JP6965042B2 - Image processing device and image processing method - Google Patents

Description

The present invention relates to an image processing apparatus and an image processing method. In particular, the present invention relates to image processing of an inkjet recording apparatus that uses both color ink and metallic ink.

In the inkjet recording apparatus, the upper limit of the amount of ink applied is set so as not to exceed the upper limit of the ink that can be absorbed per unit area in the recording medium used. Therefore, when using ink that does not directly affect the hue of the image, such as metallic ink or clear ink, the upper limit of the color ink that can be applied per unit area decreases, resulting in color. The reproduction range may be reduced.

Patent Document 1 discloses an image processing method for solving such a problem. Specifically, in a color gamut such as a dark area where the amount of ink applied is large, the upper limit value of the color ink that can be applied to the area by limiting the amount of metallic ink applied per unit area. Is increasing, and the color reproduction range by color ink is expanded.

Japanese Patent No. 5099018

However, in Patent Document 1, there is no focus on changing the color itself expressed by the color ink by applying the metallic ink. That is, even when the same amount of color ink is applied to the recording medium in order to express the same color, the color development on the recording medium differs depending on whether the metallic ink is further applied or not. However, Patent Document 1 does not pay attention to this.

For this reason, in the conventional configuration in which the color ink and the metallic ink are used in combination, the hue and the saturation differ depending on whether or not the metallic ink is applied, and stable color reproduction cannot be performed on the recording medium.

The present invention has been made to solve the above problems. Therefore, an object of the present invention is to provide an image processing apparatus for inkjet recording capable of performing stable color reproduction on a recording medium regardless of whether or not metallic ink is applied.

Therefore, the present invention is an image processing apparatus for recording an image on a recording medium using metallic ink containing a plurality of color inks and metal particles, and is a color image data which is multi-valued RGB data. , A means for acquiring data for metallic ink indicating recording or non-recording of the metallic ink for each pixel, and conversion for converting image data of the color into a plurality of multi-valued data corresponding to each of the plurality of color inks. The conversion means converts the color image data into the plurality of multi-valued data by the first conversion method for the pixels whose data for the metallic ink is 0, and the conversion means for the metallic ink. For pixels whose data is not 0, the color image data is converted into the plurality of multi-valued data by a second conversion method different from the first conversion method, and the first conversion method is a first conversion method. It is a method of converting the RGB multi-valued data into a plurality of multi-valued data corresponding to each of the plurality of color inks by using the lookup table, and the second conversion method is the same as the first lookup table. Is a method of converting the RGB multi-valued data into a plurality of multi-valued data corresponding to each of the plurality of color inks using different second lookup tables, and the second lookup table is arbitrary. Based on the result of converting the RGB multi-value data into the plurality of multi-value data corresponding to each of the plurality of color inks using the second lookup table, the color ink is used together with the metallic ink in the recording medium. The color coordinates obtained by measuring the color of the image recorded in the above by a colorimeter satisfying the SCI condition can be obtained by using the first lookup table to obtain the arbitrary RGB multi-valued data, respectively. Based on the result of conversion into the plurality of multi-valued data corresponding to the above, the image recorded on the recording medium without the metallic ink is converted into the color coordinates obtained by measuring the color with the colorimeter. The feature is that it is created so that it is close to each other.

According to the present invention, stable color reproduction can be performed on a recording medium regardless of whether or not metallic ink is applied.

It is a block diagram for demonstrating the control structure in a recording system. It is a figure for demonstrating the recording structure in a recording part. (A) and (b) are block diagrams of image processing. It is a figure which shows how the metallic ink affects the hue. It is a block diagram of image processing using the second color separation table. It is a block diagram of image processing using the second color matching table. It is a block diagram of image processing when the look-up table is different. It is a flowchart for demonstrating the process of making a 2nd color separation table. It is a layout diagram of a color patch. It is a figure which illustrates the data content of each parallel patch. It is a figure for demonstrating the colorimetric method using an integrating sphere. It is a figure which shows the difference between the color measuring method which satisfies SCI and the color measuring method which does not satisfy SCI. It is a figure for demonstrating the effect of the 2nd color separation table.

FIG. 1 is a block diagram for explaining a control configuration in a recording system that can be used in the present embodiment. The recording system of the present embodiment is composed of a host device 101 on the side of providing image data and a recording device 102 that ejects ink according to the image data received from the host device 101.

The host device 101 includes a CPU 104, a storage device 106, a working memory 105, and a data input / output device 107. The CPU 104 controls the entire device while using the working memory 105 according to the program stored in the storage device 106. The storage device 106 stores the OS, various application software, system programs, and various parameters. Such a storage device 106 can be configured by means typified by a hard disk or a flash ROM.

The operation unit 103 is a user interface including an input device such as a keyboard and a mouse and a display such as a display. The user can input a recording command for the recording device together with the recording conditions via the operation unit 103. For example, in a desired image, it is possible to set whether or not to add metallic luster due to metallic ink, and if so, the area thereof.

On the other hand, the recording device 102 includes a recording device control unit 108, a data input unit 109, an image processing unit 110, and a recording unit 111. The recording command output from the host device 101 is received by the data input unit 109. The recording command includes RGB data and metallic ink data, which are image data, as well as mechanical parameters that define an image processing method for the image data and a recording method based on recording conditions set by the user.

The image processing unit 110 performs image processing on the image data received by the data input unit 109 according to a predetermined image processing parameter, and generates recorded data that can be recorded by the recording unit 111. The recording device control unit 108 causes the recording unit 111 to execute a recording operation according to the recording data generated by the image processing unit 110 while controlling various mechanisms in the recording device 102 according to mechanical parameters.

A plurality of types of image processing parameters and mechanical parameters are stored in advance in the storage device 106 of the host device 101 according to the type of recording medium, the recording mode set by the user, the presence or absence of the use of metallic luster, and the like. Then, when a recording command is generated, only the specified image processing parameters and mechanical parameters among the plurality of types are called by the CPU 104 and provided to the recording device by the recording commands.

FIG. 2 is a diagram for explaining a recording configuration in the recording unit 111. The recording medium S is conveyed in the Y direction in the figure as the transfer roller 201 rotates. Each of the five cartridges 210 to 214 is composed of a recording head that ejects ink according to the recording data and an ink tank that supplies ink to the recording head. As the recording head, various inkjet recording methods such as a thermal jet method using a heating element and a piezo method using a piezoelectric element can be applied.

In the figure, the cartridge 210 corresponds to cyan ink, the cartridge 211 corresponds to magenta ink, the cartridge 212 corresponds to yellow ink, the cartridge 213 corresponds to black ink, and the cartridge 213 corresponds to metallic ink. The carriage 203 mounts these cartridges 210 to 214 in the order shown in the drawing, and is capable of reciprocating in the X direction while being guided and supported by the guide shaft 202.

Based on the above configuration, the recording control unit 108 moves the carriage 203 in the X direction while ejecting ink from each recording head according to the recording data. Then, the recording control unit 108 conveys the recording medium in the Y direction by a distance corresponding to the recording width of the recording head each time such a recording main scan is performed. By alternately repeating the recording main scanning and the conveying operation as described above, an image is gradually formed on the recording medium S.

The details of the metallic ink will be described below. The metallic ink used in this embodiment contains metal particles. The content (mass%) of the metal particles in the ink is preferably 0.1% by mass or more and 30.0% by mass or less, and 1.0% by mass or more and 15.0% by mass, based on the total mass of the ink. The following is more preferable.

The metal particles are not particularly limited, and specific examples thereof include particles of gold, silver, copper, platinum, aluminum, titanium, chromium, iron, nickel, zinc, zirconium, tin and the like. can. These metal particles may be simple substances or alloys, and may be used in combination. However, from the viewpoint of storage stability of the metal particles and the glossiness of the formed image, it is preferable to use gold, silver, and copper particles, and silver particles are particularly preferable. Silver particles are particularly excellent in that they can express a wide range of metallic colors in combination with colored inks because of the high glossiness and achromaticity of the formed image.

When silver particles are used, the average particle size is preferably 1 nm or more and 200 nm or less, and preferably 10 nm or more and 100 nm or less, from the viewpoint of storage stability of the ink and the glossiness of the image formed by the silver particles. More preferred.

In addition to the above metal particles, the metallic ink used in the present embodiment includes water (ion-exchanged water), a surfactant, a water-soluble organic solvent, a pH adjuster, a rust inhibitor, a preservative, an antifungal agent, and an oxidation. Various additives such as an inhibitor, a reduction inhibitor, and an evaporation accelerator may be contained. When the ink as described above is used, glossiness can be exhibited without any special operation such as firing when the ink is applied to the recording medium.

3A and 3B are block diagrams for explaining a series of image processing executed by the image processing unit 110. FIG. 3A shows a pixel in which data for metallic ink does not exist (F = 0), and FIG. 3B shows a pixel in which data for metallic ink exists (F ≠ 0).

The image data output from the host device 101 is received by the image signal I / F 301 of the image processing unit 110. The image data is composed of RGB data for color ink and F data for metallic ink, both of which are multi-valued data of 8 bits (256 gradations). The RGB data is image data having color information generated by the application of the host device 101. The F data is information indicating the amount of metallic ink applied, and in the present embodiment, the application or the printer driver generates the F data based on the information set by the user via the operation unit 103. In the figure, the F data is also shown as 8-bit multi-valued data like the RGB data, but in the present embodiment, either the metallic luster is given (255) or the metallic luster is not given (0) for each pixel. It shall have the value of.

The RGB data is input to the color matching processing unit 302. On the other hand, the F data for metallic ink having no color information passes through the color matching processing unit 302 and the color separation processing unit 303 and is input to the gradation correction processing unit 304.

The color matching processing unit 302 performs processing for associating the color space managed by the host device 101 with the color space that can be expressed by the recording device 102. Specifically, referring to the three-dimensional look-up table (LUT306) acquired from the host device 101, the RGB data of 256 gradations is converted into the R'G'B'data of 256 gradations. The output value R'G'B'data from the color matching processing unit 302 is input to the color separation processing unit 303.

The color separation processing unit 303 converts the multi-valued luminance data R'G'B'to the multi-valued density data C, M, Y, K corresponding to the ink used by the recording unit 111. Specifically, referring to the three-dimensional look-up table (LUT307) acquired from the host device 101, 256 gradations of R'G'B'data are converted into 256 gradations of C, M, Y, and K data. do. The output values C, M, Y, and K data from the color separation processing unit 303 are input to the gradation correction processing unit 304 together with the F data for metallic ink received by the image signal I / F 301.

When the pixel of interest is a pixel that does not have data for metallic ink, F = 0 is input to the gradation correction processing unit 304 as shown in FIG. 3A. On the other hand, when the pixel of interest is a pixel having data for metallic ink, F ≠ 0 is input to the gradation correction processing unit 304 as shown in FIG. 3B.

The gradation correction processing unit 304 provides linearity between each of the signal values of C, M, Y, K, and F, which are input data, and the density value of each ink color expressed on the recording medium. It is a correction process of. Specifically, referring to the one-dimensional look-up table (LUT308) prepared for each ink color acquired from the host device 101, 256 gradations of C, M, Y, K, and F data are also obtained in 256 gradations. Converted to C', M', Y', K', F'data. The output values C', M', Y', K', and F'data from the gradation correction processing unit 304 are input to the half toning processing unit 305.

By adopting a predetermined quantization method, the half toning processing unit 305 records C', M', Y', K', and F'data, which are multi-valued density data, in dot recording (1) or non-recording (1). It is converted into binary recorded data C ″, M ″, Y ″, K ″, F ″ indicating recording (0). As the quantization method, various methods such as an error diffusion method and a dither method can be adopted. This completes a series of image processing in the image processing unit 110. After that, the recording device control unit 108 causes the recording unit 111 to execute the recording operation according to the binary recording data generated by the image processing unit 110.

Here, consider a case where RGB data having the same signal value is input to both FIGS. 3A and 3B. In this case, the RGB signals are subjected to the same processing from the color matching processing unit 302 to the half toning processing unit 305. That is, in both cases of FIGS. 3A and 3B, cyan, magenta, yellow, and black inks are applied to the unit area of the recording medium in a predetermined ratio.

In FIG. 3A, metallic ink is not applied in addition to the above-mentioned predetermined proportions of cyan, magenta, yellow and black inks. On the other hand, with respect to FIG. 3B, metallic ink is applied in addition to the above-mentioned predetermined proportions of cyan, magenta, yellow and black inks. At this time, even if the metallic ink itself has no hue, it is confirmed that when the metallic ink is applied to the recording medium together with other inks, it affects the hue of the color expressed by the other inks and again. Was done.

FIG. 4 is a diagram showing how the metallic ink affects the hue. In the a * b * plane, the area surrounded by the solid line is the color area in which the RGB signal input from the host device 101 can be expressed. The area surrounded by the one-dot dashed line is a color area that can be expressed by the recording device 102 with CMYK color ink. The color matching processing unit 302 performs processing for associating the individual coordinates included in the area surrounded by the solid line with the coordinates of the area surrounded by the alternate long and short dash line. On the other hand, the area surrounded by the dotted line is a color area that can be expressed when the metallic ink F is applied to the area recorded with the CMYK color ink. It can be seen that the expressable color region is further reduced by applying the metallic ink F.

Here, attention is paid to a pixel having arbitrary input image data (RGB). When the pixel is a pixel to which metallic ink is not applied, the RGB signal input to the image processing unit 110 is subjected to various image processing according to FIG. 3A, and C ″, M ″, Y ″, K ″ is obtained. Since the signal F for metallic ink is 0 after gradation correction and halftone processing, the signal values after halftone processing are C ″, M ″, Y ″, K ″, and F ″. When the recording operation is performed according to the above, only the color ink is applied to the recording medium. The coordinates when the image output in this way is color-measured by a predetermined colorimeter are shown by (L1 *, a1 *, b1 *) in the figure.

On the other hand, when the pixel having the input image data (RGB) is a pixel to which metallic ink is applied, the RGB signal input to the image processing unit 110 is subjected to various image processing according to FIG. 3 (b), and is subjected to various image processing according to FIG. 3 (b). The same C ″, M ″, Y ″, and K ″ as in the case of a) can be obtained. The signal F for metallic ink is not 0 after gradation correction and halftone processing. Therefore, when the recording operation is performed according to the signal values C ", M", Y ", K", and F "after the halftone processing, the recording medium has the same combination as in FIG. 3A. In addition to the color ink of, metallic ink is also applied. In the figure, the coordinates when the output image is color-measured by a predetermined colorimeter are shown by (L2 *, a2 *, b2 *).

Here, consider a case where metallic ink is applied to a part of a uniform image region having the same RGB signal value. In this case, the color coordinates of the area to which the metallic ink is not applied are (L1 *, a1 *, b1 *), and the color coordinates of the area to which the metallic ink is applied are (L2 *, a2 *, b2 *). A color difference ΔE1 occurs in. If the value of such a color difference ΔE1 is sufficiently small, it is not visually noticeable, but if it is large, it is recognized as a color shift.

In the present embodiment, in order to suppress such a color difference as small as possible, the second color separation table for the region to which the metallic ink is applied is set to the color separation of the region to which the metallic ink is not applied as described with reference to FIG. 3 (a). Prepare separately from table 307. Then, the color coordinates (L3 *, a3 *, b3 *) when the image output based on the same RGB signal as above is color-measured by a predetermined colorimeter are (L2 *, a2 *, b2 *). It should be closer to (L1 *, a1 *, b1 *) than. That is, the color difference ΔE2 between (L3 *, a3 *, b3 *) and (L1 *, a1 *, b1 *) is made smaller than ΔE1. As described above, in the second color separation table, CMYK data (L3 *, a3 *, b3 *) can be obtained from R'G'B'after color matching processing is performed on the input RGB signal value. It is a table that corresponds to.

FIG. 5 is a block diagram for explaining the image processing executed by the image processing unit 110 using the second color separation table 501. The difference from FIG. 3A is that the table referred to by the color separation processing unit 303 is changed from the LUT 307 to the second color separation table (LUT 501). Referring to FIG. 4 again, the first color separation table 307 stores information for associating the RGB signal in the area surrounded by the alternate long and short dash line with the CMYK signal in the region also enclosed by the alternate long and short dash line. On the other hand, the second color separation table 501 stores information for associating the RGB signal in the region surrounded by the dashed line with the CMYK signal in the region surrounded by the dotted line.

Therefore, when various image processes are performed on the pixels having the same input image data (RGB) as described above according to FIG. 5, C1 ″, M1 ″, Y1 ″, which are different from the case of FIG. 3 (a), K1 ″ is obtained. Then, when the recording operation is performed according to the signal values C1 ″, M1 ″, Y1 ″, K1 ″, and F ″, the recording medium is added with the color ink in a ratio different from that in the case of FIG. 3 (a). Metallic ink is applied. Further, when the image output in this way is color-measured with a predetermined colorimeter, the color coordinates (L3 *, a3 *, b3 *) shown in FIG. 4 can be obtained. The distance (ΔE2) between the color coordinates (L3 *, a3 *, b3 *) and the color coordinates (L1 *, a1 *, b1 *) is the color coordinates (L2 *, a2 *, b2 *) and the color coordinates (L1 *). , A1 *, b1 *), which is smaller than the distance (ΔE1). As a result, even when metallic ink is applied to a part of a uniform image area, the color difference between the two can be made inconspicuous.

FIG. 8 is a flowchart for explaining the process of creating the second color separation table. First, in step S81, a standard color separation table is prepared. Here, the standard color separation table is a first color separation table 307 used for pixels to which metallic ink is not applied.

In step S82, a plurality of color patches are recorded using the recording device 102. FIG. 9 is a diagram showing the layout of the color patch recorded in step S2 on the recording medium, and FIG. 10 is a diagram illustrating the contents of each patch. For example, P1 and P6 are equal to (0,255,255) for RGB signals, but P1 is a patch that applies metallic ink (100%) and P2 is a patch that does not apply metallic ink (0%). .. As described above, in the present embodiment, the RGB signals that can take a value of 0 to 255 are gradually different, and the patch (100%) that applies metallic ink and the patch (0%) that does not apply metallic ink for each RGB signal value. ) Is prepared.

Return to FIG. In step S83, the colors of the plurality of patches shown in FIG. 9 are measured. In the present embodiment, the color is measured by a method satisfying the SCI condition for detecting light including specularly reflected light, instead of a general color measuring method for detecting diffusely reflected light such as 0 ° / 45 °.

FIG. 11 is a diagram for explaining a colorimetric method using an integrating sphere, which is one of the methods satisfying the SCI condition. The light emitted from the light source 11 repeats diffuse reflection on the inner wall surface of the integrating sphere 12, and the surface of the sample S to be color-measured is uniformly irradiated and received by the light receiving unit 14. At this time, if the trap 15 at a position contrasting with the light receiving portion is closed with respect to the perpendicular line of the sample S surface as shown in the figure, light including specularly reflected light can be detected. On the metal surface, the specularly reflected light tends to be stronger than the diffusely reflected light, and it is visually easily affected by the specularly reflected light.

FIG. 12 is a diagram for explaining the difference between a color measuring method that satisfies the SCI condition and a color measuring method that does not satisfy the SCI condition. Here, as an example, a case where a multi-step gradation patch using only magenta ink is recorded and the color is measured by diffuse reflection light of 0 ° / 45 ° and a case where the color is measured using the colorimeter of FIG. And, the color measurement results are compared. For the patch (Color Only) to which metallic ink is not applied, the color is measured when the color is measured with the diffuse reflection light of 0 ° / 45 ° and when the color is measured using the colorimeter shown in FIG. 11 (SCI). There is almost no difference in the results. On the other hand, for the patch (Color + Silver) to which metallic ink is applied, a large difference has appeared between the two. In the case of a patch with metallic ink (Color + Silver), when the color is measured with diffuse reflection light of 0 ° / 45 °, only low saturation and brightness values are detected, and specular reflection is used for visual color recognition. It can be seen that light contributes significantly. Therefore, when creating the second color separation table on the premise of applying metallic ink, it is preferable to adopt a color measuring method that satisfies the SCI conditions as shown in FIG.

Return to FIG. In step S84, the color measurement results of all patches are collated, and the combination having the closest color coordinates is selected. Hereinafter, the case of focusing on the RGB signal values (255, 128, 255) corresponding to magenta will be specifically described as an example.

First, the color measurement results (L13 *, a13 *, b13 *) of the patch P13 without applying metallic ink (0%) corresponding to the RGB signal values (255,128,255) are obtained. Next, a patch having the color coordinates closest to the color measurement results (L13 *, a13 *, b13 *) is selected from the patch group to which the metallic ink is applied (100%). Here, it is assumed that the patch Px having the color measurement result (Lx *, ax *, bx *) is selected. In step S84, such association is performed for all patches included in the patch group to which metallic ink is not applied (0%).

When the association for all the patches to which the metallic ink is not applied (0%) is completed in step S84, then in step S85, the color separation table for the metallic ink (second color separation table) is completed based on the above association. ) Is created. Hereinafter, a specific description will be given.

See FIG. 3A again. In the patch Pn from which the color coordinates (Ln *, an *, bn *) are obtained, the input signal value (Rn', Gn', Bn') is changed to the output signal value (Cn, Mn, Yn') by the color change processing unit 303. , Kn). On the other hand, the patch Pm of the color coordinates (Lm *, am *, bm *) determined to be the closest to the color coordinates (Ln *, an *, bn *) is an input signal value (Rm) by the color change processing unit 303. ´, Gm ′, Bm ′) are converted into output signal values (Cm, Mm, Ym, Km) and obtained.

That is, for the pixels to which the metallic ink is applied, color change processing is performed so that the input signal values (Rn', Gn', Bn') are converted into the output signal values (Cm, Mm, Ym, Km). Just do it. In this way, the color coordinates of the pixels to which the metallic ink is applied can be brought close to the color coordinates (Ln *, an *, bn *) of the pixels to which the metallic ink is not applied. Therefore, in step S85, (Rn', Gn', Bn') and (Cm, Mm, Ym, Km) are stored in association with each other. Then, such a correspondence is performed for all patches. Further, for the input signal value that is not output as a patch, interpolation calculation is performed using a plurality of signal values in the vicinity, and the output signal is associated with the input signal value. By the above work, the color separation table (second color separation table) for metallic ink can be completed. This is the end of this process.

FIG. 13 is a diagram for explaining the effect of the second color separation table. Here, the input signal values of the patch P13 and the patch P18 shown in FIG. 9 will be described as an example. These have the same RGB signal values (255, 128, 255), but the signal value for metallic ink is 0 in patch P13, and the signal value for metallic ink is not 0 in patch P18.

In the case of the present embodiment, as shown in FIG. 3A, the input signal value of the patch P13 is subjected to color separation processing using the first color separation table 307. The color measurement result of the recorded image is shown as color coordinates (LP13 *, aP13 *, bP13 *) in FIG.

On the other hand, as shown in FIG. 5, the input signal value of the patch P18 is subjected to color separation processing using the second color separation table 501. The color measurement results of the recorded image are shown as color coordinates (LP18 *, aP18 *, bP18 *) in the figure.

Further, as a comparative example, the color coordinates (LP18-M *, aP13-) of the image recorded by performing the color separation processing using the first color separation table 307 on the input signal value of the patch P18 in the same manner as the patch P13. M *, b13-M *) are also shown.

The color difference ΔE2 between the color coordinates (LP13 *, aP13 *, bP13 *) and the color coordinates (LP18 *, aP18 *, bP18 *) is the color coordinates (LP13 *, aP13 *, bP13 *) and the color coordinates (LP18-M *). , AP13-M *, b13-M *), which is smaller than the color difference ΔE1. That is, when the second color separation table is used for the input signal value of the patch P18, the color difference from the patch P13 is smaller than when the first color separation table is used.

As described above, according to the present embodiment, by separately preparing the color separation table when the metallic ink is applied and the color separation table when the metallic ink is not applied, stable color reproduction on the recording medium is performed. Can be done.

(Other embodiments)
In the first embodiment, the second color separation table 501 for the pixels to which the metallic ink is applied is prepared separately from the color separation table 307 for the pixels to which the metallic ink is not applied. However, even when the second color matching of the pixels to which the metallic ink is applied is prepared separately from the color matching table 306 of the pixels to which the metallic ink is not applied, the same effect as described above can be obtained.

FIG. 6 is a block diagram for explaining an image processing process when the second color matching table 601 is prepared. The difference from FIG. 3A is that the table referred to by the color matching processing unit 302 is changed from the LUT 306 to the second color matching table (LUT601). The flowchart shown in FIG. 8 can also be used when creating such a second color matching table. Specifically, in step S85, these are associated so that the input signals (Rn, Gn, Bn) to the color matching processing unit 302 are converted into output signals (Rm', Gm', Bm'). It can be a table.

Further, as shown in FIG. 7, both the look-up table referred to by the color matching processing unit and the lookup table referred to by the color separation processing unit may be prepared for the pixels to which the metallic ink is applied. In any case, the look-up table to be referred to when performing image processing on the RGB input signal is different depending on the presence or absence of data for metallic ink, and if similar color coordinates are finally obtained, the recording medium can be used. The recorded color can be stabilized.

In the above description, the case where the data for metallic ink is also multi-valued data of 256 gradations has been described, but the data for metallic ink is composed of "1" to be added or "0" not to be added. It may be binary data. In this case, in the image processing unit 110, the metallic input data F is used only for determining when the color matching processing unit 302 or the color separation processing unit 303 selects the look-up table. The metallic input data F may be transmitted to the recording control unit 108 together with the recording signal of the color ink after a series of image processing is performed.

When the data F for metallic ink can take a value of 0 to 255, the conversion value obtained from the first color separation table 307 and the second color separation table 501 are used according to the value of F. A new conversion value may be calculated from the obtained conversion value. That is, the closer the value of F is to 0, the closer to the conversion value obtained from the first color separation table 307, and the closer the value of F is to 255, the closer to the conversion value obtained from the second color separation table 501. All you have to do is process it.

Further, although the mode in which the recording device 102 uses the four color inks of cyan, magenta, yellow and black has been described above, the type of ink color is not limited to this. For example, special color inks such as red, green, and blue may be used in combination, or inks having different brightness such as light cyan and light magenta may be prepared. In this case, the color separation unit converts the input RGB data into multi-valued data corresponding to the color ink used by the recording device.

Further, in the above, the image processing unit 110 of the recording device 102 executes a series of image processing shown in FIGS. 3 and 5 to 7 based on the image data and the image processing parameters supplied from the host device 101. As described above, the present invention is not limited to such a form. The first and second color separation tables, the first and second color matching tables, and all the look-up tables prepared for each recording medium may be stored on the recording device side. Further, a part or all of the color matching process to the half toning process may be executed by the host device 101.

101 Host device 102 Recording device 110 Image processing unit 302 Color matching processing unit 303 Color separation processing unit S Recording medium

Claims (9)

An image processing device for recording an image on a recording medium using metallic ink containing a plurality of color inks and metal particles.
A means for acquiring color image data, which is RGB multi-valued data, and data for metallic ink indicating recording or non-recording of the metallic ink for each pixel.
A conversion means for converting the color image data into a plurality of multi-valued data corresponding to each of the plurality of color inks is provided.
The conversion means converts the color image data into the plurality of multi-valued data by the first conversion method for the pixels in which the data for the metallic ink is 0, and the data for the metallic ink is not 0. For the pixels, the color image data is converted into the plurality of multi-valued data by a second conversion method different from the first conversion method .
The first conversion method is a method of converting the RGB multi-valued data into a plurality of multi-valued data corresponding to each of the plurality of color inks by using the first lookup table, and the second conversion method. The method is a method of converting the RGB multi-valued data into a plurality of multi-valued data corresponding to each of the plurality of color inks by using a second lookup table different from the first lookup table.
The second look-up table is
Based on the result of converting arbitrary RGB multi-valued data into the plurality of multi-valued data corresponding to each of the plurality of color inks using the second lookup table, the color ink is used together with the metallic ink. The color coordinates obtained by measuring the color of the image recorded on the recording medium with a colorimeter that satisfies the SCI conditions are
Based on the result of converting the arbitrary RGB multi-valued data into the plurality of multi-valued data corresponding to each of the plurality of color inks using the first lookup table, the color ink is converted into the metallic ink. An image processing apparatus characterized in that an image recorded on the recording medium is created so as to be close to the color coordinates obtained by measuring the color with the colorimeter. An image processing device for recording an image on a recording medium using metallic ink containing a plurality of color inks and metal particles.
A means for acquiring color image data, which is RGB multi-valued data, and data for metallic ink indicating recording or non-recording of the metallic ink for each pixel.
A conversion means for converting the color image data into a plurality of multi-valued data corresponding to each of the plurality of color inks.
With
The conversion means converts the color image data into the plurality of multi-valued data by the first conversion method for the pixels in which the data for the metallic ink is 0, and the data for the metallic ink is not 0. For the pixels, the color image data is converted into the plurality of multi-valued data by a second conversion method different from the first conversion method.
In the first conversion method, after converting the RGB multi-valued data into the second RGB multi-valued data using the first look-up table, the second RGB using a predetermined color separation table is used. It is a method of converting the multi-valued data of the above into a plurality of multi-valued data corresponding to each of the plurality of color inks.
In the second conversion method, after converting the RGB multi-valued data into the third RGB multi-valued data using a second lookup table different from the first lookup table, the predetermined method is used. An image processing apparatus according to a method of converting the third RGB multi-valued data into a plurality of multi-valued data corresponding to each of the plurality of color inks using a color separation table. The second look-up table is
Based on the result of converting arbitrary RGB multi-valued data into the plurality of multi-valued data corresponding to each of the plurality of color inks using the second lookup table, the color ink is used together with the metallic ink. The color coordinates obtained by measuring the color of the image recorded on the recording medium with a colorimeter that satisfies the SCI conditions are
Based on the result of converting the arbitrary RGB multi-valued data into the plurality of multi-valued data corresponding to each of the plurality of color inks using the first lookup table, the color ink is converted into the metallic ink. The image processing apparatus according to claim 2 , wherein the image recorded on the recording medium is created so as to be close to the color coordinates obtained by measuring the color with the colorimeter. For pixels whose data for the metallic ink is not 0, the color ink is converted into the metallic ink based on the result of the conversion means converting the image data of the color into the plurality of multi-valued data by the second conversion method. The color of the image recorded on the recording medium is the color ink together with the metallic ink based on the result of the conversion means converting the image data of the color into the plurality of multi-valued data by the first conversion method. Rather than the color of the image recorded on the recording medium
For pixels in which the data for the metallic ink is 0, the color ink is converted into the metallic ink based on the result of the conversion means converting the image data of the color into the plurality of multi-valued data by the first conversion method. The image processing apparatus according to any one of claims 1 to 3 , wherein the color of the image recorded on the recording medium is close to that of the image without using the above. The image processing apparatus according to any one of claims 1 to 4 , wherein the plurality of color inks are cyan, magenta, yellow, and black inks. The image processing apparatus according to any one of claims 1 to 5 , wherein the metallic ink contains silver particles. A recording means for recording an image on the recording medium according to the plurality of multi-valued data corresponding to each of the plurality of color inks and the data for the metallic ink using the plurality of color inks and the metallic ink is further provided. The image processing apparatus according to any one of claims 1 to 6 , wherein the image processing apparatus is characterized by the above. An image processing method for recording an image on a recording medium using metallic ink containing a plurality of color inks and metal particles.
A process of acquiring color image data, which is RGB multi-valued data, and data for metallic ink indicating recording or non-recording of the metallic ink for each pixel.
A conversion step of converting the color image data into a plurality of multi-valued data corresponding to each of the plurality of color inks is provided.
In the conversion step, the color image data is converted into the plurality of multi-valued data by the first conversion method for the pixels in which the data for the metallic ink is 0, and the data for the metallic ink is not 0. For the pixels, the color image data is converted into the plurality of multi-valued data by a second conversion method different from the first conversion method .
The first conversion method is a method of converting the RGB multi-valued data into a plurality of multi-valued data corresponding to each of the plurality of color inks by using the first lookup table, and the second conversion method. The method is a method of converting the RGB multi-valued data into a plurality of multi-valued data corresponding to each of the plurality of color inks by using a second lookup table different from the first lookup table.
The second look-up table is
Based on the result of converting arbitrary RGB multi-valued data into the plurality of multi-valued data corresponding to each of the plurality of color inks using the second lookup table, the color ink is used together with the metallic ink. The color coordinates obtained by measuring the color of the image recorded on the recording medium with a colorimeter that satisfies the SCI conditions are
Based on the result of converting the arbitrary RGB multi-valued data into the plurality of multi-valued data corresponding to each of the plurality of color inks using the first lookup table, the color ink is converted into the metallic ink. An image processing method characterized in that an image recorded on the recording medium is created so as to be close to the color coordinates obtained by measuring the color with the colorimeter. An image processing method for recording an image on a recording medium using metallic ink containing a plurality of color inks and metal particles.
A process of acquiring color image data, which is RGB multi-valued data, and data for metallic ink indicating recording or non-recording of the metallic ink for each pixel.
A conversion step of converting the color image data into a plurality of multi-valued data corresponding to each of the plurality of color inks.
With
In the conversion step, the color image data is converted into the plurality of multi-valued data by the first conversion method for the pixels in which the data for the metallic ink is 0, and the data for the metallic ink is not 0. For the pixels, the color image data is converted into the plurality of multi-valued data by a second conversion method different from the first conversion method.
In the first conversion method, after converting the RGB multi-valued data into the second RGB multi-valued data using the first look-up table, the second RGB using a predetermined color separation table is used. It is a method of converting the multi-valued data of the above into a plurality of multi-valued data corresponding to each of the plurality of color inks.
In the second conversion method, after converting the RGB multi-valued data into the third RGB multi-valued data using a second lookup table different from the first lookup table, the predetermined method is used. An image processing method characterized by a method of converting the third RGB multi-valued data into a plurality of multi-valued data corresponding to each of the plurality of color inks using a color separation table.

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