Patent Grant
9162498
1. Field of the Invention
The present invention relates to an ink jet printing apparatus and an image processing apparatus.
2. Description of the Related Art
In a serial type ink jet printing apparatus, a printing scan in which a printing head is moved while causing the printing head to eject ink in accordance with image data and a conveyance operation to convey a printing medium in a direction intersecting the direction of the printing scan are repeated alternately. At this time, there is a case where a joint streak occurs at the boundary part between the regions in which printing is performed by printing scans performed twice successively in the printing medium.
For example, Japanese Patent Laid-Open No. H08-25693 (1996) has disclosed the method for causing printing regions in which printing scans are performed twice successively to overlap each other to a certain extent in the conveyance direction and adjusting the number of dots that are printed in the overlapped region by using a mask pattern. At this time, by using a gradation mask pattern by which the printing ratio at end parts of the printing head is reduced gradually, it is possible to suppress unevenness in density in each overlapped region.
Further, Japanese Patent Laid-Open No. 2002-36524 has disclosed the method for counting the number of dots that are printed in the vicinity of the boundary part and adjusting the thinning ratio at the boundary part in accordance with the number of counted dots without providing an overlapped region. Conspicuity of the joint streak depends on the gradations, i.e., the number of dots that are printed, but by adopting Japanese Patent Laid-Open No. 2002-36524, it is possible to appropriately adjust the number of dots at the boundary part in accordance with the gradations, and therefore, it is made possible to make less conspicuous the joint streak regardless of the density. On the other hand, Japanese Patent Laid-Open No. 2008-922 has disclosed a method for adding dots at the joint part region by focusing on, in particular, a white streak.
However, in the case where Japanese Patent Laid-Open No. H08-25693 (1996) is adopted, the number of times of printing scan required to print an image is different between the overlapped region and the other region. Specifically, in the case of the one-pass printing, in the overlapped region, ink is given during the printing scans performed twice, but in the other region, ink is given during the printing scan performed once. As a result of that, for example, in the case where printing is performed on glossy paper by using, for example, a pigment ink, there is produced a difference in the degree of irregularities of the image surface, i.e., smoothness between the overlapped region and the other region, and the difference may be erroneously recognized as glossiness unevenness. Further, in the case where mixed-color printing is performed by using inks in two or more colors, there is produced a difference in the color tone and saturation between the overlapped region and the other region and the difference may be erroneously recognized as color unevenness.
According to the intensive examination by the inventors etc., of the present invention, even in the case where Japanese Patent Laid-Open No. 2002-36524 was adopted and the thinning ratio at the boundary region was adjusted in accordance with the gradation without providing the overlapped region, it was recognized that the joint streak was not reduced sufficiently or the joint streak was made more conspicuous on the contrary. The reason the joint streak was not reduced sufficiently is that conventionally, the number of dots was adjusted only in specific regions adjacent to the boundary part despite the fact that the range in which the joint streak appears (thickness of the joint streak) varies depending on a variety of conditions, such as the kind of ink, printing medium, etc.
The present invention has been made in order to solve the above-described problems. Consequently, an object thereof is to provide an ink jet printing apparatus and an image processing apparatus capable of stably outputting an image with no joint streak even in the case where the printing conditions, such as the kind of ink and the kind of printing medium, vary in a variety of ways.
In a first aspect of the present invention, there is provided an ink jet printing apparatus that prints an image on a printing medium by repeating a printing scan in which an eject port column in which a plurality of eject ports for ejecting ink in accordance with image data is arrayed is moved with respect to the printing medium and a conveyance operation to convey the printing medium in a direction intersecting the direction of the printing scan, the ink jet printing apparatus comprising: a conveyance control unit configured to control the conveyance operation so that a position where printing is performed by an eject port located at one end part of the eject port column in a first printing scan and a position where printing is performed by an eject port located at the other end part of the eject port column in a second printing scan are adjacent to each other in the direction of the conveyance on the printing medium; and a correction unit configured to perform correction processing for increasing or decreasing the number of times of ink eject for image data corresponding to a first eject port group consisting of a plurality of successive eject ports including the eject port located at the one end part in the first printing scan and for image data corresponding to a second eject port group consisting of a plurality of successive eject ports including the eject port located at the other end part in the second printing scan, wherein the correction unit sets the number of eject ports included in the first eject port group and the number of eject ports included in the second eject port group in accordance with a set printing condition.
In a second aspect of the present invention, there is provided an image processing apparatus that performs processing on multivalued image data corresponding to a unit region for printing an image in the unit region including a plurality of pixel regions on a printing medium by a plurality of scans of a an eject port column in which a plurality of eject ports for ejecting ink are arrayed in a predetermined direction with respect to the printing medium, wherein the plurality of eject ports ejects ink to each of the plurality of pixel regions on the printing medium in accordance with dot printing data corresponding to each of the plurality of scans, and by conveying the printing medium between the plurality of scans, the image processing apparatus comprising: a first acquisition unit configured to acquire information on printing conditions; a second acquisition unit configured to acquire information on a density of an image that is printed in the pixel region; a third acquisition unit configured to acquire N (≧3)-valued quantized data corresponding to the pixel region based on the image data; a fourth acquisition unit configured to acquire a plurality of dot arrangement pattern groups including at least a first dot arrangement pattern group including a plurality of first dot arrangement patterns in which an arrangement of dots is determined so that the number and position of dots that are printed within the pixel region are different in accordance with a value of the N-valued quantized data and a second dot arrangement pattern group including a plurality of second dot arrangement patterns in which an arrangement of dots is determined so that the number and position of dots that are printed within the pixel region are different in accordance with a value of the N-valued quantized data; a setting unit configured to set one dot arrangement pattern group from the plurality of dot arrangement pattern groups acquired by the fourth acquisition unit in accordance with the positions of the plurality of pixel regions within the unit region; and a generation unit configured to generate the dot printing data based on the N-valued quantized data acquired by the third acquisition unit and the dot arrangement pattern group set by the setting unit, wherein the number of dots that are printed within the pixel region determined by the second dot arrangement pattern corresponding to the N-valued quantized data having a predetermined value is smaller than the number of dots that are printed within the pixel region determined by the first dot arrangement pattern corresponding to the N-valued quantized data having the predetermined value, and the setting unit sets the dot arrangement pattern group so that: (i) the number of the second dot arrangement pattern groups determined for the plurality of pixel regions located in an end part region corresponding to an end part of the eject port column in the predetermined direction within the unit region in a case where a printing condition indicated by the information acquired by the first acquisition unit is a first printing condition and the density of the image indicated by the information acquired by the second acquisition unit is a first value is smaller than the number of the second dot arrangement pattern groups determined for the plurality of pixel regions located in the end part region in a case where a printing condition indicated by the information acquired by the first acquisition unit is the first printing condition and the density of the image indicated by the information acquired by the second acquisition unit is a second value lower than the first value; (ii) the number of the second dot arrangement pattern groups determined for the plurality of pixel regions located in the end part region in a case where a printing condition indicated by the information acquired by the first acquisition unit is a second printing condition different from the first printing condition and the density of the image indicated by the information acquired by the second acquisition unit is the first value is smaller than the number of the second dot arrangement pattern groups determined for the plurality of pixel regions located in the end part region in a case where a printing condition indicated by the information acquired by the first acquisition unit is the second printing condition and the density of the image indicated by the information acquired by the second acquisition unit is the second value; and (iii) the number of the second dot arrangement pattern groups determined for the plurality of pixel regions located in the end part region in a case where a printing condition indicated by the information acquired by the first acquisition unit is the first printing condition and the density of the image indicated by the information acquired by the second acquisition unit is the second value is smaller than the number of the second dot arrangement pattern groups determined for the plurality of pixel regions located in the end part region in a case where a printing condition indicated by the information acquired by the first acquisition unit is the second printing condition and the density of the image indicated by the information acquired by the second acquisition unit is the second value, and the number of the first dot arrangement pattern groups determined for the plurality of pixel regions located in the end part region in a case where a printing condition indicated by the information acquired by the first acquisition unit is the first printing condition and the density of the image indicated by the information acquired by the second acquisition unit is the second value is larger than the number of the first dot arrangement pattern groups determined for the plurality of pixel regions located in the end part region in a case where a printing condition indicated by the information acquired by the first acquisition unit is the second printing condition and the density of the image indicated by the information acquired by the second acquisition unit is the second value.
In a third aspect of the present invention, there is provided an image processing apparatus that performs processing on multivalued image data corresponding to a unit region for printing an image in the unit region including a plurality of pixel regions on a printing medium by a plurality of scans of a an eject port column in which a plurality of eject ports for ejecting ink are arrayed in a predetermined direction with respect to the printing medium, wherein the plurality of eject ports ejects ink to each of the plurality of pixel regions on the printing medium in accordance with dot printing data corresponding to each of the plurality of scans, and by conveying the printing medium between the plurality of scans, the image processing apparatus comprising: a first acquisition unit configured to acquire information on printing conditions; a second acquisition unit configured to acquire information on a density of an image that is printed in the pixel region; a third acquisition unit configured to acquire N (≧3)-valued quantized data corresponding to the pixel region based on the image data; a fourth acquisition unit configured to acquire a plurality of dot arrangement pattern groups including at least a first dot arrangement pattern group including a plurality of first dot arrangement patterns in which an arrangement of dots is determined so that the number and position of dots that are printed within the pixel region are different in accordance with a value of the N-valued quantized data and a second dot arrangement pattern group including a plurality of second dot arrangement patterns in which an arrangement of dots is determined so that the number and position of dots that are printed within the pixel region are different in accordance with a value of the N-valued quantized data; a setting unit configured to set one dot arrangement pattern group from the plurality of dot arrangement pattern groups acquired by the fourth acquisition unit in accordance with the positions of the plurality of pixel regions within the unit region; and a generation unit configured to generate the dot printing data based on the N-valued quantized data acquired by the third acquisition unit and the dot arrangement pattern group set by the setting unit, wherein the number of dots that are printed within the pixel region determined by the second dot arrangement pattern corresponding to the N-valued quantized data having a predetermined value is larger than the number of dots that are printed within the pixel region determined by the first dot arrangement pattern corresponding to the N-valued quantized data having the predetermined value, and the setting unit sets the dot arrangement pattern group so that: (i) the number of the second dot arrangement pattern groups determined for the plurality of pixel regions located in an end part region corresponding to an end part of the eject port column in the predetermined direction within the unit region in a case where a printing condition indicated by the information acquired by the first acquisition unit is a first printing condition and the density of the image indicated by the information acquired by the second acquisition unit is a first value is smaller than the number of the second dot arrangement pattern groups determined for the plurality of pixel regions located in the end part region in a case where a printing condition indicated by the information acquired by the first acquisition unit is the first printing condition and the density of the image indicated by the information acquired by the second acquisition unit is a second value higher than the first value; (ii) the number of the second dot arrangement pattern groups determined for the plurality of pixel regions located in the end part region in a case where a printing condition indicated by the information acquired by the first acquisition unit is a second printing condition different from the first printing condition and the density of the image indicated by the information acquired by the second acquisition unit is the first value is smaller than the number of the second dot arrangement pattern groups determined for the plurality of pixel regions located in the end part region in a case where a printing condition indicated by the information acquired by the first acquisition unit is the second printing condition and the density of the image indicated by the information acquired by the second acquisition unit is the second value; and (iii) the number of the second dot arrangement pattern groups determined for the plurality of pixel regions located in the end part region in a case where a printing condition indicated by the information acquired by the first acquisition unit is the first printing condition and the density of the image indicated by the information acquired by the second acquisition unit is the second value is smaller than the number of the second dot arrangement pattern groups determined for the plurality of pixel regions located in the end part region in a case where a printing condition indicated by the information acquired by the first acquisition unit is the second printing condition and the density of the image indicated by the information acquired by the second acquisition unit is the second value, and the number of the first dot arrangement pattern groups determined for the plurality of pixel regions located in the end part region in a case where a printing condition indicated by the information acquired by the first acquisition unit is the first printing condition and the density of the image indicated by the information acquired by the second acquisition unit is the second value is larger than the number of the first dot arrangement pattern groups determined for the plurality of pixel regions located in the end part region in a case where a printing condition indicated by the information acquired by the first acquisition unit is the second printing condition and the density of the image indicated by the information acquired by the second acquisition unit is the second value.
In a fourth aspect of the present invention, there is provided an image processing apparatus that performs processing on multivalued image data corresponding to a unit region for printing an image in the unit region including a plurality of pixel regions on a printing medium by a plurality of scans of a an eject port column in which a plurality of eject ports for ejecting ink are arrayed in a predetermined direction with respect to the printing medium, wherein the plurality of eject ports ejects ink to each of the plurality of pixel regions on the printing medium in accordance with dot printing data corresponding to each of the plurality of scans, and by conveying the printing medium between the plurality of scans, the image processing apparatus comprising: a first acquisition unit configured to acquire information on printing conditions; a second acquisition unit configured to acquire information on a density of an image that is printed in the pixel region; a third acquisition unit configured to acquire N (≧3)-valued quantized data corresponding to the pixel region based on the image data; a fourth acquisition unit configured to acquire a plurality of dot arrangement pattern groups including at least a first dot arrangement pattern group including a plurality of first dot arrangement patterns in which an arrangement of dots is determined so that the number and position of dots that are printed within the pixel region are different in accordance with a value of the N-valued quantized data and a second dot arrangement pattern group including a plurality of second dot arrangement patterns in which an arrangement of dots is determined so that the number and position of dots that are printed within the pixel region are different in accordance with a value of the N-valued quantized data; a setting unit configured to set one dot arrangement pattern group from the plurality of dot arrangement pattern groups acquired by the fourth acquisition unit in accordance with the positions of the plurality of pixel regions within the unit region; and a generation unit configured to generate the dot printing data based on the N-valued quantized data acquired by the third acquisition unit and the dot arrangement pattern group set by the setting unit, wherein the number of dots that are printed within the pixel region determined by the second dot arrangement pattern corresponding to the N-valued quantized data having a predetermined value of the first and second dot arrangement pattern groups is smaller than the number of dots that are printed within the pixel region determined by the first dot arrangement pattern corresponding to the N-valued quantized data having the predetermined value, and the setting unit sets the dot arrangement pattern group so that the number of the second dot arrangement pattern groups determined for the plurality of pixel regions located in the end part region in a case where a printing condition indicated by the information acquired by the first acquisition unit is a first printing condition and the density of the image indicated by the information acquired by the second acquisition unit is a predetermined value is smaller than the number of the second dot arrangement pattern groups determined for the plurality of pixel regions located in the end part region in a case where a printing condition indicated by the information acquired by the first acquisition unit is a second printing condition different from the first printing condition and the density of the image indicated by the information acquired by the second acquisition unit is the predetermined value, and the number of the first dot arrangement pattern groups determined for the plurality of pixel regions located in the end part region in a case where a printing condition indicated by the information acquired by the first acquisition unit is the first printing condition and the density of the image indicated by the information acquired by the second acquisition unit is the predetermined value is larger than the number of the first dot arrangement pattern groups determined for the plurality of pixel regions located in the end part region in a case where a printing condition indicated by the information acquired by the first acquisition unit is the second printing condition and the density of the image indicated by the information acquired by the second acquisition unit is the predetermined value.
Further features of the present invention will become apparent from the following description of exemplary embodiments (with reference to the attached drawings).
Hereinafter, embodiments of the present invention are explained in detail with reference to the drawings.
<Explanation of Printing Apparatus>
The optical sensor 32 determines whether or not there exists a printing medium on the platen 4 by performing the detection operation while moving together with the carriage 1. At a position in the scan region of the carriage 1 and apart from the platen 4, a recovery unit 30 configured to perform maintenance processing of the printing head 5 is arranged.
<Explanation of Printing Head>
<Explanation of Control Unit>
<Explanation of Printing Data Generation Processing>
The CPU 301 having received the three-valued image data converts the 600 dpi quantized data 603 into 1,200 dpi binary printing data 604 by referring to a dot arrangement pattern stored in the ROM 302 in advance. Further, after performing processing characteristic to the present invention, as will be described later, the printing data is accumulated in a print buffer prepared within the RAM 303. The printing data is binary data that determines printing (1) or non-printing (0) for each of 2×2 pixels arrayed in 1,200 dpi.
After the printing data corresponding to one or more scans is accumulated in the RAM 303, the CPU 301 performs a printing operation based on the printing data 604 in accordance with the program stored in the ROM 302. Specifically, the CPU 301 causes the printing head 5 to perform the eject operation while reading the binary printing data 604 by an amount corresponding to one scan each time. At this time, the printing resolution in the main scan direction may be set to 1,200 dpi, but it may also be set to 600 dpi. In the case of 600 dpi, the dots corresponding to printing data 1 and 2 put side by side in the main scan direction are printed repeatedly at a pixel position A as is known by referring to printing results 605. Dots corresponding to printing data 3 and 4 are printed repeatedly at a pixel position B. The CPU 301 prints an image corresponding to one page on a printing medium by causing the printing head 5 to perform the eject operation in accordance with the printing data 604 while controlling the drive of the various kinds of motors as required via the input/output port 304.
As to level 0, the number of printing pixels (area represented in black) is zero in the patterns I to III and that is one in the pattern IV. As to level 1, the number of printing pixels is one in the patterns I and II, that is zero in the pattern III, and that is two in the pattern IV. As to level 2, the number of printing pixels is two in the patterns I and II, that is one in the pattern III, and that is three in the pattern IV. Further, as to level 3, the number of printing pixels is three in the patterns I and II, that is two in the pattern III, and that is four in the pattern IV. By comparing the four kinds of patterns, it is known that in the patterns I and II, the number of printing pixels increases in regular order as the level number increases, but in the pattern III, the number of printing pixels is made equal to or less than that in the patterns I and II and in the pattern IV, the number of printing pixels is increased compared to that in the patterns I and II. It is known that the number of low frequency components in the frequency region included in the binary data generated by using the pattern III is larger than the number of low frequency components in the frequency region included in the binary data generated by using the patterns I and II. Further, it is also known that the number of high frequency components in the frequency region included in the binary data generated by using the pattern IV is larger than the number of high frequency components in the frequency region included in the binary data generated by using the patterns I and II. In the present specification, the pattern in which the number of printing pixels increases in regular order as the level number increases, as the patterns I and II, is referred to as a first dot arrangement pattern group. The pattern in which the number of printing pixels is larger or smaller than that of the first dot arrangement pattern, such as the pattern III and the pattern IV, is referred to as a second dot arrangement pattern group. In the present embodiment, these four kinds of dot arrangement patterns are prepared and at the boundary part where the black streak is comparatively apt to be conspicuous, the binarization processing is performed by referring to the pattern III in order to make the black streak no longer conspicuous by suppressing the number of dots. At the boundary part where the white streak is comparatively apt to be conspicuous, the binarization processing is performed by referring to the pattern IV in order to make the white streak no longer conspicuous by increasing the number of dots. In
In the case where the pattern selection table A such as this is used, in the one-pixel widths at the upper end and at the lower end, printing is performed with more dots increased by addition than those at the center as a result. In other words, the number of times of eject of the first eject port group 701 and the second eject port group 702 is increased compared to that of the eject ports other than these eject port groups. Because of this, the pattern selection table A will be a table effective in the case where the white streak is conspicuous at the boundary between the region that is printed by the first eject port group in the first printing scan and the region that is printed by the second eject port group in the second printing scan.
On the other hand, in the pattern selection table B shown in
Conspicuity of the black streak or the white streak varies in accordance with the image density. For example, even in the case where printing is performed on the same printing medium by using the same ink, the black streak that is conspicuous in the low density may be less conspicuous in the high density. In such circumstances, in the case where the pattern selection table B shown in
Here, a method for setting the density increase/decrease parameter P is explained. The density increase/decrease parameter P is adjusted so that the more conspicuous the white streak, the more the pattern selection tables A are set and the more conspicuous the black streak, the more the pattern selection tables B are set in an image that is printed. At this time, conspicuity of the white streak or the black streak can be determined by, for example, the L*a*b* value of the original image data, but here, an example is explained in which the density data 602 of black K is used as an evaluation value. In this case, the evaluation value may take a value between 0 and 255.
In the present embodiment, the dot arrangement pattern that is used in each pixel is determined by comparing the parameter set for each pixel by the table setting matrix α with the density increase/decrease parameter P. Specifically, in the case where the parameter of the table setting matrix α is larger than the density increase/decrease parameter P, to the pixel, the dot arrangement pattern set to the corresponding pixel of the pattern selection table A is allocated. On the other hand, in the case where the parameter of the table setting matrix α is equal to or smaller than the density increase/decrease parameter P, to the pixel, the dot arrangement pattern set to the corresponding pixel of the pattern selection table B is allocated.
For example, in the region except for the pixel rows at the upper and lower ends of the table setting matrix α, the parameter data is uniformly “16” and this is larger than the density increase/decrease parameter P=“8”. Consequently, in this region, the dot arrangement patterns I and II set in the corresponding region of the pattern selection table A are set exactly in accordance with the array. On the other hand, the parameters in the pixel row regions at the upper and lower ends of the table setting matrix α are “1” to “16” and half the parameters are larger than the density increase/decrease parameter P=“8” but the remaining half are equal to or less than the density increase/decrease parameter P=“8”. Because of this, in these regions, the dot arrangement pattern II set in the pattern selection table A and the dot arrangement pattern I set in the pattern selection table B are allocated alternately in accordance with the pixel position. As a result of that, in the pattern table C that is used for actual printing, the dot arrangement patterns I and II are alternately arranged uniformly both in the pixel row regions at the upper and lower ends and in the other region.
Here, referring to
On the other hand,
Here, referring to
Further,
Here, referring to
As above, as explained by using
In the examples in
In a pattern selection table D shown in
On the other hand, in a pattern selection table E shown in
In the case where the density increase/decrease parameter is 8, the pattern table Z in which the dot arrangement patterns I and II are arranged alternately is generated as shown in
In the case where the density parameter is 0, the dot arrangement pattern IV is allocated to half (48 in total) the pixels in all the pixel rows in the end part regions (three pixel rows at the upper and lower ends) as shown in
Further, in the case where the density parameter is 16, the dot arrangement pattern III is allocated to half (48 in total) the pixels in all the pixel rows in the end part regions (three pixel rows at the upper and lower ends) as shown in
After this, a method in that which of the combination of the pattern selection tables A and B and the table setting matrix α and the combination of the pattern selection tables D and E and the table setting matrix β is used is determined in accordance with a variety of printing conditions and printing data (dot printing data) is generated by using the determined combination of the pattern selection tables and the table setting matrix.
In the first embodiment, a method for making the correction width different in accordance with the kind of ink (in particular, ink lightness) is explained. The degree of the dots spreading or the conspicuity of the joint streak may be different depending on the kind of ink even though the printing medium is the same. In particular, in the case where inks having the same color tone but different in lightness are used, such as cyan and light cyan, and magenta and light magenta, are used at the same time, in many cases, the ink having a high lightness is printed in a high density for all the gradation region compared to the ink having a low lightness and the joint streak is apt to be conspicuous. Then, in this case, the joint streak of the ink having a high lightness is affected not only by dots in the one pixel row at the uppermost end and the lowermost end which sandwich the boundary part but also by dots that are printed in a plurality of pixel rows around the boundary part.
Consequently, in the present embodiment, among the inks in six colors shown in
In the second embodiment, a method for making the correction width different in accordance with the kind of printing medium is explained. The degree of dots spreading or conspicuity of the joint streak is different depending on the kind of printing medium. For example, in the case of the printing medium on which ink is comparatively unlikely to blur, such as glossy paper, the diameter of printed dot is small and the number of pixel rows that affect the density of the joint streak is small. In contrast to this, in the case of the printing medium on which ink is comparatively likely to blur, such as plain paper and coated paper, the diameter of printed dot is large and the number of pixel rows that affect the density of the joint streak is large.
Consequently, in the present embodiment, in the case where the printing medium on which ink is comparatively unlikely to blur, such as glossy paper, is used, the pattern table C is acquired from the combination of the pattern selection tables A and B and the table setting matrix α shown in
In the third embodiment, the case where the correction width is made different in accordance with the eject amount in a configuration in which a printing head capable of ejecting ink droplets in a variety of eject amounts is used. In recent years, in order to implement high gradation properties, a printing head including an eject port column for printing with large dots and an eject port column for printing with small dots in the same ink color is provided. In this case, the dot diameter of the large dot is larger than that of the small dot, and therefore, the number of pixel rows that affect the density of the joint streak is larger in the case of the large dot.
Consequently, in the present embodiment, for the eject port column for printing with small dots, the pattern table C is acquired from the combination of the pattern selection tables A and B and the table setting matrix α shown in
In the fourth embodiment, a method for making the correction width different in accordance with image data that is input.
On the other hand,
In other words, by comparing
In a pattern selection table F shown in
On the other hand, in a pattern selection table G shown in
In the present embodiment, in the case of the density data at about level 1, the pattern table C that is used for printing is acquired from the combination of the pattern selection tables D and E and the table setting matrix β shown in
In the above, the case where the correction width is made different between the density data at about level 1 and the density data at about level 2 is explained by using an example in which there are three quantization values. However, it is also possible to increase the number of quantization values, i.e., the number of level values. Even in the case where there are more level values, it is possible to adjust the correction width to an appropriate value both in the case where the level value is a first value and in the case where the level value is a second value greater than the first value.
In the fifth embodiment, an aspect is explained, in which a transparent ink for facilitating fixing of inks is provided in addition to the inks in six colors shown in
Consequently, in the present embodiment, even in the case where the printing medium is the same, in the printing mode in which the transparent ink is used, the pattern table C for the colored ink is acquired from the combination of the pattern selection tables A and B and the table setting matrix α shown in
According to the present embodiment such as this, it is possible to perform the addition or reduction of dots by an appropriate amount in an appropriate correction width in accordance with use/non-use of the transparent ink, and therefore, it is made possible to output a uniform image with no joint streak regardless of the printing mode.
In the sixth embodiment, a method for correcting the joint streak in the case where the streak is limited to the black streak is explained.
In the table setting matrix α, the parameters in the region except for the pixel rows at the upper and lower ends are uniformly “16”, which is larger than the density increase/decrease parameter P=“8”. Consequently, in this region, the dot arrangement patterns I and II set in the corresponding region of the pattern selection table A′ are set exactly as they are. On the other hand, the parameter in the pixel rows at the upper and lower ends of the table setting matrix α is any of “1” to “16” and half the parameters are larger than the density increase/decrease parameter P “8” but the remaining half are equal to or less than the density increase/decrease parameter P=“8”. Because of this, to this region, the dot arrangement pattern I or II set in the pattern selection table A and the dot arrangement pattern III or IV set in the pattern selection table B are allocated alternately in accordance with the pixel position. As a result of that, in the pattern table C, only in the pixel rows at the upper and lower ends, the dot arrangement pattern III or IV that causes the reduction of dots is arranged.
Then, according to the present embodiment, it is designed so that the closer the density increase/decrease parameter to “16”, the more the number of pixels in which the dot arrangement patterns III or IV are set increases in the boundary region and also the more the number of dots that are reduced from the boundary region also increases. In other words, according to the present embodiment, by adjusting the density increase/decrease parameter P in the range of 1 to 16 in accordance with conspicuity of the black streak, it is possible to perform the reduction of dots by an appropriate amount so as to make the black streak no longer conspicuous.
At this time, also in the present embodiment, a plurality of pattern selection tables whose correction width is made different may be prepared, such as the pattern selection tables D and E and the pattern selection tables F and G with respect to the pattern selection tables A and B. Then, by making the correction width different in accordance with a variety of conditions as explained in the first to fourth embodiments, it is made possible to appropriately eliminate the black steak.
In the seventh embodiment, in contrast to the sixth embodiment, a correction method in the case where the joint streak is limited to the white streak is explained.
In the case where the dot arrangement patterns such as these are used together with the pattern selection tables A′ and B′ used in the sixth embodiment, the pattern selection table A′ will be a table that does not increase or decrease dots in the boundary region and the pattern selection table B′ will be a table that adds dots in the boundary region. Then, by using the dot arrangement patterns shown in
In
In the above, explanation is given by using the aspect in which the four kinds of dot arrangement patterns I to IV are prepared, but the present invention is not limited to this aspect. In the above explanation, 2×2 dot arrangement patterns are used in order to convert the three-valued data in 600 dpi into the binary data in 1,200 dpi, but in the case where the output resolution is still higher compared to the input resolution, the number of pixels included in the dot arrangement patterns will also increase accordingly. In this case, it is possible to prepare a larger number of kinds of dot arrangement patterns in which dot array methods or the numbers of dots that are added (or reduced) are made different from one another.
In the printing scans performed twice successively, the joint streak does not necessarily appear in symmetry with respect to the boundary part as a center. There is a case where the joint streak appears at a position above the boundary part or a case where the joint streak appears at a position below the boundary part. In view of such circumstances, in the present embodiment, a configuration is explained, in which a correction width is set at only one of the upper end and the lower end of the eject port column (i.e., at only one of the upper end and the lower end of the pattern selection table).
On the other hand, pattern selection tables J and K and a table setting matrix ε shown in
In the above, the configuration in which the correction width is set at the lower end of the pattern selection table is explained by using the case where the joint streak appears at the position at the lower end of the eject port column as an example, but in the case where the joint streak appears at the position at the upper end of the eject port column, it is sufficient to set the correction width at the upper end of the pattern selection table.
The parameter array in the correction width region in the table setting matrix is not limited to the aspect explained in the above-described embodiment. In the table setting matrix explained in the above-described embodiment, in the correction width region, one and the different one of 1 to 16 is allocated to each of the 16 pixels arrayed in the X direction and in the Y direction, these parameters are allocated in the state of being shifted in the X direction. However, a matrix that can be adopted in the present invention does not need to be a matrix having such an array. For example, it may also be possible to use a matrix in which parameters 1 to 16 are arranged in the Bayer arrangement in the two-dimensional region of 16 pixels×3 pixels as in
In the above-described embodiment, the number of pixels in the Y direction in the pattern selection table and in the table setting matrix is set to the number of pixels equal to the width of the eject port column used in printing, but the size of the pattern selection table and the table setting matrix is not limited to this. However, in the case where a plurality of pattern selection tables is arranged as in
Further, in the above, the aspect is explained in which a plurality of pattern selection tables and a plurality of table setting matrixes are prepared in advance in correspondence to several correction widths, but the present invention is not limited to the aspect such as this. A configuration may be accepted in which the pattern selection table and the table setting matrix corresponding to the correction width in accordance with the printing conditions are generated at each time of printing.
Furthermore, in the above, explanation is given by premising that the one-pass printing is performed, but the configuration of the present invention can also be adopted even in the case where multi-pass printing is performed. Even in the case of multi-pass printing, the position where the joint streak appears is fixed, and therefore, by preparing pattern selection tables and a table setting matrix whose correction width is matched with such a position and by adjusting the correction width in accordance with the printing conditions, it is possible to obtain the same effect as that in the above-described embodiment.
Still furthermore, in the above, the pattern selection tables and the table setting matrix are used in order to perform the addition or reduction of dots for the limited region in the vicinity of the boundary region, but the present invention is not limited to this. As in Japanese Patent Laid-Open No. 2002-36524 already explained, even in the aspect in which dots of the data after being turned into binary data is counted in the vicinity of the boundary region and the addition or reduction of dots is performed by using a mask pattern etc., it is possible to adopt the processing characteristic to the present invention such that the correction width is changed in accordance with the printing conditions. In this case, for example, it is sufficient to set the correction width in accordance with the lightness of the ink that is used and to perform the addition or reduction of dots by using one of a plurality of mask patterns whose thinning ratio is different from one another for the set correction width.
Embodiment(s) of the present invention can also be realized by a computer of a system or apparatus that reads out and executes computer executable instructions (e.g., one or more programs) recorded on a storage medium (which may also be referred to more fully as a ‘non-transitory computer-readable storage medium’) to perform the functions of one or more of the above-described embodiment(s) and/or that includes one or more circuits (e.g., application specific integrated circuit (ASIC)) for performing the functions of one or more of the above-described embodiment(s), and by a method performed by the computer of the system or apparatus by, for example, reading out and executing the computer executable instructions from the storage medium to perform the functions of one or more of the above-described embodiment(s) and/or controlling the one or more circuits to perform the functions of one or more of the above-described embodiment(s). The computer may comprise one or more processors (e.g., central processing unit (CPU), micro processing unit (MPU)) and may include a network of separate computers or separate processors to read out and execute the computer executable instructions. The computer executable instructions may be provided to the computer, for example, from a network or the storage medium. The storage medium may include, for example, one or more of a hard disk, a random-access memory (RAM), a read only memory (ROM), a storage of distributed computing systems, an optical disk (such as a compact disc (CD), digital versatile disc (DVD), or Blu-ray Disc (BD™), a flash memory device, a memory card, and the like.
While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
This application claims the benefit of Japanese Patent Application No. 2013-265352, filed Dec. 24, 2013, which is hereby incorporated by reference wherein in its entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2013-265352 | Dec 2013 | JP | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 7438374 | Shibata et al. | Oct 2008 | B2 |
| 7950766 | Ejiri et al. | May 2011 | B2 |
| 8007070 | Kaga et al. | Aug 2011 | B2 |
| 8434846 | Tanaka | May 2013 | B2 |
| 8926054 | Emoto et al. | Jan 2015 | B2 |
| Number | Date | Country |
|---|---|---|
| 08-025693 | Jan 1996 | JP |
| 2002-36524 | Feb 2002 | JP |
| 2008-000922 | Jan 2008 | JP |
| Entry |
|---|
| U.S. Appl. No. 14/564,449, filed Dec. 9, 2014. |
| U.S. Appl. No. 14/564,442, filed Dec. 9, 2014. |
| Number | Date | Country | |
|---|---|---|---|
| 20150174930 A1 | Jun 2015 | US |
