JPH02215541A - Recording apparatus - Google Patents

Abstract

PURPOSE:To provide a good output image with the necessary minimum amount of ink by distributing image density informations of an input image into kinds of dye densities different for each color component, and subjecting the distributed image density informations to under-color removal and black generation for every kind. CONSTITUTION:In an image input unit 1, an input image signal is converted to an image density signal for every color component (Y,M,C), and then output to a density distributing circuit 10 through a masking circuit 9. When image density signals Y2,M2,C2 are input to the density distributing circuit 10, the signals are distributed to image density signals Yk3,Mk3,Ck3 for dark ink and image density signals Yu3,Mu3,Cu3 for dim ink with the use of a distributing table 4a. The image density signals for dark ink are output to an UCR.black generating circuit 11a which in turn outputs image density signals Yk4,Mk4,CK4, Kk4 with using an UCR.black generating table 4b for dark ink with a predetermined input/output characteristic.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a recording device, for example, an inkjet type recording device that forms a color image by ejecting ink.

[Prior Art] Conventionally, in this type of apparatus, ink is ejected from a plurality of ink ejection ports formed in a print head based on a data signal, and ink droplets are attached to a print sheet for printing. This recording method is used, for example, in printers, facsimiles, copying machines, and the like.

In the above device, in order to eject ink, a heating element (electrothermal energy converter) is provided near the ejection port, and by applying an electric signal to this heating element, the ink is locally heated and a pressure change is caused. There is a method using an electrothermal energy converter that causes the ink to be ejected from the ejection port, and a method using an electromechanical converter such as a piezoelectric element. In the method using an electrothermal energy converter, it is difficult to control the amount of pressure change and the shape of the recorded dot cannot be modulated, so the ink dots are visible in the image highlights and the height of the image is There was a problem with image quality recording.

Therefore, a method is used to prevent the ink dots from becoming conspicuous by recording the image highlight portions with light ink using dark and light inks having different dye densities.

FIG. 13 shows the main part configuration of a color inkjet recording device of serial printing type using dark and light inks.

A recording head 30a that discharges dark yellow ink, a recording head 30b that discharges light yellow ink, a recording head 30c that discharges dark magenta ink, a recording head 30d that discharges light magenta ink, a recording head 30s that discharges dark cyan ink, Recording 30 for ejecting light cyan ink
f. A recording head 30g that discharges dark black ink and a recording head 30h that discharges light black ink are installed on the carriage 31. The carriage 31 moves left and right along the guide shaft 32 by detecting the position of the encoder 34. The recording paper 35 is kept horizontal to the ink ejection orifice surface of the recording head by conveyance rollers 33 installed above and below. Dark yellow, light yellow, dark magenta, light magenta.

Ink droplets are deposited on the recording paper in the order of dark cyan, light cyan, dark black, and light black, forming a multicolor image.

FIG. 14 shows an example of a conventional image signal processing circuit in the above-mentioned inkjet recording apparatus, showing yellow image density signals Y1. Magenta image density signal M1. The cyan image density signal CI is processed by a masking circuit 40, undercolor removal (hereinafter referred to as
After color processing is performed in the black generation circuit 41 (called rUCRJ), the image density signals are converted into new image density signals Y sa, M s, C, . Yellow, magenta, cyan, and black image density signals Y sy, M S? after γ correction. l
Csy, K st are image density signals Yksa, Mksa, Cksa, Kks for dark yellow, deep magenta, deep cyan, and deep black with high dye density in the circuit 43 for density distribution.
and image density signals of light yellow, light magenta, light cyan, and light black with low dye density Yusa+ Musa+
It is distributed to Cu5aKu.

FIG. 15 is a diagram illustrating an example of a table for shading. This table is set so that the image density signal value and the reflection density value of the recorded image show a proportional relationship.

This shading distribution is based on a table, and a circuit 43 generates a shading signal. Each of the image density signals divided into shading and lightness is binarized by a binarization circuit 44, and ink is ejected from each recording head according to the signal value to form a color image.

[Problem to be solved by the invention] However, in the conventional image processing signal system described above, the U
There is a drawback that the amount of ink deposited on the recording paper increases significantly due to CR/black generation.

In the case of inkjet recording, since there is a limit to the amount of ink that a recording paper can absorb, it is necessary to control the amount of ink deposited on the recording paper using UCR so as not to exceed this ink absorption limit. That is, the amount of ink is reduced by replacing a portion of gray expressed with three colors, cyan, magenta, and yellow, with black ink.

FIG. 16 is a diagram illustrating an example of a conventional UCR/black generation table. In FIG. 16, the solid line indicates the relationship between the input image density signal level and the output image signal level of the UCR/black generation amount. The UCR amount is assumed to be 50%. The UCR/black generation circuit 41 shown in FIG. 14 performs UCR/black generation according to the table shown in FIG. According to the table in FIG. 16, the output image density signal level is converted to half the input image density signal level. For example, when the input image density signal level is "255", the output image density signal level is The level is set to "128", and the amount of ink deposited on the recording paper is also halved.

However, after the subsequent density distribution is performed by the circuit 43 according to the table in FIG. 15, when the input image density signal level is "128", the output image density signal level of light ink is It becomes “255”, cyan,
The amount of magenta and yellow ink does not change before and after UCR.To reduce the amount of ink, the input image density signal level must be set to "128" or less.
Further, due to the black generation, the black input image density signal (128 levels) is also processed in the shade distribution circuit 43, and an image density signal of 255 levels is outputted for light black. Therefore, by performing UCR/black generation, the amount of ink increases by one color. As a result, the amount of ink that can be absorbed by the recording paper is exceeded, resulting in thicker ink smearing, causing black streak-like unevenness at scan transitions, and wrinkles caused by the swelling of the recording paper causing unevenness at the recording head. The problem has been that the image is contaminated by rubbing against the ejection port surface of the printer.

The present invention has been devised in view of the problems of the prior art described above, and its object is to provide a recording apparatus that can provide a good output image with the minimum necessary amount of ink.

[Means for Solving the Problems] In order to solve the above-mentioned problems and achieve the objectives, a recording device according to the present invention is a recording device that forms a color image by ejecting inks of a plurality of colors according to the dye density. , a means for distributing input image density information into different types of dye density for each color component, and a color conversion means for removing undercolor and generating black from the image density information distributed by the means for distributing, according to the type. It is characterized by comprising:

[Operation] According to the above configuration, the distribution means distributes the input image density information into different dye densities for each color component, and the color conversion means divides the input image density information into different dye densities for each color component. Undercolor removal and black generation are performed for each type of image density information.

[Embodiments] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Note that in the present invention, an inkjet type recording device is used.

First example> First, a first example will be described.

FIG. 1 is a block diagram showing the configuration of the recording apparatus of the first embodiment. In FIG. It shows an operation unit equipped with various keys for instructing the start. 3 indicates a CPU that controls the entire apparatus according to various programs in the ROMJ. 4
indicates a ROM that stores a control program, an error processing program, a program for operating the apparatus according to the flowchart of FIG. 5, and the like. This ROM
4, 4a is a table for the density distribution to be referred to in the processing of the circuit 10, and 4b is a dark ink UCR to be referred to in the processing of the dark ink UcR/black generation circuit 11a, which will be described later. A black generation table 4c indicates a light ink UCR/black generation table to be referred to in the processing of the light ink UCR/black generation circuit 11b described later, and 4d indicates a program group storing the various programs described above. . The density distribution table 4a is the same as the input/output characteristics of the image density signal according to the table shown in FIG. The black generation table 4c is U
The CR amount is 50% for each. Reference numeral 5 designates a RAM in the ROM 4 used as a work area for various programs and a temporary save area during error processing. , and 6 indicates an image signal processing unit that performs image signal processing of color components Y, M, and C, which will be described later.
This figure shows a printer unit that forms a dot image using an inkjet method based on an image signal processed by the printer. Reference numeral 8 indicates a path line for transmitting address signals, data, control signals, etc. within the device.

Next, the image signal processing section 6 will be explained.

FIG. 2 is a block diagram showing the circuit configuration of the image signal processing section 6 according to the first embodiment. In FIG. The image density signals Y*, M! are obtained by performing color correction on the signals Y+, M+, and Cr. , Cm, and 10 indicates the image density signal Yx from the masking circuit 9,
M! , Cz, which will be described later, are divided into image density signals of respective gradations using a table 4a. This density distribution is determined by Y k s in the image density signals for each density output from the circuit 10.

Mks and Cl3 indicate image density signals of dark yellow/low, dark magenta, and dark cyan, which are distributed by the circuit 10, respectively. Also Yus I Mus
, Cus similarly indicate image density signals of light yellow, light magenta, and light cyan distributed by the circuit 10, respectively. lla is the image density signal Yk for dark ink output from the circuit 10 for density distribution.
s.

Mks Ck3 shows a UCR/black generation circuit that performs UCR/black generation by referring to the dark ink UCR/black generation table 4b, and llb is the image density signal Yus for light ink output from the circuit 10 for density distribution. *Mus,C
This figure shows a UCR/black generation circuit that performs UCR/black generation by referring to the light ink UCR/black generation table 4C from us. Here, Ykn, Mka, Cks, Kk4
are the image density signals of deep yellow, deep magenta, deep cyan, and deep black (hereinafter referred to as "for dark ink") generated by tJcR/black in the UCR/black generation circuit 11a, and Ytz t Mu41 Cua, Ku4 is UCR
・Pale yellow generated by UCR and black in the black generation circuit 9b,
Image density signals of light magenta, light cyan, and light black (hereinafter referred to as "for light ink") are shown, respectively. 1
2 shows a γ correction circuit that γ corrects each image density signal from the UCR/black generation circuits 11a and 11b, and 13 binarizes each image density signal output from the γ correction circuit 12 using a dither method or the like. The figure shows a binarization circuit. Here, Yk
s, Mki, Cks, and Kks represent image density signals for dark ink that have been γ-corrected by the γ-correction circuit 12, and Yus, Musl Cus, and Kus represent image density signals for light ink that have been γ-corrected by the γ-correction circuit 12, respectively. Each shows a concentration signal. Also Yka, Mks, Cks
, Kks indicate image density signals for dark ink binarized by the binarization circuit 13, -Yus, Mus +, respectively.
Cut*Ku@ indicates image density signals for light ink that are binarized by the binarization circuit 13, respectively.

Next, a UCR/black generation method according to the first embodiment will be explained.

FIG. 3 is a diagram for explaining a light ink OCR/black generation table 4c for light ink, and FIG. 4 is a diagram for explaining a dark ink OCR/black generation table 4b for dark ink. In Figures 3 and 4, UCR for light ink
・Black generation table 4c and dark ink UCR・Black generation table 4b are tables when the UCR amount is 50%, and the curve, that is, the solid line portion corresponds to the UCR amount and the black generation amount. For example, If the input image density signal level before UCR/black generation processing is “255”, the output image density signal level after UCR/black generation processing is “O” for light ink.
", in the case of dark ink, it is "128", and the generated black is a dark black with an image density signal level of "128". In this way, the original four colors (cyan, cyan,
In the first embodiment, the amount of ink (magenta, yellow, black) is applied to the recording paper, but in the first embodiment, the amount of ink is equivalent to two colors, so there is no increase in ink during printing, and the UC
The effect of R is well demonstrated. Therefore, the ink amount is set so as not to increase regardless of the level of the input image density signal.Next, a printing method according to the first embodiment will be described.

FIG. 5 is a flowchart explaining the printing operation by the CPU 3 of the first embodiment. First, when a print start key is input from the operation unit 2 (step S1), one line of the original image is read by the image input unit 1 (step S2).

In the image input section 1, the input image signal is converted into image density signals for each color component of Y, M, and C.
The concentration distribution is output to the circuit 10 via. This density distribution is carried out by the circuit 10 as image density signals Yz, Mx of Y, M, and C.
, Cs are output, the image density signals Yks , Mks , C
Image density signals Yus, Mus for ks and light ink
, Cus (step S3). Among the image density signals thus distributed, one image density signal for dark ink is output to the UCR/black generation circuit 11a for dark ink. This UCR/black generation circuit 11a
Now, the image density signal Yk is generated using the dark ink UCR/black generation table 4b having the input/output characteristics shown in FIG.
,,Mk4. Ck4.

Outputs K k 4. The image density signal for the other light ink is output to the UCR/black generation circuit 11c for light ink. This OCR/black generation circuit 11c generates the image density signal Yun + Mo2. using the light ink UCR/black generation table 4C having the input/output characteristics shown in FIG.
Cu41 and Ku4 are output (step S4).

In this way, after the four-color conversion of yellow, magenta, cyan, and black is performed in each UCR/black generation circuit, normal γ correction (γ correction circuit 12) and binarization processing (binarization circuit 13) is performed (step S5, step S6), and in this way, image density signals for dark ink after binarization Y kg , M kg , C kg , K
km and image density signals for light ink Yus, MtJa
#Cus*Kue is output to the printer section 7. When the image signal processing for one line is completed (step S7), the process proceeds to step S2, where the next line is scanned and the above-mentioned image signal processing is performed, and this processing ends when the image signal processing of the original image is completed ( Step S8).

As explained above, according to the first embodiment, a good output image can be provided with the minimum necessary amount of ink by performing the density distribution before UCR/black generation.

<Second Example> Next, a second example will be described. In this second embodiment, magenta and cyan, whose dots are relatively easy to see, are used for light inks, and yellow, where dots are difficult to see, and black, which is not often used in bright areas of the image, are used only for dark inks. be done. As described above, the purpose of the second embodiment is to reduce the number of recording heads, and the following description will only refer to the image signal processing section that is different from the first embodiment.

FIG. 6 is a block diagram showing the circuit configuration of the image signal processing section according to the second embodiment, and FIG. 7 is a diagram illustrating the input/output characteristics of the image density signal of yellow color for dark ink. In FIG. 6, numeral 16 indicates a masking circuit for masking the image density signal for each color component, as in the first embodiment, and numeral 17 indicates a table for grayscale distribution having the input/output characteristics shown in FIG. The light/dark distribution circuit shows a circuit for outputting an image density signal for light ink and an image density signal for dark ink using a table similar to 4a.

In this second embodiment, since only dark ink is used for the yellow color, a table having input/output characteristics of the image density signal shown in FIG. 7 is used for the image density signal of the yellow color. The yellow image density signal converted using this table will hereinafter be referred to as a signal for dark ink. 18a indicates a UCR/black generation circuit that performs UCR/black generation on the yellow, magenta, and cyan image density signals for dark ink from the circuit 17 and outputs image density signals of four colors; 18b is a UCR/black generation circuit that performs OCR/black generation on the image density signals of yellow for dark ink and magenta and cyan for light ink from the circuit 17 and outputs image density signals of four colors. Shows the circuit. In the tJcR/black generation circuit 18a, the dark ink OCR/
The same table as the black generation table 4b is used, and the same table as the light ink UCR/black generation table 4C used in the first embodiment is used in the UCR/black generation circuit 18b.

And 19a is a UCR-black generation circuit 18a.

18b shows an adder that adds together the black image density signals (this signal is used for dark ink) output from each of the circuits 18b and 19b is the UCR/black generating circuit 1.
8a and 18b, an adder is shown which adds together the yellow image density signals for dark ink output from each of 8a and 18b. 20 is UCR-black generation circuit 1.8a, 18b
and a γ correction circuit that performs normal γ correction on each image density signal from the adders 19a and 19b, and 21 is a γ correction circuit 20.
This figure shows a binarization circuit that binarizes each image density signal that has been γ-corrected using a normal dither method or the like. Also Y,,M
! , CI is yellow which is outputted from an image input section (not shown) in the same way as in the first embodiment and inputted to the masking circuit 16,
Magenta and cyan image density signals, Yz, Mz,
Os is a yellow, magenta, and cyan image density signal output from the masking circuit 16; Yk+s is a yellow image density signal for dark ink output from the circuit 17 to the UCR-black generation circuits i8a and 18b; Mk
Ix, Ck I2 are magenta and cyan image density signals for dark ink output from the circuit 17 to the UCR/black generation circuit 18a for density distribution, MLlB, Cu1l are output from the circuit 17 to the UCR/black generation circuit for density distribution. 18b respectively show magenta and cyan image density signals for light ink. Ck's, Mk+s, Yk+s, Kk+s
is the image density signal for dark ink output from the UCR/black generation circuit 18a, Cu1l Muls, Yk+s'
Kkts' is an image density signal for light ink output from the UCR/black generation circuit 18ba, and Yk14. K k
14 indicates yellow and black image density signals for dark ink output from the adders 19b and 19a, respectively *Yk+s, Mkps, Muds, C
kts.

CL1+i and KklB are image density signals of dark and light inks output from the γ correction circuit 20, Ykr@.

MIC+e, Mu+6e Ckxs, C1J+s+
Kk+s indicates image density signals of dark and light inks outputted from the binarization circuit 21, respectively.

Here, the operation of the image signal processing section according to the second embodiment will be explained.

First, image density signals Yt, Mr, and CI outputted from an image input section (not shown) are masked by a masking circuit 16, and the density distribution is outputted to a circuit 17 as image density signals Y2°Ms, Cm. This density distribution is determined by the circuit 17, and the image density signals M*, Cm are determined by the table 4a.
The image density signal M for dark ink is determined by a table similar to
The image density signal Y3 is divided into the image density signals Mulz and CLX Hl for light ink and the image density signal Yk+i for dark ink using the input/output characteristic table shown in FIG. 0th order U
In the CR/black generation circuit 18a, the input image density signal M k
s*, Ck Ix.

OCR/black generation is performed on Yk+* using a table similar to the dark ink UCR/black generation table 4b, and thereby image density signals Ck+s, Mk+s, Yk ls,
Color conversion processing to K k Is is performed. Similarly UCR
- In the black generation circuit 18b, the input image density signal M ult
, Cu +z, Y k t* as UCR- for light ink
Using a table similar to black generation table 4C, UCR/
Black generation is performed, which results in an image density signal Cuts,M
Color conversion processing to u+s,'(k's', Kks3') is performed.Furthermore, the image density signal YkIs.

Yk+s' is added by an adder 19b, and the addition result is output to the γ correction circuit 20 as an image density signal Yk+4. Also, K k ls and K k tso are added by the adder 19.
a, and the addition result is output to the γ correction circuit 20 as an image density signal Kk14.゛In this way, the output image density signals from each UCR/black generation circuit and each adder are γ-corrected by the γ-correction circuit 20, and further processed by the binarization circuit 2.
It is binarized at 1.

As explained above, according to the second embodiment, not only the same operation and effect as the first embodiment can be obtained, but also the number of recording heads can be reduced depending on the conspicuousness of dots caused by dark and light inks. A good image can be obtained without further increase in the amount of ink.

Third embodiment> Next, a third example will be described.

FIG. 6 is a block diagram showing a circuit configuration in an embodiment of the present invention using dark, medium and light inks. The purpose of the third embodiment is to reduce the amount of ink even when using dark, medium and light inks, and in the following description, the first Only the image signal processing section is different from the embodiment.

FIG. 8 is a block diagram showing the circuit configuration of the image signal processing unit according to the third embodiment, FIG. 9 is a diagram explaining the dark/medium/light distribution table according to the third embodiment, and FIGS. 10 to L2. The figure shows UC suitable for dark, medium and light inks according to the third embodiment.
FIG. 3 is a diagram illustrating an R/black generation table. In FIG. 8, 25 is a masking circuit for masking the image density signal for each color component as in the first embodiment, and 26 is Y.

A circuit for dividing and outputting M and C image density signals for each of dark, medium and light inks shown in FIG. 9, which will be described later, shows a circuit. 27a is a UCR that performs UCR/black generation on each yellow, magenta, and cyan image density signal for dark ink from the circuit 26 and outputs image density signals of four colors including black.・The black generation circuit is shown, and 27b shows the dark/medium color division by performing UCR/black generation on each yellow, magenta, and cyan image density signal for medium ink from the circuit 26, and generating four colors including black. 27 shows a UCR/black generation circuit that outputs an image density signal.
c is the UCR/C for each yellow, magenta, and cyan image density signal for light ink from the circuit 26 for dark/medium/light distribution.
It shows a UCR/black generation circuit that generates black and outputs image density signals of four colors including black. UCR・
In the black generation circuit 27a, the input/output characteristics of the image density signal shown in FIG. 12 are used as a dark ink UCR/black generation table. Also, the UCR/black generation circuit 27b
In this case, the input/output characteristics of the image density signal shown in FIG. 11 are used as the UCR/black generation table. Furthermore, the UCR/black generation circuit 27c uses the input/output characteristics of the image density signal shown in FIG. 10 as a UCR/black generation table.

Reference numeral 28 denotes a gamma correction circuit that performs normal gamma correction on each image density signal from the UCR/black generation circuits 27a to 27c, and reference numeral 29 indicates a gamma correction circuit that performs normal gamma correction on each image density signal from the UCR/black generation circuits 27a to 27c. This shows a binarization circuit that performs binarization using, etc. Here, Y+, Mr, and Cr represent yellow, magenta, and cyan image density signals, respectively, which are output from an image input unit (not shown) in the same manner as in the first embodiment and input to the masking circuit 25, and Yz, Mn, and Cm 1 and 2 show yellow, magenta, and cyan image density signals output from the masking circuit 25, respectively. Yks
a, Mkas, and Ckss indicate yellow, magenta, and cyan image density signals for dark ink output from the circuit 26 to the UCR/black generation circuit 27a, respectively, and Y n *** M n * **Cn■ indicates the image density signals of yellow, magenta, and cyan for medium ink outputted from the circuit 26 to the UCR/black generation circuit 27b, and Y u *** M ut
x+ Cu ** is the dark/medium distribution from the circuit 26 to the UCR・
yellow for light ink output to the black generation circuit 27c;
Image density signals of magenta and cyan are shown, respectively. Yk*s, Mkas, Ckas, Kk2. is U
CR- indicates image density signals for dark ink output from the black generation circuit 27a, Ynzs, Mnzs+
Cnzs and Knss respectively indicate image density signals for medium ink output from the UCR-black generation circuit 27b;
Y u *s, M u ss+Cu ys, and Ku tomi represent image density signals for light ink output from the UCR/black generation circuit 27c, respectively.

And Y kz4. M kg4. Cki4. K
k*4 indicates the image density signal for dark ink output from the γ correction circuit 28, Y n , 4. M n
14+Cn*41Knm4 represents the image density signal for medium ink output from the γ correction circuit 28, and Y-u! 4+ Mu 14+ Cu *4
．． K u 24 each indicates an image density signal for light ink. Also, Yk as, M k *s, C
k ss and K k as respectively indicate image density signals for dark ink output from the binarization circuit 29, and Ynz
s, Mn1i, Cn*s+ Knis is the binarization circuit 29
The image density signals for medium ink output from
u zs indicates an image density signal for light ink output from the binarization circuit 29, respectively. Furthermore, Figure 1O~
Each table shown in Figure 12 shows the input/output characteristics when the UCR amount is 50%.
This corresponds to the amount of R and the amount of black production.

As mentioned above, when using dark, medium and light inks as in the third embodiment, the explanation of all operations will be omitted, but in an image signal processing section (not shown), image density signals Yt, Mz, Cz
After dividing the inks into dark, medium and light inks, Figure 10~
Using each table in Figure 12, calculate the UC for each dark, medium and light ink.
By performing R/black generation processing, the final dark ink,
Medium ink.

And a binary image density signal Yk*s suitable for light ink,
Mkzs, Ck*s, Kk proverbs, Ynss.

M n ill, C n alto K n zs+
Y Ll 111. M u xl * Cu *** K
u *m can be obtained. In this way, similar to the first embodiment, it is possible to achieve image signal processing that can prevent an increase in the amount of ink on the recording paper during printing.

As explained above, according to the third embodiment, not only can the same functions and effects as the first embodiment be obtained, but also by using various types of ink such as three levels of dark, medium and light. An output image with smooth gradation reproduction can be obtained by suppressing the conspicuousness of dots in bright areas of the image.

In this third embodiment, three levels of ink, dark, medium and light, are used, but the present invention is not limited to this.
There is no particular limitation as long as it does not depart from the spirit of the present invention, and four stages are also possible.

[Effects of the Invention] As explained above, according to the present invention, a good output image can be provided using the minimum necessary amount of ink.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of the recording apparatus according to the first embodiment, FIG. 2 is a block diagram showing the circuit configuration of the image signal processing section 6 according to the first embodiment, and FIG. FIG. 4 is a diagram for explaining the ink UCR/black generation table 4c. FIG. 4 is a diagram for explaining the dark ink UCR/black generation table 4b for dark ink. FIG. 5 is for explaining the printing operation by the CPU 3 of the first embodiment. FIG. 6 is a block diagram showing the circuit configuration of the image signal processing unit according to the second embodiment; FIG. 7 is a diagram explaining the input/output characteristics of the image density signal of yellow color for dark ink; The figure is a block diagram showing the circuit configuration of the image signal processing unit according to the third embodiment, FIG. 9 is a diagram explaining the dark/medium/light distribution table according to the third embodiment, and FIGS. 10 to 12 are FIG. 13 is a diagram illustrating a UCR/black generation table suitable for each of dark, medium and light inks according to the third embodiment; FIG. FIG. 14 is a diagram showing an example of a conventional image signal processing circuit in the above-mentioned inkjet recording apparatus, FIG. 15 is a diagram explaining an example of a table for color distribution, and FIG. 16 is an example of a conventional UCR/black generation table. FIG. In the figure, 1... image input section, 2... operation section, 3-C,
PU, 4...ROM, 5...RAM, 6 image signal processing unit, 7...printer unit, 8...pass line, 9.
16,25.40...Masking circuit, 10.17.
43-...Darkness distribution is a circuit, 11a, llb, 18a,
18b, 27a. 27b, 27c, 41 = UCR/black generation circuit, 12.2
0,28.42...γ correction circuit, 13.21,29.
44...Binarization circuit, 19a, 19b=adder, 26
- Dark/medium/light distribution circuit, 30a to 30h... Recording head, 31... Carriage, 32... Guide shaft, 3... Conveyance roller, 34... Encoder, 5... It is a recording paper. Diagram

Claims (3)

[Claims] (1) In a recording device that forms a color image by ejecting ink of a plurality of colors according to the dye density, a sorting means that sorts input image density information into different dye density types for each color component; 1. A recording apparatus comprising: color conversion means for removing undercolor and generating black from the sorted image density information according to the type. (2) The recording apparatus according to claim 1, wherein the sorting means has a table for sorting by type of dye density. (3) The recording apparatus according to claim 1, wherein the color conversion means has a table for removing undercolor and generating black for each type of dye density.