JP2011037180A - Image processing method and apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image processing method and apparatus, which forms a dot arrangement pattern for recording an image of high quality without generating a curling and cockle when performing a recording with an ink jet recorder. <P>SOLUTION: For each pixel, the amount of color material for every ink color is calculated from image data, and the data on the amount of color material for every ink color is converted into the data on the dot arrangement using a conversion table for predetermined color material amount/dot arrangement. In this case, the conversion table to be used is chosen based on the amount of other color material (total of the amounts of color material of ink colors other than the ink color which is going to obtain the dot arrangement). <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image processing method and apparatus, and more particularly to an image processing method and apparatus for converting image data into dot arrangement data for each ink color.

  When an image is recorded on a general printing paper by an ink jet recording apparatus, paper warpage called curl or cockle occurs. Such curl and cockle are likely to occur remarkably in a region where the amount of ink droplets is large. A normal ink jet recording apparatus can eject ink of Bk (black) in addition to C (cyan), M (magenta), and Y (yellow). It is an image of “secondary color”. Therefore, in Patent Document 1, the occurrence of curling and cockle is suppressed by providing RGB ink in addition to YCMBk.

JP-A-9-272198

  However, as disclosed in Patent Document 1, when RGB ink is provided in addition to YCMBk, there is a disadvantage that the number of heads increases and the cost increases. In particular, in the case of a full-line head, since the head per color is large, increasing the number of heads greatly increases the cost.

  The present invention has been made in view of such circumstances, and an image processing method capable of generating a dot arrangement pattern capable of recording a high-quality image without causing curling or cockle when recording with an inkjet recording apparatus. And an apparatus.

  In order to achieve the above object, the invention according to claim 1 converts the image data into dot arrangement data for each ink color used in the inkjet recording apparatus in order to record the image data on a recording medium by the inkjet recording apparatus. In the image processing method to be converted, for each pixel, a step of obtaining a color material amount for each ink color from image data, and a sum of color material amounts of ink colors other than the ink color for which a dot arrangement is to be obtained for each pixel A conversion table that is applied to an ink color for which a dot arrangement is to be obtained from a plurality of prepared color material quantity / dot arrangement conversion tables for each pixel. The step of selecting for each ink color based on the amount of other color material and the conversion table selected for each ink color applied to each pixel To provide an image processing method comprising the step of converting the color material amount data for each of the ink colors in the dot arrangement data of each of the ink colors, in that it consists of.

  In the present invention, for each pixel, a color material amount for each ink color is obtained from image data, and a predetermined color material amount / dot arrangement conversion table (a conversion table for converting color material amount into dot arrangement data) is used. The color material amount data is converted into dot arrangement data for each ink color. At this time, the conversion table to be used is selected based on the amount of other color materials (the sum of the color material amounts of ink colors other than the ink color whose dot arrangement is to be obtained). For example, when the amount of other color material is large, the amount of droplet ejection of other ink is large, so a conversion table with a small total ink amount per pixel (the sum of the volumes of each ink droplet ejected to the pixel) is selected. . Decreasing the total amount of ink per pixel results in a large number of small volume ink droplets being ejected, so that the uneven color tends to be noticeable, but other colors of ink are also ejected. As a result, it is generally not noticeable. As a result, it is possible to suppress the total droplet ejection amount and prevent the occurrence of curling and cockle, and to record a high-quality image without streaks. On the other hand, when the amount of other color material is small, the amount of droplet ejection of the other color ink is small, so a conversion table with a large total ink amount per pixel is selected. When the total amount of ink per pixel is increased, a large volume of ink droplets is ejected in a small amount, so that it is difficult to visually recognize stripes. On the other hand, the amount of ink droplets to be ejected increases, but the amount of ink droplets to be ejected by other inks is small, so that the total droplet ejection amount can be suppressed, and the occurrence of curling and cockle can be prevented.

  According to a second aspect of the present invention, in order to achieve the object, a plurality of conversion tables having different total ink amounts per pixel are prepared as the conversion table, and the other color material is selected in the step of selecting the conversion table. The image processing method according to claim 1, wherein a conversion table having a smaller total ink amount per pixel is selected as the amount is larger.

  According to the present invention, a plurality of conversion tables having different total ink amounts per pixel are prepared. In the conversion table selection step, a conversion table with a smaller total ink amount per pixel is selected as the other color material amount is larger. That is, when the other color material amount is large, a conversion table with a small total ink amount per pixel is selected, and when the other color material amount is small, a conversion table with a large total ink amount per pixel is selected. When a conversion table with a small total ink amount per pixel is selected, stripe unevenness tends to be noticeable for that ink color, but ink of other colors is also ejected, so that stripe unevenness is generally not noticeable. As a result, it is possible to suppress the total droplet ejection amount and prevent the occurrence of curling and cockle, and to record a high-quality image without streaks. On the other hand, when a conversion table having a large total ink amount per pixel is selected, it is difficult to visually recognize stripes. In this case, although the amount of droplet ejection of the ink color increases, the amount of droplet ejection of other inks is small, so that the total droplet ejection amount can be suppressed and the occurrence of curling and cockle can be prevented. As a result, it is possible to suppress the total ink ejection amount and prevent the occurrence of curling and cockle, and to record a high-quality image in which uneven stripes are difficult to be visually recognized.

  According to a third aspect of the present invention, in order to achieve the object, two conversion tables having different total ink amounts per pixel are prepared as the conversion table. In the step of selecting the conversion table, the other color material is selected. When the amount of other color material exceeds the threshold value, a conversion table with a small total ink amount per pixel is selected, and when the amount of other color material is less than or equal to the threshold value, The image processing method according to claim 2, wherein a conversion table having a large total ink amount is selected.

  According to the present invention, two conversion tables having different total ink amounts per pixel are prepared. In the step of selecting the conversion table, the other color material amount is compared with the threshold value, and when the other color material amount exceeds the threshold value, a conversion table with a small total ink amount per pixel is selected, and the other color material amount is selected. Is equal to or smaller than the threshold value, a conversion table having a large total ink amount per pixel is selected. As a result, it is possible to suppress the total ink ejection amount and prevent the occurrence of curling and cockle, and to record a high-quality image in which uneven stripes are difficult to be visually recognized.

  In the invention according to claim 4, in order to achieve the object, the conversion table with a small total ink amount per pixel has a smaller average volume of ejected ink droplets than the conversion table with a large total ink amount per pixel. An image processing method according to claim 3 is provided.

  According to the present invention, the conversion table with a small total ink amount per pixel is set to have a smaller average volume of ejected ink droplets than the conversion table with a large total ink amount per pixel. That is, the conversion table is set so that the color materials are evenly arranged. Thereby, even if the total ink amount is suppressed, the color materials can be arranged uniformly and the color reproduction range can be improved.

  The invention according to claim 5 provides the image processing method according to claim 3 or 4, wherein the threshold is changed according to the type of the recording medium in order to achieve the object.

  According to the present invention, the threshold value is changed according to the type of the recording medium. By optimizing the threshold according to the type of the recording medium, it is possible to adjust the threshold for suppressing curl and cockle and the threshold for suppressing unevenness. That is, the threshold value is set high for a recording medium in which curling and cockle are unlikely to occur (a recording medium in which curling and cockle are unlikely to occur even if the total droplet ejection amount is large). Thereby, generation | occurrence | production of a stripe unevenness can be suppressed more effectively.

  In order to achieve the above object, the invention according to claim 6 measures the variation in the ejection direction of the ink droplets ejected from the head of the ink jet recording apparatus, and changes the threshold according to the measured variation. An image processing method according to claim 3 or 4 is provided.

  According to the present invention, the threshold value is changed according to variations in the ejection direction of the ink droplets ejected from the head. As a result, it is possible to perform image processing according to the variation in the ejection direction, and it is possible to record a high-quality image in which the uneven stripes are hardly visible. The threshold is set high when the variation is large.

  According to a seventh aspect of the present invention, in order to achieve the object, the image data is recorded in dot arrangement data for each ink color used in the ink jet recording apparatus in order to record the image data on a recording medium by the ink jet recording apparatus. In the image processing method to be converted, for each pixel, a step of obtaining a color material amount for each ink color from image data, and a color material amount / dot arrangement conversion table to be used for each ink color according to the pixel color The conversion table to be used for each ink color is determined for each pixel from the color information of each pixel, and each pixel is determined for each ink color. Applying a conversion table to convert the color material amount data for each ink color into dot arrangement data for each ink color. To provide an image processing method according to symptoms.

  In the present invention, for each pixel, the color material amount for each ink color is obtained from the image data, and the color material amount data for each ink color is converted to dot arrangement data using a predetermined color material amount / dot arrangement conversion table. Convert to At this time, the conversion table to be used is determined based on the color of each pixel. That is, since the color material amount of each ink color can be estimated by looking at the color of each pixel, the conversion table to be used can be estimated without obtaining the other color material amount. Therefore, a selection table that defines a conversion table to be used for each ink color corresponding to the pixel color is prepared in advance, and the conversion table to be used is determined based on the pixel color. As a result, the time required for image processing can be significantly reduced.

  In the invention according to claim 8, in order to achieve the object, the selection table estimates the color material amount for each ink color from the color of the pixel, and for each ink color, the color material amount of the other ink color. 8. The image processing method according to claim 7, wherein the conversion table is set such that the larger the sum is, the smaller the total ink amount per pixel is.

  According to the present invention, the selection table estimates the color material amount for each ink color from the color of the pixel, and for each ink color, the greater the sum of the color material amounts of the other ink colors, the greater the total ink amount per pixel. Set to use fewer translation tables.

  In the invention according to claim 9, in order to achieve the object, the conversion table is set so that an average volume of ejected ink droplets decreases as the total ink amount per pixel increases. An image processing method according to claim 8 is provided.

  According to the present invention, the conversion table is set so that the average volume of the ejected ink droplets decreases as the total ink amount per pixel increases. That is, the conversion table is set so that the color materials are evenly arranged. Thereby, even if the total ink amount is suppressed, the color materials can be arranged uniformly and the color reproduction range can be improved.

  According to a tenth aspect of the present invention, in order to achieve the object, the image data is converted into dot arrangement data for each ink color used in the ink jet recording apparatus in order to record the image data on a recording medium by the ink jet recording apparatus. In the image processing method to be converted, for each pixel, it should be used for each ink color according to the step of obtaining the color material amount for each ink color from the image data and the color material amount for each ink color obtained for each pixel A conversion table to be used for each ink color from the information on the color material amount for each ink color obtained for each pixel with reference to a selection table in which a conversion table for the color material amount / dot arrangement is defined. And a conversion table determined for each ink color is applied to each pixel, and the color material amount data for each ink color is applied to the pixel. To provide an image processing method comprising the steps of converting the dot arrangement data for each ink color, in that it consists of.

  In the present invention, for each pixel, the color material amount for each ink color is obtained from the image data, and the color material amount data for each ink color is converted to dot arrangement data using a predetermined color material amount / dot arrangement conversion table. Convert to At this time, the conversion table to be used is determined based on the color material amount of each ink color obtained for each pixel. In other words, if the color material amount for each ink color is known, the other color material amount can be obtained without obtaining it each time. Therefore, if the color material amount for each ink color is known, the conversion table to be used is uniquely determined. Therefore, a selection table that defines a conversion table to be used for each ink color is prepared in advance corresponding to the color material amount of each ink, and the conversion table to be used is determined based on the color material amount of each ink color. . As a result, the time required for image processing can be significantly reduced.

  According to an eleventh aspect of the present invention, in order to achieve the object, the selection table includes a conversion table in which the total ink amount per pixel is smaller as the sum of the color material amounts of other ink colors is larger for each ink color. The image processing method according to claim 10, wherein the image processing method is set to be used.

  According to the present invention, the conversion table is set such that the average volume of the ejected ink droplets increases as the total ink amount per pixel increases. That is, the conversion table is set so that the color materials are evenly arranged. Thereby, even if the total ink amount is suppressed, the color materials can be arranged uniformly and the color reproduction range can be improved.

  In the invention according to claim 12, in order to achieve the object, the conversion table is set so that an average volume of ejected ink droplets decreases as the total ink amount per pixel increases. An image processing method according to claim 11 is provided.

  According to the present invention, the conversion table is set so that the average volume of the ejected ink droplets decreases as the total ink amount per pixel increases. That is, the conversion table is set so that the color materials are evenly arranged. Thereby, even if the total ink amount is suppressed, the color materials can be arranged uniformly and the color reproduction range can be improved.

  According to a thirteenth aspect of the present invention, in order to achieve the above object, the ink jet recording apparatus performs a process of reacting with components in the ink on the recording medium before ejecting ink onto the recording medium and recording an image. The image processing method according to claim 1, wherein a liquid is applied and dried.

  According to the present invention, an ink jet recording apparatus that records image data on a recording medium is constituted by an ink jet recording apparatus that records an image by ejecting ink after applying a predetermined treatment liquid to the recording medium. In an ink jet recording apparatus that records an image by applying and drying a treatment liquid that reacts with components in the ink and then drying the dots due to reaction with the treatment liquid and drying of the solvent component. On the other hand, it is easier to notice stripes. Since the image processing method of the present invention can make it difficult to visually recognize stripes, it is particularly effective when recording image data with such an ink jet recording apparatus.

  In order to achieve the above object, the invention according to claim 14 converts the image data into dot arrangement data for each ink color used in the inkjet recording apparatus in order to record the image data on a recording medium by the inkjet recording apparatus. In the image processing apparatus to be converted, for each pixel, color material amount conversion means for obtaining the color material amount for each ink color from the image data, and ink colors other than the ink color for which dot arrangement is to be obtained for each pixel Other color material amount calculation means for obtaining the total amount of material as another color material amount for each ink color, conversion table recording means in which a plurality of color material amount / dot arrangement conversion tables are recorded, and the conversion for each pixel Based on the amount of other color material, a conversion table to be applied to the ink color for which the dot arrangement is to be obtained from a plurality of conversion tables recorded in the table recording means. Conversion table selecting means for selecting each ink color, and applying the conversion table selected for each ink color to each pixel, and the dot arrangement data for each ink color from the color material amount data for each ink color And an image processing apparatus characterized by comprising: a conversion means for converting into

  In the present invention, for each pixel, a color material amount for each ink color is obtained from image data, and a predetermined color material amount / dot arrangement conversion table (a conversion table for converting color material amount into dot arrangement data) is used. The color material amount data is converted into dot arrangement data for each ink color. At this time, the conversion table to be used is selected based on the amount of other color materials (the sum of the color material amounts of ink colors other than the ink color whose dot arrangement is to be obtained). For example, when the amount of other color material is large, the amount of droplet ejection of other ink is large, so a conversion table with a small total ink amount per pixel (the total volume of ink droplets ejected to the pixel) is selected. Decreasing the total amount of ink per pixel results in a large number of small volume ink droplets being ejected, so that the uneven color tends to be noticeable, but other colors of ink are also ejected. As a result, it is generally not noticeable. As a result, it is possible to suppress the total droplet ejection amount and prevent the occurrence of curling and cockle, and to record a high-quality image without streaks. On the other hand, when the amount of other color material is small, the amount of droplet ejection of the other color ink is small, so a conversion table with a large total ink amount per pixel is selected. When the total amount of ink per pixel is increased, a large volume of ink droplets is ejected in a small amount, so that it is difficult to visually recognize stripes. On the other hand, the amount of ink droplets to be ejected increases, but the amount of ink droplets to be ejected by other inks is small, so that the total droplet ejection amount can be suppressed, and the occurrence of curling and cockle can be prevented.

  In the invention according to claim 15, in order to achieve the object, the conversion table includes a plurality of conversion tables having different total ink amounts per pixel. The image processing apparatus according to claim 14, wherein a conversion table having a smaller total ink amount per pixel is selected as the number increases.

  According to the present invention, a plurality of conversion tables having different total ink amounts per pixel are prepared. In the conversion table selection step, a conversion table with a smaller total ink amount per pixel is selected as the other color material amount is larger. That is, when the other color material amount is large, a conversion table with a small total ink amount per pixel is selected, and when the other color material amount is small, a conversion table with a large total ink amount per pixel is selected. When a conversion table with a small total ink amount per pixel is selected, stripe unevenness tends to be noticeable for that ink color, but ink of other colors is also ejected, so that stripe unevenness is generally not noticeable. As a result, it is possible to suppress the total droplet ejection amount and prevent the occurrence of curling and cockle, and to record a high-quality image without streaks. On the other hand, when a conversion table having a large total ink amount per pixel is selected, it is difficult to visually recognize stripes. In this case, although the amount of droplet ejection of the ink color increases, the amount of droplet ejection of other inks is small, so that the total droplet ejection amount can be suppressed and the occurrence of curling and cockle can be prevented. As a result, it is possible to suppress the total ink ejection amount and prevent the occurrence of curling and cockle, and to record a high-quality image in which uneven stripes are difficult to be visually recognized.

  In order to achieve the above object, according to a sixteenth aspect of the present invention, the conversion table includes two conversion tables having different total ink amounts per pixel, and the conversion table selecting unit includes the other color material amount and the conversion table selecting unit. When the other color material amount exceeds the threshold value, a conversion table with a small total ink amount per pixel is selected, and when the other color material amount is equal to or less than the threshold value, the total ink per pixel is compared. The image processing apparatus according to claim 15, wherein a conversion table having a large amount is selected.

  According to the present invention, two conversion tables having different total ink amounts per pixel are prepared. In the step of selecting the conversion table, the other color material amount is compared with the threshold value, and when the other color material amount exceeds the threshold value, a conversion table with a small total ink amount per pixel is selected, and the other color material amount is selected. Is equal to or smaller than the threshold value, a conversion table having a large total ink amount per pixel is selected. As a result, it is possible to suppress the total ink ejection amount and prevent the occurrence of curling and cockle, and to record a high-quality image in which uneven stripes are difficult to be visually recognized.

  In the invention according to claim 17, in order to achieve the object, the conversion table with a small total ink amount per pixel has a larger average volume of ejected ink droplets than the conversion table with a large total ink amount per pixel. An image processing apparatus according to claim 15 is provided.

  According to the present invention, the conversion table with a small total ink amount per pixel is set to have a smaller average volume of ejected ink droplets than the conversion table with a large total ink amount per pixel. That is, the conversion table is set so that the color materials are evenly arranged. Thereby, even if the total ink amount is suppressed, the color materials can be arranged uniformly and the color reproduction range can be improved.

  The invention according to claim 18 provides the image processing apparatus according to claim 16 or 17, wherein the threshold value is changed according to the type of the recording medium in order to achieve the object.

  According to the present invention, the threshold value is changed according to the type of the recording medium. By optimizing the threshold according to the type of the recording medium, it is possible to adjust the threshold for suppressing curl and cockle and the threshold for suppressing unevenness. That is, the threshold value is set high for a recording medium in which curling and cockle are unlikely to occur (a recording medium in which curling and cockle are unlikely to occur even if the total droplet ejection amount is large). Thereby, generation | occurrence | production of a stripe unevenness can be suppressed more effectively.

  According to a nineteenth aspect of the present invention, in order to achieve the above object, the variation in the ejection direction of the ink droplets ejected from the head of the ink jet recording apparatus is measured, and the threshold value is changed according to the measured variation. An image processing apparatus according to claim 16 or 17 is provided.

  According to the present invention, the threshold value is changed according to variations in the ejection direction of the ink droplets ejected from the head. As a result, it is possible to perform image processing according to the variation in the ejection direction, and it is possible to record a high-quality image in which the uneven stripes are hardly visible. The threshold is set high when the variation is large.

  In order to achieve the object, the invention according to claim 20 converts the image data into dot arrangement data for each ink color used in the inkjet recording apparatus in order to record the image data on a recording medium by the inkjet recording apparatus. In the image processing apparatus for conversion, for each pixel, color material amount conversion means for obtaining the color material amount for each ink color from the image data, and conversion table recording means in which a plurality of color material amount / dot arrangement conversion tables are recorded The conversion table to be used for each ink color is determined for each pixel from the color information of each pixel with reference to a selection table in which a conversion table to be used for each ink color is determined according to the color of the pixel. A conversion table determining means for determining, and applying a conversion table determined for each ink color to each pixel, Providing a converting means for converting the amount data to the dot arrangement data of each of the ink colors, the image processing apparatus characterized by comprising a.

  In the present invention, for each pixel, the color material amount for each ink color is obtained from the image data, and the color material amount data for each ink color is converted to dot arrangement data using a predetermined color material amount / dot arrangement conversion table. Convert to At this time, the conversion table to be used is determined based on the color of each pixel. That is, since the color material amount of each ink color can be estimated by looking at the color of each pixel, the conversion table to be used can be estimated without obtaining the other color material amount. Therefore, a selection table that defines a conversion table to be used for each ink color corresponding to the pixel color is prepared in advance, and the conversion table to be used is determined based on the pixel color. As a result, the time required for image processing can be significantly reduced.

  In the invention according to claim 21, in order to achieve the object, the selection table estimates a color material amount for each ink color from a pixel color, and for each ink color, the color material amount of another ink color is estimated. 21. The image processing apparatus according to claim 20, wherein a conversion table having a smaller total ink amount per pixel is used as the sum is larger.

  According to the present invention, the selection table estimates the color material amount for each ink color from the color of the pixel, and for each ink color, the greater the sum of the color material amounts of the other ink colors, the greater the total ink amount per pixel. Set to use fewer translation tables.

  According to a twenty-second aspect of the invention, in order to achieve the above object, the conversion table is set so that the average volume of ejected ink droplets decreases as the total ink amount per pixel increases. An image processing apparatus according to claim 21 is provided.

  According to the present invention, the conversion table is set so that the average volume of the ejected ink droplets decreases as the total ink amount per pixel increases. That is, the conversion table is set so that the color materials are evenly arranged. Thereby, even if the total ink amount is suppressed, the color materials can be arranged uniformly and the color reproduction range can be improved.

  According to a twenty-third aspect of the invention, in order to achieve the above object, the image data is converted into dot arrangement data for each ink color used in the ink jet recording apparatus in order to record the image data on a recording medium by the ink jet recording apparatus. In the image processing apparatus for conversion, for each pixel, color material amount conversion means for obtaining the color material amount for each ink color from the image data, and conversion table recording means in which a plurality of color material amount / dot arrangement conversion tables are recorded The ink color obtained for each pixel for each pixel with reference to a selection table in which a conversion table to be used for each ink color is determined according to the amount of color material of each ink color obtained for each pixel Conversion table determining means for determining a conversion table to be used for each ink color from the information on the amount of color material for each pixel, and for each pixel An image processing apparatus comprising: conversion means that converts a color material amount data for each ink color into dot arrangement data for each ink color by applying a conversion table determined for each color To do.

  In the present invention, for each pixel, the color material amount for each ink color is obtained from the image data, and the color material amount data for each ink color is converted to dot arrangement data using a predetermined color material amount / dot arrangement conversion table. Convert to At this time, the conversion table to be used is determined based on the color material amount of each ink color obtained for each pixel. In other words, if the color material amount for each ink color is known, the other color material amount can be obtained without obtaining it each time. Therefore, if the color material amount for each ink color is known, the conversion table to be used is uniquely determined. Therefore, a selection table that defines a conversion table to be used for each ink color is prepared in advance corresponding to the color material amount of each ink, and the conversion table to be used is determined based on the color material amount of each ink color. . As a result, the time required for image processing can be significantly reduced.

  In the invention according to claim 24, in order to achieve the above object, the selection table includes a conversion table in which the total ink amount per pixel is smaller as the sum of the color material amounts of the other ink colors is larger for each ink color. The image processing apparatus according to claim 23, wherein the image processing apparatus is set to be used.

  According to the present invention, the conversion table is set such that the average volume of the ejected ink droplets increases as the total ink amount per pixel increases. That is, the conversion table is set so that the color materials are evenly arranged. Thereby, even if the total ink amount is suppressed, the color materials can be arranged uniformly and the color reproduction range can be improved.

  In the invention according to claim 25, in order to achieve the object, the conversion table is set such that the average volume of the ejected ink droplets decreases as the total ink amount per pixel increases. An image processing apparatus according to claim 24 is provided.

  According to the present invention, the conversion table is set so that the average volume of the ejected ink droplets decreases as the total ink amount per pixel increases. That is, the conversion table is set so that the color materials are evenly arranged. Thereby, even if the total ink amount is suppressed, the color materials can be arranged uniformly and the color reproduction range can be improved.

  According to a twenty-sixth aspect of the present invention, in order to achieve the object, the ink jet recording apparatus performs a process of reacting with components in the ink on the recording medium before the ink is ejected onto the recording medium to record an image. The image processing apparatus according to any one of claims 14 to 25, wherein a liquid is applied and dried.

  According to the present invention, an ink jet recording apparatus that records image data on a recording medium is constituted by an ink jet recording apparatus that records an image by ejecting ink after applying a predetermined treatment liquid to the recording medium. In an ink jet recording apparatus that records an image by applying and drying a treatment liquid that reacts with components in the ink and then drying the dots due to reaction with the treatment liquid and drying of the solvent component. On the other hand, it is easier to notice stripes. Since the dot arrangement data generated by the image processing apparatus of the present invention can make it difficult to visually recognize the uneven stripes, it works particularly effectively when recording image data with such an ink jet recording apparatus.

  ADVANTAGE OF THE INVENTION According to this invention, when recording with an inkjet recording device, the dot arrangement pattern which can record a high quality image can be produced | generated, without generating curl and cockle.

1 is a block diagram showing a first embodiment of an image processing apparatus according to the present invention. The figure which shows the ratio of the droplet ejection ratio of the large / small dot with respect to the color material amount in the conversion tables A and B The figure which shows an example of the dot arrangement at the time of the color material amount 0.5, 0.8, 1 in the conversion tables A and B The flowchart which shows the procedure of the image processing by the image processing apparatus of this Embodiment The block diagram which shows 2nd Embodiment of the image processing apparatus which concerns on this invention The flowchart which shows the procedure of the threshold setting process in a threshold setting part The block diagram of 3rd Embodiment of the image processing apparatus which concerns on this invention The block diagram which shows 4th Embodiment of the image processing apparatus which concerns on this invention. The figure which shows an example of a selection table The block diagram which shows 5th Embodiment of the image processing apparatus which concerns on this invention The figure which shows an example of a selection table

  Hereinafter, preferred embodiments of an image processing method and apparatus according to the present invention will be described in detail with reference to the accompanying drawings.

<First Embodiment>
[Device configuration]
FIG. 1 is a block diagram showing a first embodiment of an image processing apparatus according to the present invention.

  As shown in the figure, the image processing apparatus 10 according to the present embodiment includes a color material amount calculation unit 12 that obtains the color material amount of each ink color for each pixel from the image data, and the ink material obtained for each pixel. A conversion table in which an other color material amount calculation unit 14 for obtaining the other color material amount for each ink color from the color material amount and a color material amount / dot arrangement data conversion table for converting the color material amount data into the dot arrangement data are recorded. The recording unit 16, the conversion table selection unit 18 for selecting a conversion table to be used for each ink color in each pixel, and the color material amount data for each ink color obtained for each pixel using the selected conversion table are arranged in dots. And a data conversion unit 20 for converting data.

  In this example, image data expressed in RGB format is converted into CMYBk four-color dot arrangement data (when image data is recorded by an ink jet recording apparatus that records an image using CMYBk four-color ink). Explained.

  The color material amount calculation unit 12 converts the input image data into color material amount data for each ink (C, M, Y, Bk) in units of pixels, and obtains the color material amount for each ink color for each pixel.

  Here, the unit of the pixel for obtaining the color material amount for each ink color is a unit larger than the final droplet ejection density of dots ejected onto the recording medium. For example, 8 × 8 dots are 1 unit. A pixel.

  Various methods can be used as the method of converting the image data into the color material amount data. For example, a method using a three-dimensional lookup table or a method of calculating by calculation can be used.

  The color material amount data for each ink color of each pixel obtained by the color material amount calculation unit 12 is output to the other color material amount calculation unit 14 and the data conversion unit 20.

  The other color material amount calculation unit 14 calculates the other color material amount for each ink color based on the color material amount data for each ink color of each pixel calculated by the color material amount calculation unit 12.

  Here, the other color material amount is the sum of the color material amounts of ink colors other than the ink color in the pixel. For example, the other color material amount of cyan is the sum of the color material amounts of magenta, yellow, and black other than cyan, and the other color material amount of magenta is the sum of the color material amounts of cyan, yellow, and black other than magenta. is there. The other color material amount in yellow is the sum of the color material amounts of cyan, magenta and black other than yellow, and the other color material amount of black is the sum of the color material amounts of cyan, magenta and yellow other than black. It is.

  In this manner, the other color material amount calculation unit 14 obtains the other color material amount for each ink color for each pixel, with the sum of the color material amounts of the ink colors other than itself as the other color material amount for each ink color. .

  The conversion table recording unit 16 records a plurality of color material amount / dot arrangement conversion tables. In this example, two conversion tables, conversion table A and conversion table B, are recorded.

  Here, the conversion table A is composed of a table in which small dots are arranged with a large droplet ejection density, and the conversion table B is composed of a table in which large dots are arrayed with a small droplet ejection density.

  FIG. 2 is a diagram showing the ratio of the large / small dot ejection ratio to the color material amount in the conversion tables A and B. FIG. 3 is a diagram showing an example of dot arrangement when the color material amounts are 0.4, 0.8, and 1.0 in the conversion tables A and B. In the figure, small circles represent small droplets and large circles represent large droplets.

  The conversion table A has a smaller total ink amount per pixel (total volume of ink droplets ejected to the pixel). In other words, the conversion table A can express the same color with a smaller droplet ejection amount than the change table B. This is because, in the conversion table A, small droplets are arranged at a high droplet ejection density, so that the color materials can be evenly arranged on the recording medium, and wasteful color materials are reduced. .

  On the other hand, from the viewpoint of the visibility of the uneven stripe, the conversion with the conversion table B using large-diameter dots has a lower visibility of the uneven stripe with respect to the converted ink color than the conversion with the conversion table A. It becomes possible to do. This is because even if a position error occurs, white streaks are filled by ejecting large diameter dots.

  That is, it can be said that the conversion table A has a high effect of reducing the amount of ink used, and the conversion table B has a high effect of making it difficult to visually recognize the uneven stripes.

  Therefore, if the conversion table A is selected, the amount of ink to be used can be suppressed for the converted ink color. Further, if the conversion table B is selected, it is possible to make it difficult for the converted ink color to visually recognize the stripes.

  The conversion table selection unit 18 selects a conversion table to be used for each ink color in each pixel. The conversion table selection unit 18 selects a change table to be used based on the other color material amount of the ink color to be converted.

  That is, when the amount of the other color material is large (= when a lot of ink other than the ink color is ejected), the conversion table A is selected. Thereby, the total droplet ejection amount of the ink is reduced, and the total ink ejection amount can be reduced. On the other hand, for the ink color, it becomes easy to visually recognize the uneven stripe, but since the ink of other ink colors is also ejected, the uneven stripe is generally not conspicuous.

  On the other hand, when the amount of the other color material is small (= when a small amount of ink other than the ink color is ejected), the conversion table B is selected. Thereby, as a whole, it is possible to make it difficult to visually recognize stripes. On the other hand, although the total droplet ejection amount for the ink color increases, the total ink amount decreases because the droplet ejection amount for inks other than the ink color is small.

  Specifically, the conversion table is selected by comparing the other color material amount of the ink color to be converted with a threshold value, and when the other color material amount exceeds the threshold value (when the other color material amount is large), the conversion table A is selected. When the other color material amount is less than or equal to the threshold value (when the other color material amount is small), the conversion table B is selected.

  Information on the conversion table selected for each ink color by the conversion table selection unit 18 is output to the data conversion unit 20.

  The data conversion unit 20 uses the conversion table selected by the conversion table selection unit 18 to convert color material amount data for each ink color in each pixel into dot arrangement data.

[Image processing method]
Next, an image processing method using the image processing apparatus 10 of the present embodiment configured as described above will be described.

  FIG. 4 is a flowchart illustrating a procedure of image processing by the image processing apparatus 10 according to the present embodiment.

  When image data to be processed is input (step S11), first, for each pixel, color material amount data Vj (k) [k = 1, 2,..., K j = 0, 1,. 2, 3] are obtained (step S12).

  Here, the image data is image data in the RGB format, and is image data having a total number of pixels K. In the image data, the upper left pixel of the screen is the first pixel, the right adjacent pixel is the second pixel,..., And the lower right pixel is the Kth pixel. Here, the unit of the pixel is a unit larger than the final droplet ejection density of the droplets ejected on the recording medium. For example, 8 × 8 pixels are one pixel.

  The color material amount data Vj (k) is set to j = 0, 1, 2, 3, and C, M, Y, and Bk, respectively. That is, 0 = C (cyan), 1 = M (magenta), 2 = Y (yellow), 3 = Bk (black). Therefore, V0 (k) is C (cyan) color material amount data, V1 (k) is M (magenta) color material amount data, V2 (k) is Y (yellow) color material amount data, V3. (K) is Bk (black) color material amount data.

  Color material amount data Vj (k) for each ink color is obtained for each pixel (Vj (1) to Vj (K)).

  Once the color material amount data Vj (k) for each ink color is obtained for each pixel, the other color material amount Sj is obtained for each ink color for each pixel, and the other color material amount for each obtained ink color is obtained. Based on Sj, a conversion table is selected for each ink color, and for each pixel, color material amount data is converted into dot arrangement data for each ink color using the selected conversion table.

  First, k = 1 is set (step S13), j = 0 (0 = C) is set (step S14), and the other color material amount S0 of C in the first pixel (k = 1) is calculated (step S15). ).

  The other color material amount Sj is calculated by Sj = ΣVn−Vj (n = 0, 1, 2, 3).

  Here, ΣVn is the sum of the color material amounts V0, V1, V2, and V3 of the respective ink colors.

  Therefore, Sj = ΣVn−Vj is obtained by subtracting the color material amount Vj of the ink color j from the sum ΣVn of the color material amounts V0, V1, V2, and V3 of the respective ink colors, that is, the ink colors other than the ink color j. The sum of the color material amounts (if J = 0, S0 is the sum of the color material amounts V1, V2, and V3 of MYBk, which are ink colors other than C).

  Once the C color material amount S0 is calculated, the calculated C color material amount S0 is compared with the threshold value T, and it is determined whether or not the calculated C color material amount S0 exceeds the threshold value T. (Step S16).

  If it is determined that the other color material amount S0 of C calculated by this determination exceeds the threshold T, the conversion table A is selected for C of the first pixel (step S17). Then, using the selected conversion table A, the color material amount data of C is converted into dot arrangement data for C of the first pixel (step S18).

  On the other hand, if it is determined that the calculated other color material amount S0 of C is equal to or less than the threshold value T, the conversion table B is selected for C of the first pixel (step S19). Then, using the selected conversion table B, the C color material amount data is converted into dot arrangement data for C of the first pixel (step S20).

  As described above, when the amount of the other color material is large (when Sj exceeds the threshold T), the color material amount data is converted into the dot arrangement data using the conversion table A, and the other color material amount is small (Sj). Is equal to or less than the threshold value T), the color material amount data is converted into dot arrangement data using the conversion table B.

  As described above, when conversion is performed using the conversion table A, the total ink ejection amount can be reduced. In this case, for the ink color j, the stripe unevenness is easily visible, but other ink is also ejected, and the stripe unevenness is generally not noticeable.

  On the other hand, when conversion is performed using the conversion table B, it is possible to make it difficult to visually recognize the uneven stripe as a whole. On the other hand, although the total droplet ejection amount for the ink color j is large, the total ink amount is small because the droplet ejection amount for inks other than the ink color j is small.

  When the color material amount data for C is converted into dot arrangement data, it is determined whether J = 3 or not (step S21). That is, since the conversion to the dot arrangement data is performed for each ink color, it is determined whether or not the conversion process from the color material amount data to the dot arrangement data is completed for all ink colors.

  If it is determined in this determination that j = 3 is not satisfied (when it is determined that conversion for all ink colors has not been completed), 1 is added to j (step S22), and the process returns to step 15. The next color conversion process is performed (the above steps S15 to S21 are performed). In the above, since the process for the dot arrangement data for C has been completed, the processes of steps S15 to S21 are performed for M, and the M color material amount data is converted into the dot arrangement data. Similarly, the color material amount data after Y is converted into Y and the color material amount data after Bk is converted into dot arrangement data.

  In this way, for one pixel, the other color material amount is obtained for each ink color, the conversion table to be used is selected based on the obtained other color material amount, and the color material amount data is selected using the selected conversion table. Is converted to dot arrangement data.

  When conversion of dot arrangement data of all ink colors is completed for one pixel (when it is determined that j = 3 in step S21), it is determined whether or not k = K (step S23). That is, it is determined whether or not conversion to dot arrangement data has been completed for all pixels.

  If it is determined in this determination that k = K is not satisfied (when it is determined that conversion to dot arrangement data for all pixels has not been completed), 1 is added to k (step S24). Referring back to FIG. 5, the color material amount data of each ink color is converted into dot arrangement data for the next pixel (the above steps S15 to S23 are performed).

  In this way, the color material amount data of each ink color is converted into dot arrangement data for each pixel in order from the first pixel. When the color material amount data for all ink colors is converted into dot arrangement data for all pixels (when it is determined that k = K in step S23), the image processing is completed. Thereby, dot arrangement data for each ink color to be obtained is generated.

  As described above, according to the image processing apparatus and method of the present embodiment, it is possible to suppress the total ink amount per pixel while preventing the occurrence of unevenness. As a result, a high-quality image can be formed, and the occurrence of curling and cockle can be suppressed.

<Second Embodiment>
In the image processing apparatus 10 of the first embodiment described above, when selecting the conversion table for converting the color material amount into the dot arrangement data, the other color material amount obtained for each ink color is compared with a certain threshold T. The conversion table to be used is selected by determining whether or not the amount of other color material exceeds the threshold value T.

  In the image processing apparatus 30 according to the present embodiment, the threshold value used when selecting the conversion table is changed according to variations in the ink ejection direction. In other words, when the variation in the ink ejection direction is large, even when the same color is expressed, the large dot is smaller in the case where the small dots are arranged with a large droplet ejection density (conversion table A). This makes it easier to visually recognize stripes as compared with the case of the arrangement (conversion table B). Therefore, in the image processing apparatus 30 of the present embodiment, the threshold value is changed according to the variation in the ink ejection direction (if the variation is large, the threshold value is increased).

  FIG. 5 is a block diagram showing a second embodiment of the image processing apparatus according to the present invention.

  As shown in the figure, the image processing apparatus 30 of the present embodiment is different from the image processing apparatus 10 of the first embodiment described above in that it includes a threshold setting unit 32 that sets a threshold. . Other configurations are basically the same as those of the image processing apparatus 10 according to the first embodiment described above. Therefore, only the configuration of the threshold setting unit 32 will be described here.

  The threshold setting unit 32 sets a threshold Tj (j is an ink color (C, M, Y, Bk)) for each ink color based on the test pattern data in advance.

  Here, the test pattern data is image data obtained by recording a predetermined test pattern image on a predetermined recording medium and reading it with a scanner.

  The threshold setting unit 32 acquires the test pattern data, and measures the displacement amount δj (m) of the droplet ejection position in units of nozzles for each ink color (head) from the obtained test pattern data (j is the ink color). (C, M, Y, Bk) and m are nozzle numbers (1, 2,..., M)), and the average value <δj (m)> is calculated. Then, the average value <δj (m)> of the displacement amount of the droplet ejection position for each ink color is set as a variation amount in the ink ejection direction, and a threshold value Tj is set for each ink color from the variation amount for each ink color. To do. For example, the threshold value is set to increase as the variation amount increases (the conversion table B is easily selected as the variation amount increases).

  FIG. 6 is a flowchart illustrating a procedure of threshold setting processing in the threshold setting unit 32.

  First, test pattern data is input (step S31). The threshold setting unit 32 changes the droplet ejection position of each nozzle m (m = 1, 2,..., M) for each ink color j (J = C, M, Y, Bk) from the input test pattern data. The quantities δj (m) (δC (m), δM (m), δY (m), δBk (m)) are measured (step S32).

  Next, an average value of displacement amounts <δj (m)> (<δC (m)>, <δM (m)>, <δY (m)>, <δBk (m)>) is calculated for each ink color j. (Step S33).

  Next, a threshold value Tj (TC, TM, TY, TBk) is calculated for each ink color j from the obtained average value <δj (m)> of the displacement amount for each ink color j (step S34).

  Then, the obtained threshold value Tj for each ink color is output to the conversion table selection unit 18 (step S35). The conversion table selection unit 18 stores the obtained threshold value Tj for each ink color in a built-in memory.

  The conversion table selection unit 18 performs conversion table selection processing for each ink color using the threshold value Tj set for each ink color when the conversion table is selected. That is, for example, when a conversion table for C of a certain pixel is selected, the threshold TC set for C is compared with the other color material amount of C (the sum of the color material amounts of MYBk other than C) for that pixel. To select the conversion table to be used. Similarly, when selecting a conversion table for M, Y, and Bk, the other color material amounts of M, Y, and Bk in the pixel and the threshold values TM, TY, and TBk set for M, Y, and Bk are used. Compare and select the conversion table to be used.

  As described above, by setting the threshold value Tj according to the variation in the ink ejection direction of the head mounted on the ink jet recording apparatus, more optimal image processing can be performed.

  In the above example, the average value of the displacement amount for all the nozzles is used as a variation, and a threshold value is set collectively for each ink color. However, for each ink color (head), the variation is calculated for each pixel, You may make it set a threshold value per pixel. In this case, for example, an average value of the displacement amounts of the nozzles that deposit droplets on the same pixel is obtained in pixel units, and a threshold value is set in pixel units from the obtained average value of displacement amounts for each pixel. Thereby, further optimal image processing can be performed.

  The threshold setting process can be performed every time the operation of the inkjet recording apparatus is started, can be performed every predetermined time, every time a predetermined number of sheets are printed, or after maintenance is performed. It can also be performed at an arbitrary timing from the operator.

  The test pattern data may be manually input by the operator, or may be automatically acquired from the ink jet recording apparatus.

<Third Embodiment>
The degree of occurrence of curl and cockle varies depending on the type of recording medium used. Therefore, image processing can be further optimized by changing the threshold value according to the type of recording medium to be used. For example, by setting a high threshold value for a recording medium that is less likely to curl or curl, the occurrence of unevenness can be further prevented and a higher quality image can be recorded.

  FIG. 7 is a block diagram of a third embodiment of the image processing apparatus according to the present invention.

  As shown in the figure, the image processing apparatus 40 according to the present embodiment includes the threshold value setting unit 42 that sets a threshold value according to the type of recording medium, and the image processing according to the first embodiment described above. This is different from the apparatus 10. Other configurations are basically the same as those of the image processing apparatus 10 according to the first embodiment described above. Therefore, only the configuration of the threshold setting unit 42 will be described here.

  The threshold setting unit 42 has a table in which a threshold is set for each type of recording medium (stored in a built-in storage unit). This table is set in accordance with the likelihood of occurrence of curling and cockle of the corresponding recording medium, and a high threshold is set for the recording medium in which curling and cockle are likely to occur.

  On the other hand, recording medium type data (recording medium type data) is input to the threshold setting unit 42.

  The threshold setting unit 42 refers to the above table, reads the threshold corresponding to the type of the input recording medium, and outputs it to the conversion table selection unit 18.

  The conversion table selection unit 18 stores the obtained threshold data in a built-in memory. Then, the conversion table selection unit 18 performs a conversion table selection process using a threshold set according to the type of the recording medium when selecting the conversion table.

  In this way, more optimal image processing can be performed by setting a threshold according to the type of recording medium on which image data is recorded.

  In the second embodiment, the threshold value is set according to the variation in the ink ejection direction. However, the threshold value set according to the variation in the ink ejection direction is further set according to the type of the recording medium. (You may increase or decrease the set threshold according to the difficulty of curling or curling.) Thereby, the image processing can be further optimized.

<Fourth embodiment>
In the image processing apparatus 10 according to the first embodiment described above, after obtaining the color material amount for each ink color for each pixel, the other color material amount is referred to for each ink color, and the referred other color material amount is set. Based on this, a conversion table to be used for each ink color is selected.

  Since the other color material amount is the sum of the color material amounts of the ink colors other than itself, if the color material amount of each ink color is known, the other color material amount for each ink color can be uniquely obtained. If the other color material amount is known, the conversion table to be used for the ink color can be uniquely determined.

  Therefore, the relationship of the conversion table to be used for each ink color can be determined in advance from the combination of the color material amounts of the respective ink colors.

  In the image processing apparatus 50 according to the present embodiment, a conversion table to be used for each ink color is determined in advance for each combination of color material amounts of each ink color, and is recorded in the table. Refer to this table. Then, the conversion table to be used for each ink color is selected from the combination of the color material amounts of the respective ink colors.

  FIG. 8 is a block diagram showing a fourth embodiment of the image processing apparatus 50 according to the present invention.

  The image processing apparatus 50 according to the present embodiment is different from the image processing apparatus 10 according to the first embodiment described above in that it includes a selection table storage unit 52 and does not include the other color material amount calculation unit 14. Therefore, only the configuration of the selection table storage unit 52 and the operation of the conversion table selection unit 18 will be described here.

  As shown in FIG. 9, the selection table storage unit 52 is a selection in which a conversion table (conversion table A or conversion table B) to be used for each ink color is determined for each combination of color material amounts of each ink color. The table is stored.

  The conversion table selection unit 18 receives color material amount data for each ink color calculated by the color material amount calculation unit 12. The conversion table selection unit 18 refers to the selection table stored in the selection table storage unit 52 and selects a conversion table to be used for each ink color from the color material amount data for each ink color. Then, the information of the conversion table for each selected ink color is output to the data conversion unit 20.

  The data conversion unit 20 converts the color material amount data of each ink color into dot arrangement data using the selected conversion table.

  In this way, by defining a conversion table to be used for each ink color in advance for each combination of color material amounts for each ink color, it is possible to use each ink color without calculating other color material amounts. A power conversion table can be selected.

  As in the third embodiment, it is preferable that a selection table is prepared for each type of recording medium and switched according to the type of recording medium to be used.

  Further, it is preferable that the selection table is appropriately corrected according to variations in the ink ejection direction.

<Fifth embodiment>
In the image processing apparatus 50 according to the fourth embodiment described above, a conversion table to be used for each ink color is determined in advance for each combination of the color material amounts of the respective ink colors, and is referred to for each ink color. The conversion table to be used is selected.

  Here, the color material amount for each ink color in each pixel can be estimated from the color of the corresponding pixel, that is, R, G, and B image data. Therefore, if the color of the corresponding pixel, that is, R, G, B image data is known, the color material amount for each ink color in each pixel can be obtained, and if the color material amount for each ink color in each pixel is known. The conversion table (conversion table A or conversion table B) to be used for each ink color can be obtained.

  Therefore, in the image processing apparatus 60 of the present embodiment, a conversion table to be used for each ink color is determined in advance for each combination of R, G, and B image data, and is recorded in the table. With reference to the table, a conversion table to be used for each ink color is directly selected from the R, G, and B image data.

  FIG. 10 is a block diagram showing a fifth embodiment of the image processing apparatus 60 according to the present invention.

  The image processing apparatus 60 of the present embodiment is different from the image processing apparatus 10 of the first embodiment described above in that it includes a selection table storage unit 62 and does not include the other color material amount calculation unit 14. Therefore, only the configuration of the selection table storage unit 62 and the operation of the conversion table selection unit 18 will be described here.

  As shown in FIG. 11, the selection table storage unit 62 has a conversion table (conversion table A or conversion table B) to be used for each ink color for each combination of 8-bit R, G, and B image data. A predetermined selection table is stored.

  R, G, and B image data are input to the conversion table selection unit 18. The conversion table selection unit 18 refers to the selection table stored in the selection table storage unit 62 and selects a conversion table to be used for each ink color from the R, G, and B image data in each pixel. Then, the information of the conversion table for each selected ink color is output to the data conversion unit 20.

  The data conversion unit 20 converts the color material amount data of each ink color into dot arrangement data using the selected conversion table.

  In this way, a conversion table to be used for each ink color is determined in advance for each combination of R, G, and B image data, so that it can be used for each ink color without calculating the amount of other color materials. A conversion table to be selected can be selected.

  As in the third embodiment, it is preferable that a selection table is prepared for each type of recording medium and switched according to the type of recording medium to be used.

  Further, it is preferable that the selection table is appropriately corrected according to variations in the ink ejection direction.

<Other embodiments>
In the above embodiment, the color material amount data is converted into dot arrangement data using two types of conversion tables, conversion table A and conversion table B. However, a plurality of types of conversion tables are prepared and other colors are prepared. The conversion table to be used may be switched according to the material amount.

  In the above embodiment, the case where image data is recorded by an ink jet recording apparatus using CMYBk four color inks has been described. However, the application of the present invention is not limited to this. The present invention can be similarly applied to a case where image data is recorded by an ink jet recording apparatus that uses ink of a color other than CMYBk.

  Further, the image processing apparatus according to the present invention can be configured by a hardware circuit or can be configured by software (can be realized by a computer by a program).

  In addition, the image processing apparatus according to the present invention can be directly incorporated into an ink jet recording apparatus, or can be configured separately from the ink jet recording apparatus.

  In addition, the ink jet recording apparatus to which the present invention is applied is not particularly limited, but a recording medium that reacts with a processing liquid that reacts with components in the ink (for example, a liquid that reacts with the ink and insolubilizes or aggregates the coloring material) When applied to an ink jet recording apparatus for recording an image by ejecting ink after being applied and dried, the method is more effective. This type of ink jet recording apparatus has a characteristic that dots are sharpened and bleeding is reduced by reaction with a processing solution and drying of a solvent component, but stripes are easily noticeable. Since the dot arrangement data generated by the image processing apparatus and method according to the present invention can make it difficult to visually recognize stripes, it is particularly effective when recording image data with such an ink jet recording apparatus.

  Curling and cockle are noticeable when recording with a water-based ink (ink containing at least water and a coloring material) on printing paper (for example, coated paper such as coated paper). This is particularly effective when applied to an ink jet recording apparatus for recording an image.

  DESCRIPTION OF SYMBOLS 10 ... Image processing apparatus, 12 ... Color material amount conversion part, 14 ... Other color material amount calculating part, 16 ... Conversion table recording part, 18 ... Conversion table selection part, 20 ... Data conversion part, 30 ... Image processing apparatus, 32 ... Threshold setting unit, 40 ... Image processing device, 42 ... Threshold setting unit, 50 ... Image processing device, 52 ... Selection table storage unit, 60 ... Image processing device, 62 ... Selection table storage unit

Claims (26)

In the image processing method for converting the image data into dot arrangement data for each ink color used in the inkjet recording apparatus in order to record the image data on a recording medium by the inkjet recording apparatus,
For each pixel, obtaining a color material amount for each ink color from image data;
For each pixel, a step of obtaining, for each of the ink colors, a sum of the color material amounts of ink colors other than the ink color for which the dot arrangement is to be obtained, as other color material amounts;
For each pixel, a conversion table to be applied to an ink color for which a dot arrangement is to be obtained is selected from a plurality of prepared color material quantity / dot arrangement conversion tables for each ink color based on the other color material quantity. When,
Applying a conversion table selected for each ink color for each pixel, and converting the color material amount data for each ink color into dot arrangement data for each ink color; and
An image processing method comprising:   As the conversion table, a plurality of conversion tables having different total ink amounts per pixel are prepared, and in the step of selecting the conversion table, a conversion table having a smaller total ink amount per pixel is selected as the other color material amount is larger. The image processing method according to claim 1, wherein:   As the conversion table, two conversion tables having different total ink amounts per pixel are prepared, and in the step of selecting the conversion table, the other color material amount is compared with a threshold value, and the other color material amount is determined as the threshold value. When the value exceeds the threshold, a conversion table with a small total ink amount per pixel is selected, and when the other color material amount is equal to or less than the threshold, a conversion table with a large total ink amount per pixel is selected. The image processing method according to claim 2.   The image processing method according to claim 3, wherein the conversion table having a small total ink amount per pixel has a smaller average volume of ejected ink droplets than the conversion table having a large total ink amount per pixel.   The image processing method according to claim 3 or 4, wherein the threshold value is changed according to a type of the recording medium.   5. The image processing method according to claim 3, wherein a variation in an ejection direction of ink droplets ejected from a head of the inkjet recording apparatus is measured, and the threshold value is changed according to the measured variation. In the image processing method for converting the image data into dot arrangement data for each ink color used in the inkjet recording apparatus in order to record the image data on a recording medium by the inkjet recording apparatus,
For each pixel, obtaining a color material amount for each ink color from image data;
With reference to a selection table in which a conversion table of color material amount / dot arrangement to be used for each ink color is determined according to the color of the pixel, for each pixel, for each ink color from the color information of each pixel Determining the conversion table to be used;
Applying a conversion table determined for each ink color for each pixel, and converting the color material amount data for each ink color into dot arrangement data for each ink color; and
An image processing method comprising:   The selection table estimates the color material amount for each ink color from the color of the pixel, and for each ink color, the conversion table uses a smaller total ink amount per pixel as the sum of the color material amounts of the other ink colors increases. The image processing method according to claim 7, wherein the image processing method is set as described above.   9. The image processing method according to claim 8, wherein the conversion table is set such that an average volume of ejected ink droplets decreases as the total ink amount per pixel increases. In the image processing method for converting the image data into dot arrangement data for each ink color used in the inkjet recording apparatus in order to record the image data on a recording medium by the inkjet recording apparatus,
For each pixel, obtaining a color material amount for each ink color from image data;
Refer to the selection table in which the conversion table of the color material amount / dot arrangement to be used for each ink color is determined according to the color material amount of each ink color required for each pixel. Determining a conversion table to be used for each ink color from the information of the obtained color material amount for each ink color;
Applying a conversion table determined for each ink color for each pixel, and converting the color material amount data for each ink color into dot arrangement data for each ink color; and
An image processing method comprising:   11. The selection table is set such that, for each ink color, a conversion table having a smaller total ink amount per pixel is used as the sum of the color material amounts of other ink colors increases. An image processing method described in 1.   12. The image processing method according to claim 11, wherein the conversion table is set such that an average volume of ejected ink droplets decreases as the total ink amount per pixel increases.   2. The ink jet recording apparatus according to claim 1, wherein before the ink is ejected onto the recording medium and an image is recorded, a treatment liquid that reacts with a component in the ink is applied to the recording medium and dried. The image processing method according to claim 12. In order to record image data on a recording medium with an ink jet recording apparatus, the image data is converted into dot arrangement data for each ink color used in the ink jet recording apparatus.
For each pixel, color material amount conversion means for obtaining the color material amount for each ink color from image data;
For each pixel, other color material amount calculation means for determining the total color material amount of ink colors other than the ink color for which the dot arrangement is to be obtained as the other color material amount for each ink color,
Conversion table recording means in which a plurality of color material amount / dot arrangement conversion tables are recorded;
For each pixel, a conversion table is selected for each ink color based on the amount of other color material from among a plurality of conversion tables recorded in the conversion table recording means. Table selection means;
For each pixel, by applying a conversion table selected for each ink color, conversion means for converting the color material amount data for each ink color into dot arrangement data for each ink color;
An image processing apparatus comprising: As the conversion table, a plurality of conversion tables having different total ink amounts per pixel are prepared,
The image processing apparatus according to claim 14, wherein the conversion table selection unit selects a conversion table having a smaller total ink amount per pixel as the other color material amount is larger. As the conversion table, two conversion tables having different total ink amounts per pixel are prepared,
The conversion table selection means compares the amount of other color material with a threshold value, and if the amount of other color material exceeds the threshold value, selects a conversion table with a small total ink amount per pixel, and selects the other color material. The image processing apparatus according to claim 15, wherein when the amount is equal to or less than the threshold value, a conversion table having a large total ink amount per pixel is selected.   16. The image processing apparatus according to claim 15, wherein the conversion table with a small total ink amount per pixel has a larger average volume of ejected ink droplets than the conversion table with a large total ink amount per pixel.   The image processing apparatus according to claim 16, wherein the threshold value is changed according to a type of the recording medium.   18. The image processing apparatus according to claim 16, wherein a variation in an ejection direction of an ink droplet ejected from a head of the inkjet recording apparatus is measured, and the threshold value is changed according to the measured variation. In order to record image data on a recording medium with an ink jet recording apparatus, the image data is converted into dot arrangement data for each ink color used in the ink jet recording apparatus.
For each pixel, color material amount conversion means for obtaining the color material amount for each ink color from image data;
Conversion table recording means in which a plurality of color material amount / dot arrangement conversion tables are recorded;
Refer to the selection table in which the conversion table to be used for each ink color is determined according to the color of the pixel, and for each pixel, the conversion table to be used for each ink color is determined from the color information of each pixel. Conversion table determination means to
For each pixel, by applying a conversion table determined for each ink color, conversion means for converting the color material amount data for each ink color into dot arrangement data for each ink color;
An image processing apparatus comprising:   The selection table estimates the color material amount for each ink color from the color of the pixel, and for each ink color, the conversion table uses a smaller total ink amount per pixel as the sum of the color material amounts of the other ink colors increases. The image processing apparatus according to claim 20, wherein the image processing apparatus is set to   The image processing apparatus according to claim 21, wherein the conversion table is set such that an average volume of ejected ink droplets decreases as the total ink amount per pixel increases. In order to record image data on a recording medium with an ink jet recording apparatus, the image data is converted into dot arrangement data for each ink color used in the ink jet recording apparatus.
For each pixel, color material amount conversion means for obtaining the color material amount for each ink color from image data;
Conversion table recording means in which a plurality of color material amount / dot arrangement conversion tables are recorded;
Each ink color obtained for each pixel for each pixel with reference to a selection table in which a conversion table to be used for each ink color is determined according to the amount of color material of each ink color obtained for each pixel Conversion table determining means for determining a conversion table to be used for each ink color from the color material amount information of
For each pixel, a conversion unit that applies a conversion table determined for each ink color and converts the color material amount data for each ink color into dot arrangement data for each ink color; and
An image processing apparatus comprising:   24. The selection table is set such that, for each ink color, a conversion table having a smaller total ink amount per pixel is used as the total sum of the color material amounts of other ink colors increases. An image processing apparatus according to 1.   25. The image processing apparatus according to claim 24, wherein the conversion table is set such that an average volume of ejected ink droplets decreases as the total ink amount per pixel increases.   The inkjet recording apparatus applies a treatment liquid that reacts with components in the ink and dries the recording medium before the ink is ejected onto the recording medium to record an image. 26. The image processing apparatus according to any one of 25.

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