenta, cyan) ink cartridges 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 easy. (Furthermore, 6-color, 7-color, or 8-color colors obtained by adding light cyan, light magenta, etc. to these colors are also in practical use).

  In addition, in this type of ink jet printer in which printing is performed while the print head on the carriage is reciprocated in the left and right direction (width direction of the printing paper) in the paper feeding direction, printing is performed in order to print the entire page cleanly. Since it is necessary to reciprocate the head several tens of times to 100 times or more, the printing time is significantly longer than that of other types of printing apparatuses such as laser printers using electrophotographic technology such as copying machines. There is such a drawback.

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

  By the way, a print head indispensable for such an ink jet printer is formed by arranging fine nozzles having a diameter of about 10 to 70 μm in series at a predetermined interval or in multiple stages in the printing direction. Depending on the error, the ink ejection direction of some nozzles may be tilted, or the position of the nozzles may be shifted from the ideal position, and the dots formed by the nozzles may be shifted from the target point. A so-called “flight bend phenomenon” may occur.

  As a result, a printing defect referred to as a so-called “banding (streaks) phenomenon” may occur in a print portion corresponding to the defective nozzle portion, and the print quality may be significantly reduced. That is, when the “flying curve phenomenon” occurs, the distance between adjacent dots becomes non-uniform, and “white streaks (when the printing paper is white)” occurs in a portion where the distance between adjacent dots is long. A “dark streak” occurs in a portion where the distance is short.

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

Therefore, in order to prevent a kind of printing failure 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 that does not cause 100% “banding phenomenon” due to manufacturing cost, print quality, and technical aspects.
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 the “printing apparatus and printing method” of Patent Document 1 below, “white streaks” extending in the sub-scanning direction due to the “banding phenomenon” are generated by printing dots with a half-shift in the main scanning direction for each line. I try to reduce it.
Japanese Patent Laid-Open No. 2000-25211

However, in the above-described prior art, since dots must be shifted by half a pitch, there is a problem that at least two passes or more are required for printing, and it takes a long printing time.
In addition, since the portion where dots overlap is dark, there is a problem that “white stripes” can be reduced, but “dark stripes” remain.
Accordingly, the present invention has been devised in order to effectively solve such a problem, and the object thereof is a novel printing apparatus capable of eliminating or almost inconspicuous the banding phenomenon caused by the flight bending phenomenon. The present invention provides a printing program, a printing method and an image processing apparatus, an image processing program, an image processing method, and a recording medium on which the program is recorded.

[Mode 1] In order to solve the above problems, a printing apparatus according to mode 1
Print data for setting dots corresponding to each pixel of N-value (2 ≦ N) image data, a print head for printing dots of different sizes, a flight curve information acquisition means for acquiring flight curve information of the print head Print data generation means for generating the print curve, and the flight curve phenomenon determined based on the flight curve information of the print head acquired by the flight curve information acquisition means among the dots of the print data generated by the print data generation means Dot size changing means for changing the size of the dot causing the dot and its neighboring dots, and printing means for executing printing based on the print data whose dot size has been changed by the dot size changing means It is characterized by.

As a result, the banding phenomenon caused by the flight bending phenomenon is reduced to eliminate “white streaks” and “dark streaks” or become almost inconspicuous, so that a high-quality printed matter can be obtained efficiently.
Here, the “banding phenomenon” in this embodiment means not only “white streaks” caused by “flight bend phenomenon”, but also printing defects in which “dark streaks” occur simultaneously with “white streaks”. (Forms relating to “printing device”, “printing program”, “printing method”, “image processing device”, “image processing program”, “image processing method”) , As well as the description relating to the “recording medium on which the program is recorded” and the best mode for carrying out the invention.

  In addition, as described above, the “flight bend phenomenon” is different from the non-ejection phenomenon of some nozzles, as described above. Although ink is ejected, the ejection direction of some of the nozzles is inclined and the dots are positioned at the target position. Phenomenon that is formed more deviated (forms relating to “printing apparatus”, forms relating to “printing program”, forms relating to “printing method”, forms relating to “image processing apparatus”, forms relating to “image processing program”, The same applies to the description relating to the “image processing method”, the description relating to the “recording medium on which the program is recorded”, the best mode for carrying out the invention, and the like.

  Also, “white streaks” are parts where the distance between adjacent dots continuously increases due to the “flying curve phenomenon” and the background color of the print medium stands out in a streak shape. The “dark streaks” are the same as the “flying bend phenomenon”, in which the phenomenon in which the distance between adjacent dots is continuously shorter than a predetermined distance and the color of the background of the print medium is changed. It becomes invisible or appears darker due to the shorter distance between the dots, and moreover, some of the misaligned dots overlap with normal dots and the overlapping parts stand out as dark stripes (Forms relating to the “printing apparatus”, forms relating to the “printing program”, forms relating to the “printing method”, forms relating to the “image processing apparatus”, Form an image processing program ", is the same in the description, such as the best mode field for the embodiment, the invention relates to" a recording medium recording an image processing method "for the form, as well as" the program ").

  The reason why the “N value” is set to “N ≧ 2” is that it is necessary to at least define binarization or more regarding whether or not to hit dots in order to generate print data ( The following forms related to “printing apparatus”, forms related to “printing program”, forms related to “printing method”, forms related to “image processing apparatus”, forms related to “image processing program”, forms related to “image processing method”, and “the above-mentioned The same applies to the description of the form relating to the “recording medium on which the program is recorded” and the column of the best mode for carrying out the invention.

[Mode 2] The printing apparatus of mode 2 is
In the printing apparatus according to aspect 1, a block dividing unit that divides image data into blocks for each of a plurality of pixels, and pixels in other blocks adjacent to pixel values of pixels in each block divided by the block dividing unit And a pixel value distribution unit that distributes the pixel value to the pixel value.
Accordingly, banding can be reduced by processing N-value image data in units of blocks, and high image quality can be maintained without impairing the area gradation of the original image.

[Mode 3] The printing apparatus of mode 3 is
In the printing apparatus according to aspect 2, the block dividing unit is configured to divide the image data into blocks in units of 2 × 2 pixels.
In this way, the image data can be divided into blocks by 2 × 2 pixels, whereby block division can be efficiently performed, and block noise is not generated because the block division unit is small.

[Mode 4] A printing apparatus according to mode 4
The printing apparatus according to any one of Embodiments 1 to 3, further comprising a gradation identifying unit that identifies a gradation of the image data, and only a region of the image data that is identified as an intermediate gradation by the gradation identifying unit. The above-described block division, pixel value distribution, and dot size change processing are performed.
That is, the banding phenomenon due to the flight curve has a property that it is difficult to stand out in an extremely high density part (high gradation part) or an extremely low part (low gradation part), and is particularly noticeable in a so-called intermediate gradation part.
Therefore, efficient processing is realized if processing is performed only on the intermediate gradation area of the image data as in this embodiment, instead of processing processing uniformly over the entire image data. can do.

[Mode 5] A printing apparatus according to mode 5
In the printing apparatus according to the fourth aspect, the gradation identification unit may determine an intermediate gradation area from an area where the duty ratio is 50% when the dot size is minimum to 50% when the dot size is maximum. It is characterized by being identified as.

As a result, it is possible to accurately identify an intermediate gradation in which the banding phenomenon is particularly noticeable.
Here, “duty ratio (duty ratio)” refers to the ratio of dots actually printed in a certain area to the maximum number of dots that can be printed in a certain area. For example, if a maximum of 10 large dots can be printed in an area and 10 large dots of the same size are printed in that area, the duty ratio is 100%. If five large dots of the same size are printed, the duty ratio is 50% (forms relating to “printing device”, “printing program”, “printing method”, “image” In the description of the form relating to the "processing device", 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, etc. The same).

[Mode 6] A printing apparatus according to mode 6 includes:
In the printing apparatus according to any one of the first to fifth aspects, the dot size changing unit changes the dot causing the flight curve phenomenon to a size smaller than the original size and causes the flight curve phenomenon. Any one or more dots adjacent to the dots are changed to a size larger than the original size.
As a result, the banding phenomenon can be reduced, and the area gradation of the banding occurrence area is kept the same as the area gradation of the original image because part of the dot size is reduced and other dot sizes in the vicinity are increased. can do.

[Mode 7] A printing apparatus according to mode 7 includes:
In the printing apparatus according to any one of the first to fifth aspects, the dot size changing unit changes the dot causing the flight curve phenomenon to a size larger than the original size and causes the flight curve phenomenon. Any one or more dots adjacent to the dots are changed to a size smaller than the original size or eliminated.
As a result, the banding phenomenon can be reduced, and the area gradation of the banding generation area is kept the same as the area gradation of the original image because the size of some dots is increased and other dot sizes in the vicinity are reduced. can do.

[Mode 8] The print program of mode 8 is
The computer generates the flight curve information acquisition means for acquiring the flight curve information of the print head that prints dots of different sizes, and print data in which dots corresponding to each pixel of the N-value (2 ≦ N) image data are set. A print data generation means, and a flight curve phenomenon determined based on flight curve information of the print head acquired by the flight curve information acquisition means among the dots of print data generated by the print data generation means The dot size changing means for changing the size of the dot causing the dot and the neighboring dots, and the printing means for executing printing based on the print data whose dot size has been changed by the dot size changing means It is characterized by this.

As in the first aspect, this reduces the banding phenomenon caused by the flight bending phenomenon and eliminates or hardly stands out “white streaks” and “dark streaks”, so that a high-quality printed matter can be obtained efficiently.
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 9] The print program of mode 9 is
In the printing program according to aspect 8, a block division unit that divides the image data into blocks for each of a plurality of pixels, and pixel values of pixels in each block divided by the block division unit in other adjacent blocks It functions as a pixel value distribution unit that distributes the pixel values of the pixels.

As a result, the banding can be reduced by processing efficiently as in the second mode, and the high image quality can be maintained without impairing the area gradation of the original image.
Further, since each means can be realized by software using a computer system provided in most printing apparatuses currently on the market, as in the case of the eighth embodiment, dedicated hardware is created to create the hardware. This can be realized more economically and easily than when each means is realized. Furthermore, it is possible to easily upgrade the version by modifying or improving the function by rewriting a part of the program.

[Mode 10] The print program of mode 10 is
The printing program according to the ninth aspect is characterized in that the block dividing unit divides the image data into blocks by 2 × 2 pixels.

As a result, block noise does not occur even if the image data is divided into blocks as in the third embodiment.
Further, since each means can be realized by software using a computer system provided in most printing apparatuses currently on the market, as in the case of the eighth embodiment, dedicated hardware is created to create the hardware. This can be realized more economically and easily than when each means is realized. Furthermore, it is possible to easily upgrade the version by modifying or improving the function by rewriting a part of the program.

[Mode 11] The printing program of mode 11 is
The printing program according to any one of Embodiments 8 to 10, further comprising a gradation identifying unit that identifies a gradation of the image data, wherein the block division is performed only on an area identified as an intermediate gradation by the gradation identifying unit. Further, pixel value distribution and dot size change processing are performed.

  As a result, it is possible to realize an efficient process as in the fourth aspect, and in the same way as in the eighth aspect, the software is used by a computer system that is provided in most printing apparatuses currently on the market. Since each means can be realized, it can be realized more economically and easily than when dedicated hardware is created and each means is realized. Furthermore, it is possible to easily upgrade the version by modifying or improving the function by rewriting a part of the program.

[Mode 12] The printing program of mode 12 is
12. The printing program according to claim 11, wherein the gradation identifying means determines an intermediate gradation area from an area having a duty ratio of 50% when the dot size is minimum to 50% when the dot size is maximum. It is characterized by being identified as.

As a result, as in the case of the fifth aspect, it is possible to accurately identify an intermediate gradation in which the banding phenomenon is particularly noticeable.
Further, since each means can be realized by software using a computer system provided in most printing apparatuses currently on the market, as in the case of the eighth embodiment, dedicated hardware is created to create the hardware. This can be realized more economically and easily than when each means is realized. Furthermore, it is possible to easily upgrade the version by modifying or improving the function by rewriting a part of the program.

[Mode 13] The print program of mode 13 is
In the printing program according to any one of Forms 8 to 12, the dot size changing unit changes the dot causing the flight curve phenomenon to a size smaller than the original size and causes the flight curve phenomenon. Any one or more dots adjacent to the dots are changed to a size larger than the original size.

As a result, the banding phenomenon can be reduced in the same manner as in the sixth aspect, and the area gradation of the banding occurrence region is set to the area of the original image because some of the dot sizes are reduced and other dot sizes in the vicinity thereof are increased. It can be kept the same as the gradation.
Further, since each means can be realized by software using a computer system provided in most printing apparatuses currently on the market, as in the case of the eighth embodiment, dedicated hardware is created to create the hardware. This can be realized more economically and easily than when each means is realized. Furthermore, it is possible to easily upgrade the version by modifying or improving the function by rewriting a part of the program.

[Mode 14] The print program of mode 14 is
In the printing program according to any one of Forms 8 to 12, the dot size changing unit changes the dot causing the flight curve phenomenon to a size larger than the original size and causes the flight curve phenomenon. Any one or more dots adjacent to the dots are changed to a size smaller than the original size or eliminated.

As a result, the banding phenomenon can be reduced in the same manner as in the seventh aspect, and the area gradation of the banding occurrence region is set to the area of the original image because some of the dot sizes are reduced and other dot sizes in the vicinity thereof are increased. It can be kept the same as the gradation.
Further, since each means can be realized by software using a computer system provided in most printing apparatuses currently on the market, as in the case of the eighth embodiment, dedicated hardware is created to create the hardware. This can be realized more economically and easily than when each means is realized. Furthermore, it is possible to easily upgrade the version by modifying or improving the function by rewriting a part of the program.

[Mode 15] The computer-readable recording medium of mode 15 is
It is a computer-readable recording medium which recorded the printing program of form 8-14.
Accordingly, the printing program according to any one of the above embodiments 8 to 14 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 16] The printing method of mode 16 is
Print data for generating print data in which a flight curve information acquisition step for acquiring flight curve information of a print head that prints dots of different sizes and a dot corresponding to each pixel of N-value (2 ≦ N) image data is set. Among the dots of the printing data generated in the generation step and the printing data generation step, the flight bending phenomenon determined based on the flight bending information of the print head acquired in the flight bending information acquisition step occurs. A dot size changing step for changing the size of the existing dot and its neighboring dots, and a printing step for executing printing based on the print data whose dot size has been changed by the dot size changing step Is.

  As in the first aspect, this reduces the banding phenomenon caused by the flight bend phenomenon and eliminates “white streaks” and “dark streaks” or makes them hardly noticeable, so that a high-quality printed matter can be obtained efficiently. .

[Mode 17] The printing method of mode 17 is
In the printing method according to the sixteenth aspect, a block division step for dividing the image data into blocks for each of a plurality of pixels, and pixel values of the pixels in each block divided by the block division step in other adjacent blocks And a pixel value distribution step of distributing the pixel values of the pixels.
As a result, the banding can be reduced by processing efficiently as in the second mode, and the high image quality can be maintained without impairing the area gradation of the original image.

[Form 18] The printing method of form 18 includes:
In the printing method according to the seventeenth aspect, in the block dividing step, the image data is divided into blocks in units of 2 × 2 pixels.
As a result, block noise does not occur even if the image data is divided into blocks as in the third embodiment.

[Form 19] The printing method of form 19 includes:
The printing method according to any one of Forms 16 to 18, further comprising: a gradation identifying step for identifying a gradation of the image data, and only a region of the image data identified as an intermediate gradation in the gradation identifying step. The above-described block division, pixel value distribution, and dot size change processing are performed.
As a result, as in the fourth embodiment, efficient processing can be realized.

[Mode 20] The printing method of mode 20 includes
20. The printing method according to claim 19, wherein in the gradation identifying step, an area having a duty ratio of 50% when the dot size is minimum to an area of 50% when the dot size is maximum is an intermediate gradation area. It is characterized by identifying as.
As a result, as in the case of the fifth aspect, it is possible to accurately identify an intermediate gradation in which the banding phenomenon is particularly noticeable.

[Form 21] The printing method of form 21 is
In the printing method according to any one of forms 16 to 20, in the dot size changing step, the dot causing the flying curve phenomenon is changed to a size smaller than the original size, and the flying curve phenomenon is caused. Any one or more dots adjacent to the dots are changed to a size larger than the original size.
As a result, the banding phenomenon can be reduced in the same manner as in the sixth aspect, and the area gradation of the banding occurrence region is set to the area of the original image because some of the dot sizes are reduced and other dot sizes in the vicinity thereof are increased. It can be kept the same as the gradation.

[Mode 22] The printing method of mode 22 is
In the printing method according to any one of forms 16 to 20, in the dot size changing step, the dot causing the flying curve phenomenon is changed to a size larger than the original size, and the flying curve phenomenon is caused. Any one or more dots adjacent to the dots are changed to a size smaller than the original size or eliminated.
As a result, the banding phenomenon can be reduced in the same manner as in the seventh aspect, and the dot size of some dots is increased and other dot sizes in the vicinity thereof are reduced, so that the area gradation of the banding occurrence region is set to the area of the original image. It can be kept the same as the gradation.

[Form 23] An image processing apparatus of form 23 is
Print data for generating print data in which the flight curve information acquisition means for acquiring the flight curve information of the print head that prints dots of different sizes and the dot corresponding to each pixel of the N-value (2 ≦ N) image data are set. Among the dots of the printing data generated by the generating means and the printing data generating means, the flight bending phenomenon determined based on the flight bending information of the print head acquired by the flight bending information acquiring means is caused. And a dot size changing means for changing the size of the dots in the vicinity thereof.
As a result, it is possible to reduce the banding phenomenon caused by the flight bending phenomenon and efficiently generate print data in which “white stripes” and “dark stripes” are eliminated or hardly noticeable.

[Mode 24] An image processing apparatus according to mode 24
24. The image processing device according to claim 23, wherein a block dividing unit that divides the image data into blocks for each of a plurality of pixels and a pixel value of a pixel in each block divided by the block dividing unit in another adjacent block And a pixel value distribution unit that distributes the pixel values of the pixels.
As a result, the M-value (M ≧ 3) image data acquired by the image data acquisition means can be reduced in resolution by a block unit to reduce banding, and the area gradation of the original image is not impaired.

[Mode 25] An image processing apparatus according to mode 25
In the image processing device according to mode 24, the block dividing unit divides the image data into blocks of 2 × 2 pixels.
As a result, block noise does not occur even when N-value image data is divided into blocks as in the above-described embodiment.

[Mode 26] An image processing apparatus according to mode 26
26. The image processing apparatus according to any one of Forms 23 to 25, further comprising a gradation identifying unit that identifies a gradation of the image data, wherein the gradation is identified as an intermediate gradation by the gradation identifying unit. The block division, the pixel value distribution, and the dot size changing process are performed only on the image.
As a result, it is possible to realize efficient resolution reduction processing as compared with the case where processing is uniformly performed on the entire image data.

[Mode 27] An image processing apparatus according to mode 27
27. The image processing apparatus according to claim 26, wherein the gradation identifying means applies an intermediate gradation to an area having a duty ratio of 50% when the dot size is minimum to 50% when the dot size is maximum. It is characterized in that it is identified as a region.
As a result, it is possible to accurately identify an intermediate gradation in which the banding phenomenon is particularly noticeable.

[Mode 28] An image processing apparatus according to mode 28 is
In the printing device according to any one of Forms 23 to 27, the dot size changing unit changes the dot causing the flight curve phenomenon to a size smaller than the original size and causes the flight curve phenomenon. Any one or more dots adjacent to the dots are changed to a size larger than the original size.
As a result, the banding phenomenon can be reduced, and the area gradation of the banding occurrence area is kept the same as the area gradation of the original image because part of the dot size is reduced and other dot sizes in the vicinity are increased. can do.

[Mode 29] An image processing apparatus according to mode 29
In the image processing device according to any one of Forms 23 to 27, the dot size changing unit changes the dot causing the flight curve phenomenon to a size larger than the original size and causes the flight curve phenomenon. Any one or more dots adjacent to a certain dot are changed to a size smaller than the original size or eliminated.
As a result, the banding phenomenon can be reduced, and the area gradation of the banding generation area is kept the same as the area gradation of the original image because the size of some dots is increased and other dot sizes in the vicinity are reduced. can do.

[Mode 30] The image processing program of mode 30 is
The computer generates the flight curve information acquisition means for acquiring the flight curve information of the print head that prints dots of different sizes, and print data in which dots corresponding to each pixel of the N-value (2 ≦ N) image data are set. A print data generation means, and a flight curve phenomenon determined based on flight curve information of the print head acquired by the flight curve information acquisition means among the dots of print data generated by the print data generation means And functioning as dot size changing means for changing the size of the dot causing the dot and the dot in the vicinity thereof.

As a result, as in the case of Form 23, it is possible to reduce the banding phenomenon caused by the flight bending phenomenon, and to efficiently generate print data in which “white stripes” and “dark stripes” are eliminated or hardly noticeable.
Further, since each means can be realized by software using a general-purpose computer system such as a personal computer (PC), it is more economical and easier than the case where the 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 31] The image processing program of mode 31 is
In the image processing program according to the thirtieth aspect, a block division unit that divides the image data into blocks for each of a plurality of pixels, and pixel values of pixels in each block divided by the block division unit in other adjacent blocks It functions as a pixel value distribution unit that distributes the pixel values of the pixels.

As a result, as in the form 24, the image data can be processed in units of blocks to reduce banding, and the area gradation of the original image is not impaired.
Further, since each means can be realized by software using a general-purpose computer system such as a personal computer (PC) in the same manner as in the thirtieth embodiment, compared with the case where each means is realized by creating dedicated hardware. 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 32] The image processing program of mode 32 is
In the image processing program according to mode 31, the block division unit divides the image data into blocks by 2 × 2 pixels.
As a result, as in the case of form 25, block noise does not occur even when image data having M values (M ≧ 3) is divided into blocks.
Further, since each means can be realized by software using a general-purpose computer system such as a personal computer (PC) in the same manner as in the thirtieth embodiment, compared with the case where each means is realized by creating dedicated hardware. 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 33] The image processing program of mode 33 is
33. The image processing program according to any one of forms 30 to 32, further comprising a gradation identifying unit that identifies a gradation of the image data, wherein the gradation is identified as an intermediate gradation by the gradation identifying unit in the image data The block division, the pixel value distribution, and the dot size changing process are performed only on the image.
As a result, as in the case of the form 26, it is possible to realize efficient processing as compared with the case where processing is uniformly performed on the entire image data.
Further, since each means can be realized by software using a general-purpose computer system such as a personal computer (PC) in the same manner as in the thirtieth embodiment, compared with the case where each means is realized by creating dedicated hardware. 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 34] The image processing program of form 34 is
34. The image processing program according to claim 33, wherein the gradation identifying means applies an intermediate gradation to an area having a duty ratio of 50% when the dot size is minimum to 50% when the dot size is maximum. It is characterized in that it is identified as a region.

As a result, as in the case of the form 27, it is possible to accurately identify the intermediate gradation in which the banding phenomenon is particularly conspicuous.
Further, since each means can be realized by software using a general-purpose computer system such as a personal computer (PC) in the same manner as in the thirtieth embodiment, compared with the case where each means is realized by creating dedicated hardware. 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 any one of forms 30 to 34, the dot size changing unit changes the dot causing the flight curve phenomenon to a size smaller than the original size and causes the flight curve phenomenon. Any one or more dots adjacent to a certain dot are changed to a size larger than the original size.

As a result, like the mode 28, the banding phenomenon can be reduced, and other dot sizes in the vicinity thereof are increased by reducing the size of some of the dots, so that the area gradation of the banding occurrence region is set to the area of the original image. It can be kept the same as the gradation.
Further, since each means can be realized by software using a general-purpose computer system such as a personal computer (PC) in the same manner as in the thirtieth embodiment, compared with the case where each means is realized by creating dedicated hardware. 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 any one of forms 30 to 34, the dot size changing unit changes the dot causing the flying curve phenomenon to a size larger than the original size, and causes the flying curve phenomenon. Any one or more dots adjacent to a certain dot are changed to a size smaller than the original size or eliminated.

As a result, like the mode 29, the banding phenomenon can be reduced, and since the dot size of some of the dots is reduced, other dot sizes in the vicinity thereof are increased, so that the area gradation of the banding occurrence region is set to the area of the original image. It can be kept the same as the gradation.
Further, since each means can be realized by software using a general-purpose computer system such as a personal computer (PC) in the same manner as in the thirtieth embodiment, compared with the case where each means is realized by creating dedicated hardware. 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 37] The computer-readable recording medium of mode 37 is
It is a computer-readable recording medium which recorded the image processing program of form 30-36.
Accordingly, the printing program according to any one of the above embodiments 8 to 14 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 38] An image processing method according to mode 38 is
Print data for generating print data in which a flight curve information acquisition step for acquiring flight curve information of a print head that prints dots of different sizes and a dot corresponding to each pixel of N-value (2 ≦ N) image data is set. Among the dots of the printing data generated in the generation step and the printing data generation step, the flight bending phenomenon determined based on the flight bending information of the print head acquired in the flight bending information acquisition step occurs. And a dot size changing step for changing the size of the dots in the vicinity thereof.
As a result, as in the case of Form 23, it is possible to reduce the banding phenomenon caused by the flight bending phenomenon, and to efficiently generate print data in which “white stripes” and “dark stripes” are eliminated or hardly noticeable.

[Mode 39] An image processing method according to mode 39
The image processing method according to aspect 38, wherein the image data is divided into blocks for each of a plurality of pixels, and the pixel values of the pixels in each block divided in the block division step are stored in other adjacent blocks. And a pixel value distribution step for distributing the pixel values of the pixels.
As a result, as in the form 24, the image data can be processed in units of blocks to reduce banding, and the area gradation of the original image is not impaired.

[Form 40] An image processing method according to form 40 includes:
40. The image processing method according to claim 39, wherein the block dividing step divides the M-value (M ≧ 3) image data acquired in the image data acquiring step into blocks in units of 2 × 2 pixels. It is.
As a result, as in the case of form 25, block noise does not occur even if the image data is divided into blocks.

[Form 41] An image processing method according to form 41 includes:
41. The image processing method according to any one of forms 38 to 40, further comprising: a gradation identifying step for identifying a gradation of the image data, wherein the area identified as an intermediate gradation in the gradation identifying step in the image data The block division, the pixel value distribution, and the dot size changing process are performed only on the image.
As a result, as in the case of the form 26, it is possible to realize efficient processing as compared with the case where processing is uniformly performed on the entire image data.

[Form 42] An image processing method according to form 42 includes:
42. In the image processing method according to mode 41, in the gradation identifying step, an intermediate gradation is applied to an area where the duty ratio is 50% when the dot size is minimum to 50% when the dot size is maximum. It is characterized by identifying as a region.
As a result, as in the case of the form 27, it is possible to accurately identify the intermediate gradation in which the banding phenomenon is particularly conspicuous.

[Form 43] The image processing method of form 43 is
43. In the image processing method according to any one of forms 38 to 42, the dot size changing step changes the dot causing the flight curve phenomenon to a size smaller than the original size and causes the flight curve phenomenon. Any one or more dots adjacent to a certain dot is changed to a size larger than the original size.
As a result, like the mode 28, the banding phenomenon can be reduced, and other dot sizes in the vicinity thereof are increased by reducing the size of some of the dots, so that the area gradation of the banding occurrence region is set to the area of the original image. It can be kept the same as the gradation.

[Form 44] The image processing method of form 44 is as follows.
43. In the printing method according to any one of forms 38 to 42, the dot size changing step changes the dot causing the flight curve phenomenon to a size larger than the original size and causes the flight curve phenomenon. Any one or more dots adjacent to the dots are changed to a size smaller than the original size or eliminated.
As a result, like the mode 29, the banding phenomenon can be reduced, and since the dot size of some of the dots is reduced, other dot sizes in the vicinity thereof are increased, so that the area gradation of the banding occurrence region is set to the area of the original image. It can be kept the same as the gradation.

Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the accompanying drawings.
1 to 19 show an embodiment of a printing apparatus 100 and a printing program, printing method, image processing apparatus, image processing program, image processing method, and computer-readable recording medium of the present invention.
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 includes a print head 200 having a plurality of nozzles, a flight bend information acquisition unit 10 that acquires flight bend information of the print head 200, and a multi-value (M value) used for printing. The image data acquisition means 12 for acquiring the image data, the gradation identification means 14 for identifying the gradation of the multivalued image data acquired by the image data acquisition means 12, and the multiple acquired by the image data acquisition means 12 The resolution reducing means 16 for reducing the resolution of the value image data, the image data reduced in resolution by the resolution reducing means 16 and the multivalued image data acquired by the image data acquiring means 12 are represented by N values (N ≧ 2) N-valued data generating means 18 for generating N-valued image data by conversion into dots and dots corresponding to the pixel values of the N-valued image data generated by the N-valued data generating means 18 The print data generation means 20 for setting the size and generating the print data, the dot size change means 22 for changing the dot size of a part of the print data generated by the print data generation means 20, and the print head 200 It is mainly composed of an ink jet type printing unit 24 that executes printing based on the print data generated by the print data generation unit 22.

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 has a long structure extending in the paper width direction of printing paper used in a so-called line head type printer, and has a nozzle N for discharging black (K) ink exclusively. A plurality (18 in the figure) of black nozzle modules 50 arranged in a straight line in the main scanning direction and a plurality of nozzles N dedicated to eject yellow (Y) ink are also arranged in a straight line in the main scanning direction. Yellow nozzle module 52, a plurality of nozzles N that specifically eject magenta (M) ink, and a magenta nozzle module 54 that is also linearly arranged in the main scanning direction, and cyan (M) ink exclusively Four nozzle modules 50, 52, 5 such as a cyan nozzle module 56 in which a plurality of nozzles N are arranged in a straight line in the main scanning direction. , 56 which are arranged integrally so as to overlap in the printing direction (sub scanning direction). In the case of a print head intended for monochrome, only a black (K) nozzle module, and in the case of a print head targeting a high-quality image, a light magenta module that exclusively ejects light magenta (LM) ink. There are also 6-color and 7-color types, including a light cyan module that discharges light cyan (LC) ink exclusively.

  FIG. 4 shows, for example, the 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 has a flight bend phenomenon. This shows a state in which ink is ejected obliquely from the nozzle N6 and dots are printed (ink landing) in the vicinity of the adjacent normal nozzle N7.

  Therefore, when printing is performed using the black nozzle module 50, as shown in FIG. 5, in the state where no flying curve occurs, all dots are printed at the specified printing position (ideal As shown in FIG. 6, for example, if the sixth nozzle N6 from the end of the nozzle undergoes a flight bending phenomenon, the dot printing position is a normal nozzle next to the target printing position by a distance a. As a result, printing is shifted to the N7 side.

The characteristics of the print head 200 are fixed to some extent at the manufacturing stage, and it is considered that it is relatively rare to change after manufacturing, except for ejection failures due to ink clogging.
Next, the flight bend information acquisition means 10 provides a function of acquiring the flight bend information from the characteristics of the print head 200. More specifically, as shown in FIG. Whether or not the flight bend phenomenon has occurred, and if the flight bend phenomenon has occurred, which of the abnormal nozzles N causes the flight bend phenomenon, and the dot printing position due to the flight bend phenomenon The function of acquiring and notifying specific information on the amount of deviation is provided.

  That is, as shown in FIG. 1, the flight curve information acquisition means 10 is further provided with a print head characteristic storage unit 10a or a print head characteristic detection unit 10b, which is stored in advance in the print head characteristic storage unit 10a. In addition, by reading out the characteristic information of the print head 200 or by reading out the characteristic information of the print head 200 detected by the print head characteristic detection unit 10b, the flight bending information of the print head 200 can be easily obtained at a necessary time. Can be obtained.

  Here, the print head characteristic storage unit 10a is readable, for example, in which a print head characteristic test result written at the time of manufacture of the print head 200 or when incorporated into the printing apparatus 100 (printing means 24) is written. The print head characteristic detection unit 10b is composed of storage means such as a ROM and a RAM. The print head characteristic detection unit 10b is provided with a scanner unit or the like periodically or at a predetermined time to cope with a change in the characteristic of the print head 200 after use. The characteristic of the print head 200 is inspected from the print result of the print head 200 using an optical print result reading means or the like, and the inspection result is overwritten on the data together with the data of the print head characteristic storage unit 10a. To save. The characteristics of the print head 200 are fixed to some extent at the manufacturing stage, and it is considered that it is relatively rare to change after manufacturing, except for ejection failures due to ink clogging.

  Next, the image data acquisition means 12 is a multi-value (M-value) color used for printing sent from a print instruction device (not shown) such as a personal computer (PC) or a printer server connected to the printing device 100. A function is provided for acquiring image data via a network or by directly reading and acquiring from an image (data) reading device such as a scanner or a CD-ROM drive (not shown). Value color image data is multi-value RGB data, for example, image data in which gradation (luminance value) for each color (R, G, B) per pixel is represented by 8 bits and 256 gradations (0 to 255). If this is the case, the color conversion process is performed so that the multi-value CMYK (in the case of four colors) data corresponding to each ink of the print head 200 can be simultaneously displayed. Going on.

  The gradation identifying unit 14 divides the multi-valued image data acquired by the image data acquiring unit 16 into a plurality of areas and calculates the average of the pixel values of the divided areas, as will be described in detail later. The gradation of the area is identified, and each of these areas is divided into an intermediate gradation area (medium density area) and other gradation areas, that is, a high gradation area (high density area) and a low gradation area (low density area). ) Function to be classified.

  The resolution reduction means 16 applies to the intermediate gradation area identified as the intermediate gradation by the gradation identification means 14 from the M-value (M ≧ 3) image data acquired by the image data acquisition means 12. A function for reducing the apparent resolution is provided, and a specific example thereof will be described in detail later. A block dividing unit 16a that further divides each of the intermediate gradation regions into blocks for each of a plurality of pixels. And a pixel value distribution unit 16b that distributes the pixel values of the pixels in each block divided by the block division unit 16a to the pixel values of the pixels in another adjacent block.

The N-value data generation means 18 converts the multi-value image data acquired by the image data acquisition means 12 and the image data apparently reduced in resolution by the resolution reduction means 16 into an N-value to generate an N-value image. Provides the ability to generate data.
Specifically, the pixel value (density value) of each pixel of the image data acquired by the image data acquisition unit 12 and the image data whose resolution is apparently reduced by the resolution reduction unit 16 is 8 bits, 256 In the case where the gradation is specified, and this is converted into quaternary with gradation: N = 4, as shown in the dot / gradation conversion table 300A of FIG. The values are classified into four.

The right column of the dot / gradation conversion table 300A in FIG. 7 shows the relationship between the threshold values and the respective pixel values when the multivalued pixel values are converted into quaternary values with gradation: N = 4.
That is, according to the dot / gradation conversion table 300A, when the pixel value (luminance value) of each pixel of the multivalued image data is specified by 8 bits (0 to 255), “200 (first threshold value) ) ”,“ 110 (second threshold) ”,“ 35 (third threshold) ”, and when the pixel value is“ 201 to 255 ”, N = 1 (luminance“ 255 ”, density“ 0 ”), when the pixel value is“ 111 to 200 ”, N = 2 (luminance“ 150 ”, density“ 70 ”), and when the pixel value is“ 36 to 110 ”, N = 3 (luminance“ 70 ”). ”, Density“ 150 ”), and pixel value“ 0 to 35 ”, four values are set as N = 4 (luminance“ 0 ”, density“ 255 ”).

Then, 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 manner, and is used in the inkjet printing unit 24. A function to generate data for use is provided.
The left column of the dot / gradation conversion table 300A in FIG. 7 is a reference diagram showing the relationship between the pixel value of each pixel of the N-ary data and the dot size performed by the print data generation means 18.

  In the example shown in the figure, when “gradation: N = 4” is set to quaternarization and “luminance value” is selected as the pixel value, the dot size in the case of “N = 1” is “no dot”, “N = The dot size in the case of “2” is “small dot” with the smallest dot area, and the dot size in the case of “N = 3” is slightly larger than the small dot “medium dot”, “N = 4” The dot size is converted into a “large dot” having the largest dot area. When a “density value” is used as the pixel value, each pixel value is converted into a dot having a reverse relationship to the “density value”.

The dot size changing unit 22 is a flight curve determined based on the flight curve information of the print head 200 acquired by the flight curve information acquiring unit 10 among the dots of the print data generated by the print data generating unit 20. This provides a function of changing the size of a dot causing a phenomenon and a dot in the vicinity thereof.
For example, by making the size of dots printed by the nozzle causing the flight bending phenomenon larger than the original size, the banding phenomenon (white stripes) occurring in the vicinity thereof disappears or becomes almost inconspicuous. At the same time, by reducing the size of some dots printed by normal nozzles in the vicinity along with the size change, the banding phenomenon (dark streaks) occurring in the vicinity is reduced. In addition to disappearance or almost inconspicuousness, the area gradation of the portion is kept constant to prevent deterioration in image quality.

  Next, the printing unit 24 drops ink from the nozzle modules 50, 52, 54, and 56 formed on the print head 200 while moving one or both of the print medium (paper) S and the print head 200, respectively. In addition to the print head 200 described above, the print head 200 is placed on the print medium S to form a predetermined image consisting of a large number of dots on the print medium S. A print head feeding mechanism (not shown) that reciprocates the paper in the width direction (multi-pass type), a paper feeding mechanism (not shown) for moving the print medium S, and the ink of the print head 200 based on the printing data. It comprises known components such as a print controller mechanism (not shown) that controls the discharge.

  Here, the printing apparatus 100 includes various controls for printing, the flight curve information acquisition unit 10, the image data acquisition unit 12, the gradation identification unit 14, the resolution reduction unit 16, the N-valued data generation unit 18, A computer system for realizing the print data generating means 20, dot size changing means 22, printing means 24, and the like on software is provided, and the hardware configuration includes various controls and arithmetic processes as shown in FIG. A central processing unit (CPU) 60 that is a central processing unit, 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 (Periphera It is connected by various internal / external buses 68 such as a component interconnect (BUS) or an ISA (Industrial Standard Architecture) bus, and is connected to the bus 68 via an input / output interface (I / F) 66 and an external device such as an HDD (Hard Disk Drive). 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 or the like is connected.

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

Next, an example of the flow of a printing process 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 or 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, as shown in the flow of FIG. 8, after a predetermined initial operation for printing processing is completed after the power is turned on, the printing apparatus 100 is connected to a printing instruction terminal (not shown) such as a personal computer. In the first step S100 and step S102, it is monitored whether there is an explicit print instruction from the print instruction terminal.
When it is determined that the print instruction and multi-value image data to be processed have been sent (Yes), the process proceeds to the next step S104 to divide the image data into a plurality of areas and the next step. In S106, whether or not the gradation for each divided area is an intermediate gradation is identified based on the pixel value in that area.

Specifically, when the dot size corresponding to the pixel value is set from the pixel value of each pixel in each divided region, the duty ratio when the set dot size of the pixel is the minimum is 50%. An area having a duty ratio of 50% when the size is maximum is identified as an intermediate gradation area.
That is, the banding phenomenon is most noticeable when the duty ratio is 50% when the dot size is the minimum and the duty ratio when the dot size is the maximum 50%. This is because inconveniences such as pixel dropping and pixel surplus can be avoided during resolution processing.

Note that this gradation identification processing is performed on all the divided regions sequentially or in parallel. In the gradation identification process, the entire image data may be processed in a lump without dividing the image data into a plurality of areas.
When it is determined in the next determination step S108 that the divided area is not an intermediate gradation area (No), the process proceeds to step S122 and the N-value conversion process and the dot conversion process are performed as they are. When it is determined that the divided area is an intermediate gradation area (Yes), the process proceeds to the next step S110 as it is to acquire the flight curve information of the print head 200, and the flight curve is determined in the next determination step S112. Based on the information, it is determined whether or not a banding phenomenon has occurred in the divided area determined to be the intermediate gradation area. That is, it is determined whether or not any dot corresponding to the pixel in the divided region is printed by the nozzle causing the flying curve phenomenon.

Strictly speaking, since most of the nozzles of the actual print head 200 usually cause a flight curve to some extent, a certain threshold (for example, 3 μm) is set for the flight curve amount. In addition, it is determined whether or not the banding phenomenon has occurred depending on the presence or absence of a nozzle whose flight bending amount exceeds the threshold value.
In step 112, when it is determined that no banding phenomenon has occurred in the divided area (No), the process proceeds to step S122 as in step 108, but the banding phenomenon has occurred. When it is determined that there is (Yes), the process proceeds to the next step S114 as it is, and the resolution reduction processing as shown in FIG.

FIG. 9 is a flowchart showing an example of the flow of resolution reduction processing in step S114.
As shown in the drawing, in the first step S200, the divided area is further divided into blocks. For example, as shown in FIG. 10A, when each pixel is continuous vertically and horizontally (main scanning direction and sub-scanning direction), the adjacent 2 pixels × 2 pixels (4 pixels in total) are regarded as one block and the image Data is divided into blocks vertically and horizontally. Here, as a unit for dividing the block, for example, a pattern of 2 pixels × 1 pixel having a smaller number of pixels than the example of FIG. 10 (1), or 3 pixels × having a larger number of pixels than the example of FIG. 10 (1) × Although the number of blocks to be processed is increased in the former pattern and the processing amount of the entire resolution reduction processing is increased, the area of the divided block is increased in the latter pattern. The pattern may be visible and the image quality may deteriorate.

If the block is further finely divided in this way, the process proceeds to the next step S202 to determine the divided blocks to be actually thinned out in order to reduce the apparent resolution. In step S204, the pixel value (luminance value) in the divided block is saturated, and the pixels in the divided block are thinned out.
In the example of FIG. 10B, the pixel values of the four pixels in the thinned block selected by selecting the divided blocks indicated by the broken-line circles in the figure as a block to be thinned out in a staggered pattern are all “100”. → "255" is saturated (8 bits, 256 gradations).

Next, when the pixel value (luminance value) in the divided block to be thinned out is saturated in this way, the process proceeds to the next step S206, and the error generated by the saturation processing is distributed to the pixels in the block that is not thinned out. .
For example, as shown in FIG. 11 (3), if the pixel value of the pixel in the block to be thinned out is saturated, the error value generated by the saturation process is distributed to the adjacent pixel in the block that is not thinned out.

In the next step S208, the total value of the pixel values in the error-distributed block is calculated, and whether or not the total value is “0 (luminance)” or more, that is, the error caused by the saturation processing is calculated. Judge whether all have been distributed.
As a result, when it is determined that the sum of the pixel values of the pixels in the distribution destination block is equal to or greater than “0 (luminance)” (Yes), all the errors generated by the saturation processing are distributed in one distribution destination block. If it is determined that the total pixel value of the distribution destination block is not equal to or greater than “0 (luminance)”, that is, it has become negative (No), In step S210, the sum of the pixel values of the distribution destination block is set to “0 (luminance)”, and then in step S212, the remaining errors that could not be distributed are saturated. The processing is ended after returning to the pixels in the block.

For example, as shown in FIG. 10A, when the pixel value of each pixel in the original block is “100” and the pixel value of each pixel is set to “255” and saturated, Therefore, an error of total “−620 (−155 (255−100) × 4)” occurs.
Then, as shown in FIG. 11 (3), if this error is distributed to adjacent blocks that are not thinned out, “−220 ((100 × 4) −620)” cannot be distributed. Therefore, the remaining pixel value “ -220 "is returned, and as a result, the pixel value of any one pixel in the original block changes from" 255 "to" 35 (255-220) "as shown in FIG. 11 (4). Become.

  FIGS. 12A to 12C show todd printing states when blocks are thinned out in a staggered pattern and the pixel values are distributed to blocks that are not thinned out. Each grid in the figure corresponds to each pixel constituting the image data, and the image data is divided into blocks of 2 × 2 pixels, and the filled portion indicates the pixels on which dots are actually printed. It is.

  In this way, when the image data is divided into blocks of 2 × 2 pixels, the total luminance of the two blocks having a small dot duty ratio of 50% is “255” × 4 + “150” × 4 = 1620, The total luminance of the two blocks having a duty ratio of 50% is “255” × 4 + “0” × 4 = 1020. The average luminance of one pixel with a small dot duty ratio of 50% is “1620” / 8 = “202.5”, and the average luminance of one pixel with a large dot duty ratio of 50% is “1020” / 8 = “127.5”.

That is, in the above example, when the average luminance is larger than “202.5”, the number of dots is less than four in the 2 × 2 block as shown in FIG. On the other hand, when the average luminance is “127.5” or less, as shown in FIG. 12B, it is not possible to fit four dots in a 2 × 2 block.
Therefore, in the block division as described above, when the average luminance is larger than “127.5” and smaller than “202.5”, as shown in FIG. It is possible to express with one dot, and the process of returning pixel values that cannot be distributed as shown in FIG. 11 becomes unnecessary.

  Next, returning to the flow of FIG. 8, when the resolution reduction process in step S114 is completed in this way, the process proceeds to the next step S116, and the image data of the apparently reduced resolution area is processed. After performing the N-value conversion process, the process proceeds to the next step S118, assigns dots of a size corresponding to each pixel value subjected to the N-value process, performs the dot conversion process, and then proceeds to the next step S120. Then, a process of changing the dot causing the flying curve and the dot size in the vicinity thereof is performed.

FIGS. 13 to 16 show an example of the dot size changing process in step S120.
First, when the flight curve phenomenon occurs in some of the lines as shown in FIGS. 15 and 16, for example, as shown in the first step S300 of the flow of FIG. 13, the dot causing the flight curve is generated. A dot whose dot size is to be increased is selected from the above, and the process proceeds to the next step S302 to change the selected dot to a larger size.

In the example of FIGS. 15 and 16, among the dots on the line where the flying curve occurs, every other filled dot is selected as a selection dot. The original size of all dots in FIGS. 15 and 16 is a medium dot.
As a result, the banding phenomenon is caused and the white stripe portion of the portion is filled with the resized large dots, so that the white stripe generated in the flight curve line portion is eliminated or reduced so that it is hardly noticeable. be able to.

Next, if the dot size selected in this way is greatly changed, the process proceeds to the next step S304, the dot size on the right or left side (main scanning direction) of the enlarged dot is reduced, and then the next dot size is changed. The process proceeds to determination step S306.
In the examples of FIGS. 15 and 16, since a dot exists only on the right side of the selected dot as shown in each processing pattern A, the dot size on the right side is changed from a medium dot to a small dot. ing.

  In determination step S306, it is determined whether or not there is a dot immediately above each of the selected dots that have been further changed. If it is determined that a dot exists immediately above (Yes), the process moves to step S308 and immediately above it. When it is determined that the dot is erased and, on the contrary, it is determined that there is no dot immediately above (No), the process proceeds to step S310, and the process of eliminating the upper right or upper left dot of the selected dot is executed. To finish the process. In step S310, if there is no dot in the upper right or upper left of the selected dot, the process is of course terminated.

In the example of FIG. 15, since there is no dot immediately above the selected dot as shown in the processing pattern A, the upper left dot size is eliminated. In the example of FIG. 16, the dot immediately above the selected dot is eliminated as shown in the processing pattern A.
As a result, the density in the vicinity of the selected dot that has been resized to a large dot decreases, and dark stripes disappear or become almost inconspicuous, and the area gradation becomes uniform with other parts, and the image quality associated with the dot size changing process is improved. Reduction can also be avoided.

Further, depending on the position of the flight curve line, as shown in the first step S400 and step S402 of the flow of FIG. 14, the dot selected from the dots causing the flight curve is changed to a smaller size contrary to the above. This may reduce the banding phenomenon.
That is, after changing the selected dot to a small dot, the process proceeds to the next determination step S404, where it is determined whether or not there is a dot immediately below the reduced dot. When it is determined that it exists (Yes), the process proceeds to step S406 to increase the dot size immediately below it, and then proceeds to the next step S408 to perform processing to reduce the lower left dot of the large dot ( Process pattern B in FIG.

On the other hand, when it is determined in this determination step S404 that there is no dot immediately below (No), the process proceeds to step S410 and a large dot is arranged immediately below, and then the process proceeds to the next step S412 and the large dot. Is processed so as to eliminate the dot on the left side of the pattern (processing pattern B in FIG. 16).
As a result, the banding phenomenon is reduced as in the processing pattern A, and at the same time, the area gradation of the area becomes uniform with the other areas, and the deterioration of the image quality can be avoided.

  Next, returning to the flow of FIG. 8, if the dot size changing process in step S120 is completed, the process proceeds to the next step S126, and printing of the non-halftone area created through steps S122 and S124 is performed. After the print data corresponding to the entire image data is generated by combining with the data, the process moves to the last step S128 and the print process is executed based on the print data, thereby completing the process.

As described above, since the present invention is implemented by using both the resolution reduction processing and the dot conversion processing for the intermediate gradation region where the banding phenomenon is conspicuous, the banding phenomenon is achieved without greatly degrading the original image quality. Can be reliably reduced.
Note that the resolution reduction processing in the present embodiment is a process in which adjacent dots are grouped into blocks to reduce the “apparent” resolution, and the distance between dots is actually the same. . For example, when the resolution is 720 dpi, the inter-dot distance is 1 inch (2.54 cm) /720=0.0035 (cm) = 35 μm, and this inter-dot distance does not change before and after the resolution reduction processing.

  Further, as shown in FIG. 7, the size of the dots that can be divided by the present invention and the normal print head 200 includes four patterns of “large dots”, “medium dots”, “small dots”, and “no dots”. However, the type of the dot size is not limited to this, and it is sufficient that there are at least two patterns other than “no dot”, and it is preferable that the number of patterns is larger.

  Further, the print head 200 in the present embodiment corresponds to the print head in the printing apparatus such as the form 1 of means for solving the problem, and the flight curve information acquisition means 10, the image data acquisition means 12, the gradation identification. Means 14, hand resolution means 16, N-value data generation means 18, print data generation means 20, dot size change means 22, and print means 24 are the flight curve information acquisition means and image data acquisition in the printing apparatus of the first embodiment. Means, gradation identification means, resolution reduction means, N-value data generation means, print data generation means, dot size change means, and printing means.

  In addition, the present invention is characterized in that the image data is converted into printing data in accordance with the print head characteristics with little modification to the existing print head 200 and the printing means 24 itself. In addition, it is not necessary to prepare a dedicated one as the printing unit 24, and the existing inkjet print head 200 and the printing unit 24 (printer) can be used as they are.

Therefore, if the print head 200 and the printing unit 24 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.
Needless to say, the printing apparatus 100 according to the present invention is not limited to a form in which all of the functions are accommodated in the casing, and a part of the functions, for example, the flight bend removal method obtaining unit 10. To N-valued data generation means 20 may be realized on the personal computer side, and the functional data may be divided so that the print data generation means 30 and the printing means 40 are realized on the printer side.

In addition, the present invention is not limited to the flying bend phenomenon, but the ink ejection direction is vertical (normal), but the nozzle formation position is deviated from the normal position. As a result, the dots formed are the same as the flying bend phenomenon. Of course, the same applies to the case where the result is obtained.
Furthermore, the present invention can be similarly applied to a problem in which ink is not discharged from a specific nozzle due to ink clogging or the like.

  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 the line head type ink jet printer is used, a flight bending phenomenon occurs. However, it is possible to obtain a high-quality printed matter with almost no noticeable white or dark streaks in one pass, and a multi-pass ink jet printer can reduce the number of reciprocating operations. High-speed printing is also possible. 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.

FIG. 17 shows respective printing methods using a line head type ink jet printer and a multi-pass type ink jet printer.
As shown in FIG. 3A, when the width direction of the rectangular printing paper P is the main scanning direction of the image data and the longitudinal direction is the sub-scanning direction of the image data, the line head type inkjet printer As shown in (B), the print head 200 has a length corresponding to the paper width of the printing paper S, the printing head 200 is fixed, and the printing paper S is sub-scanned with respect to the printing head 200. The printing is completed in one pass (operation) by moving in the direction. Note that it is also possible to perform printing while fixing the printing paper S and moving the print head 200 side in the sub-scanning direction, or moving both in the opposite direction, as in a so-called flatbed scanner. . On the other hand, in the multi-pass type ink jet printer, as shown in FIG. 5C, the print head 200, which is much shorter than the paper width, is positioned in the direction perpendicular to the main scanning direction. Printing is executed by moving the printing paper S in the sub-scanning direction by a predetermined pitch while reciprocating in the main scanning direction many times. Therefore, the latter multi-pass type ink jet printer has a drawback that it takes longer printing time than the former line head type ink jet printer, but the 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 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 group 50, 52, 54, 56 provided for each color of the print head 200 has a form in which the nozzles N are continuous linearly in the longitudinal direction of the print head 200. As shown in FIG. 18, each of these nozzle groups 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 groups 50, 52, 54, 56 is composed of 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 incorporated in a product in a state stored in a semiconductor ROM in advance 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.

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 flight bending phenomenon does not generate | occur | produce. It is a conceptual diagram which shows an example of the dot pattern formed by the flight curve phenomenon of one nozzle. It is a figure which shows the dot and gradation conversion table which showed the relationship between the pixel value referred at the time of N-value conversion, N value, and the N value and dot size. It is a flowchart figure which shows the whole processing flow of the printing apparatus of this invention. It is a flowchart figure which shows an example of the flow of a resolution reduction process. It is a schematic diagram which shows an example of the block division | segmentation and thinning-out process which are implemented in the case of resolution reduction. It is a schematic diagram which shows an example of the block division | segmentation and thinning-out process which are implemented in the case of resolution reduction. It is explanatory drawing which shows an example of a pixel value distribution process result. It is a flowchart figure which shows an example of a dot size change process. It is a flowchart figure which shows an example of a dot size change process. It is a conceptual diagram which shows an example of a dot size change process result. It is a conceptual diagram which shows an example of a dot size change process result. It is explanatory drawing which shows the difference in the printing system by a multipass type | mold inkjet printer and a line head type inkjet printer. It is a conceptual diagram which shows the other example of the structure of a print head. It is a conceptual diagram which shows an example of the computer-readable recording medium which recorded the program which concerns on this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 100 ... Printing apparatus, 200 ... Print head, 300A ... Dot / tone conversion table, 10 ... Flight curve information acquisition means, 10a ... Print head characteristic storage part, 10b ... Print head characteristic detection part, 12 ... Image data acquisition means, 14 ... gradation identifying means, 16 ... resolution reducing means, 16a ... block dividing section, 16b ... pixel value distributing section, 18 ... N-valued data generating means, 20 ... print data generating means, 22 ... dot size changing means, 24 ... Printing means, 60 ... CPU, 62 ... RAM, 64 ... ROM, 66 ... Interface, 70 ... Storage device, 72 ... Output device, 74 ... Input device, 50 ... Black nozzle group, 52 ... Yellow nozzle group, 54 ... Magenta nozzle group, 56... Cyan nozzle group, P... Pixel, S... Print medium (paper), N.

Claims (14)

A print head that prints dots of different sizes;
Flight curve information acquisition means for acquiring flight curve information of the print head;
Print data generation means for generating print data in which dots corresponding to each pixel of N (2 ≦ N) value image data are set;
Among the dots of the print data generated by the print data generation unit, the dot causing the flight curve phenomenon determined based on the flight curve information of the print head acquired by the flight curve information acquisition unit and the vicinity thereof Dot size changing means for changing the dot size;
A printing apparatus comprising: printing means for executing printing based on print data whose dot size has been changed by the dot size changing means. The printing apparatus according to claim 1,
A pixel dividing unit that divides the image data into blocks for each of a plurality of pixels, and a pixel value that distributes pixel values of pixels in each block divided by the block dividing unit to pixel values of pixels in other adjacent blocks And a distribution unit. The printing apparatus according to claim 2,
The printing apparatus according to claim 1, wherein the block dividing unit divides the image data into blocks by 2 × 2 pixels. The printing apparatus according to any one of claims 1 to 3,
A gradation identifying means for identifying the gradation of the image data;
The printing apparatus is configured to perform the block division, pixel value distribution, and dot size change processing only on an area of the image data identified as intermediate gradation by the gradation identifying means. . The printing apparatus according to claim 4,
The gradation identifying means identifies an area having a duty ratio of 50% when the dot size is minimum to 50% when the dot size is maximum as an intermediate gradation area. A printing apparatus characterized by the above. The printing apparatus according to any one of claims 1 to 5,
The dot size changing means changes the dot causing the flying curve phenomenon to a size smaller than the original size, and at least one dot adjacent to the dot causing the flying curve phenomenon to the original A printing apparatus characterized in that the size is changed to a size larger than the size. The printing apparatus according to any one of claims 1 to 5,
The dot size changing means changes the dot causing the flying curve phenomenon to a size larger than the original size, and at least one dot adjacent to the dot causing the flying curve phenomenon to the original A printing apparatus characterized in that it is changed to a size smaller than the size or disappears. Computer
Flight curve information acquisition means for acquiring flight curve information of a print head that prints dots of different sizes;
Print data generating means for generating print data in which dots corresponding to each pixel of N-value (2 ≦ N) image data are set;
Among the dots of the print data generated by the print data generation unit, the dot causing the flight curve phenomenon determined based on the flight curve information of the print head acquired by the flight curve information acquisition unit and the vicinity thereof Dot size changing means for changing the dot size;
A printing program that functions as a printing unit that executes printing based on print data whose dot size has been changed by the dot size changing unit.   A computer-readable recording medium on which the printing program according to claim 8 is recorded. A flight curve information acquisition step for acquiring flight curve information of a print head that prints dots of different sizes;
A print data generation step for generating print data in which dots corresponding to each pixel of N-value (2 ≦ N) image data are set;
Among the dots of the print data generated in the print data generation step, the dot causing the flight curve phenomenon determined based on the flight curve information of the print head acquired in the flight curve information acquisition step and the dot A dot size changing step for changing the size of neighboring dots;
And a printing step for executing printing based on the print data whose dot size has been changed by the dot size changing step. Flight curve information acquisition means for acquiring flight curve information of a print head that prints dots of different sizes;
Print data generating means for generating print data in which dots corresponding to each pixel of N-value (2 ≦ N) image data are set;
Among the dots of printing data generated by the printing data generation means, the dots causing the flight bending phenomenon determined based on the flight bending information of the print head acquired by the flight bending information acquisition means, and the dot An image processing apparatus comprising: dot size changing means for changing the size of neighboring dots. Computer
Flight curve information acquisition means for acquiring flight curve information of a print head that prints dots of different sizes;
Print data generating means for generating print data in which dots corresponding to each pixel of N-value (2 ≦ N) image data are set;
Among the dots of the printing data generated by the printing data generation means, the dot causing the flight bending phenomenon determined based on the flight bending information of the print head acquired by the flight bending information acquisition means and the dot An image processing program that functions as dot size changing means for changing the size of neighboring dots.   A computer-readable recording medium on which the image processing program according to claim 12 is recorded. A flight curve information acquisition step for acquiring flight curve information of a print head that prints dots of different sizes;
A print data generation step for generating print data in which dots corresponding to each pixel of N-value (2 ≦ N) image data are set;
Among the dots of the print data generated in the print data generation step, the dot causing the flight curve phenomenon determined based on the flight curve information of the print head acquired in the flight curve information acquisition step and the dot And a dot size changing step for changing the size of neighboring dots.

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