JP2012096468A - Apparatus and method for processing image - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enlarge a color area, while reducing the bias of the use frequency of each recording element of a recording head.SOLUTION: A used color combination obtaining part 52 obtains a combination of ink colors used at each gradation value, on the basis of data after color conversion. A binarization part 53 executes binarization processing for the data after color conversion. An assigned pattern storage part 54 stores a plurality of pass mask patterns set for each combination of ink colors. An assigned pattern selection part 55 selects an assigned pass mask pattern, on the basis of the combination of ink colors obtained by the used color combination obtaining part 52, by referring to the plurality of pass mask patterns stored in the assigned pattern storage part 54. An assignment part 56 assigns the pass mask pattern selected by the assigned pattern selection part 55 to the data after the binarization processing by the binarization part 53.

Description

  The present invention relates to an image processing apparatus and an image processing method for forming an image by superimposing a plurality of color materials of different colors.

There are various types of image processing apparatuses for recording information such as images and characters on a recording medium. As one of representative examples, an inkjet type image processing apparatus (inkjet image processing apparatus) is known. Yes. An inkjet image processing apparatus performs recording by ejecting small droplets of color material (ink) from a recording element and attaching them to a recording medium.
In an inkjet image processing apparatus, two types of dye ink and pigment ink are widely used. The dye ink contains a dye that dissolves in water as a coloring material, and the pigment ink contains a particulate pigment that does not dissolve in water as a coloring material. In recent years, attention has been paid to the property that pigment ink has better weather resistance than dye ink and the property that color stability immediately after printing is better than that of dye ink, and inkjet image processing apparatuses using pigment ink have been increasing.
Since the pigment ink includes the color material of the particulate pigment as described above, when forming an image on the recording medium, the pigment ink does not penetrate into the recording medium and tends to remain on the surface of the recording medium. . That is, the pigment ink is a so-called overlay ink. For this reason, it is known that when a plurality of pigment inks of different colors are recorded on a recording medium, the color gamut can be expanded by controlling the overlapping order of the inks. As a technique for realizing color gamut expansion, Patent Document 1 discloses recording (fixing) an ink having a relatively high brightness on the upper layer (front side) with respect to an ink having a relatively low brightness (transmittance). An image forming technique for reducing a decrease in color development characteristics and expanding a color reproduction range is described. In the above technique, the recording order of ink colors is controlled by varying the recording ratio in each pass in ink jet multi-pass printing for each ink color using a so-called pass mask.

JP 2008-162094 A

However, in the image processing method in which the printing ratio of the pass mask is different for each ink color in multipass printing, the usage frequency of each printing element is biased. For this reason, problems such as a short head life and fluctuations in dot landing characteristics due to temperature distribution bias are likely to occur.
Here, for example, in the case of forming an image using a recording head in which recording element arrays capable of recording yellow (Y) and black (K) are arranged in parallel with the same recording element array length, one for each color. An example in which the yellow ink layer is the lower layer and the black ink layer is the upper layer will be described. FIG. 14 shows the relationship between the printing element array and the pass mask at this time. Each of the yellow and black printing element arrays has eight printing elements, and printing is performed in two passes using a pass mask corresponding to each printing element. The data filled with white in the pass mask masks (blocks) binary data before applying the pass mask (halftone pattern indicating whether dots are recorded), and the data filled with black indicates binary data before applying the pass mask. Do not mask. In the first pass, which is the first half of multi-pass printing, printing is performed using the printing elements (four printing elements on the lower side in FIG. 14) in the first half of the printing element array for printing yellow. Then, in the second pass, which is the second half of the multi-pass printing, printing is performed using the printing elements (four printing elements on the upper side in FIG. 14) in the latter half of the printing element array that records black. By the above recording, an image in which the yellow ink layer is on the lower layer side and the black ink layer is on the upper layer side can be formed. FIG. 15 shows the relative positional relationship between the recording head and the recording medium when performing multipass recording using the recording head. In order to make the explanation of multi-pass printing easier to understand, here, a state is shown in which an image is formed while the print head is moved downward in FIG. 15 with respect to the print medium. In practice, in general multi-pass printing, each time the print head is scanned, the print medium is sent with a length shorter than the print element array length, and the image is completed while being thinned out for each scan. I am letting.
When such multi-pass printing is performed, the latter half of the recording element array for recording yellow (the upper four recording elements in FIG. 14) and the first half of the recording element array for recording black (lower part in FIG. 14). The four recording elements on the side are not used. That is, in each recording element array for recording yellow or black, only one of the first half part or the second half part of each recording element array is always used for recording, and the other is not always used for recording. As described above, since the use frequency of each recording element is biased, various problems such as a short head life and fluctuations in dot landing characteristics due to a biased temperature distribution are likely to occur.
In addition, the conventional technique has a problem that the printing speed is lower than when recording is performed using all the recording elements in order to limit the number of recording elements used for recording.

  An object of the present invention is to widen the color gamut while alleviating the uneven usage frequency of each recording element of the recording head.

  An image processing apparatus according to the present invention scans a recording head having a plurality of recording element arrays that form a color material on a recording medium relative to the recording medium in a main scanning direction, and for each scan of the recording head. An image processing apparatus for forming an image on a recording medium by performing scanning a plurality of times while transporting the recording medium in a sub-scanning direction intersecting the main scanning direction, wherein input image data is converted into a plurality of colors The color conversion means for converting the color material data of the color material, the acquisition means for acquiring the color combination of the color materials used for recording based on the color material data, and the color for each of the color combinations Storage means for storing a plurality of assignment patterns for assigning material data to each data of the plurality of scans, and one of the plurality of assignment patterns based on the combination of colors. Selection means for selecting the allocation pattern, and allocation means for allocating the color material data to each data in the plurality of scans using the allocation pattern selected by the selection means, The recording order of the color material of each color on the recording medium is the same in each of the color combinations acquired by the acquisition unit among the plurality of allocation patterns stored in the storage unit. .

  According to the present invention, the color gamut can be expanded while alleviating the uneven usage frequency of each recording element of the recording head.

It is a figure which shows the structure of an inkjet recording device. It is a block diagram which shows the structure of the control system of an inkjet recording device. It is a functional block diagram which shows the functional structure of an inkjet recording device. It is a flowchart which shows operation | movement of an inkjet recording device. It is a figure which shows the recording element used when using all the inks of each color. It is a figure which shows the cross section of the image formed by multipass recording. It is a figure which shows the pass mask pattern in the case of performing 4-pass multipass printing. It is a figure which shows the pass mask pattern in the case of performing 8-pass multipass printing. It is a figure which shows the example of the candidate of a path mask pattern. It is a figure which shows the other example of the candidate of a path mask pattern. It is a functional block diagram which shows the functional structure of an inkjet recording device. It is a flowchart which shows operation | movement of an inkjet recording device. It is a figure which shows the usage frequency of a printing element, and the usage ratio of a pass mask pattern. It is a figure which shows the relationship between a printing element row | line | column and a pass mask. FIG. 3 is a diagram illustrating a relative positional relationship between a recording head and a recording medium.

(First embodiment)
First, a first embodiment of the present invention will be described.
[Structure of inkjet recording apparatus]
FIG. 1 is a diagram showing the structure of an ink jet recording apparatus (image processing apparatus) according to an embodiment of the present invention. The transport unit 1030 is disposed along the longitudinal direction of the casing 1008 and intermittently transports the recording paper 1028 in the direction of the arrow P. The recording unit 1010 reciprocates along the guide shaft 1014 arranged in the direction of the arrow S substantially perpendicular to the direction P by the movement driving unit 1006.
The movement drive unit 1006 is stretched between pulleys 1026a and 1026b that are pivotally supported on rotating shafts that are opposed to each other at a predetermined interval, a carriage motor 1018 that is coupled to the shaft of the pulley 1026b, and pulleys 1026a and 1026b. A belt 1016 is included. The belt 1016 is connected to the carriage member 1010 a of the recording unit 1010. Accordingly, the belt 1016 can be driven by the forward / reverse rotation of the carriage motor 1018, and the recording unit 1010 can be freely moved in the forward / reverse direction substantially parallel to the roller units 1022a and 1022b.
When the carriage motor 1018 operates and the pulley 1026b rotates in the direction of the arrow R, the recording unit 1010 moves by a predetermined amount of movement in the direction of the arrow S by the follow-up of the belt 1016. When the carriage motor 1018 is activated and the pulley 1026b rotates in the direction opposite to the arrow R, the recording unit 1010 moves by a predetermined amount of movement in the direction opposite to the arrow S by the follow-up of the belt 1016.
The recovery unit 1024 is disposed at one end of the casing 1008 in the longitudinal direction and at the home position of the carriage member 1010a. The recovery unit 1024 is disposed to face the array of ink discharge ports of the recording unit 1010 in order to perform the discharge recovery process of the recording unit 1010.
The recording unit 1010 includes inkjet cartridges (hereinafter simply referred to as “cartridges”) 1012Y, 1012M, 1012C, and 1012K that respectively store a plurality of colors (for example, four colors) (color materials). Each cartridge contains pigment ink (colored ink) containing, for example, yellow Y, magenta M, cyan C, and black K pigments, and is detachably engaged with the carriage member 1010a. The ink stored in each cartridge is supplied to a recording head (not shown) and ejected from the recording head according to the image data to form an image. Specifically, the recording head is scanned relative to the recording medium in the main scanning direction, and the image is obtained by performing scanning a plurality of times while transporting the recording medium in the sub-scanning direction intersecting the main scanning direction for each scan. It is formed.

[Control system configuration]
FIG. 2 is a block diagram showing the configuration of the control system of the ink jet recording apparatus.
A central processing unit (CPU) 402, which is a microprocessor, uses a random access memory (RAM) area of the memory 403 as a work memory according to a control program stored in a nonvolatile memory area of the memory 403. Various functions and operations of the inkjet recording apparatus 400 are controlled.
The ink jet recording apparatus 400 is connected to a host computer 2000, which is an external apparatus, via a predetermined interface. The reception buffer 401 receives image data representing an image to be printed output from the host computer 2000. The CPU 402 transmits a signal indicating whether the image data has been normally received, a signal indicating the operation state of the inkjet recording apparatus 400, and the like to the host computer 2000 via the reception buffer 401.
The CPU 402 temporarily stores the data received by the reception buffer 401 in the RAM area of the memory 403. The nonvolatile memory area of the memory 403 stores, for example, a control program for recording operation and recovery operation performed by the inkjet recording apparatus 400, a color conversion table for converting image data into ink values, a mask pattern for multipass recording, and the like. To do.
The machine control unit 404 controls the operation of the machine unit 405 including a carriage motor 1018 and a line feed motor (not shown) under the control of the CPU 402.
The sensor / SW control unit 406 controls the sensor / SW unit 407 including various sensors and switches (SW) under the control of the CPU 402, and transfers the signal received from the sensor / SW unit 407 to the CPU 402.
The display control unit 408 controls the display operation of the display unit 409 including an LED (light emitting diode) and / or a liquid crystal display (LCD) under the control of the CPU 402.
The recording head control unit 410 controls the recording head 411 under the control of the CPU 402, detects the state (for example, temperature) of the recording head 411, and notifies the CPU 402 of the detected state.

[Functional configuration of inkjet recording apparatus]
FIG. 3 is a functional configuration diagram showing a functional configuration of the ink jet recording apparatus according to the first embodiment.
As shown in FIG. 3, the inkjet recording apparatus 400 includes a color conversion unit 51, a used color combination acquisition unit 52, a binarization unit 53, an allocation pattern storage unit 54, an allocation pattern selection unit 55, an allocation unit 56, and an image. A forming portion 57 is provided. These are mainly composed of a CPU 402, a memory 403, and the like.
Based on the input image data, the color conversion unit 51 converts the amount of each ink color applied at each gradation into color-converted data (CMYK data) that is color material data.
The used color combination acquisition unit 52 acquires a combination of ink colors used in each gradation value based on the data after color conversion.
The binarization unit 53 executes binarization processing on the color-converted data.
The allocation pattern storage unit 54 stores a plurality of pass mask patterns set for each ink color combination. As the allocation pattern storage unit 54, for example, a memory 403 or a recording medium (such as a CD-ROM) is used.
The allocation pattern selection unit 55 refers to the plurality of path mask patterns stored in the allocation pattern storage unit 54 and selects the path mask pattern to be allocated based on the ink color combination acquired by the used color combination acquisition unit 52. .
The allocation unit 56 allocates the path mask pattern selected by the allocation pattern selection unit 55 to the data after the binarization processing by the binarization unit 53. That is, the assigning unit 56 performs a path mask assigning process.
The image forming unit 57 forms an image from the data after the pass mask assigning process by the assigning unit 56.

[Operation of Inkjet Recording Apparatus (Image Processing Method)]
FIG. 4 is a flowchart showing the operation of the ink jet recording apparatus according to the first embodiment. An image is formed by this operation.
First, in step S601, the reception buffer 401 acquires input image data (RGB data) input to the inkjet recording apparatus 400. Input image data is provided by the host computer 2000.
Next, in step S602, based on the input image data acquired in step S601, the color conversion unit 51 converts the amount of ink color for each gradation into post-color conversion data (CMYK data). Note that color matching processing may be performed before color conversion processing.
Thereafter, in step S603, the binarization unit 53 executes binarization processing on the color-converted data. As a binarization processing method, an arbitrary method such as an error diffusion method, a dither method, or an INDEX method can be used.

Further, after step S602, in step S604, the used color combination acquisition unit 52 acquires a combination of ink colors used in each gradation value based on the color-converted data. For example, as data after color conversion, the values of cyan (C), magenta (M), yellow (Y), and black (K) are 10%, 20%, 0%, and 0%, respectively, and cyan and magenta. Is used, the combination of ink colors to be used is represented as (C, M). As another example, when the values of cyan, magenta, yellow, and black are 40%, 20%, 30%, and 30%, respectively, the combination of ink colors to be used is (C, M, Y, K). All combinations of ink colors are (C), (M), (Y), (K), (C, M), (C, Y), (C, K), (M, Y), (M, K), (Y, K), (C, M, Y), (C, M, K), (C, Y, K), (M, Y, K), (C, M, Y, K) There are 15 types.
Next, in step S <b> 605, the allocation pattern selection unit 55 refers to a plurality of path mask patterns stored in the allocation pattern storage unit 54. In step S606, the allocation pattern selection unit 55 selects a path mask pattern to be allocated based on the combination of ink colors acquired in step S604.

After step S603 and step 606, in step S607, the allocation unit 56 executes a path mask allocation process for the binarized data using the path mask pattern selected in step S606.
Thereafter, in step S608, the image forming unit 57 forms an image from the data after the pass mask assignment process.

FIG. 5 is a diagram illustrating printing elements used when multi-pass printing is performed using all the inks of the respective colors. The combination of ink colors when performing multi-pass printing using all the inks of the respective colors is (C, M, Y, K). FIG. 5 shows a case where a recording head having eight recording elements for each color is recorded in four passes using inks of four colors of cyan, magenta, yellow, and black. At this time, two recording elements are used for recording, and each ink color is represented by a hatched or filled state in FIG. The image is completed by moving the recording medium by two recording element widths and recording the image while thinning out each time the recording head is scanned. In order to make the explanation of multi-pass printing easier to understand, FIG. 5 shows a process of forming an image while moving the print head downward in FIG. 5 for each scan with respect to the print medium.
FIG. 6 is a diagram illustrating an example of a cross section of an image formed by the multipass printing in FIG. When the multipass printing shown in FIG. 5 is performed, printing is performed in the order of yellow, cyan, magenta, and black. For this reason, an image is formed so that the cross section is layered in the order of yellow, cyan, magenta, and black from the lower layer to the upper layer.
FIG. 7 is a diagram illustrating an example of a pass mask pattern when the multi-pass printing of FIG. Each of the eight pixels in the vertical direction in FIG. 7 in the pass mask pattern of each color corresponds to eight recording elements that record the respective colors. At this time, black portions in the pass mask pattern represent pixels that record dots (do not mask), and white portions represent pixels that do not record dots (mask). By performing an AND operation of the binarized data and this pass mask pattern, the dot to be recorded in each pass is determined. As can be seen from FIG. 7, the pass mask pattern is configured so that four-pass printing is performed for each pass in the order of yellow, cyan, magenta, and black. That is, the recording order of yellow, cyan, magenta, and black is the same.
FIG. 8 is a diagram showing an example of a pass mask pattern when the multi-pass printing of FIG. As in FIG. 7, each of the eight pixels in the vertical direction in FIG. 8 in the pass mask pattern of each color corresponds to eight recording elements that record the respective colors. In this case, each of the yellow, cyan, magenta, and black colors is recorded in two passes in the 8-pass mask pattern.

  In the conventional technique shown in FIG. 14, a pass mask pattern capable of forming an image in a layered manner in a predetermined ink recording order as shown in FIGS. 7 and 8 is similarly applied to any gradation. Yes. In this embodiment, a plurality of pass mask patterns in which a combination of ink colors used to record the gradation for each gradation of the image is acquired and a predetermined ink recording order is maintained based on the combination. The path mask to be used is switched from among the above. Here, this switching process will be further described.

FIG. 9 is a diagram illustrating a plurality of candidates for a pass mask pattern when an image is formed using only yellow. In this case, the combination of ink colors is (Y). A pass mask pattern at the time of normal image formation for forming an image with all ink colors of yellow, cyan, magenta, and black is as shown on the upper side in FIG. On the other hand, when an image is formed using only yellow, one of the plurality of pass mask patterns shown on the lower side in FIG. 9 is switched to one of the pass mask patterns. When an image is formed only with yellow, it is not necessary to consider the recording order of each color. Therefore, a recording element that records yellow that is not used when forming an image with (C, M, Y, K) may be used. it can. Therefore, the uneven usage frequency of each recording element of the recording head of the recording element is alleviated. Here, as an example, seven types of pass-pasque patterns are shown, but other pass mask patterns may be used as candidates.
In such path mask pattern switching, one path mask pattern is selected by the allocation pattern selection unit 55 according to the order stored in the allocation pattern storage unit 54.

FIG. 10 is a diagram showing a plurality of pass mask pattern candidates when an image is formed with two colors of yellow and magenta. In this case, the combination of ink colors is (M, Y). As in FIG. 9, the pass mask pattern for forming an image with all ink colors of yellow, cyan, magenta, and black is as shown on the upper side in FIG. On the other hand, when an image is formed with only two colors of yellow and magenta, one of the plurality of pass mask patterns shown on the lower side in FIG. 10 is switched to one of the pass mask patterns. When forming an image with only two colors of yellow and magenta, only the recording order of yellow and magenta needs to be considered without considering the recording order of cyan and black. Therefore, since it is sufficient that yellow is recorded first and magenta is recorded later, it is possible to use a recording element that records yellow or magenta that is not used when images of all ink colors are formed. Therefore, the uneven usage frequency of each recording element of the recording head of the recording element is alleviated.
In such switching of the path mask patterns, one path mask pattern is selected by the allocation pattern selection unit 55 according to the order stored in the allocation pattern storage unit 54, as in the case where yellow is used.

As described above, according to the present embodiment, the color gamut can be expanded while alleviating the uneven usage frequency of each recording element of the recording head mounted on the ink jet recording apparatus (image processing apparatus).
Further, according to the present embodiment, the printing speed can be improved. For example, as in the example shown in FIG. 9, when recording with a combination of (C, M, Y, K) ink colors, only two of the eight yellow recording elements are used, but (Y) However, in the case of (C, M, Y, K), six recording elements that are not used can also be used. Therefore, when only (Y) is recorded, the printing speed can be improved up to four times (using all eight recording elements).

Note that the combinations of ink colors to be used are not limited to (C, M, Y, K), (Y), (Y, M), and the same effect can be obtained when other combinations are selected. Can be obtained.
Further, the number of ink colors, the number of printing elements, and the number of passes are not limited to those described above, and may be arbitrary values.
In general, the pass mask pattern has a certain finite size, for example, 64 × 64, 128 × 128, etc., and therefore, the pass mask process is repeatedly associated with binary data before application of the pass mask pattern. Applied. In this embodiment, when referring to a combination of ink colors to be used, the combination of colors used can be acquired each time in association with the size of the pass mask pattern. However, the area size in the binary data when acquiring the size of the pass mask pattern and the combination of the used colors does not necessarily need to match. That is, it is possible to determine the region size in the binary data when acquiring the used color combination without being limited by the size of the pass mask pattern.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. In the second embodiment, the pattern selection processing in the allocation pattern selection unit 55 is different from that in the first embodiment.
In the first embodiment, as described above, the allocation pattern selection unit 55 selects one path mask pattern according to the order stored in the allocation pattern storage unit 54 when switching the path mask pattern. On the other hand, in the second embodiment, the allocation pattern selection unit 55 selects a plurality of path mask patterns stored in the allocation pattern storage unit 54 based on a random number generated separately when switching the path mask pattern. One path mask pattern is selected from among them.
For example, when there are four candidate path mask patterns, a random number generator that generates a real value between 0.0 and 1.0 is provided. The allocation pattern selection unit 55 is first when the output of the random number generator is 0.0 or more and less than 0.25, second when the output is 0.25 or more and less than 0.5, and 0.5 or more and 0.75. If it is less than 3, the third pass mask pattern is selected. If it is 0.75 or more and less than 1.0, the fourth pass mask pattern is selected.
As the random number, an arbitrary random number such as a uniform random number that is not correlated or related to each generated random number and a pseudo random number that can be regarded as a uniform random number can be used, and the frequency of use of each recording element of the recording head A random number generator may be designed so as to reduce the bias.
Other configurations and operations are the same as those in the first embodiment.

  Also by such 2nd Embodiment, the effect similar to 1st Embodiment can be acquired. That is, the color gamut can be expanded while alleviating the uneven usage frequency of each recording element of the recording head, and the printing speed can be improved.

(Third embodiment)
Next, a third embodiment of the present invention will be described. In the third embodiment, the pattern selection processing in the allocation pattern selection unit 55 is different from that in the first embodiment and the second embodiment.
FIG. 11 is a functional configuration diagram showing a functional configuration of the ink jet recording apparatus according to the third embodiment. As shown in FIG. 11, as in the first embodiment, the color conversion unit 51, the used color combination acquisition unit 52, the binarization unit 53, the allocation pattern storage unit 54, the allocation pattern selection unit 55, the allocation unit 56, In addition, an image forming unit 57 is provided. The third embodiment further includes a printing element usage frequency acquisition storage unit 60.
The recording element usage frequency acquisition storage unit 60 acquires the usage frequency at which the recording element is used for all the recording elements of the recording head, and stores it in the memory 403 or the like.

FIG. 12 is a flowchart showing the operation of the ink jet recording apparatus according to the third embodiment. An image is formed by this operation.
First, similarly to the first embodiment, the processes in steps S601 to S603 are performed. Further, after step S602, the processes of steps S604 to S605 are performed as in the first embodiment. After step S605, the allocation pattern selection unit 55 selects a path mask pattern to be allocated in step S606 based on the combination of ink colors acquired in step S604 and the frequency of use of printing elements described later.

After step S603 and step 606, the processes of steps S607 to S608 are performed as in the first embodiment.
Further, after step S607, in step S610, the printing element usage frequency acquisition storage unit 60 acquires the usage frequency of the printing element used for all the printing elements of the printing head, and stores it in the memory 403 or the like. To do. This usage frequency is referred to by the allocation pattern selection unit 55 in step S606.

FIG. 13 is a diagram illustrating an example of the usage frequency of each printing element and the usage ratio of a plurality of candidate pass mask patterns in the third embodiment. FIG. 13A shows the frequency of use of each recording element in a recording element array having eight recording elements. FIG. 13B shows the usage ratio of each printing element in a plurality of pass mask pattern candidates stored in the allocation pattern storage unit 54. The total of the usage ratios of the recording elements is designed to be 100%.
In the example shown in FIG. 13, as shown in FIG. 1 and no. 2 is frequently used. In such a case, the allocation pattern selection unit 55 determines the recording element No. in step S606. 3-No. 8 is the recording element No. 1 and no. The path mask pattern is switched so that it is used more frequently than 2. For example, in FIG. 3 and no. 4 is the least frequently used, the printing element No. 4 is selected from the plurality of pass mask patterns. 3 and no. The pattern 3 having the largest usage ratio of 4 is selected by the allocation pattern selection unit 55. In other cases, each recording element is selected by selecting the pass mask pattern to be applied so that the usage frequency of each printing element is averaged as much as possible, that is, the difference in the usage frequency of each printing element is reduced. The uneven use frequency of the elements can be alleviated.
Other configurations and operations are the same as those in the first embodiment.

  According to the second embodiment as described above, the same effects as those of the first embodiment and the second embodiment can be obtained. That is, the color gamut can be expanded while alleviating the uneven usage frequency of each recording element of the recording head, and the printing speed can be improved.

  Each process of the present invention can also be realized by executing software (program) acquired via a network or various storage media by a processing device (CPU, processor) such as a personal computer.

Claims (6)

A recording head having a plurality of recording element arrays for forming a color material on the recording medium is scanned relative to the recording medium in the main scanning direction, and the sub-scan that intersects the main scanning direction is scanned each time the recording head is scanned. An image processing apparatus for forming an image on a recording medium by scanning a plurality of times while conveying the recording medium in a scanning direction,
Color conversion means for converting input image data into color material data of a plurality of color materials;
Based on the color material data, acquisition means for acquiring a color combination of color materials used for recording;
Storage means for storing a plurality of assignment patterns for assigning the color material data to each of the plurality of scans for each of the color combinations;
Selection means for selecting one allocation pattern from the plurality of allocation patterns based on the combination of colors;
Using the assignment pattern selected by the selection means, the assignment means for assigning the color material data to each data in the plurality of scans;
Have
The recording order of the color materials of the respective colors on the recording medium is the same in each of the color combinations acquired by the acquisition unit among the plurality of allocation patterns stored in the storage unit. An image processing apparatus.   The image processing apparatus according to claim 1, wherein the selection unit selects one allocation pattern in the order stored in the storage unit from among a plurality of allocation patterns stored in the storage unit.   The image processing apparatus according to claim 1, wherein the selection unit randomly selects one allocation pattern from a plurality of allocation patterns stored in the storage unit.   2. The selection unit according to claim 1, wherein the selection unit selects one allocation pattern in which a difference in use frequency of each recording element is reduced from a plurality of allocation patterns stored in the storage unit. Image processing device. A recording head having a plurality of recording element arrays for forming a color material on the recording medium is scanned relative to the recording medium in the main scanning direction, and the sub-scan that intersects the main scanning direction is scanned each time the recording head is scanned. An image processing method for forming an image on a recording medium with a plurality of scans while conveying the recording medium in a scanning direction,
A color conversion step of converting the input image data into color material data of a plurality of color materials;
Based on the color material data, an acquisition step of acquiring a color combination of color materials used for recording;
One of the plurality of assignment patterns for assigning the color material data to each data of the plurality of scans is stored in advance in the storage means for each of the color combinations. A selection step of selecting based on the combination of colors;
Using the assignment pattern selected in the selection step, assigning the color material data to each data in the plurality of scans;
Have
The recording order of the color material of each color on the recording medium is the same in each of the color combinations acquired in the acquisition step among a plurality of allocation patterns stored in advance in the storage unit. Image processing method. A recording head having a plurality of recording element arrays for forming a color material on the recording medium is scanned relative to the recording medium in the main scanning direction, and the sub-scan that intersects the main scanning direction is scanned each time the recording head is scanned. A program for causing a computer to control an image processing apparatus for forming an image on a recording medium by scanning a plurality of times while conveying the recording medium in a scanning direction,
In the computer,
A color conversion step of converting the input image data into color material data of a plurality of color materials;
Based on the color material data, an acquisition step of acquiring a color combination of color materials used for recording;
One of the plurality of assignment patterns for assigning the color material data to each data of the plurality of scans is stored in advance in the storage means for each of the color combinations. A selection step of selecting based on the combination of colors;
Using the assignment pattern selected in the selection step, assigning the color material data to each data in the plurality of scans;
And execute
The recording order of the color material of each color on the recording medium is the same in each of the color combinations acquired in the acquisition step among a plurality of allocation patterns stored in advance in the storage unit. Program to do.

Images