JP4075657B2 - Image processing apparatus and printing apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image processing apparatus that performs various image processing on received print data to generate data that can be printed by a print engine, and more particularly to efficiently perform printing when the print data is gray data. The present invention relates to an image processing apparatus and the like.
[0002]
[Prior art]
Normally, in color printing in a color laser printer or the like using a color format of C (cyan), M (magenta), Y (yellow), and K (black), the input colors of R (red), G (green), and B (blue) A process of converting the image data expressed in the format into the CMYK format is performed. In such color conversion processing, a look-up table (hereinafter referred to as 3D-LUT) in which CMYK density values (for example, 0 to 255) are associated with three-dimensional coordinate values composed of RGB density values (for example, 0 to 255). Is used). The 3D-LUT differs depending on the type of media such as plain paper and OHP, the type of screen processing, and the type of image such as characters and images. Usually, a plurality of types of 3D-LUTs are prepared. .
[0003]
Also, when the input image data is gray data having the same RGB density values (for example, R = G = B = 0 to 255), the above-mentioned 3D is usually not particularly distinguished. -Normal color printing processing such as color conversion processing by LUT has been executed.
[0004]
On the other hand, the following patent documents disclose an apparatus and a method for determining whether an image to be processed is a natural image or a text image and performing a color conversion process suitable for each image. In the case of a colored text image, a one-dimensional lookup table (hereinafter referred to as 1D-LUT) that associates one value of R = G = B with one value of C = M = Y is used. The fact that color conversion is performed is described.
[0005]
[Patent Document 1]
JP-A-10-145616
[0006]
[Problems to be solved by the invention]
However, as described above, even when the input image data is gray data, there is a problem that data processing time and data storage space are wasted if processing similar to normal color printing is performed. For example, when expressing the density of each color in 256 gradations from 0 to 255, in the case of gray data, the data before color conversion can be expressed by 8-bit information because R = G = B as described above. In addition, the data after color conversion can be expressed by K 8-bit information. Accordingly, as in normal color printing, it is not efficient to use RGB 24-bit information before color conversion and to use CMYK 32-bit information after color conversion.
[0007]
Further, as described in the above-mentioned patent document, in the case of gray data, processing using a 1D-LUT can be performed in distinction from the case of other image data. As in the case, it is necessary to prepare in advance a plurality of types of 1D-LUTs that differ depending on the type of media, the type of screen processing, and the type of image. In such a case, there is a problem that it is necessary to further secure storage areas for a plurality of 1D-LUTs, and further man-hours for creating the 1D-LUT are required.
[0008]
Therefore, an object of the present invention is an image processing apparatus that performs various image processing on received print data to generate data that can be printed by a print engine, and efficient printing is performed when the print data is gray data. It is to provide an image processing apparatus or the like that enables the above. It is another object of the present invention to provide an image processing apparatus and the like that can suppress an increase in storage area and an increase in the number of work steps for creating a lookup table when performing color conversion of the gray data with a 1D-LUT.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, according to one aspect of the present invention, image processing including color conversion processing for converting a color expression format is performed on received print data to generate printable data, When the image processing apparatus that outputs the data to the print engine stores storage means for storing at least one three-dimensional lookup table generated in advance for the color conversion process, and the print data is gray data Generating a one-dimensional lookup table using the three-dimensional lookup table stored in the storage means, executing the color conversion process using the generated one-dimensional lookup table, A gray color conversion means for generating data having information, and a three-dimensional lookup table stored in the storage means when the print data is not gray data; Run the color conversion process using, it is to have a color-converting means for generating data having color information of a plurality of colors. Therefore, according to the present invention, when the data to be printed is gray data, the image data has only one color information after color conversion, so that the data is printed more than when gray data is printed by normal color printing. Data processing capacity can be reduced. Further, since it is not necessary to prepare a one-dimensional lookup table for color conversion of gray data in advance, it is not necessary to increase the storage capacity for the lookup table even if printing for gray data is performed. The number of lookup table creation man-hours will not increase.
[0010]
Furthermore, in the above-mentioned invention, a preferable aspect thereof is that the three-dimensional lookup table used by the gray color conversion means for generating the one-dimensional lookup table is a lookup generated for an image whose image type is a character. It is a table.
[0011]
In order to achieve the above object, according to another aspect of the present invention, image processing including color conversion processing using a three-dimensional lookup table generated in advance is performed on received print data. An image processing apparatus that outputs processed data to a print engine generates a one-dimensional lookup table using the three-dimensional lookup table when the received print data is gray data, The color conversion process is performed using a one-dimensional lookup table.
[0012]
Furthermore, in the above invention, a preferred aspect is that the three-dimensional lookup table used for generating the one-dimensional lookup table is a lookup table generated for an image whose type is an image. It is characterized by.
[0013]
In order to achieve the above object, another aspect of the present invention includes a color conversion process for converting a color expression format and a gradation correction process for correcting a gradation value of each color for received print data. An image processing apparatus that performs image processing and outputs the image-processed data to a print engine includes a three-dimensional lookup table generated in advance for the color conversion processing and a floor for the gradation correction processing. A storage means for storing an adjustment correction lookup table; and when the print data is gray data, a one-dimensional lookup table is generated using the three-dimensional lookup table stored in the storage means, and Gray data processing means for generating first bitmap data having a gradation value of one color based on print data, and when the print data is not gray data, Color conversion means for executing the color conversion processing using a three-dimensional lookup table stored in the means to generate second bitmap data having gradation values of a plurality of colors, and the print data is gray data If the print data is not gray data, the color gradation value of the first bitmap data is converted using the one-dimensional lookup table generated by the gray data processing means. And a gradation correction means for correcting the gradation value of each color of the second bitmap data based on the gradation correction lookup table stored in the storage means. As a result, the color conversion process dedicated to gray data can be executed using the necessary gradation correction means even when printing for gray data is not performed.
[0014]
In order to achieve the above object, still another aspect of the present invention generates printable data by performing image processing including color conversion processing for converting a color expression format on received print data. A printing device that performs printing based on the data, storage means for storing at least one three-dimensional lookup table generated in advance for the color conversion processing, and the print data is gray data In addition, a one-dimensional lookup table is generated using the three-dimensional lookup table stored in the storage unit, and the color conversion process is executed using the generated one-dimensional lookup table. Gray color conversion means for generating data having color information, and a three-dimensional lookup table stored in the storage means when the print data is not gray data Use executing the color conversion process is that it has a color-converting means for generating data having color information of a plurality of colors.
[0015]
Furthermore, in the above-described invention, a preferred aspect is that the three-dimensional lookup table used by the gray color conversion unit to generate the one-dimensional lookup table is a lookup table generated for an image whose type is an image. It is characterized by being.
[0016]
Further objects and features of the present invention will become apparent from the embodiments of the invention described below.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. However, such an embodiment does not limit the technical scope of the present invention. In the drawings, the same or similar elements are denoted by the same reference numerals or reference symbols.
[0018]
FIG. 1 is a configuration diagram according to an embodiment of an image processing apparatus and a printing apparatus to which the present invention is applied. As shown in FIG. 1, a printing apparatus 2 according to this embodiment includes an image processing apparatus 3 and a print engine 4, and performs color printing based on print data 5 transmitted from a host computer 1. It is a printer. The image processing device 3 is a controller portion of the printing device 2 that generates various data that can be printed by the print engine 4 by executing various image processing including color conversion processing based on the print data 5. When the print data 5 is gray data, the printing apparatus 2 and the image processing apparatus 3 according to this embodiment reduce the amount of data to be processed and store a 1D-LUT necessary for color conversion in advance. In addition, by generating at the time of printing from the 3D-LUT, it is intended to efficiently print gray data (hereinafter referred to as gray printing).
[0019]
A host computer 1 shown in FIG. 1 is a request source that requests the printing apparatus 2 to print, and includes a personal computer or the like. A driver 10 provided in the host computer 1 is a driver for the printing apparatus 2 and is a part that generates and transmits print data 5 expressed in a page description language. The driver 10 also determines whether or not the current printing is gray printing.
[0020]
Next, as shown in FIG. 1, the image processing apparatus 3 includes a plurality of processing units, has a gray printing mode for gray printing, and includes a gray data processing unit 34 for the mode. It is a great feature. First, the interpretation unit 30 is a part that receives the print data 5 described above, interprets the data, generates an intermediate code, and issues a command to each unit based on the result of the interpretation. The intermediate code buffer 31 is a part for storing the generated intermediate code. The expansion unit 32 is a part that expands the intermediate code stored in the intermediate code buffer 31 into bitmap data for each pixel.
[0021]
Next, the LUT storage unit 33 (storage means) is a ROM that stores a 3D-LUT 6 for color conversion processing and a tone correction LUT 7 for tone correction processing. The 3D-LUT 6 is a correspondence table for converting pixel color density data expressed in RGB into CMYK format data, as described in the related art, and includes a media type, a screen processing type, and an image. Different types are prepared in advance depending on the type. For example, when there are two types of media, two types of screens, and three types of images, 2 × 2 × 3 = 12 types of 3D-LUTs are prepared.
[0022]
FIG. 2 is a diagram for explaining such a 3D-LUT. 2A conceptually shows the 3D-LUT, and FIG. 2B is a correspondence table between grids and RGB values, which will be described later. Here, the case where the density of each color of RGB is expressed by 256 gradations from 0 to 255 is shown.
[0023]
As described above, since the 3D-LUT associates each density value of CMYK with a three-dimensional coordinate value composed of each density value of RGB of a pixel, conceptually, (a) in FIG. A 3D-LUT is one in which the corresponding CMYK values are stored in each point of the cube shown in FIG. However, instead of storing the values corresponding to all the points composed of 256 gradations as described above, as shown in FIG. 2A, 0 to 256 are equally divided into several sections smaller than 256. Corresponding CMYK values are stored only for each possible grid (such as g in FIG. 2A). In the example shown in the figure, 9 grids are set between 0 and 255, but 17 grids and 33 grids may be used depending on accuracy.
[0024]
For RGB values located between the grids, corresponding CMYK values are obtained by interpolation based on the values stored in the surrounding grids. FIG. 2B shows the grid positions of the 9 grids in the respective RGB axis directions and the corresponding RGB values. For example, the grid position indicated by g ′ in FIG. The corresponding value of R is 223.
[0025]
Next, the tone correction LUT 7 is a look-up table for tone correction processing in a tone correction unit 37 described later. The gradation correction LUT 7 is a one-dimensional correspondence table. Normally, the LUT storage unit 33 stores a gradation correction LUT 7 that uses an input value as it is as an output value.
[0026]
Next, the gray data processing unit 34 (gray data processing means) is a characteristic part of the present invention that executes processing at the time of gray printing, and generates a 1D-LUT 8 that is a color conversion table for gray data, and a bit. The map data is mainly written to the band buffer 36. Specific processing contents will be described later. Note that the gray data processing unit 34 has a RAM, and this RAM is used to temporarily hold the 3D-LUT 6 and the like read from the LUT storage unit 33.
[0027]
Next, the color conversion unit 35 (color color conversion means or color conversion means) is a part that executes color conversion processing when performing normal color printing instead of gray printing, and is suitable for 3D- data suitable for data to be printed. Color conversion is executed by the LUT 6, and the converted bitmap data is stored in the band buffer 36. The color conversion unit 35 also has a RAM, and temporarily holds the 3D-LUT 6 and the like read from the LUT storage unit 33.
[0028]
Next, the band buffer 36 is a buffer for storing the bitmap data processed by the gray data processing unit 34 or the color conversion unit 35 for one page of printing for each band. Each pixel of the stored bitmap data has CMYK 4-color data as color data in the case of normal color printing, but has only K data in the case of gray printing.
[0029]
Next, the gradation correction unit 37 (gradation correction means) is a part that corrects the color data stored in the band buffer 36 in accordance with an instruction from the host computer 1 or the like. The tone correction unit 37 has a RAM, and temporarily holds the tone correction LUT 7 stored in the LUT storage unit 33 described above or the 1D-LUT 8 generated by the gray data processing unit 34.
[0030]
Next, the screen unit 38 is a part that executes processing for converting each color data (density value) of the bitmap data stored in the band buffer 36 into a pulse width. The PWM section 39 is a section for converting the pulse width data output from the screen section 38 into an ON / OFF signal for laser emission. Finally, the print engine 4 is a part that executes actual printing based on the signal from the PWM unit 39.
[0031]
FIG. 3 is a flowchart illustrating the flow of processing in the printing apparatus 2 and the image processing apparatus 3 according to this embodiment. Hereinafter, specific processing contents will be described with reference to FIG. First, the interpretation unit 30 of the image processing apparatus 3 receives the print data 5 from the host computer 1 (step S1 in FIG. 3). Information about whether or not the print data is gray data is added to the print data 5. The determination as to whether or not the data is gray data is made by the driver 10 of the host computer 1, and if all colors are R = G = B in units of print requests or in units of print pages, the gray data is determined. It is judged that there is.
[0032]
In addition, information about the type of media and the type of screen processing described above is added to the header portion of the print data 5 by the driver 10. Further, the above-described information on the type of image (for example, characters, images, or graphics) is added to the header portion in the case of gray data, and to each image data in the case of not gray data. In the case of gray data, information indicating that the type of image is “character” is added.
[0033]
The interpretation unit 30 that has received the print data 5 first determines whether or not to perform printing by gray printing based on the information on whether or not the data is gray data (step S2 in FIG. 3). If the print data 5 is gray data, it is determined that gray printing is to be performed (Yes in step S2 in FIG. 3), and the 3D-LUT 6 conforming to the print data 5 is stored in the LUT in the gray data processing unit 34. The data is read from the unit 33 (step S3 in FIG. 3). Specifically, as described above, since the header portion of the print data 5 includes information on the type of media, the type of screen processing, and the type of image, one 3D that matches those information. -LUT 6 is extracted from the LUT storage unit 33 and held in the RAM of the gray data processing unit 34. As described above, in the case of gray data, since the type of image is “character”, the 3D-LUT 6 for characters is held.
[0034]
On the other hand, if the print data 5 is not gray data, it is determined not to perform gray printing (No in step S2 in FIG. 3), and the 3D-LUT 6 suitable for the print data 5 is stored in the color conversion unit 35 as the LUT storage unit 33 (step S4 in FIG. 3). In this case, the 3D-LUT 6 suitable for the type of media and the type of screen processing included in the header of the print data 5 is taken out, but the type of image differs depending on the object of the image, so it is determined as one type. Instead, three 3D-LUTs 6 that match the two types are taken out and held in the RAM of the color conversion unit 35. That is, three 3D-LUTs 6 for characters, images, and graphics are held.
[0035]
Next, the interpretation unit 30 generates an intermediate code from the print data 5, and stores the generated intermediate code in the intermediate code buffer 31 (step S5 in FIG. 3). The intermediate code stored in the intermediate code buffer 31 is read by the expansion unit 32 and sequentially converted into bitmap data for each pixel (step S6 in FIG. 3). Here, image data in which each pixel has a density value (tone value) of each color is generated. However, since the color representation format of the print data 5 is RGB, each pixel has each RGB density value. It becomes. However, when the print data 5 is gray data, since the RGB density values are equal, only one value is provided as the gray density value (tone value) as the color information. If the data is not gray data, each pixel has the RGB density values and image type information (attribute information).
[0036]
Next, in the case of gray printing, the bitmap data is transferred to the gray data processing unit 34. Here, the gray data processing unit 34 first generates a 1D-LUT 8 which is a one-dimensional conversion table for color conversion of gray data, based on the 3D-LUT 6 held in the RAM (step of FIG. 3). S7).
[0037]
FIG. 4 is a diagram for explaining generation of the 1D-LUT 8. 4A shows a 3D-LUT for characters held in the RAM of the gray data processing unit 34, and FIG. 4B shows the generated 1D-LUT 8 in a graph. It is a thing. Hereinafter, the generation of the 1D-LUT 8 will be described with reference to FIG. First, the 3D-LUT 6 for characters held in the RAM is set so that the gray axis is printed with a single color of K toner. That is, the X axis shown in FIG. 4A is a gray axis, and the CMYK values associated with the grid on this axis are all in the form (0, 0, 0, β). Therefore, this gray axis represents CMYK values in the form (0, 0, 0, β) with respect to input values (Gray density values) in the form (α, α, α) where R = G = B. Are associated with each other. This means that this gray axis provides a color conversion table for gray printing in which gray data is printed with a single color of K toner.
[0038]
In the present embodiment, using this point, the 1D-LUT 8 is generated as follows. First, as shown in FIG. 4B, the horizontal density represents the gray density value of the input value, and the vertical axis represents the K density value of the output value. Then, nine grids on the gray axis of the character 3D-LUT 6 are plotted on this graph. That is, the α of the RGB value (α, α, α) is plotted on the horizontal axis, and the CMYK value of (0, 0, 0, β) β is plotted on the vertical axis. The white circle in the figure represents the plot result. Here, as described based on FIG. 2, the 9D (0 to 8) 3D-LUT 6 is used, but a 3D-LUT having another number of grids may be used.
[0039]
Next, each corresponding value is determined by linear interpolation between the nine grids. Specifically, output values (K density values) are determined based on the following expression (1) for 256 gradation input values (Gray density values) from 0 to 255, respectively.
[0040]
K [in] = (in−grid [n]) × (K [n + 1] −K [n]) / (grid [n + 1] −grid [n]) + K [n]
in: Input value (Gray density value)
K [in]: Output value (K concentration value)
n, n + 1: Grid position of plot points located immediately before and immediately after in on the horizontal axis
grid [n]: Input value of plot point at grid position n
K [n]: Output value of plot point at grid position n (1)
A line connecting the plotted points (white circles in the figure) in FIG. 4B represents the 256 gradation input values and the determined output values. Such a line represents the 1D-LUT 8 for converting the Gray density value to the K density value in a graph format. As described above, the gray data processing unit 34 generates the 1D-LUT 8 by using the 3D-LUT 6 for characters, and then writes the generated 1D-LUT 8 in the RAM of the gradation correction unit 37 described above (FIG. 3 step S8). In the generation of the 1D-LUT 8, the method using linear interpolation is used between the nine grids, but other interpolation methods may be used.
[0041]
Next, the gray data processing unit 34 uses the gray density value (gradation value) of the received bitmap data as the K value as it is to generate bitmap data in which each pixel has only the K value, Data is stored in the band buffer 36 (step S9 in FIG. 3).
[0042]
On the other hand, if it is not gray printing, after the bitmap data is generated (step S6 in FIG. 3), the color conversion unit 35 receives the data and sequentially executes color conversion processing (step S10 in FIG. 3). ). Since each pixel has the attribute information indicating the type of image as described above, the color conversion unit 35, based on the information, matches the 3D-LUT 6 that matches from the three 3D-LUTs 6 read into the RAM. To execute color conversion processing. By the color conversion process, each pixel has CMYK four color values, and such bitmap data is stored in the band buffer 36 (step S11 in FIG. 3).
[0043]
Regardless of whether gray printing or gray printing is performed, when one page of data is stored in the band buffer 36, the print engine 4 is activated, and the gradation correction unit 37 and the subsequent ones described above are synchronized with the operation. The processing unit executes processing. In the case of gray printing, since each pixel has only a K value, the processing after the gradation correction unit 37 is executed only for the K value. First, the bitmap data stored in the band buffer 36 is stored. Then, gradation correction processing is performed for each pixel (step S12 in FIG. 3).
[0044]
Specifically, the gradation correction unit 37 converts the K value of each pixel into a new value based on the 1D-LUT 8 generated by the gray data processing unit 34 held in the RAM. More specifically, the K value included in the bitmap data stored in the band buffer 36 is set as the input value of the 1D-LUT 8, and the output value corresponding to the K value is set as the new value to be the K value of the pixel. That is, the actual color conversion process for gray data is performed by the gradation correction unit 37. Therefore, it can be said that the gray data converting unit 34 and the gradation correcting unit 37 constitute a gray color converting unit that performs color conversion of gray data. The bitmap data corrected in this way is sequentially output from the gradation correction unit 37 to the screen unit 38.
[0045]
Next, the screen unit 38 executes a process of converting the K value (K density value) of the bitmap data into a pulse width (step S13 in FIG. 3), and then the PWM unit 39 performs a pulse width modulation process. The pulse width data output from the screen unit 38 is converted into a laser emission ON / OFF signal (step S14 in FIG. 3). The converted signal is output to the print engine 4 (step S15 in FIG. 3),
Finally, the printing engine 4 performs printing with a single color of K toner (step S16 in FIG. 3).
[0046]
On the other hand, when the printing is not gray printing, the processing after the gradation correction unit 37 is sequentially executed for each color of CMYK of the bitmap data stored in the band buffer 36. The gradation correction unit 37 extracts data for each color from the band buffer 36 and sequentially performs gradation correction processing (step S12 in FIG. 3). Specifically, the gradation correction LUT 7 stored in the LUT storage unit 33 is read into the RAM, the gradation correction LUT 7 is changed based on an instruction from the host computer 1 side, and processing is being performed by the changed LUT. A color value (for example, a C value) is converted. The converted data is output to the screen unit 38. When there is no instruction from the host computer 1, the color value is not changed and the data is output as it is.
[0047]
Thereafter, screen processing and pulse width modulation processing are performed in the same manner as in the case of gray printing (steps S13 and S14 in FIG. 3), and a signal after pulse width modulation is output to the print engine 4 (step S15 in FIG. 3). Color printing is performed in the print engine 4 (step S16 in FIG. 3).
[0048]
As described above, in the printing apparatus 2 and the image processing apparatus 3 according to the present embodiment, when the data to be printed is gray data, printing in a gray printing mode different from normal color printing is performed. Execute. As a result, in the processing up to storing the bitmap data in the band buffer 36 and the processing synchronized with the print engine 4 thereafter, only one color data needs to be processed for each pixel, and the gray data is also processed. The processing time can be shortened and the data holding capacity can be reduced as compared with the conventional method of processing in the same manner as color printing.
[0049]
Further, since the 1D-LUT 8 used in the color conversion process from the gray input value to the K output value performed in gray printing is generated from the 3D-LUT 6 for color printing at the time of printing, the type of media and the type of screen processing In addition, it is not necessary to prepare in advance a plurality of types of 1D-LUTs that differ depending on the type of image, and it is not necessary to increase the storage area for LUTs even if gray printing is performed. No work man-hours are required.
[0050]
In the embodiment described above, the color conversion based on the 1D-LUT 8 generated by the gray data processing unit 34 is performed by the gradation correction unit 37. However, the color conversion is performed by the gray data processing unit 34. The tone correction unit 37 may perform the same processing as in color printing. That is, the gray data processing unit 34 changes the original gray value to the K value based on the generated 1D-LUT 8, and the tone correction unit 37 performs only correction based on an instruction from the host computer 1 side. You may make it do.
[0051]
The protection scope of the present invention is not limited to the above-described embodiment, but covers the invention described in the claims and equivalents thereof.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of an image processing apparatus and the like according to an embodiment.
FIG. 2 is a diagram for explaining a 3D-LUT.
FIG. 3 is a flowchart of processing in the printing apparatus 2 and the like.
FIG. 4 is a diagram for explaining generation of a 1D-LUT 8;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Host computer, 2 Printing apparatus, 3 Image processing apparatus, 4 Print engine, 5 Print data, 6 3D-LUT, 7 Gradation correction LUT, 81D-LUT, 10 Driver, 30 Interpretation part, 31 Intermediate code buffer, 32 Expansion | deployment Section, 33 LUT storage section, 34 gray data processing section, 35 color conversion section, 36 band buffer, 37 gradation correction section, 38 screen section, 39 PWM section

Claims (7)

An image processing apparatus that performs image processing including color conversion processing for converting a color expression format on received print data, generates printable data, and outputs the data to a print engine,
Storage means for storing at least one three-dimensional lookup table generated in advance for the color conversion processing;
When the print data is gray data, a one-dimensional lookup table is generated using a three-dimensional lookup table stored in the storage unit, and the color is generated using the generated one-dimensional lookup table. Gray color conversion means for executing conversion processing and generating data having color information of one color;
Color color conversion means for executing the color conversion processing using a three-dimensional lookup table stored in the storage means and generating data having color information of a plurality of colors when the print data is not gray data; An image processing apparatus comprising: In claim 1,
An image processing apparatus, wherein the three-dimensional lookup table used for generating the one-dimensional lookup table is a lookup table generated for an image whose type is an image. An image processing apparatus that performs image processing including color conversion processing using a three-dimensional lookup table generated in advance on received print data, and outputs the data after the image processing to a print engine,
If the received print data is gray data, a one-dimensional lookup table is generated using the three-dimensional lookup table, and the color conversion process is executed using the generated one-dimensional lookup table. An image processing apparatus. In claim 3,
The image processing apparatus, wherein the three-dimensional lookup table used to generate the one-dimensional lookup table is a lookup table generated for an image whose type is an image. The received print data is subjected to image processing including color conversion processing that converts the color expression format and tone correction processing that corrects the tone value of each color, and the image processed data is output to the print engine An image processing apparatus that
Storage means for storing a pre-generated three-dimensional lookup table for the color conversion process and a gradation correction lookup table for the gradation correction process;
When the print data is gray data, a one-dimensional lookup table is generated using the three-dimensional lookup table stored in the storage unit, and one tone value is provided based on the print data. Gray data processing means for generating first bitmap data;
When the print data is not gray data, the color conversion processing is executed using a three-dimensional lookup table stored in the storage unit, and second bitmap data having gradation values of a plurality of colors is generated. Color conversion means to
When the print data is gray data, the tone value of the color of the first bitmap data is converted using a one-dimensional lookup table generated by the gray data processing means, and the print data If the data is not gray data, the image processing apparatus has gradation correction means for correcting the gradation value of each color of the second bitmap data based on the gradation correction lookup table stored in the storage means. An image processing apparatus. A printing device that performs image processing including color conversion processing for converting a color expression format on received print data, generates printable data, and executes printing based on the data,
Storage means for storing at least one three-dimensional lookup table generated in advance for the color conversion processing;
When the print data is gray data, a one-dimensional lookup table is generated using a three-dimensional lookup table stored in the storage unit, and the color is generated using the generated one-dimensional lookup table. Gray color conversion means for executing conversion processing and generating data having color information of one color;
Color color conversion means for executing the color conversion processing using a three-dimensional lookup table stored in the storage means and generating data having color information of a plurality of colors when the print data is not gray data; A printing apparatus comprising: In claim 6,
The printing apparatus, wherein the three-dimensional lookup table used by the gray color conversion unit to generate the one-dimensional lookup table is a lookup table created for an image whose type is an image.

Images