JP2009012261A - Image processing method and method for forming lut - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image processing method for recording an image superior in glossiness without reducing smoothness as much as possible in an inkjet recorder for recording an image by using pigment inks in a plurality of colors. <P>SOLUTION: In each pixel, recording or non-recording of a pigment ink of which the deposited height on a recording medium is relatively low, is controlled corresponding to recording or non-recording of a pigment ink of which the deposited height on a recording medium is relatively high so that the deposited heights of an image recorded by the plurality of pigment inks are equalized to make the image smooth. Alternatively, gradation data capable of suppressing variation in glossiness as much as possible is selected from a plurality of pieces of gradation data having similar chromaticity and is set to an LUT which is looked up in the event of color separation processing with respect to each luminance. With the above image processing, smoothness of a recording medium can be suppressed in a prescribed range and an image free from uneven glossiness can be output. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image processing method for an ink jet recording apparatus using a plurality of color pigment inks. In particular, the present invention relates to a binarization processing method and a color separation processing method devised so as not to impair the glossiness of a recording medium, and to an LUT creation method for realizing such a color separation processing method.

  In recent years, color ink jet recording apparatuses using a plurality of colors of ink are rapidly spreading as recording apparatuses that can output digital images easily and at low cost. In a color ink jet recording apparatus, conventionally, a dye ink using a dye as a coloring material has been generally used from the viewpoints of color developability of an image and easy handling of the ink. However, images recorded with dye inks have the disadvantage of being inferior in weather resistance (water resistance, light resistance, etc.) compared to conventional printing, and cannot be suitably used for posters displayed outdoors. It was.

  On the other hand, Patent Document 1 discloses an ink jet recording apparatus using a pigment ink using a pigment having a more excellent weather resistance as a coloring material. In particular, large-sized recording media such as A0 size and B0 size have many uses that are displayed outdoors as posters, and an ink jet recording apparatus that records images using a plurality of colors of pigment ink on such a recording medium. Has been useful.

JP-A-1-204979

  However, an image output using pigment ink is often inferior to an image using dye ink in terms of color development and gloss. This is because the dye permeates the recording medium and is fixed, whereas the pigment is fixed on the surface thereof. Hereinafter, these problems and general countermeasures will be described in detail.

  In general, a color ink jet recording apparatus uses four basic colors of cyan, magenta, yellow, and black, and all color gamuts are expressed by combinations thereof. For example, the hue is expressed by a combination of magenta and yellow for red, a combination of cyan and yellow for green, and a combination of cyan and magenta for blue. In the pigment ink, the pigment color material is deposited on the surface of the recording medium to develop the ink color. Therefore, the secondary color expressed by superimposing the two colors is inevitably compared to the primary color. Saturation tends to decrease. That is, in order to express the same secondary color, even if the same combination of colors is used, the color expressed by superimposing two pigment inks is a color expressed by superimposing two dye inks. Compared to, the saturation will be low.

  In order to cope with this problem, in recent years, a recording apparatus has been provided in which secondary colors such as red, green and blue are prepared in advance as independent ink colors in addition to the four basic colors. With such a configuration, it is possible to suppress the frequency of ink overlay, and as a result, it is possible to suppress a reduction in image saturation to some extent.

  On the other hand, with a pigment ink having the property of being deposited on the surface of a recording medium, many irregularities are formed on the recording surface. The light incident due to the unevenness causes irregular reflection, and the surface of the image recorded with the pigment ink is deteriorated in glossiness even if the recording medium originally has high glossiness (smoothness). In order to cope with this problem, pigment inks that maintain the smoothness of images as much as possible have been developed in recent years.

  However, when using multiple colors of ink, the degree of unevenness formed on the recording medium varies depending on the ink. The amount of pigment deposited on the surface of the recording medium, that is, the degree of unevenness to be formed, is inevitably affected by the type of pigment employed and the concentration of the pigment contained in the ink (hereinafter referred to as pigment concentration). It is. As a result, even when recording in a single color, an image with a low glossiness is obtained with an ink with a high pigment concentration, and an image with a high glossiness is obtained with an ink with a low pigment concentration. A difference appears in the degree.

  FIG. 13A is a diagram for explaining the pigment deposition state and the light reflection state on the surface of the recording medium when recording is performed using a plurality of inks having different pigment concentrations. Here, ink 1 having a relatively low pigment concentration is thin and easy to maintain smoothness, ink 2 having a relatively high pigment concentration and thick and difficult to maintain smoothness, and an intermediate ink. 3 shows a state where recording is performed. In this area, there are a portion where two types of ink are recorded in an overlapping manner, a portion where one type of ink is recorded, a blank portion, and the like, and the degree of unevenness varies. As a result, light incident at a fixed angle with respect to the surface of the recording medium is also irregularly reflected in various directions, and a visually high glossiness cannot be obtained. Further, when an area in which an image is recorded in such a state or a blank area with high smoothness is mixed in one image, uniform glossiness cannot be obtained in the same image, and uneven glossiness is obtained. It is recognized as a harmful effect called.

  The present invention has been made to solve the above problems. Therefore, an object of the present invention is to provide an image processing method for recording an image in which gloss unevenness is suppressed without damaging smoothness as much as possible in an inkjet recording apparatus that records an image using pigment inks of a plurality of colors. It is to be.

  Therefore, in the present invention, for recording an image on the recording medium using at least the first pigment ink and the second pigment ink deposited at a lower height on the recording medium than the first pigment ink. An image processing method, which corresponds to a first binarization step for determining a pixel for recording the first pigment ink using a first dither matrix, and a pixel for recording the first pigment ink A step of calculating a new pigment height coefficient by adding a first deposition coefficient to the pigment height coefficient to be performed, and a smaller threshold value corresponding to a pixel having a smaller new pigment height coefficient. A step of determining a threshold value of the second dither matrix, and a second binarization step of determining pixels for recording the second pigment ink using the second dither matrix. .

  Also, binarization processing for recording an image on the recording medium using at least the first pigment ink and the second pigment ink deposited on the recording medium lower than the first pigment ink is performed. An image processing apparatus that performs the first binarization unit that determines a pixel for recording the first pigment ink using a first dither matrix, and a pixel for recording the first pigment ink. Means for calculating a new pigment height coefficient by adding a first deposition coefficient to the corresponding pigment height coefficient, and a smaller threshold value corresponding to a pixel having a smaller new pigment height coefficient. And a second binarizing unit for determining a pixel for recording the second pigment ink by using the second dither matrix. To do.

  The image processing method further includes a color separation process step for converting multi-value luminance data into multi-value gradation data corresponding to a plurality of ink colors by referring to the LUT. Among a plurality of gradation data in which the color difference between the chromaticity of the luminance data of the value and the chromaticity of the image recorded on the recording medium is included in a predetermined range, the glossiness of the image recorded on the recording medium is a predetermined value The gradation data that is closest to is set in correspondence with the multivalued luminance data.

  Furthermore, a method for creating an LUT that is referred to in order to convert multi-value luminance data into multi-value gradation data corresponding to a plurality of ink colors, the gradation data of the plurality of ink colors being stepwise. Recording a plurality of different patches on a recording medium, measuring chromaticity of the plurality of patches, measuring glossiness of the plurality of patches, and average glossiness of the plurality of patches A step of calculating a value, a step of extracting a plurality of patches such that a color difference with respect to the luminance data is included in a predetermined range, and the glossiness measured in the measurement step among the plurality of extracted patches. The method includes a step of selecting a patch closest to the average value, and a step of storing gradation data corresponding to the selected patch in association with the luminance data.

  According to the present invention, smoothness in a recording medium can be suppressed within a certain range, and an image without uneven gloss can be output.

  Based on the recording characteristics as described above, the present inventor arranges various pigment inks to be as smooth as possible on the surface of the recording medium even when images are recorded using pigment inks. As a result, the inventors have found that the desired color can be expressed without impairing the gloss.

  FIG. 13B shows an example in which individual pigments are arranged so as to maintain smoothness when the same number of inks of the same type as in FIG. Since the same number of inks of the same type are recorded, color development substantially equal to that in FIG. In this way, if the superposition of the respective inks can be changed so that the deposition height of the recording area is as parallel as possible to the recording medium surface, the light incident on the recording medium at a certain angle is also substantially incident. It is assumed that the light is reflected at an equal reflection angle and high glossiness is obtained.

  Such positions for recording ink of each color (determination of recording pixels / non-recording pixels) and the number thereof are generally determined by image processing (mainly color separation and binarization processing). However, such determination of recording pixels / non-recording pixels is often determined independently for each color, and is not performed in consideration of the overlapping state and glossiness of each other.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a schematic diagram for explaining an image recording configuration of an ink jet recording apparatus suitable for applying the present invention. In the recording head 10 for recording an image, nozzle rows 11 including a plurality of nozzles that eject the same type of ink are arranged in parallel in the main scanning direction by the number of types of ink to be used. Here, nozzle rows for four colors of cyan (C), magenta (M), yellow (Y), and black (K) are prepared. The recording head 10 performs recording scanning at a constant speed in the main scanning direction while ejecting ink from individual nozzles according to the recording data, thereby recording an image for one band on the recording medium 12. When one recording scan is completed, the recording medium 12 is conveyed in the sub-scanning direction by an amount corresponding to the width of one band. By alternately repeating the recording scan and the conveying operation as described above, an image is recorded on the recording medium 12 step by step.

  FIG. 2 is a block diagram for explaining image processing steps in the host apparatus 201 and the recording apparatus 202 applicable to the present invention. The recording apparatus 202 of this embodiment receives binary data for each ink color (for each nozzle array) that is determined to be recorded / non-recorded with respect to each nozzle from the host apparatus 201, and according to the received binary data in FIG. An image is recorded on the recording medium by the method described. The host apparatus 201 can perform recording by the recording apparatus 202 by performing various image processes as shown in the figure for multi-value luminance data composed of R (red), G (green), and B (blue). Signal value conversion is performed on binary data. Below, each image processing process is demonstrated.

  The input γ conversion processing unit 101 performs γ conversion processing on the input RGB signal according to the brightness adjustment parameter designated by the user. Specifically, the input multi-value RGB signal is similarly converted into a multi-value RGB signal by referring to a one-dimensional LUT set according to the brightness adjustment parameter.

  The subsequent color matching processing unit 102 performs color gamut mapping. Then, data conversion for mapping the color gamut reproduced by the image data R, G, B into the color gamut reproduced by the recording apparatus is performed. More specifically, data in which each of R, G, and B is expressed in multiple values is converted into multivalued data of R, G, and B having different contents by using a three-dimensional LUT.

  In the ink color separation processing unit 103, multi-value color separation data (C, M, Y, K) corresponding to the ink prepared in the recording apparatus based on the data R, G, B on which the color gamut is mapped. The process which calculates | requires is performed. Here, as in the color matching process, signal value conversion is performed by referring to a three-dimensional LUT prepared in advance.

  The output γ conversion processing unit 104 performs gradation value conversion for each color data of the color separation data obtained by the ink color separation processing unit 103. Specifically, by using a one-dimensional LUT corresponding to the gradation characteristics of each color ink of the recording apparatus, conversion is performed so that the color separation data is linearly associated with the gradation characteristics of the recording apparatus.

  The halftone processing unit 105 performs binarization processing (quantization processing) for converting multi-value color separation data C, M, Y, and K into binary data. In this embodiment, multi-level multi-value data is converted into 2-level 1-bit data using a predetermined dither matrix.

  In the present invention, the recording apparatus can record an image with better smoothness by adding a device to the three-dimensional LUT referred to by the ink color separation processing unit 103 and the dither matrix used by the halftone processing unit 105 described above. There is a feature in doing so. Several embodiments for realizing the present invention will be specifically described below.

  FIG. 3 is a schematic diagram for explaining a binarization processing method by a general dither method. Here, a case where gradation data having level 8 is uniformly input to the region 300 in 16 gradations represented by 0 to 15 is shown. In the dither method, a dither matrix 301 (4 pixels × 4 pixels in this case) in which threshold values for individual recording pixels are determined is prepared in advance, and individual gradation data is compared with individual threshold values. Then, “1” (recording) is output when the gradation data is larger than the threshold value, and “0” (non-recording) is output when the gradation data is smaller than the threshold value. As a result of such processing, in a 4 pixel × 4 pixel area expressed by the intermediate level 8, dots are recorded in substantially half of the recording pixels, and as a result, the density of the area is preserved. Conventionally, such processing has been carried out independently for each ink color, such as the first dither matrix, the second dither matrix, the third dither matrix, etc. Was done without having.

  FIG. 4 is a block diagram for explaining detailed steps of the dither method employed in this embodiment. FIG. 5 is a schematic diagram for specifically explaining each process performed in the above steps. In the present embodiment, the dither processing as described above is performed in order from the ink color having the highest height of the pigment deposited on the recording medium surface, and the result of the ink color processing performed in advance at that time is followed. The present invention is characterized in that it is used for ink color processing. In both figures, the dither process for one color (for example, the first pigment ink) is shown. First, in step S01, the first binarization process is performed on the input data using the first dither matrix 501 prepared in advance, as in the method described with reference to FIG. Also here, output data 502 is shown as a result of performing binarization processing using a dither matrix 501 of 4 pixels × 4 pixels when gradation data having level 8 is uniformly input to the region 500. ing.

  In the subsequent step S02, a pigment height coefficient addition matrix 505 is calculated based on the binarization result for the ink color thus far. Specifically, first, the product of the binarized output data obtained in step S01 and the deposition coefficient (the first deposition coefficient is 0.7) is obtained for each pixel, and this is calculated as the pigment height of each pixel. The pigment height coefficient matrix 503 is created using the coefficients. The deposition coefficient is a coefficient of 0 to 1 determined for each ink color, and becomes a larger value as the deposition height increases. That is, when the first deposition coefficient is 0.7, the second deposition coefficient that performs the second binarization process is smaller than that, and the subsequent third deposition coefficient is set to a smaller value. . Then, the obtained pigment height coefficient matrix 503 is added to a pigment height coefficient addition matrix 504 that is the sum of the pigment height coefficients of ink colors that have already been processed in advance. As a result, a pigment height coefficient addition matrix 505 composed of a plurality of pixels having a new pigment height coefficient is obtained. Since FIG. 5 shows the binarization process for the first pigment ink, the pigment height coefficient of the pigment height coefficient addition matrix 504 so far is 0 for all pixels.

  Referring to FIG. 4 again, in step S03, the threshold value of each pixel of the second dither matrix 506 prepared in advance for the second pigment ink color to be processed next is set to the pigment height obtained in step S03. Replacement based on the coefficient addition matrix 505 is performed. Specifically, the threshold values of the second dither matrix are arranged so that a smaller threshold value corresponds to a pixel having a smaller pigment height coefficient value in the pigment height coefficient addition matrix 505. For the second pigment ink, a second binarization process is performed using the new dither matrix 501 thus obtained. The steps shown in steps S01 to S03 as described above are performed in order of increasing pigment height for all ink colors. That is, the result obtained by the second binarization process is multiplied by the second deposition coefficient, and then added to the pigment height coefficient addition matrix 504 to correct the third dither matrix. Then, the corrected third dither matrix is used for the third binarization process for the third pigment ink. When the binarization processing of the region of interest 4 pixels × 4 pixels is completed for all ink colors, the attention region is moved to the next adjacent region, and the same processing as described above is repeated.

  With the processing described above, it is difficult for the next pigment to be stacked on a pixel where the pigment is highly deposited, and the next pigment is easily deposited on a pixel where the pigment is not deposited. As a result, in all the pixels, the deposition height can be made uniform. That is, when the binarization processing of each color is performed independently as in the prior art, the recording state as shown in FIG. 13A is replaced with the processing shown in FIG. Thus, it is possible to output an image excellent in glossiness while suppressing irregular reflection.

  In the present embodiment, the ink color separation processing described with reference to FIG. 2 is used so that the height of the pigment deposited on the surface of the recording medium is made uniform.

  FIG. 6 is an image diagram for explaining a general ink color separation process. In the ink color separation processing, for example, multi-value color separation data (for example, C, M, Y, K) corresponding to the ink prepared in the recording apparatus based on luminance data (R, G, B) composed of, for example, 8 bits 256 gradations. ). 106 is an image diagram of a three-dimensional LUT with luminance data (R, G, B) as an axis. Each axis corresponds to input data of RGB represented by 0 to 255, and any luminance data (R, G, B) is included in one of the subdivided cubes. Multi-value color separation data (C, M, Y, K) corresponding to ink can be determined for all luminance data, but usually from a plurality of grid point data included in a cube including the luminance data. Then, color separation data (C, M, Y, K) is calculated by performing an interpolation process.

  Generally, a plurality of LUTs are created in advance according to the type of recording medium and stored in the memory of the host device. When such an LUT is created, output data (C, M, Y, K, etc.) that minimizes the color difference between the original and the arbitrary input data (R, G, B) as much as possible. R) is set. However, in practice, there are several output data candidates with a small color difference for the same input data (R, G, B), and there are many cases in which the difference is hardly recognized visually. Therefore, in the present embodiment, this is utilized, and output data whose glossiness is included in a certain range as much as possible when actually recording on a recording medium from among several candidates of output data with small color difference. Select (C, M, Y, K, R) and store it in the LUT.

  The LUT as described above may be stored in advance in the memory of the host device according to the type of the recording medium, but a system that calculates as necessary may be prepared.

  FIG. 8 is a block diagram for explaining a system for calculating each parameter of the LUT according to the present embodiment. In this system, the host device 201 is connected to a spectrocolorimeter 203 and a gloss meter 204 in addition to the recording device 202.

  FIG. 9 is a flowchart for explaining a process executed by the host apparatus 201 when setting each parameter of the LUT. When this process is started, first, in step S401, the host apparatus 201 causes the recording apparatus 202 to record a predetermined test patch.

  FIG. 7 is a diagram showing recording data of a plurality of test patches recorded in step S401. Here, a case is shown in which the printing apparatus prepares ink of cyan, magenta, yellow, black, and red (R) that is a chromatic color. No. in the left column. Indicates the serial number of the test patch, and the column corresponding to each ink color on the right side indicates the gradation value of each ink color. As can be seen from the figure, the plurality of patches recorded here are obtained by slicing 256 gradation data of each ink used by the recording apparatus at a predetermined count and corresponding to all gradation combinations between ink colors. is there.

  FIG. 10 is a diagram showing an arrangement example of test patches actually recorded on a recording medium.

In subsequent step S <b> 402, the host device 201 operates the spectrocolorimeter 203 to perform color measurement of individual patches. The obtained chromaticity data (L ^* a ^* b ^* ) is stored in the memory in the host device 201.

  In step S403, the glossiness meter 204 is operated to measure the glossiness Gi of each patch. The measurement angle at this time may be any value such as 20 °, 45 ° or 60 ° as long as the angle is adapted to the glossiness of the recording medium. The obtained result is stored in a memory in the host device 201.

  Thereafter, in step S404, the average value Gave of all (N) glossiness data Gi obtained is calculated by the following equation.

Further, in step S405, a patch having a color difference ΔE of chromaticity data (L ^* a ^* b ^* ) with respect to the original luminance data (R, G, B) smaller than 1 is extracted for each lattice point. Then, the patch having the glossiness Gi closest to the average glossiness Gave of the entire range is selected from these patches. Further, the gradation data (C, M, Y, K, R) for recording this patch is stored in the LUT as parameters for the luminance data (R, G, B).

More specifically, for example, consider a case where a parameter corresponding to (L ^* a ^* b ^* ) = (63.38, 49.46, 27.08) is set as one grid point. At this time, it is assumed that among the chromaticity information stored in step S402, there are the following three types in which the color difference ΔE from the chromaticity is less than 1.
(1) (C, M, Y, K, R) = (0, 127, 120, 0, 0)
(2) (C, M, Y, K, R) = (0, 0, 0, 0, 128)
(3) (C, M, Y, K, R) = (0, 50, 55, 0, 64)
Further, the glossiness measured in step S403 corresponding to (1) to (5) is respectively
(1) 44.8
(2) 53.3
(3) 41.8
Suppose that On the other hand, if the average glossiness value in step S404 is Gave = 45.2, the patch having the glossiness value closest to this is the patch (1). Therefore, in this example, as a parameter for one lattice point (L ^* a ^* b ^* ) = (63.38, 49.46, 27.08) of the LUT, (C, M, Y, K, R) = ( 0, 127, 120, 0, 0) is stored. The above process is executed for all the lattice points.

As another example, one gray lattice point (L ^* a ^* b ^* ) = (50, 0, 0) for a recording apparatus that prepares cyan (magenta), yellow, black, and gray (Gr) as an achromatic color, for example. Consider the case where a parameter corresponding to is set. FIG. 11 is a diagram showing recording data of a plurality of test patches recorded in such a case. At this time, it is assumed that among the chromaticity information stored in step S402, there are the following six types in which the color difference ΔE from the chromaticity is less than 1.
(1) (C, M, Y, K, Gr) = (107, 123, 82, 0, 0)
(2) (C, M, Y, K, Gr) = (10, 14, 0, 0, 200)
(3) (C, M, Y, K, Gr) = (51, 64, 34, 0, 128)
(4) (C, M, Y, K, Gr) = (57, 73, 32, 50, 0)
(5) (C, M, Y, K, Gr) = (10, 14, 0, 50, 100)
(6) (C, M, Y, K, Gr) = (51, 64, 34, 50, 28)
And the glossiness measured in step S403 corresponding to these is respectively
(1) 41.1
(2) 70.4
(3) 46.9
(4) 36.0
(5) 44.7
(6) 38.5
Suppose that On the other hand, if the average glossiness value in step S404 is Gave = 47.6, the pattern having the glossiness value closest to this is the pattern (3). Therefore, in this example, as a parameter for one lattice point (L ^* a ^* b ^* ) = (50, 0, 0) of the LUT, (C, M, Y, K, Gr) = (51, 64, 34, 0, 128) is stored. The above process is executed for all the lattice points.

As another example, one gray lattice point (L ^* a ^* b ^* ) = (50,0) for a recording apparatus prepared with cyan, magenta, yellow, black, light cyan (Lc) and light magenta (Lm), for example. , 0) will be described. Light cyan (Lc) and light magenta (Lm) are inks that have the same hue as the chromatic cyan and magenta inks, but contain a lower concentration of pigment.

FIG. 12 is a diagram showing recording data of a plurality of test patches recorded in such a case. At this time, let us consider a case where among the chromaticity information stored in step S402, there are the following six types in which the color difference ΔE from the chromaticity is less than 1.
(1) (C, M, Y, K, Lc, Lm) = (107, 123, 82, 0, 0)
(2) (C, M, Y, K, Lc, Lm) = (0, 0, 82, 0, 208, 235)
(3) (C, M, Y, K, Lc, Lm) = (42, 63, 82, 0, 121, 139)
(4) (C, M, Y, K, Lc, Lm) = (57, 73, 32, 50, 0, 0)
(5) (C, M, Y, K, Lc, Lm) = (0, 0, 32, 50, 96, 115)
(6) (C, M, Y, K, Lc, Lm) = (12, 17, 28, 50, 90, 104)
And the glossiness measured in step S403 corresponding to these is respectively
(1) 41.1
(2) 65.3
(3) 49.8
(4) 36.0
(5) 53.4
(6) 44.9
Suppose that On the other hand, if the average glossiness value in step S404 is Gave = 50.4, the pattern having the glossiness value closest to this is the pattern (3) out of the above three. Therefore, in this example, as a parameter for one lattice point (L ^* a ^* b ^* ) = (50, 0, 0) of the LUT, (C, M, Y, K, Lc, Lm) = (42, 63, 82, 0, 121, 139). The above process is executed for all the lattice points.

  As in the example described above, as the number of ink colors used is larger than the basic four colors, the range of combinations for expressing one color also increases, and the smoothness on the recording surface is easily within a predetermined range, that is, near Gave. Become. Therefore, if the ink color separation process as in this embodiment is used, as a result, a recording state as shown in FIG. 13B can be realized, irregular reflection is suppressed, and glossiness is uniform. An image can be output.

  In the above description, a patch having a color difference ΔE smaller than 1 is extracted as a condition in which almost no color difference is visually confirmed. However, the present embodiment is not limited to this. Depending on the balance between the recognizability of the gloss difference and the recognizability of the color difference, it may be set to a more gradual condition or a more severe condition. These conditions may be varied depending on the hue. For example, in terms of human visual characteristics, conditions may be set strictly in the vicinity of gray or near skin color where a hue difference is easily detected, and may be set loosely in an area where the hue difference is difficult to detect.

It is a schematic diagram for demonstrating the image recording structure of the inkjet recording device suitable for applying this invention. FIG. 4 is a block diagram for explaining image processing steps in a host apparatus and a recording apparatus applicable to the present invention. It is a schematic diagram for demonstrating the binarization processing method by a general dither method. 3 is a block diagram for explaining detailed steps of a dither method employed in Embodiment 1. FIG. FIG. 3 is a schematic diagram for specifically explaining each process performed in a dither process of Example 1. It is an image figure for demonstrating a general ink color separation process. It is the figure which showed an example of the recording data of a some test patch. FIG. 10 is a block diagram for explaining a system for calculating parameters of an LUT according to the second embodiment. It is a flowchart for demonstrating the process which a host apparatus performs when calculating each parameter of LUT. It is the figure which showed the example of the test patch. It is the figure which showed an example of the recording data of a some test patch. It is the figure which showed an example of the recording data of a some test patch. It is a figure for demonstrating the accumulation state of the pigment in the surface of a recording medium, and the reflective state of light at the time of recording using the several ink from which pigment concentration differs mutually.

Explanation of symbols

1 Thin ink
2 Accumulated ink
3 Intermediate ink
10 Carriage
11 Nozzle rows
DESCRIPTION OF SYMBOLS 12 Recording medium 101 Input gamma conversion process part 102 Color matching process part 103 Ink color separation process part 104 Output gamma conversion process part 105 Halftone process part 106 Three-dimensional LUT
201 Host device 202 Recording device 203 Spectral colorimeter 204 Gloss meter
300 Input data 301 Dither matrix 500 Input data 501 Dither matrix 502 Output data
503 Pigment height coefficient matrix 504 Pigment height coefficient addition matrix 505 Pigment height coefficient addition matrix 506 Dither matrix

Claims (15)

An image processing method for recording an image on the recording medium using at least a first pigment ink and a second pigment ink deposited on a recording medium lower than the first pigment ink,
A first binarization step for determining a pixel for recording the first pigment ink using a first dither matrix;
Calculating a new pigment height coefficient by adding a first deposition coefficient to a pigment height coefficient corresponding to a pixel that records the first pigment ink;
Determining a threshold value of the second dither matrix so that a smaller threshold value corresponds to a pixel having a smaller new pigment height coefficient;
An image processing method comprising: a second binarization step for determining a pixel for recording the second pigment ink using the second dither matrix. The first deposition coefficient is added to the pigment height coefficient corresponding to the pixel for recording the first pigment ink, and the second deposition is performed for the pigment height coefficient corresponding to the pixel for recording the second pigment ink. Calculating a new pigment height coefficient by adding the coefficients;
Determining a threshold value of the third dither matrix so that a smaller threshold value corresponds to a pixel having a smaller new pigment height coefficient;
A third binarization step of determining, by using the third dither matrix, a pixel for recording a third pigment ink that is deposited on a recording medium at a lower height than the second pigment ink. The image processing method according to claim 1, further comprising:   The first and second deposition coefficients are the height at which the first pigment ink is deposited on the recording medium, the height at which the second pigment ink is deposited on the recording medium, and the recording with the third pigment ink. The image processing method according to claim 2, wherein the image processing method is a value determined based on a height accumulated on the medium. An image for performing binarization processing for recording an image on the recording medium, using at least the first pigment ink and the second pigment ink deposited on the recording medium lower than the first pigment ink. A processing device comprising:
First binarization means for determining a pixel to record the first pigment ink using a first dither matrix;
Means for calculating a new pigment height coefficient by adding a first deposition coefficient to a pigment height coefficient corresponding to a pixel for recording the first pigment ink;
Means for determining a threshold value of the second dither matrix so that a smaller threshold value corresponds to a pixel having a smaller new pigment height coefficient;
An image processing apparatus comprising: a second binarization unit that determines a pixel to record the second pigment ink using the second dither matrix. An image processing method including a color separation process for converting multi-value luminance data into multi-value gradation data corresponding to a plurality of ink colors by referring to an LUT,
In the LUT, among a plurality of gradation data in which a color difference between the chromaticity of the multi-value luminance data and the chromaticity of the image recorded on the recording medium is included in a predetermined range, the image recorded on the recording medium is recorded. An image processing method, characterized in that gradation data whose glossiness is closest to a predetermined value is set corresponding to the multivalued luminance data.   The predetermined value is an average value of the glossiness of an image recorded on a recording medium according to the gradation data corresponding to the multivalued luminance data in the entire range of the multivalued luminance data. The image processing method according to claim 5.   7. The image processing method according to claim 5, wherein the plurality of ink colors include at least cyan, magenta, and yellow.   The image processing method according to claim 7, wherein the plurality of ink colors further include an achromatic color.   The image processing method according to claim 7, wherein the plurality of ink colors further include a chromatic color having a hue different from cyan, magenta, and yellow.   The image processing method according to claim 7, wherein the plurality of ink colors further include chromatic colors having a hue equal to cyan, magenta, or yellow and having different densities. A method of creating an LUT that is referred to in order to convert multi-value luminance data into multi-value gradation data corresponding to a plurality of ink colors,
A step of recording a plurality of patches in which gradation data of the plurality of ink colors are changed in stages on a recording medium;
Measuring the chromaticity of the plurality of patches;
Measuring the glossiness of the plurality of patches;
Calculating an average glossiness of the plurality of patches;
Extracting a plurality of patches such that a color difference with respect to the luminance data is included in a predetermined range;
A step of selecting a patch whose glossiness measured in the measurement step is closest to the average value among the plurality of extracted patches;
And a step of storing gradation data corresponding to the selected patch in correspondence with the luminance data.   12. The LUT creation method according to claim 11, wherein the plurality of ink colors include at least cyan, magenta, and yellow.   The LUT creation method according to claim 12, wherein the plurality of ink colors further include an achromatic color.   The LUT creation method according to claim 12 or 13, wherein the plurality of ink colors further include a chromatic color having a hue different from cyan, magenta, and yellow.   15. The LUT creation method according to claim 12, wherein the plurality of ink colors further include a chromatic color having a hue equal to cyan, magenta, or yellow and having a different density.

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