JP2003300312A - Ink jet recorder and ink jet recording method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an ink jet recorder provided with a plurality of kinds of ink, e.g. a dark ink and a light ink, in which streaks or unevenness occurring due to increase in the duty of single pass at the time of multi-pass recording as a liquid drop being ejected from a recording head is reduced in size is suppressed. <P>SOLUTION: Assuming the maximum ejection quantity of dark ink is 100%, recording is performed while lowering the ejection quantity of light ink to 50%. Ejection quantity of light ink is limited by limiting the maximum number of dots in the dot pattern of light ink to 50% that of dark ink when a dot pattern of a specified size is developed for input pixels. Alternatively, in the output gamma correction processing, the maximum output value of light ink on an output gamma correction table is limited to 50% that of dark ink. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording apparatus for performing a recording operation using a plurality of types of ink, and more particularly to an ink jet recording apparatus and an ink jet recording method for performing a recording operation using a dark ink and a light ink.

[0002]

2. Description of the Related Art In recent years, in ink jet recording apparatuses, recording droplets have been made smaller in order to obtain a photographic image output, and at the same time, for ink colors such as cyan and magenta in which the granular feeling of dots is conspicuous. It has been attempted to improve image quality by using a so-called light and shade system in which light ink is added. Further, in order to stably record a high quality photographic image, a multi-pass recording system is also used in the inkjet recording apparatus. This multi-pass printing method is a method of printing an image by dividing a large number of nozzles in a print head into a plurality of nozzle groups and performing N times of scanning on the same printing area using different nozzle groups. According to this method, it is possible to reduce streaks and unevenness caused by variations in the ejection amount of each nozzle of the recording head, landing deviations, and paper feed errors.

Taking a recording apparatus as an example, the droplet amount is 4 p
It is possible to stably obtain a high-quality photo-tone image by recording an image recording area by scanning the recording head four times at a recording resolution of 1200 × 1200 dpi using the recording head of 1 l. Duty when one 4pl dot is recorded on a 1200 x 1200dpi grid
When (duty) is defined as 100%, the average of 25% per scan is obtained by performing the multi-pass printing four times.
It becomes the duty of. Generally, the lower the average duty per scan, the less likely it is to be affected by variations in the nozzles of the print head, paper feed errors, and the like. On the contrary, the higher the average duty, the stronger the influence of the nozzle variation, the landing deviation, the paper feed error, and the like, which causes the bad image such as the generation of streaks and unevenness.

Next, a method of designing a dark and light ink system, which is one of the methods for achieving high image quality in the ink jet recording method, will be described. FIG. 7 shows an example of a distribution table of dark cyan ink and light cyan ink for input signal values 0 to 255 of cyan single color. The vertical axis represents the amount of ink ejected (average duty per unit area). In a region where the input signal value is small, only the light ink is used, and the dark ink is started to be introduced at a signal value 128 when the light ink reaches 100%. This is to suppress the graininess of dark ink dots as much as possible.
Further, the total ink consumption can be suppressed by decreasing the ratio of the light ink as the amount of dark ink increases.

On the other hand, when the amount of ejected ink is small as in the case of forming the primary color, the distribution table as shown in FIG. 7 is obtained, but the ink such as the secondary color or the tertiary color is used. When the ejection amount is increased or when recording is performed on a recording medium having an extremely small ink absorption capacity, the density distribution table as shown in FIG. 8 is used. Here, in order to simplify the description, a case where the recording medium has an ink absorption capacity up to 80% duty will be described as an example.

In this case, dark ink is started to be introduced from the point of the input signal 102 where the light ink ejection amount becomes 80%. In this case, the dark ink is put in before the light ink hit amount reaches 100%, but since it is not possible to hit the ink more than the ink absorption capacity of the recording medium, the granular feeling due to putting the dark ink is to some extent. I am making a sacrifice. In this example, the primary color has been described as an example, but the usage rate of each ink also varies depending on the ink absorption capacity of the recording medium even for secondary colors or more. However, within the ink absorption capacity, the light ink is generally used as much as possible in order to improve the connection with the dark ink.

[0007]

In the above description, a recording head in which one droplet is 4 pl has been described as an example, but at present, ink can be ejected in small droplets such as 3 pl and 2 pl. A possible recording head has also been realized, and by using this recording head, it is possible to achieve higher image quality. However, when a recording head that ejects such small droplets is used, in order to obtain the same density as when using a recording head that ejects large droplets, the smaller the ejection amount, the larger the number. The problem arises that droplets must be ejected.

For example, using a head having a discharge amount of 4 pl,
The case where one droplet of 4 pl is arranged on a grid of 200 × 1200 dpi is defined as 100%, and the density when recorded with 100% solid is O.S. D. If 2.0 is set to 2.0, in order to obtain the same density with a head having a discharge amount of 2 pl,
It is necessary to record 100% of one 2 pl droplet on a 2400 × 1200 dpi grid.

At this time, in order to form an image with dots having a double recording density in the main scanning direction without decreasing the recording speed, the ejection frequency is doubled or the main scanning direction is performed in one scan. Is ejected at a timing of 1200 dpi, and the recording start position is offset by 2400 dpi in the sub-scanning direction for each pass (scan) of the multi-pass printing, so that 2400 × 1200 dpi is obtained.
2 pl dots can be placed in the grid.

In any case, the problem remains that the higher the recording density, the higher the average duty of one pass in multi-pass printing. Ie 1
When setting 1 dot for 200 × 1200 dpi as 100%, it is necessary to hit 200% by hitting 2 dots for 2 pl, so when printing with 4 passes, the former is The latter has an average duty of 25%, while the latter has an average duty of 50%. In other words, in the latter case, since the nozzle usage ratio of the recording head becomes high, there is a problem that image defects such as streak and unevenness due to variations in the ejection amount of each nozzle and landing deviation are likely to occur.

Further, as a method for obtaining image quality,
There is also known a method of ejecting droplets of different ejection amounts from one nozzle as disclosed in Japanese Patent Laid-Open No. 10-016251. In this case, by forming an image by combining two types of dots, large and small, it is possible to secure a sufficient density without increasing the recording density.
However, with this conventional method, the circuit configuration of the recording head for ejecting ink of different sizes and the printer main body that controls this becomes complicated, and it becomes difficult to eject two types of droplets in a stable manner. There was a problem. Further, in terms of image quality, there is also a disadvantage that the quality is inferior in terms of uniformity and graininess as compared with the case of forming an image with only small droplets.

Further, in Japanese Patent Laid-Open No. 10-329343, in order to prevent beading that occurs when an amount of ink that is more than an allowable amount of ink to be ejected onto a recording medium is recorded, the duty is reduced for recording. A method of doing so is disclosed. However, with this method, it is determined whether or not the maximum density value is for a certain ink color, and as a result, the duty of the ink color is reduced. It was difficult to avoid image defects such as streaks and unevenness caused by an increase in the hit duty.

The present invention has been made in view of the above problems of the prior art, and in the multi-pass printing, an ink jet printing apparatus which suppresses the occurrence of streaks and unevenness by preventing the average duty per scan from increasing as much as possible. Another object of the present invention is to provide an inkjet recording method.

It is another object of the present invention to provide an ink jet recording apparatus and an ink jet recording method capable of suppressing the generation of streaks and unevenness by using a novel density distribution table when recording is performed using dark and light ink. To do.

[0015]

In order to solve the above problems, the ink jet recording apparatus of the present invention has the following constitution. That is, according to the present invention, a plurality of print heads that eject different types of ink are used to perform multi-pass printing that completes an image by performing a plurality of scans on an image forming area on a print medium. In the inkjet recording apparatus according to the present invention, the maximum ink ejection amount for a predetermined unit area by at least one of the recording heads is lower than the maximum ink ejection amount for the other recording heads for the predetermined unit area. It is characterized in that it is provided with a driving amount limiting means for limiting to.

Further, according to the present invention, a plurality of print heads ejecting different kinds of ink are used to perform multi-pass printing for completing an image by scanning the image forming area on the print medium N times. An inkjet recording apparatus configured to execute the predetermined number of print heads among the plurality of print heads such that an average duty of one scan in the N print scans is D / N% or less. It is characterized in that it comprises an ejecting amount limiting means for limiting the maximum ink ejecting amount per unit area to D% which is less than 100%.

Further, according to the present invention, a plurality of print heads for ejecting different kinds of ink are used to perform multi-pass printing for completing an image by performing a plurality of scans on an image forming area on a print medium. In the inkjet recording method to be executed, the maximum ink ejection amount for a predetermined unit area by at least one of the recording heads is lower than the maximum ink ejection amount for the other recording heads for the predetermined unit area. It is characterized by being limited to.

Further, according to the present invention, a plurality of print heads for ejecting different kinds of ink are used to perform multi-pass printing for completing an image by scanning the image forming area on the print medium N times. An inkjet recording method to be performed, wherein an average duty of one scan in the N recording scans is D / N% or less,
The maximum ink ejection amount for a predetermined unit area of some of the plurality of recording heads is 100%.
It is characterized in that it is limited to less than D%.

According to the present invention, a dark ink head for ejecting dark ink and a light ink head for ejecting light ink having a density lower than the dark ink are provided in an image forming area on a recording medium. A program for controlling an inkjet recording apparatus that executes multi-pass recording that completes an image by scanning a plurality of times with respect to a predetermined unit area of light ink ejected from the light ink head. The computer may be caused to execute a step of limiting the maximum ink ejection amount to a value lower than the maximum recording ejection amount for the predetermined unit area of the dark ink ejected from the dark ink head.

Further, according to the present invention, a dark ink head for ejecting dark ink and a light ink head for ejecting light ink having a density lower than the dark ink are provided in an image forming area on a recording medium. Is a program for controlling an inkjet printing apparatus that executes multi-pass printing that completes an image by scanning N times, and the average duty of one scan in the N printing scans is D / N%. As described below, the computer is caused to execute a step of limiting the maximum ink ejection amount per predetermined unit area of the light ink ejected from the light ink head to D% which is less than 100%. .

Further, the present invention is a computer-readable storage medium characterized by storing the above program.

Further, according to the present invention, a dark ink head for ejecting dark ink and a light ink head for ejecting light ink having a density lower than the dark ink are used. An ink jet recording apparatus for recording an image by ejecting a dark ink and a light ink from a light ink head onto a recording medium, the gradation of image data corresponding to a predetermined unit area on the recording medium. Determining means for determining the ink ejection amounts of dark ink and light ink for the predetermined unit area according to the level, and recording control means for ejecting ink with the ink ejection amount determined by the determining means to record an image. The determining means includes: (A) the light ink is applied to the unit area as the gradation level increases. The amount is gradually increased to the first amount and then gradually decreased, and (B) in the range of the gradation level higher than the predetermined gradation level corresponding to the first amount, the gradation Determining the ink ejection amounts of the dark ink and the light ink by gradually increasing the ejection amount of the dark ink to a second amount larger than the first amount as the level increases. Is characterized by.

Further, according to the present invention, a dark ink head for ejecting dark ink and a light ink head for ejecting light ink having a density lower than the dark ink are used. An inkjet recording method for recording an image by ejecting a dark ink and a light ink from a light ink head onto a recording medium, wherein the gradation of image data corresponds to a predetermined unit area on the recording medium. A determination step of determining the ink ejection amounts of the dark ink and the light ink for the predetermined unit area according to the level, and a recording step of ejecting the ink with the ink ejection amount determined in the determination step and recording an image. In the determining step, (A) the light ink is applied to the unit area as the gradation level increases. The amount is gradually increased to the first amount and then gradually decreased, and (B) in the range of the gradation level higher than the predetermined gradation level corresponding to the first amount, the gradation Determining the ink ejection amounts of the dark ink and the light ink by gradually increasing the ejection amount of the dark ink to a second amount larger than the first amount as the level increases. Is characterized by.

Further, according to the present invention, a dark ink head for ejecting dark ink and a light ink head for ejecting light ink having a density lower than the dark ink are used. A program for controlling an inkjet recording apparatus that records an image by ejecting a dark ink and a light ink from a light ink head onto a recording medium, and an image corresponding to a predetermined unit area on the recording medium. In determining the ink ejection amounts of the dark ink and the light ink for the predetermined unit area according to the gradation level of the data, (A) as the gradation level becomes higher, The amount of driving is gradually increased to the first amount and then gradually decreased, and (B) a predetermined floor corresponding to the first amount. In the range of the gradation level higher than the level, as the gradation level becomes higher, the ejection amount of the dark ink is gradually increased to the second amount which is larger than the first amount. The step of determining the ink ejection amounts of the dark ink and the light ink is executed by a computer.

Further, the present invention is a computer-readable storage medium, characterized in that the program is stored therein.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. The following embodiment is an application example to an inkjet recording apparatus.

First, prior to the description of the embodiment of the present invention,
An example of the basic configuration of an inkjet recording apparatus to which the present invention can be applied will be described based on FIGS. 1 to 3.

(Basic configuration example of ink jet recording apparatus)
FIG. 1 is a schematic configuration diagram of a main part of an inkjet recording apparatus to which the present invention can be applied.

The chassis M3019 housed in the exterior member of the recording apparatus is composed of a plurality of plate-shaped metal members having a predetermined rigidity and forms the skeleton of the recording apparatus. Hold the mechanism. M3022
Is an automatic feeding unit that automatically feeds a sheet (recording medium) into the main body of the apparatus. M3029 is an automatic feeding unit M3
This is a conveyance unit that guides the papers, which are sent out one by one from 022, to a predetermined recording position and guides the papers from the recording position to the discharge unit M3030. The arrow Y is the paper conveyance direction (sub-scan direction). The recording unit performs desired recording on the sheet conveyed to the recording position. Recovery processing is performed on the recording section by the recovery section M5000. M2015 is the paper interval adjusting lever, M3006 is L
This is a bearing of the F roller M3001.

In the recording section, the carriage M4001
Are supported by a carriage shaft M4021 so as to be movable in the main scanning direction of arrow X. This carriage M
An inkjet recording head H1001 (see FIG. 2) capable of ejecting ink is detachably mounted on the 4001. The print head H1001 of this example constitutes a print head cartridge H1000 together with an ink tank H1900 that stores ink, as shown in FIG. As the ink tank H1900, in order to enable high-quality color recording of a photo quality, for example, ink tanks of black, light cyan, light magenta, cyan, magenta, and yellow are prepared independently. Each of these ink tanks H1900 has a printhead H1001.
It is removable with respect to.

The recording head H1001 may use thermal energy generated from the electrothermal converter as energy for ejecting ink. In that case, the heat of the electrothermal converter causes film boiling in the ink, and the foaming energy at that time allows the ink to be ejected from the ink ejection port.

The recovery unit M5000 includes a recording head H10.
No. 01 is provided with a cap (not shown) that caps the surface on which the ink ejection port is formed. A suction pump capable of introducing a negative pressure into the cap may be connected to the cap. In that case, a negative pressure is introduced into the cap that covers the ink ejection port of the recording head H1001 to suck and discharge the ink from the ink ejection port, so that a good ink ejection state of the recording head H1001 is maintained. Recovery processing (also referred to as “suction recovery processing”) can be performed.
A recovery process (also referred to as “ejection recovery process”) is performed to maintain a good ink ejection state of the recording head H1001 by ejecting ink that does not contribute to image recording from the ink ejection port toward the inside of the cap. can do.

Further, as shown in FIG. 1, the carriage M4001 is provided with a carriage cover M4002 for guiding the recording head H1001 to a predetermined mounting position on the carriage M4001. Further, the carriage M4
001 is a tank holder H of the recording head H1001.
A head set lever M4007 that engages with 1500 and sets the recording head H1001 to a predetermined mounting position is provided. The head set lever M4007 is provided rotatably with respect to the head set lever shaft located above the carriage M4001.
A spring-biased headset plate (not shown) is provided at an engaging portion that engages with 1001. Due to the spring force, the headset lever M4007 is mounted on the carriage M4001 while pressing the recording head H1001.

FIG. 3 is a block diagram of a main PCB (Printed Circuit Board) E0014 which constitutes a control system of the printing apparatus.

In FIG. 3, reference numeral E1001 is a CPU, which has a clock generator (CG) E1002 connected to an oscillation circuit E1005, and its output signal E1019 generates a system clock. Also,
The CPU E1001 is R through the control bus E1014.
OM E1004 and ASIC (Application Specif
ic Integrated Circuit) E1006 and controls the ASIC E1006 in accordance with a program stored in the ROM E1004, and also receives an input signal E1017 from the power key E0018, an input signal E1016 from the resume key E0019, and a cover sensor E0022. The cover detection signal E1042 and the head detection signal (HSENS) E1013 are input and the states corresponding to these input signals are detected. Also, CPU
The E1001 drives the buzzer E0021 by the buzzer signal (BUZ) E1018. Furthermore, CPU E1
001 detects the state corresponding to these inputs based on the exhaustion detection signal (INKS) E1011 input to the A / D converter E1003 and the temperature detection signal (TH) E1012 from the thermistor.
In addition, the CPU E1001 controls the inkjet recording apparatus by performing various logical operations and condition determination.

The head detection signal E1013 is a head mounting detection signal input from the recording head cartridge H1000 via the flexible flat cable E0012 (see FIG. 1). In addition, the emptyness detection signal E1011 is output from the emptyness sensor E0.
Analog signal and temperature detection signal E1 output from 006
012 is an analog signal from a thermistor (not shown) provided on the carriage substrate of the carriage M4001.

E1008 is a CR motor driver,
CR motor control signal E10 from ASIC E1006
Based on 36, a CR motor drive signal E1037 is generated by using a motor power source (VM) E1040 as a drive source to drive the CR motor E0001. E1009
Is an LF / PG motor driver, and ASIC E10
Pulse motor control signal (PM control signal) E1 from 06
Based on 033, the LF motor drive signal E1035 and the PG motor drive signal E1034 are generated using the motor power source E1040 as a drive source. The driving signals E1035 and E1024 drive the LF motor E0002 and the PG motor E0003.

Here, the CR motor E0001 is a drive source for reciprocating the carriage M4001 in the main scanning direction of the arrow X. In the case of this example, as shown in FIG. 1, via a belt spanned between the left and right pulleys,
The carriage M4001 is reciprocated in the main scanning direction. LF motor E0002. LF roller M3001
By driving (see FIG. 1), the sheet is conveyed in the sub-scanning direction of arrow Y. The PG motor E0003 is
It is also used as a drive source for the recovery operation of the print head H1001 and the paper feeding operation.

E1010 is a power supply control circuit,
According to the power supply control signal E1024 from C E1006, power supply to each sensor having a light emitting element is controlled. Parallel I / F E0016 is ASIC E1
The parallel I / F signal E1030 from 006 is transmitted to the external parallel I / F cable E1031, and the signal from the parallel I / F cable E1031 is transmitted to the ASIC E
1006. Serial I / F E0017 is
Serial I / F signal E10 from ASIC E1006
28 is transmitted to the external serial I / F cable E1029, and the signal from the cable E1029 is transmitted to the ASIC.
Transmit to E1006.

Head power supply (VH) E1039, motor power supply (VM) E1040, logic power supply (VDD) E10
41 is supplied from the power supply unit E0015. In addition, the power supply unit E0015 is the ASIC E1006.
Based on the head power ON signal (VHON) E1022 and the motor power ON signal (VMOM) E1023 from
ON / OFF of head power supply E1039 and motor power supply E1040
Control OFF. The logic power supply (VDD) E1041 supplied from the power supply unit E0015 is subjected to voltage conversion as necessary, and then supplied to each part inside and outside the main PCB E0014. Also, the head power signal E1039
After being smoothed on the main PCB E0014,
It is sent to the flexible flat cable E0012 and used for driving the recording head cartridge H1000.

E1007 is a reset circuit, which detects a decrease in the logic power supply voltage E1041 and detects the CPU E10.
01 and ASIC E1006 reset signal (RE
SET) E1015 is supplied to perform initialization.

The ASIC E1006 is a one-chip semiconductor integrated circuit, and a CPU through the control bus E1014.
It is controlled by E1001 and outputs the CR motor control signal E1036, PM control signal E1033, power supply control signal E1024, head power supply ON signal E1022, motor power supply ON signal E1023 and the like. Also, A
As described above, the SIC E1006 is a parallel I / O.
Signals are exchanged through F E0016 and serial I / F E0017. Furthermore, ASICE1006
Is a PE detection signal (PE
S) E1025, ASF from ASF sensor E0009
Detection signal (ASFS) E1026, recording head H100
GAP detection signal (GAPS) E10 from the GAP sensor E0008 for detecting the gap between 1 and the sheet
27, PG detection signal (PG
S) E1032 is input, the state corresponding to those signals is detected, and data indicating the state is sent to the control bus E101.
4 to CPU E1001. Based on the data, the CPU E1001 determines that the LED drive signal E10
38 controls the blinking of the LED E0020.

Here, the PE sensor E0007 is a sensor for detecting the edge of the sheet (sheet edge), the PG sensor E0.
Reference numeral 010 is a sensor for detecting the position of the cap in the recovery unit M5000. In addition, LED E002
0 lights up when the power key E0018 is pressed to inform the operator that recording is possible. Also LED
By changing the blinking method and color of E0020 and sounding the buzzer E0021, it is possible to notify the operator of a trouble of the recording apparatus. When the trouble or the like is solved, the resume key E0019 can be pressed to restart the recording.

Further, the ASIC E1006 generates a timing signal based on the encoder signal (ENC) E1020, and controls the recording operation while interfacing with the recording head cartridge H1000 by the head control signal E1021. Encoder signal (EN
C) E1020 is a flexible flat cable E0
CR encoder sensor E00 input through 012
The output signal of 04. The CR encoder sensor E0
004 outputs an encoder signal E1020 (pulse signal) along with the movement of the carriage M4001, and the moving position of the carriage M4001 can be detected from the signal. Also, the head control signal E1021
Is supplied to the recording head H1000 via a flexible flat cable E0012 or the like.

When printing is performed by the ink jet printing apparatus having the above configuration, first, the print data sent from the external I / F is temporarily stored in the print buffer in the ASIC E1006. Then, the recording operation of ejecting ink from the recording head H1001 based on the recording data while moving the recording head H1001 together with the carriage M4001 in the main scanning direction by the CR motor E0001 and a predetermined amount of paper in the sub scanning direction by the LF motor E0002. By repeating the carrying operation of carrying, the images are sequentially recorded on the paper.

(First Embodiment) Next, a first embodiment of the present invention applicable to the above-described ink jet recording apparatus and the like will be described with reference to FIGS.

FIG. 4 is a block diagram schematically showing the configuration of an image input / output system using the image processing method and apparatus according to the present invention. In FIG. 4, 10 is an image input unit. Image data is input to the image input unit 10 from an image input device such as a scanner or a digital camera, or image data extracted from image data stored in various recording media such as a hard disk is converted into multi-valued data. Is entered. Reference numeral 11 is an image processing unit. The image processing unit 11 performs the image processing peculiar to this embodiment on the multi-valued image data input from the image input unit 10 and converts it into binary image data. Reference numeral 12 is an image output unit. The image output unit receives the binary image data converted by the image processing unit 11, and actually forms an image on a recording medium.

Here, the configuration of the image processing unit 11 shown in FIG. 4 will be described in more detail with reference to the block diagram shown in FIG.
In FIG. 5, the input image data is separated into six colors by a color conversion process (not shown), cyan (Cyan), magenta (Magenta), yellow (Yellow), black (Bla).
ck), light cyan (LightCyan), light magenta (LightMage)
nta) data. Below, each color is C, M, Y,
Shown as K, LC, LM. The image processing unit 11 shown here is
Of the input data, dark ink-based image data, that is, dark ink-based processing unit 200A that processes C, M, Y, and K image data, and light ink-based image data, that is, LC and L.
And a light ink processing unit 200A for processing M image data. Then, the C, M, Y, and K image data are input to the input data correction unit 200, and LC, L
The image data of M is input to the input correction unit 207. The image data input to each of the processing units 200A and 200B is multi-valued image data that has been subjected to color conversion processing (not shown) in the image input unit 10, and is, for example, 8 bits.
Image data of 256 gradations. Further, the error data generated in the already quantized pixel is read from the error memories 203 and 210 and input to each of the data correction units 200 and 207, and this error data is added to the image data of the current pixel. By doing so, the input data is corrected. At this time, since 9-bit error data of -255 to 255 is added to 8-bit of input data 0 to 255, the result is 10-bit data of -255 to 510, but this data is in the range of 0 to 255. And output as 8-bit data.

Further, 201 and 208 are quantizers. The multivalued image data corrected by the input data correction units 200 and 207 is quantized into N-value gradation values. In the quantizer 201, which processes dark ink-based C, M, Y, and K, the N value is converted into a nine-valued gradation,
The quantization unit 208 that performs the LM process converts the gradation into five levels. Therefore, the quantizer 201 outputs 0, 3
2, 64, 96, 128, 160, 192, 224, 2
The value quantized into 9 values of 55 is output from the quantization unit 208, and the value quantized into 5 values of 0, 64, 128, 192, and 255 is output.

Reference numerals 202 and 209 are error calculation units.
The error calculators 202 and 209 are the same as the quantizer 201.
And 208, the difference between the quantized gradation value and the multi-valued image data corrected by the input data correction unit 200 is calculated. In this embodiment, the quantizer 201 quantizes the multi-valued image data into nine values, so that the gradation values thereof are 0, 32, 64, 96, 128, 160, 192, 22.
The 4-bit data of 4 and 255 are input to the error calculation unit 202. Similarly, in the quantizing unit 208, since the multi-valued image data is quantized into five values, the gradation value becomes 8-bit data of 0, 64, 128, 192, 255, and this is input to the error calculating unit 209. To be done.
Further, since 8-bit multi-valued image data of 0 to 255 output from the input data correction units 200 and 207 is input to the error calculation units 202 and 209, the error data is 9 bits of −255 to 255. It becomes the data of.

203 and 210 are error memories.
In the error memories 203 and 210, the error calculator 2
The errors generated in 02 and 209 are distributed to the surrounding pixels and stored for the unprocessed input pixels. FIG. 6 shows the distribution state of the error. The grid in the figure shows pixels,
The pixel marked with * represents the pixel of interest. And
The error generated in the target pixel is distributed to the surrounding four pixels at the ratio shown in the figure. Therefore, in the case of this example, a memory for at least two lines is required as an error memory.

Next, the pattern conversion units 204 and 211.
Is quantized by the quantizers 201 and 208
Values and five-value gradation data are input. Then, the pattern conversion units 204 and 211 convert the input gradation data into a dot pattern on the 4 × 2 pixel matrix shown in FIG. 9 and output the dot pattern. Here, it is the pattern table storage units 206 and 213 and the address generation units 205 and 2 that determine what kind of dot pattern is output for the gradation data for each input pixel.
Twelve.

Next, a method of setting the maximum number of dots for each of the dark ink and the light ink (ink having a relatively lower density than the dark ink), which is one of the features of the first embodiment, will be described. Assuming that the resolution before quantization in this first embodiment is 600 × 600 dpi, after being quantized to an N value, the pattern conversion unit outputs 2400 × 1200 dpi.
Convert to a dot pattern on a 4 × 2 pixel matrix of i. As shown in FIG. 9, the C, M, Y, and K patterns of the dark ink system are quantized into nine values, and their gradation values are within the 4 × 2 pixel matrix inside the pattern conversion unit 204 in FIG. Is converted into a gradation code of 0 to 8 indicating the number of dots, that is, gradation. The gradation codes 0 to 8 are converted into a dot pattern as shown in FIG. At this time, for the gradation code 8, dots are arranged at all pixel positions of the 4 × 2 pixel matrix. That is, if one dot is arranged at 2400 × 1200 dpi and 100% duty is defined, the gradation code 8
For, the dots are arranged with 100% duty. Also, gradation code 7, gradation code 6, gradation code 5, gradation code 4, gradation code 3, gradation code 2,
87.5% for gradation code 1 and gradation code 0
Duty, 75% duty, 62.5% duty, 50% duty, 37.5% duty, 25%
The dots are arranged with a duty of 12.5%, and a duty of 0%.

On the other hand, the image data of the light inks LC and LM are quantized into 5 values, and for the gradation codes 0 to 4,
It is converted into a dot pattern on a 4 × 2 pixel matrix as shown in FIG. 9B. At this time, since the dot pattern for the gradation code 4 having the highest gradation level has a configuration in which four dots are arranged in a 4 × 2 pixel matrix, it is considered that the definition of duty is 50.
The duty of% corresponds to the highest gradation level.

By using the dot patterns shown in FIGS. 9A and 9B, the distribution table of dark and light ink is as shown in FIG. Here, in order to simplify the explanation, a gradation distribution table for primary colors will be described as an example. Further, in this density distribution table, the ink ejection amount limit based on the ink absorption characteristics of the recording medium is 100% or more.

Conventionally, as shown in FIG. 7, it is possible to record using only a single light ink without using the dark ink as much as possible until the duty at which the ink ejection amount is limited by the ink absorption characteristic of the recording medium. Becomes a duty, for example 4 ×
A dark / light distribution table is configured such that dots are printed in all pixel positions of the pixel matrix of 2 (8 dots are printed) until 100% is reached without using dark ink.

However, in this first embodiment,
As shown in FIG. 9B, the light and dark distribution table is configured so that the light ink has a pattern in which only a maximum of 4 dots are printed in the 4 × 2 pixel matrix. The maximum ink ejection amount of
As shown in FIG. 10, it becomes 50%.

FIG. 11 shows the relationship between the printing resolution and the average duty due to multi-pass printing. Recording resolution is 120
The case where one dot is arranged in a grid (pixel) of 0 × 1200 dpi and 1200 dpi is defined as 100% duty. As shown in FIG. 11, when the number of passes (the number of main scans) is changed to 1 pass, 2 passes, 4 passes, and 8 passes, the average duty corresponding to each pass number is 100%, 50%, It becomes 25% and 12.5%.

For example, in the case of an ink jet recording apparatus having a droplet size of 4 pl, if a high quality photographic image without stripes or unevenness is to be obtained, the duty is suppressed to 25% or less on average as described in the section of the prior art. There was a need. That is, it has been premised that the multi-pass printing is performed with four or more passes. However, the droplet size is 2p
If it is reduced to about l, the recording resolution becomes higher and 1
The number of dots printed in each scan also increases. That is, if 100% is defined as the case where 1 dot is arranged in a 1200 dpi grid as described above, 1 pass, 2
The average duty of each of 4 passes, 8 passes and 20 passes is 20
It becomes 0%, 100%, 50%, 25%. Therefore, in order to obtain a high-quality photographic image without streaks and unevenness, if the average duty of each pass is suppressed to 25%, it is necessary to perform multi-pass printing with the number of passes of 8 or more. However, this reduces the recording speed.

Therefore, in the first embodiment, as shown in FIG.
As shown in, by limiting the number of dots to be imprinted in a dot pattern using light ink to less than 100% (50% in this case), the maximum amount of imprinting is 1200 × 12.
Since it is 100% when converted to 00 dpi, the average duty of each of multi-pass printing of 1 pass, 2 passes, 4 passes, and 8 passes is 100%, 50%, as in the case of 4 pl.
The duty is 25% and 12.5%, and the duty is 25% in four passes. For this reason, the average duty per scan can be suppressed without increasing the number of passes, and as a result, high-quality recording in which streaks and unevenness are suppressed without reducing the recording speed is achieved. You will be able to do it.

By adopting the method of this embodiment,
The dark ink starts to be ejected earlier than the input signal value, which may deteriorate the granularity of the dark ink. However, the six colors of 2 pl described in this embodiment are extremely small. With a small droplet size, the granularity of the dark ink itself is very small, so that a predetermined unit area (2400 × 1200 dp) is used as in this embodiment.
Even if the maximum amount of light ink applied to a region corresponding to a 4 × 2 dot matrix of i) is suppressed to about 50%, the overall graininess is reduced as compared with the system of 4 colors of 6 colors. Further, as shown in FIG. 10, while the maximum ink ejection amount of light ink for a predetermined unit area (area corresponding to a 4 × 2 dot matrix of 2400 × 1200 dpi) is limited to 50%, The maximum ink ejection amount of dark ink for a predetermined unit area (area corresponding to a 4 × 2 dot matrix of 2400 × 1200 dpi) is set to 100%. The reason for this is that if the maximum ink ejection amount of the dark ink is reduced to about 50% as in the case of the light ink, the maximum density that can be reproduced becomes low, the color reproduction range becomes narrow, and the entire image is adversely affected. This is because. In a dark and light ink system, dark ink has less streaks and unevenness as light ink, although it depends on the hue and density. Therefore, regarding the dark ink, the maximum density is emphasized and the maximum duty is not limited.

As described above, the density distribution table used in this embodiment (the density distribution table shown in FIG. 10) corresponds to a predetermined unit area as (A) the gradation level becomes higher (0 → 255). The light ink ejection amount is gradually increased to a first amount (50%) and then gradually decreased, and (B) a predetermined gradation level (=) corresponding to the first amount (50%). In a range of gradation levels higher than the gradation level at which the dark ink is started to be ejected), as the gradation level becomes higher, the ejection amount of the dark ink is larger than the first amount (50%). Since it is configured to gradually increase to the amount of 2 (100%), if the ejection amount of the dark and light ink is determined using this table, the maximum ejection amount of the light ink for a predetermined unit area will be increased. It can be limited to a value lower than the maximum applying amount link.

As described above, in this embodiment,
Limiting the maximum ink ejection amount of light ink to a predetermined unit area (area corresponding to a 4 × 2 dot matrix of 2400 × 1200 dpi) to a predetermined amount, specifically, the maximum dot of a dot pattern used for light ink By limiting the number to half the number of printable dots (50% duty), the average duty in each pass can be suppressed in multi-pass printing without increasing the number of passes. Therefore, it is possible to prevent streaks and unevenness from occurring without reducing the recording speed.
Good image quality can be obtained.

(Second Embodiment) Next, a second embodiment of the present invention will be described.

In the first embodiment, in order to limit the amount of light ink shot, the number of print dots of light ink for the pixel matrix is limited, and the type of dot pattern used differs between dark ink and light ink. However, in the second embodiment, the dot pattern used is a common dot pattern for the dark ink and the light ink, and the ink ejection amount of the light ink is set when the output gamma correction of the color conversion processing is performed. By suppressing the occurrence of streaks and unevenness, this point is different from the first embodiment.

FIG. 12 is a block diagram showing the arrangement of an image processing unit from the input RGB image data to the N-value quantization in the second embodiment. In the figure, reference numeral 901 denotes a color correction unit, and this color correction unit 901 is an input RGB2
The correction processing of the output RGB 24 bit data is performed on the 4 bit data. This correction process is a process of mapping the color space of the input image data into a color space that can be expressed by the output device, and normally, a three-dimensional lookup table conversion process is used directly. Perform mapping. Reference numeral 902 denotes a color conversion unit, and this color conversion unit 902
Then, 8 bits for each RGB color input from the color correction unit 901
24 bits of data are converted into ink colors of the inkjet recording device which is an output device. In this embodiment, each color of 6 colors of C, M, Y, K, LC and LM is converted into 8-bit data.

At this time, cyan (C) system and magenta (M) system
Both dark and light inks are distributed to the system.
Reference numeral 903 denotes an output gamma correction unit, and the output gamma correction unit 903 performs conversion using a one-dimensional conversion table so that the gradation of each color is linear in density. This content is shown in Figure 1.
3 (a) and (b).

FIG. 13A shows a reflection density characteristic when an input signal representing gradations of 0 to 255 is subjected to a half-toning process, which will be described later, and then dot pattern conversion is performed and the resultant is output by an output device. Is shown. In order to make the characteristics shown in FIG. 13 (a) the density characteristics linear with respect to the input signal value, the output gamma correction table should be provided with the inverse conversion characteristics shown in FIG. 13 (b). Good.

FIG. 14 illustrates the contents of the output gamma correction table used in the output gamma correction unit 903 shown in FIG. 12 when divided into dark ink and light ink. . For the dark ink, the output signal value of the output gamma characteristic is used up to the maximum value 255 of 8 bits, whereas for the light ink, only the output value 128 which is half the maximum value 255 of 8 bits is used.

In the half-toning section 904 shown in FIG. 12, the input signal values of 0 to 255 of each color of 8 bits are quantized into N-value data. In the second embodiment, it is assumed that the data is converted into 9-valued data similar to the first embodiment. Further, the dot pattern conversion unit 905 in FIG. 12 converts 9-valued data into a dot pattern. This dot pattern conversion is performed, for example, in FIG.
Use the dot pattern described in. At this time, FIG.
As shown in FIG. 9, since the maximum input signal value of 255 is used for the dark ink, 4 × 2 shown in FIG.
Dots are arranged (8 dots are arranged) at all of the pixel positions in the pixel matrix.

On the other hand, since the maximum value of the output gamma correction table of FIG. 14 is only 128 for light ink, the dot pattern shown in FIG. 9A is also used for only 4 dots of the 4 × 2 pixel matrix. It will not be done.
Therefore, assuming that 8 dots are arranged in a 4 × 2 pixel matrix and the duty is 100%, the dark ink is used up to 100% and the light ink is used up to 50%.

Therefore, according to the configuration of the second embodiment, as described in the first embodiment, the amount of light ink ejected is suppressed to half the amount of dark ink, so that the nozzles for ejecting light ink are It is possible to reduce the occurrence of streaks and unevenness due to variations in ejection characteristics. Moreover, in the second embodiment, since the dot pattern as shown in FIG. 9A can be shared by the dark ink and the light ink, the processing circuit can be made common, which reduces the cost. Contribute.

(Other Embodiments) In each of the above-mentioned embodiments, the amount of light ink applied to a predetermined unit area (4 × 2 dot matrix of 2400 × 1200 dpi) is limited to about 50%. Although described as an example, the limitation rate of the light ink ejection amount is not limited to 50%, and may be between 100% and 50% based on the relationship between the ejection amount of the recording head and the recording resolution. Value of, for example, about 75%, and further 50%
It is also possible to set it to less than. Further, in each of the above embodiments, the area corresponding to a 4 × 2 dot matrix of 2400 × 1200 dpi, that is, 600 × 600 dpi
Although the ink ejection amount is limited with the area corresponding to i as one unit, the present invention is not limited to this area. For example, the ink ejection amount may be limited with an area corresponding to 300 × 300 dpi or an area corresponding to 1200 × 1200 dpi as one unit.

As is apparent from the above, in the present invention, the maximum amount of light ink ejected on a predetermined unit area may be limited to a value lower than the maximum amount of dark ink ejected on a predetermined unit area. It should be noted that it is preferable to use a table as shown in FIG. 10 when determining the ejection amounts of the dark ink and the light ink.

Further, in each of the above-described embodiments, the ink jet recording apparatus provided with the inks of six colors has been described. However, if the ink jet recording apparatus uses a so-called light and shade system using dark ink and light ink, The present invention can be applied to a recording apparatus having the number of inks of 6 colors or more.

Further, the recording head is not limited to the one using the electrothermal converter, but it is also possible to apply the one which ejects the ink by the electromechanical converter such as piezo.
Further, the present invention is not limited to the mode in which the process for limiting the amount of light ink ejected is performed on the inkjet recording device side, and may be performed on the host computer or the like connected to the inkjet recording device. In this case, the ejection amount limitation of the above-described embodiment is executed by reading out the "program for executing the light ink ejection amount limiting process" installed in the host computer.

An object of the present invention is to supply a storage medium having a program code of software for realizing the functions of the above-described embodiments to a system or apparatus, and to supply a computer (or CPU or MPU) of the system or apparatus.
It is needless to say that is also achieved by reading and executing the program code stored in the storage medium.

In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiments, so that the storage medium storing the program code and the program itself constitute the present invention.

As the storage medium for supplying the program code, for example, a floppy disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM, a CD-R, a magnetic tape, a non-volatile memory card, a ROM or the like is used. You can

Moreover, not only the functions of the above-described embodiments are realized by executing the program code read by the computer, but also the OS (operating system) running on the computer based on the instructions of the program code. It is needless to say that this also includes a case where the above) performs a part or all of the actual processing and the processing realizes the functions of the above-described embodiments.

Furthermore, after the program code read from the storage medium is written in the memory provided in the function expansion board inserted in the computer or the function expansion unit connected to the computer, the program code is read based on the instruction of the program code. It goes without saying that a case where a CPU or the like included in a function expansion board or a function expansion unit performs a part or all of the actual processing and the processing realizes the functions of the above-described embodiments is also included.

[0082]

As described above, according to the present invention, in the ink jet recording apparatus which executes the multi-pass recording, the maximum ink ejection amount by at least one recording head among the recording heads is Since the print head is limited to a value lower than the maximum print ejection amount, for example, when an image of a constant density is formed by using two types of ink, dark and light, the maximum ejection amount of the light ink is the maximum of the dark ink. By setting the value lower than the driving amount, the average duty recorded by one scan can be suppressed. For this reason, it is possible to suppress the occurrence of streaks and unevenness without increasing the number of passes in multi-pass printing, and since the dark ink can be set to a high value, an image can be printed from low density to high density. It becomes possible to reproduce. Therefore, the present invention is particularly effective when a recording head that ejects small droplets is used.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a main part of an inkjet recording apparatus applicable to an embodiment of the present invention.

FIG. 2 is a perspective view showing a recording head cartridge used in an embodiment of the present invention.

FIG. 3 is a block diagram showing a main configuration of an electric circuit used in the embodiment of the present invention.

FIG. 4 is a block diagram showing a schematic configuration of an image input / output system using the inkjet recording apparatus of the present invention.

5 is a block diagram for explaining a configuration of an image processing unit in FIG.

6 is a diagram illustrating a diffusion coefficient of an error diffusion process used in the image processing unit of FIG.

FIG. 7 is a diagram for explaining an example of a conventional shading distribution table.

FIG. 8 is a diagram for explaining an example of a conventional shading distribution table.

FIG. 9 is a diagram showing an example of dot pattern arrangement of dark ink and light ink according to the first embodiment of the present invention,
(A) shows an example of a dot pattern arrangement of dark ink, and (b) shows an example of a dot pattern arrangement of light ink.

FIG. 10 is a diagram for explaining an example of a density distribution table when the dot pattern of FIG. 9 is used.

FIG. 11 is a diagram illustrating the relationship between the printing resolution and the average duty during multi-pass printing.

FIG. 12 is a diagram illustrating input RGB in the second embodiment of the present invention.
FIG. 3 is a block diagram showing a configuration of an image processing unit from image data to N-value quantization.

13A is a diagram showing an input signal and an output characteristic of an output device, and FIG. 13B is an output gamma correction unit for making the output characteristic shown in FIG. 13A a linear characteristic with respect to an input signal value. It is a diagram which shows the inverse conversion characteristic performed by.

FIG. 14 is a diagram for explaining the contents of the output gamma correction table used in the output gamma correction unit shown in FIG. 12 when divided into dark ink and light ink.

[Explanation of symbols]

10 Image input section 11 Image processing unit 200 Data correction unit 200A dark ink processing section 200B Light ink processing unit 201 quantizer 202 error calculator 203 Error memory 204 pattern converter 205 address generator 206 pattern table storage 207 Input correction unit 208 Quantizer 209 Error calculator 901 Color correction unit 902 color converter 903 Output gamma correction unit 904 Half-toning section 905 dot pattern converter H1001 recording head M4001 carriage

Continued front page    (72) Inventor Tetsuya Eedura             3-30-2 Shimomaruko, Ota-ku, Tokyo             Non non corporation (72) Inventor Takayuki Ogasawara             3-30-2 Shimomaruko, Ota-ku, Tokyo             Non non corporation (72) Inventor Mitsuhiko Masuyama             3-30-2 Shimomaruko, Ota-ku, Tokyo             Non non corporation (72) Inventor Daisaku Ide             3-30-2 Shimomaruko, Ota-ku, Tokyo             Non non corporation (72) Inventor Akiko Maru             3-30-2 Shimomaruko, Ota-ku, Tokyo             Non non corporation F-term (reference) 2C056 EA06 EA08 EA11 EC71 EC74                       EC76 ED05 ED07 EE18 FA10                 2C057 AF25 AF31 AF39 AF91 AH13                       AM15 AM28 AN01 CA05 CA07

Claims (16)

[Claims] 1. A multi-pass printing for completing an image by performing a plurality of scans on an image forming area on a printing medium using a plurality of printing heads for ejecting different kinds of ink. In the ink jet recording apparatus described above, the maximum ink ejection amount for a predetermined unit area by at least one recording head among the recording heads is
An ink jet recording apparatus, further comprising: an ejection amount limiting means for limiting a value lower than a maximum recording ejection amount for the predetermined unit area of the other recording head. 2. A multi-pass print for completing an image by performing N scans on an image forming area on a print medium using a plurality of print heads for ejecting different kinds of ink. The inkjet recording apparatus according to claim 1, wherein a predetermined unit area of some of the plurality of print heads is set so that the average duty of one scan in the N print scans is D / N% or less. An ink jet recording apparatus comprising an ejection amount limiting means for limiting the maximum ink ejection amount to D% which is less than 100%. 3. The different kind of ink is yellow,
3. The ink jet recording apparatus according to claim 1, which has six or more colors of ink including cyan, magenta, black, light cyan, and light magenta. 4. The different types of ink include dark ink and light ink having a lower density than the dark ink,
4. The ink jet recording apparatus according to claim 1, wherein the ejection amount limiting unit limits the ejection amount of the light ink. 5. The inkjet according to claim 1, wherein the ejection amount limiting means limits the maximum number of dots of the density pattern used in the ink color for which the ejection amount is to be limited. Recording device. 6. The ejection amount limiting means limits the maximum value of the output signal value of the output gamma correction table used for the ink color for which the ejection amount is to be limited. An inkjet recording device according to claim 1. 7. An ink jet recording for performing a multi-pass recording for completing an image by performing a plurality of scans on an image forming area on a recording medium using a plurality of recording heads ejecting different kinds of ink. In the method, the maximum ink ejection amount for a predetermined unit area by at least one recording head among the recording heads is
An ink jet recording method, wherein a value other than the maximum recording drive amount for the predetermined unit area of the other recording head is limited. 8. An ink jet recording for performing multi-pass recording for completing an image by scanning N times an image forming area on a recording medium using a plurality of recording heads ejecting different kinds of ink. A method for ejecting maximum ink for a predetermined unit area by some of the plurality of print heads so that the average duty of one scan in the N print scans is D / N% or less. An ink jet recording method, wherein the amount is limited to D% which is less than 100%. 9. The ink according to claim 7, wherein the different types of ink include dark ink and light ink having a lower density than the dark ink, and limit the amount of light ink to be ejected. Inkjet recording method. 10. A plurality of dark ink heads for ejecting dark ink and light ink heads for ejecting light ink having a density lower than the dark ink are provided in plural with respect to an image forming area on a recording medium. A program for controlling an inkjet recording apparatus that executes multi-pass recording that completes an image by scanning once, and is a maximum ink ejection amount for a predetermined unit area of light ink ejected from the light ink head. A program for causing a computer to execute the step of limiting the value of the dark ink ejected from the dark ink head to a value lower than the maximum recording ejection amount for the predetermined unit area. 11. A dark ink head for ejecting dark ink and a light ink head for ejecting light ink having a density lower than the dark ink are provided for an image forming area on a recording medium. A program for controlling an inkjet printing apparatus that executes multi-pass printing that completes an image by scanning once, so that an average duty of one scan in the N printing scans is D / N% or less. A computer-readable storage medium storing a program for causing a computer to execute the step of limiting the maximum ink ejection amount of the light ink ejected from the light ink head to a predetermined unit area to D% which is less than 100%. 12. A computer-readable storage medium having the program according to claim 10 or 11 stored therein. 13. A dark ink head for ejecting dark ink and a light ink head for ejecting light ink having a density lower than the dark ink are used, and the dark ink head and light ink are used. An inkjet recording apparatus for recording an image by ejecting dark ink and light ink from a head onto a recording medium, respectively, according to a gradation level of image data corresponding to a predetermined unit area on the recording medium. A determination unit that determines an ink ejection amount of a dark ink and a light ink with respect to the predetermined unit area, and a recording control unit that ejects ink with the ink ejection amount determined by the determination unit to record an image, The determining means (A) determines, as the gradation level becomes higher, a first amount of the light ink ejection amount per unit area. Gradually increases and then gradually decreases, and (B) in a range of gradation levels higher than a predetermined gradation level corresponding to the first amount, as the gradation level becomes higher. A recording apparatus, wherein the ink ejection amount of the dark ink and the light ink is determined by gradually increasing the ejection amount of the dark ink to a second amount larger than the first amount. . 14. A dark ink head for ejecting dark ink and a light ink head for ejecting light ink having a density lower than the dark ink are used, and the dark ink head and light ink are used. An ink jet recording method for recording an image by ejecting dark ink and light ink from a head to a recording medium, according to a gradation level of image data corresponding to a predetermined unit area on the recording medium. And a recording step of recording an image by ejecting ink with the ink ejection amount determined in the determination step, and a determination step of determining the ink ejection amounts of the dark ink and the light ink with respect to the predetermined unit area. In the determining step, (A) as the gradation level becomes higher, the ejection amount of the light ink per unit area is changed to a first amount. Gradually increases until the gradation level gradually decreases to (B), and (B) in a range of gradation levels higher than a predetermined gradation level corresponding to the first amount, as the gradation level becomes higher, A recording method for determining the ink ejection amounts of the dark ink and the light ink by gradually increasing the ejection amount of the dark ink to a second amount larger than the first amount. . 15. A dark ink head for ejecting dark ink and a light ink head for ejecting light ink having a density lower than the dark ink are used, and the dark ink head and light ink are used. A program for controlling an inkjet recording device that records an image by ejecting dark ink and light ink from a head onto a recording medium, and a gradation of image data corresponding to a predetermined unit area on the recording medium. In determining the ink ejection amounts of the dark ink and the light ink with respect to the predetermined unit area according to the level, (A) as the gradation level becomes higher, the ejection amount of the light ink with respect to the unit area is set to Gradually increase to an amount of 1 and then gradually decrease, and (B) above a predetermined gradation level corresponding to the first amount. In the range of high gradation levels,
As the gradation level becomes higher, the amount of dark ink ejected is gradually increased to a second amount which is larger than the first amount so that the amount of dark ink and light ink ejected is increased. A program that causes a computer to execute the step of determining. 16. A computer-readable storage medium on which the program according to claim 15 is stored.