JP2003145809A - Apparatus and method for correcting printing data, and software recording medium with printing data correction program recorded - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that it is utterly impossible to compare patches with each other for all reproducible colors if a printing head has the machine specificity. SOLUTION: When a recording material such as a color ink for constituting dots as in an ink jet system printer 31 changes by the machine specificity, it is impossible to set a correction amount for a color shift for each color. However, by obtaining the correction amount for at least a single color, detecting a mixed color degree of each dot, and adopting while reducing the correction amount in accordance with an increase of the mixed color degree, the color shift is corrected with an optimum correction amount conforming to the mixed color degree of each dot and the individual machine specificity is compensated for, so that the color reproducibility can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a print data correction device, a print data correction method, and a medium recording a print data correction program.

[0002]

2. Description of the Related Art In recent years, color ink jet printers have been improved in definition and have come to be called so-called photographic image quality. Such an ink jet printer ejects a predetermined color ink in a granular form to attach dots of a predetermined color at a desired position and express an image in a dot matrix form. In this case, a color image is reproduced using three color inks of cyan (C), magenta (M), and yellow (Y) or four color inks in which black (K) is added.

By the way, in order to be called photographic image quality, it is important that the dots be fine, but color reproducibility is also extremely important. Although the color is represented by multi-tone data of red, green, and blue (RGB) inside the computer, the printer can only handle CMYK two-tone data, so color space conversion and gradation conversion are performed. It is being appreciated. That is, CMYK two-gradation display is realized while maintaining the colors expressed by RGB multi-gradation. Of course,
Here, it is premised that each dot develops color at a specified density.

However, despite the fact that the print data is output while maintaining the color reproducibility, the weight of the color ink particles varies depending on the machine body of each print head, and as a result, each dot has its original color. In some cases, it may not be said that the color is developed depending on the density.

[0005]

In the above-mentioned conventional color ink jet printer, if the amount of ink particles ejected differs due to the difference in the print heads, it cannot be said that each dot develops its original density. As a result, there is a problem that the color reproducibility may deteriorate.

Therefore, the applicant of the present invention has decided to improve the color reproducibility by correcting the print data in advance to compensate for the machine difference and printing based on the corrected print data. Such modification uses a modification table. To create this correction table, first,
A reference print head that ejects color ink particles of a reference weight prints a patch over all tones, and a print head with a machine-difference also prints a patch over all tones. Then, each patch is compared to obtain a combination of patches having no error, and the combination list is used as a correction table.

Since it is necessary to compare and contrast patches in this manner, it is very difficult to compare patches for all reproducible colors. Therefore, when a correction table is created for each element color, when printing a single color, it is possible to obtain almost the same color development as in the case of the reference head, but when color mixing occurs, a deviation occurs again.

The present invention has been made in view of the above problems, and a print data correction device, a print data correction method, and a print data correction method capable of reproducing colors more accurately regardless of machine differences such as a print head. An object of the present invention is to provide a software recording medium recording a print data correction program.

[0009]

In order to achieve the above object, the invention according to claim 1 provides a recording material for each element color in order to print out a color image with a plurality of element colors based on print data. A print data correction device that corrects the above print data in order to compensate for a color change due to a bias in the usage amount of the recording material for a printing device that is attached to a recording medium in a dot matrix form, and for each element color A correction amount storage unit that stores a correction amount that compensates for the deviation in the usage amount of the recording material that has been set, determines the color mixture order for each dot, and when the color mixture order increases, the correction amount is set to a value greater than that for a single color. A correction amount adjusting unit that adjusts the correction amount to reduce the amount and a correction unit that corrects the print data based on the adjusted correction amount are provided.

In the invention according to claim 1 configured as described above, the correction amount storage means is provided for each element color in response to the deviation of the usage amount of the recording material caused by the machine difference of the printing device. The correction amount for compensating for the bias of the same usage amount is stored, and the correction amount adjusting means determines the color mixture order for each dot and reduces the correction amount compared to the case of a single color when the color mixture order increases. The corrected amount. Then, the correction means corrects the print data based on the adjusted correction amount.

When the correction amount for a single color is applied to mixed colors, an experimental result has been obtained that the correction amount set as a single color is too strong. There are various possible causes for this, but it is reasonable to think that the amount of correction for each element color will have a strong effect due to color mixing, and by reducing the amount of correction during color mixing, it is possible to set a single color state. The corrected amount is not used as it is in the case of color mixing, and the reproducibility of color mixing is improved. In this case, the color mixture order is also the secondary color,
It can be judged that there is a width such as a tertiary color, and the influence of the correction amount in the case of a single color decreases as the order increases. Therefore, the color reproducibility is improved by determining the color-mixing order for each dot and reducing the order to be optimal.

The correction amount storage means may store a correction amount capable of compensating the bias of the usage amount of the recording material for each element color, and the correction amount can be realized in various modes.
For example, assuming that the print data is gradation data, it may be stored in the form of a conversion table including conversion data corresponding to each gradation, or the print data may be input to perform a predetermined calculation. A function that stores the calculation parameter may be stored. Further, it may not be stored individually, but may be stored in a fused or compressed form.

The correction amount adjusting means may determine the color mixing order for each dot and reduce the correction amount, and various methods can be used for determining the color mixing order. As an example thereof, the invention according to claim 2 is the print data correction device according to claim 1, wherein the correction amount adjusting means determines the variation in the component amount of each element color, and The configuration is such that it is determined that the color mixing order is the highest.

In the invention according to claim 2 configured as described above, the correction amount adjusting means determines the variation in the component amount of each element color. If each element color has the same amount of components, it is possible to judge that the color mixture order is large because they are mixed at the same ratio, and even if there are mixed colors, the amount of components of other element colors is small compared to one element color. When considering the correction amount, it is appropriate to consider the degree of influence to be low and to judge that the color mixture order is small. Therefore, when the component amounts of the respective element colors are evenly distributed, it is determined that the color mixture order is the highest.

Various methods can be adopted as the method for obtaining the variation of the component amounts, and it is not necessarily limited to a specific method. As an example of a simple method in such a case, the invention according to claim 3 is the print data correction device according to claim 2, wherein the correction amount adjusting means includes the minimum component amount for each element color and the above The above-mentioned variation is determined based on the ratio of the component amount to the average value.

In the invention according to claim 3 configured as described above, the correction amount adjusting means obtains the ratio between the minimum component amount for each element color and the average value of the component amounts. Here, the ratio is calculated, and if there are three element colors, the ratio of the total value to three times the minimum value is also included. Then, the variation is determined based on this ratio.

When the correction amount adjusting means determines the color mixture order, the correction amount adjusting means need not be limited to the determination based on the component amount. The invention according to claim 4 is the print data correcting device according to claim 1. The correction amount adjusting means is configured to determine the saturation and determine that the color mixture order is high when the saturation is low.

In the invention according to claim 4 configured as described above, the correction amount adjusting means determines the saturation. However, this saturation is similar in nature to the variation of the component amount, and the saturation When the color saturation is low, the element colors are uniform, and when the saturation is high, the difference between the element colors is often large. Therefore, when the saturation can be easily determined, it can be adopted as a method of determining the color mixture order.

When the correction amount adjustment means obtains the adjustment amount for reducing the correction amount for each dot, it is also arbitrary at which point the adjustment amount is obtained. As an example thereof, the invention according to claim 5 is the print data correction device according to any one of claims 1 to 4, wherein the correction amount adjusting means is
With respect to the print data for each dot, the color mixture order is determined and the adjustment amount of the correction amount is obtained.

In the invention according to claim 5 configured as described above, the correction amount adjustment means determines the color mixing order each time print data is input for each dot, and obtains the adjustment amount of the correction amount. Of course, if the print data is input for each unit, the determination may be made for each unit. That is, the correction amount is adjusted according to the flow of print data.

On the other hand, as another example, the invention according to claim 6 is the print data correcting device according to any one of claims 1 to 4, wherein the correction amount adjusting means is
The adjustment amount of the correction amount is obtained in advance based on the combination of each element color.

In the invention according to claim 6 configured as described above, the correction amount adjusting means obtains the adjustment amount of the correction amount in advance based on the combination of each element color. The adjustment amount obtained in advance may be used as a conversion table, or if there is another conversion table such as color conversion, it may be incorporated into them so that color conversion and correction can be performed with a single reference. May be.

The method of reducing and applying the correction amount set for each element color at the time of color mixture as described above does not necessarily have to be a substantial device. As an example, the invention according to claim 7 is Based on the deviation of the usage amount of the recording material for the printing device that attaches the recording material for each element color to the recording medium in a dot matrix form in order to print out a color image with a plurality of element colors based on the print data A print data correction method for correcting the print data in order to compensate for a color change, in which a correction amount for compensating for a bias in the usage amount of the recording material set for each element color is stored and for each dot. When the color mixture order is determined and the color mixture order increases, the correction amount is adjusted to reduce the correction amount compared to the case of a single color, and the print data is adjusted based on the adjusted correction amount. There is a positive to configure.

That is, there is no difference in that the method is not limited to the work of correcting with a substantial device, and that the method is effective.

By the way, as described above, the print data correction device for correcting print data may exist as a single device or may be used in a state of being incorporated in a certain device. It includes the aspect of. Further, it can be changed as appropriate, such as being realized by hardware or software.

In the case of software for color correction as an example of embodying the idea of the invention, it naturally exists on a software recording medium recording such software,
There is no choice but to say that it will be used.

As an example thereof, in the invention according to claim 8, the recording material for each element color is attached to the recording medium in a dot matrix form in order to print out a color image with a plurality of element colors based on the print data. A software recording medium recording a print data correction program for correcting the print data by a computer in order to compensate for a color change based on a deviation of the usage amount of the recording material for the printing device,
The correction amount for compensating for the deviation of the usage amount of the recording material set for each element color is stored, and the color mixing order is determined for each dot, and when the color mixing order increases, the correction amount is higher than that for a single color. Adjust the correction amount to reduce
The print data is corrected based on the adjusted correction amount.

Of course, the software recording medium may be a magnetic recording medium or a magneto-optical recording medium, and any software recording medium to be developed in the future can be considered in exactly the same manner. In addition, the duplication stage of the primary duplication product, the secondary duplication product, and the like is absolutely the same. In addition, the present invention is used even when a communication line is used as a supply method, and the same applies to a case where the present invention is written in a semiconductor chip.

Further, even when a part is software and a part is realized by hardware, there is no difference in the idea of the invention, and it is necessary to store a part on a software recording medium. It may be in a form that can be appropriately read according to the above.

[0030]

As described above, according to the present invention, it is not difficult to obtain the correction amount of color mixture in the sense that the correction amount is set for each element color, and it is optimal for the mixed dots. Since the correction amount is weakened so as to cope with the problem, it is possible to provide the print data correction device capable of substantially eliminating the color shift due to the machine difference and improving the color reproducibility.

Further, according to the second aspect of the invention, by obtaining the color mixture order by referring to the component amounts, it is possible to determine not only the simple color mixture number but also the degree of influence thereof.
Color reproducibility can be improved.

Further, according to the invention of claim 3,
The variation of the component amount can be calculated by a relatively simple calculation.

Further, according to the invention of claim 4,
The degree of color mixture can be obtained by utilizing one reproduction element of color called saturation, which is suitable when the saturation is obtained for other reasons.

Further, according to the invention of claim 5,
By obtaining the adjustment amount for each dot, only the necessary colors are calculated, and it is not necessary to obtain the adjustment amounts for the unused colors. In particular, if the result is cached, the calculation amount will be further reduced.

Further, according to the invention of claim 6,
If the adjustment amount is first obtained and the conversion table is formed, the conversion table is only referred to thereafter, and the reference labor is reduced when referring to another conversion table.

Further, according to the invention of claim 7,
Similarly, it is possible to provide a print data correction method capable of improving color reproducibility during color mixing.

Further, according to the invention of claim 8,
Similarly, it is possible to provide a software recording medium recording a print data correction program capable of improving color reproducibility during color mixing.

[0038]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing a print data correction device according to an embodiment of the present invention. FIG. 2 is a block diagram showing a hardware configuration example of a printing system to which the print data correction device is applied. Shows.

The printing system can be roughly classified into an image input device 10, an image processing device 20, and a printing device 30. The image input device 10 corresponds to a scanner 11, a digital still camera 12 or a video camera 14, and the image processing device 20 includes a computer 21, a hard disk 22, a keyboard 23 and a CD-R.
The OM drive 24, the floppy (registered trademark) disk drive 25, the modem 26, the display 27 and the like correspond, and the printer 31 and the like correspond to a specific example of the printing device 30. It should be noted that the modem 26 is connected to a public communication line and can be connected to an external network via the same public communication line so that software and data can be downloaded and introduced.

Here, the scanner 11 and the digital still camera 12 as the image input device 10 output image data of 256 gradations of RGB (green, blue, red) as image data, and the printer 31 as the printing device 30 Image data of two gradations of CMYK (cyan, magenta, yellow, black) is required as an input. Therefore, in the computer 21 as the image processing apparatus 20, the 256-gradation image data is input, predetermined image processing and printing processing are performed, and output as 2-gradation image data. An operating system 21 a is operating in the computer 21, and the printer driver 21 b and the display driver 21 corresponding to the printer 31 and the display 27 are provided.
c is installed and the application 21
d is controlled by the operating system 21a to perform processing, and displays on the display 27 in cooperation with the display driver 21c, and executes print processing in cooperation with the printer driver 21b as necessary.

In the present embodiment, the print data correction device 30a inputs the generated print data in the process of generating the print data in such a printing system, corrects the predetermined data and outputs the corrected data. in this case,
The correction amount storage unit 30a1 holds the correction amount for correcting the machine difference for each element color as described later, and the correction amount adjustment unit 30a2 determines the color mixing order for each dot and gives a reduction instruction. The correction unit 30a3 performs data correction in a substantial sense while reducing the correction amount for each element color stored in the correction amount storage unit 30a1 based on the correction amount reduction instruction from the correction amount adjustment unit 30a2. become. Hereinafter, this step will be described in detail.

First, the printer 31 that prints based on the corrected print data will be described. FIG. 3 shows a schematic configuration of the printer 31, which includes a print head 31a including three print head units and the print head 31a.
a, a print head controller 31b for controlling a, a print head digit moving motor 31c for moving the print head 31a in the digit direction, a paper feed motor 31d for feeding the print paper in the row direction, the print head controller 31b and the print head. A dot printing mechanism including a digit moving motor 31c and a printer controller 31e, which is an interface with an external device in the paper feed motor 31d, is provided, and an image can be printed according to print data.

FIG. 4 shows a more specific structure of the print head 31a, and FIG. 5 shows the operation during ink ejection. The print head 31a is formed with a fine conduit 31a3 from the color ink tank 31a1 to the nozzle 31a2, and the ink chamber 31a is formed at the end of the conduit 31a3.
4 are formed. The wall surface of the ink chamber 31a4 is formed of a flexible material, and the wall surface is provided with a piezo element 31a5 which is an electrostrictive element. The piezo element 31a5 has a crystal structure that is distorted by applying a voltage and performs high-speed electrical-mechanical energy conversion.
The wall surface of 1a4 is pushed to reduce the volume of the ink chamber 31a4. Then, a predetermined amount of color ink particles are vigorously ejected from the nozzle 31a2 communicating with the ink chamber 31a4. This pump structure will be called a micro pump mechanism.

Two independent rows of nozzles 31a2 are formed in one print head unit, and color inks are independently supplied to the nozzles 31a2 of each row. Therefore, each of the three print head units has two rows of nozzles, and it is possible to use six color inks to the maximum extent. In the example shown in FIG. 3, two rows in the print head unit in the left column are used for black ink, only one row in the middle print head unit is used for cyan ink, and two rows in the print head unit in the right column are used. The two columns on the left and right are used for magenta ink and yellow ink, respectively.

As described above, the present embodiment is applied to the ink jet type printer 31 employing the micro pump mechanism. In the printer 31 having an ink jet type dot attachment mechanism,
Printing is performed by ejecting one ink particle for each dot from the print head 31a described above. However,
The size of one dot applied in this way is not always constant, and there is a machine difference in the print head 31a. In the case where the print density does not change due to so-called overprinting, the dot size affects the print density. Therefore, when the dot size varies from machine to machine, the print density varies, and in color, the color balance and lightness vary, and in monochrome, the density of gray varies.

In the present embodiment, the ink jet type printer 31 which employs the micro pump mechanism has been described, but any printer having another dot attaching mechanism may be used as long as the dot size causes a machine difference. Applicable.

For example, as shown in FIG. 6, the nozzle 31a6
A heater 31a8 is provided on the wall surface of the nearby conduit 31a7, and a bubble jet (registered trademark) type pump mechanism that heats the heater 31a8 to generate bubbles and discharges color ink by the pressure is also put into practical use. Has been done. Also in this case, the ability of the heater 31a8 and the nozzle 31a6
It is undeniable that there will be differences in the aircraft due to the shape of the openings in the.

As another mechanism, FIG. 7 shows a schematic structure of a so-called electrophotographic printer 33. A charging device 33b, an exposure device 33c, and a developing device 33 are provided on the peripheral edge of the rotary drum 33a as a photoconductor in correspondence with the rotation direction.
d and the transfer device 33e are arranged, the charging device 33b uniformly charges the peripheral surface of the rotary drum 33a, and then the exposure device 33c removes the charge on the image portion, and the developing device 3
Toner is attached to the uncharged portion in 3d, and the toner is transferred onto paper as a recording medium by the transfer device 33e. After that, the toner is melted by passing between the heater 33f and the roller 33g and fixed on the paper.

Even in the case of such an electrophotographic printer 33, the amount of toner adhered varies due to the difference between the charging device 33b, the exposure device 33c and the rotating drum 33a itself. Therefore, the same problem as in the inkjet printer 31 occurs.

In the present embodiment, the image input device 10
Although a computer system is incorporated between the printer and the printing device 30 to perform the printing process, such a computer system is not necessarily required. For example, as shown in FIG. 8, in the printer 32 that inputs and prints image data without going through a computer system, the scanner 11b and the digital still camera 12 are used.
It is also possible to input image data as print data input via b or the modem 26b and make a correction to eliminate the machine difference.

Next, a process of outputting print data to the printer 31 will be described. FIG. 9 shows the flow of image data. The image input device 10 represents RGB multi-gradation (2
Image data of 56 gradations) is output to the image processing device 20,
The image processing apparatus 20 performs predetermined image processing and C
It is output to the printing device 30 as MYK two-gradation image data (binary data). In the image processing device 20, color conversion processing from the RGB color space to the CMYK color space is performed, and in this processing, image data of 256 gradations of RGB is 25 of CMYK.
It is converted into image data of 6 gradations. Next, in view of the fact that the data that can be input to the printing device 30 has two gradations, halftone processing is executed to convert the image data of 256 gradations into the image data of two gradations. The image data is output to the printing apparatus 30 as print data through such a process, but since it is data about the same image even in the process before that, it can be called print data in a broad sense. In principle, the above-described print data correction device 30a can perform correction processing on print data at any stage. It shall be done on the data.

FIG. 10 shows a procedure of rewriting the color conversion table for performing the correction processing as the color conversion processing. Here, the contents will be described according to the procedure.

First, in step S100, a correction lookup table for a primary color (single color) is created. Here, the procedure for creating this correction lookup table will be described.
As described above, first, the patch is printed over the entire gradation by the reference print head 31a that ejects the reference color ink particles. In the present embodiment, since there are 256 gradations, the printed patch has a grid pattern of 16 rows and 16 columns as shown in FIG. Next, the print head 31a having a different machine body
But in the same way, patches are printed over all gradations. In the print head 31a having a different machine body, since the weight of the ejected ink particles is different, the print density is different, and the reference print head 31
It does not match the patch printed over all gradations in a.

Therefore, as shown in FIG. 12, each patch printed by the reference print head 31a is individually compared with each patch printed by the print head 31a having a machine body difference, and the gradation of the matching patch is compared. . In the figure, a combination of patches that are printed when predetermined gradation data is input and have the same print density is shown. Therefore, this combination directly constitutes the correction lookup table. In the present embodiment, three print heads 31a are provided, so a correction lookup table is created for each print head 31a. The correction look-up table has the correction amount described above, and in this sense, it can be said that the correction amount is a correction amount for each element color.

By using the correction look-up table created for each print head 31a in this manner, it is conceivable that corrections other than the primary color can be similarly corrected. In reality, however, the secondary color and the tertiary color can be corrected. When it comes to mixed colors like this, a deviation appears.

Therefore, in step S110, the correction amount in the correction lookup table is reduced to print the secondary color patch. Here, the adjustment of the reduction amount is represented by multiplying the correction amount by a predetermined coefficient, and the same coefficient is set to "0.
FIG. 1 shows a correction look-up table in the case of 1 ”increments.
3 shows. Since the amount of correction is small in the low gradation region and the high gradation region, it is difficult to see the change. However, when looking at the gradation "180" where the correction amount is the maximum, when the coefficient is "1.0", the correction amount becomes " It can be seen that the correction amount is reduced by almost "2" gradation data by decreasing the coefficient in increments of "0.1" for the difference of 20 "gradation data. Of course, for secondary colors, each print head 3
Use a separate correction look-up table in 1a, multiplied by the same coefficient. The step size of the coefficient in this case does not necessarily have to be "0.1".

In step 120, the patches of the reference print head 31a thus printed for the secondary color and the patch of the print head 31a having a machine difference with a different coefficient α2 are subjected to color measurement, and as a whole. The coefficient α2 that reduces the error is determined. According to the experimental results, the coefficient α2
Was most preferably "0.8".

Next, the coefficient α3 for the tertiary color is determined by the same method. That is, in step S130, the coefficient α3 is changed to print the patches of the tertiary color, and in step S14
At 0, the optimum coefficient α3 is determined in comparison with the patch on the reference print head 31a. It was confirmed that the optimum coefficient α3 for this tertiary color is about “0.6”.

Here, the patches of the secondary color and the tertiary color are those in which the respective element colors are evenly added and printed,
In these cases, it can be said that the coefficient confirmed as described above is optimum. However, the color mixture of element colors in each pixel in actual print data is mixed,
The coefficient α2 is not necessarily optimal for secondary colors, and the coefficient α3 is not optimal for tertiary colors.

Here, referring to FIG. 14 in which the component of each pixel is represented by the component value of the element color, when the largest component value is H, the smallest component value is L, and the middle component value is M, the component is For the value L, all the element colors are satisfied, and for the portion of the component value L or more and the component value M or less, the two element colors are satisfied, and for the component value M or more, only one element color Is satisfied. Therefore, the component s1 having a component value L or less satisfying all the element colors is considered as a tertiary color component, and the part having a component value L or more and a component value M or less is considered as a secondary color component,
A coefficient α0 is obtained by considering a portion having a component value M or more as a primary color component and multiplying each sum component s1, s2, s3 with respect to the sum S of all components by a coefficient α3, a coefficient α2, and a coefficient 1.0. To That is, the coefficient α0 that satisfies α0 = α3 × (s1 / S) + α2 × (s2 / S) + 1.0 × (s3 / S) (1) is used.

In this case, the hardware and software for storing the correction lookup table for at least the primary color constitute the correction amount storage means 30a1, and the hardware and software for calculating the coefficient α0 based on the equation (1) are The correction amount adjusting means 30a2 is configured.

Of course, the equation (1) used by the correction amount adjusting means 30a2 is merely an example, and the correction lookup table for at least the primary color is used to correct the secondary color and the tertiary color as the color mixing order increases. The coefficient α0 that reduces the amount may be used.

For example, a parameter indicating how close the color is to a tertiary color can be used. Taking RGB as an example, a parameter (gray degree) is set such that it is “100” when it is close to gray and “0” when it is close to the primary color. If this gray degree is “100”, the coefficient α3 is adopted. , And the same gray level is “0”, the coefficient “1.
0 ”is adopted. This gray level can be obtained as follows. Now, the input data value (component amount) for each ink is in_dataC1, in_dataC2, in
If _dataC3, the minimum input data value MIN_value is MIN_value = min (in_dataC1, i
n_dataC2, in_dataC3), which has the largest input data value MAX_value
e is MAX_value = max (in_dataC1, i
n_dataC2, in_dataC3), which is the middle of the input data values MID_value
e is MID_value = mid (in_dataC1, i
n_dataC2, in_dataC3). In this case, the gray scale gray is gray = (MIN_value × 3) / (MIN_v
value + MAX_value + MID_value). Of course, the molecule is MIN_value
As for the denominator, the average value can be used. Further, the coefficient αg for the gray scale gray can be calculated by αg = 1-0.4 × (gray / 100) (2).

In the present embodiment, the gray scale gray and the coefficient αg are made to correspond to each other based on the equation (2), but it is also possible to make fine adjustments. For example, FIG. 15 shows a graph as an example thereof, in which a change rate of the coefficient αg is set to be slightly large in a region where the gray level gray is high.

FIG. 16A shows a case where the gray level is "100". This is the case where the input data values of the respective inks match. Further, FIG. 7B shows the case where the gray level is “0”, and only one element color is a primary color having a component amount. Further, FIG. 7C shows the case where the gray level is “50”. When the input data value of each ink is 1: 2: 3, the gray level is "5".
It becomes "0". In this case, the coefficient αg is “0.
8 ”, the coefficient α0 is“ 0.733 ”from the equation (1).
3 ”, and both are different. Therefore, it may be appropriately selected based on the output result.

On the other hand, such a concept of grayness has a property common to the concept of saturation, which is a color expression element. FIG. 17 schematically shows the L * a * b * color space. Taking the brightness L * in the vertical direction in the three-dimensional space,
Color is expressed by plane coordinates in the horizontal plane. The plane coordinates in the horizontal plane are represented by the orthogonal coordinates of the a * axis and the b * axis. The closer to the origin, the closer to gray the color becomes, and the closer to the periphery, the brighter the color becomes. Of course, it can be said that the distance from the origin is the saturation, and the distance from the origin is inversely proportional to the gray level. When the print data has such an indirect or direct saturation element, the coefficient αs is determined using this saturation, and the correction amount is used when referring to the correction lookup table for each element color. Can be reduced.

The correction means 30a3, which realizes the above-mentioned correction method, can correct the correction data by using the coefficient and the correction lookup table based on the equations (1) and (2) based on the CMYK print data. It doesn't matter, but from RGB to C
Since the color conversion table is also referred to when the color conversion to MYK is performed, by rewriting this color conversion table, the correction work can be completed with a single table reference. Therefore, in step S150, the correction lookup table of the determined coefficient is written in the color conversion table.

The above-described procedure is executed when the printer driver 21b is started by the computer 21, and the operation of the present embodiment having the above-mentioned configuration will be described below with reference to the flowchart of the printer driver 21b shown in FIG. Will be explained.

Assuming that the image data read by the scanner 11 is printed by the printer 31, first, the application 21d is started in the computer 21 while the operating system 21a is running.
The scanner 11 is caused to start reading. When the read image data is loaded into the application 21d via the operating system 21a, predetermined image processing is performed and print processing is selected.

When the printing process is selected, the operating system 21a activates the printer driver 21b. Since the primary color correction lookup table does not exist at the first startup of the printer driver 21b, step S2 is performed.
After the determination of 00, a monochrome patch is printed in step S205. On the other hand, the patch printed by the reference print head 31a is prepared separately, and compared with the patch printed by the print head 31a provided for each printer 31,
In step S210, the value for which the correspondence is obtained is input.

Using this result, the patch of the secondary color is printed in step S215. At this time, the coefficient is changed to print some patches, and in step S220, the coefficient α2 for the patch considered to be optimum is determined. Similarly, in step S225, a patch of a tertiary color is printed, and in step S230, the coefficient α for the patch considered to be optimum is printed.
Determine 3. In other words, the coefficient α2 and the coefficient α3 are input as coefficients for what seems to be optimal. The above processing is effective once performed as long as the print head 31a does not change.

However, these steps S215 to S23
The processing of 0 is premised on that it is necessary to obtain the coefficients α2 and α3. The coefficients α2 and α3 were experimentally determined to be “0.8” and “0.6”, respectively.
Have been found to be suitable, and these values can be used as defaults with good results. Therefore, at least steps S205 and S21
If a single-color patch is printed at 0 and a predetermined corresponding value can be input, the processes of steps S215 to S230 may be omitted.

At the first start-up, the above-described printing and input are performed, and in the next step S240, a process of writing in the color conversion table is performed. That is, the correction amount is reduced for each color of the color conversion table by using the formula (1) or the formula (2), and the conversion value is calculated and rewritten.

After that, the RGB print data created by the application 21d is CMY in step S250.
Color conversion to print data of K. Of course, what is used for the color conversion at this time is the color conversion table in which the predetermined correction amount is written in step S240, and the necessary correction is added at the same time as the color conversion.

When the color conversion is completed, the print data is 2
Since there are still 56 gradations, in step S255, the printer 31 converts the print data into two gradations that can be input and outputs the print data to the printer 31. When the printer 31 inputs such print data, the reduction amount of the correction look-up table has an optimum value in the vicinity of the aiming color, and as in the case of printing with the reference print head 31a, clear printing without color misregistration can be performed. It will be possible.

As described above, when the recording material such as the color ink forming the dots such as the ink jet printer 31 varies due to the difference between the machines, it is impossible to set the correction amount of the color misregistration for each color. However, after determining the correction amount for at least a single color, the color mixture order of each dot is determined, and as the color mixture order increases, the correction amount is reduced while applying the correction amount, thereby adjusting the color mixture order of each dot. It is corrected with the optimum correction amount, and it is possible to improve the color reproducibility by compensating for the differences between the machines.

[Brief description of drawings]

FIG. 1 is a diagram corresponding to claims of a print data correction device of the present invention.

FIG. 2 is a block diagram showing a specific hardware configuration example of a printing system to which the same print data correction apparatus is applied.

FIG. 3 is a schematic block diagram of a printer.

FIG. 4 is a schematic explanatory diagram of a print head unit in the printer.

FIG. 5 is a schematic explanatory diagram showing a situation in which color ink is ejected by the print head unit.

FIG. 6 is a schematic explanatory view showing a situation in which color ink is ejected by a bubble jet type print head.

FIG. 7 is a schematic explanatory diagram of an electrophotographic printer.

FIG. 8 is a schematic block diagram showing another application example of the print data correction apparatus of the present invention.

FIG. 9 is a block diagram illustrating a specific procedure of print processing.

FIG. 10 is a flowchart showing a procedure for rewriting a color conversion table.

FIG. 11 is a diagram showing patches to be printed.

FIG. 12 is a diagram showing a comparison state of a patch by a reference print head and a patch by a print head having a machine body difference.

FIG. 13 is a diagram showing a correction lookup table in which the coefficient is changed.

FIG. 14 is a diagram showing a situation in which coefficients according to a color mixing order are weighted and added according to pixel components.

FIG. 15 is a graph showing another example of correspondence between gray levels and coefficients.

FIG. 16 is a diagram showing a specific example of gray levels.

FIG. 17 is a diagram showing an L * a * b * color space when using saturation.

FIG. 18 is a flowchart of a printer driver.

[Explanation of symbols]

10 ... Image input device 20 ... Image processing device 21 ... Computer 23 ... Keyboard 30 ... Printing device 31-33 ... Printer

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Claims (8)

[Claims] 1. Use of a recording material for a printing device, wherein a recording material for each element color is attached to a recording medium in a dot matrix form in order to print out a color image with a plurality of element colors based on print data. A print data correction device that corrects the print data in order to compensate for a color change based on an amount bias, and a correction amount that stores a correction amount that compensates for the use amount bias of the recording material set for each element color. Quantity storing means, correction amount adjusting means for determining the color mixture order for each dot, and adjusting the correction amount to reduce the correction amount when the same color mixture order increases compared to the case of a single color, and the adjusted correction A print data correction apparatus comprising: a correction unit that corrects the print data based on an amount. 2. The print data correction device according to claim 1, wherein the correction amount adjustment means determines a variation in the component amount of each element color, and when the variation is even, the color mixture order is the highest. A print data correction device characterized by making a judgment. 3. The print data correction device according to claim 2, wherein the correction amount adjusting means determines the variation based on a ratio between a minimum component amount for each element color and an average value of the component amounts. A print data correction device characterized by: 4. The print data correction device according to claim 1, wherein the correction amount adjustment means determines the saturation and determines that the color mixture order is high when the saturation is low. Print data correction device. 5. The print data correction device according to any one of claims 1 to 4, wherein the correction amount adjustment means determines the correction amount by determining the color mixture order of the print data for each dot. A print data correction device characterized by obtaining an adjustment amount. 6. The print data correction apparatus according to any one of claims 1 to 4, wherein the correction amount adjustment means obtains an adjustment amount of the correction amount in advance based on a combination of each element color. A print data correction device characterized by the above. 7. Use of a recording material for a printing device, which adheres a recording material for each element color to a recording medium in a dot matrix form in order to print out a color image with a plurality of element colors based on print data. A print data correction method for correcting the print data in order to compensate for a color change based on a bias in the amount, and storing a correction amount for compensating for the bias in the usage amount of the recording material set for each element color. , The color mixture order is determined for each dot, and when the same color mixture order increases, the correction amount is adjusted to reduce the correction amount compared to the case of a single color, and the print data is corrected based on the adjusted correction amount. A method for correcting print data, comprising: 8. Use of a recording material for a printing device, which adheres a recording material for each element color to a recording medium in a dot matrix form in order to print out a color image with a plurality of element colors based on print data. A medium in which a print data correction program for correcting the print data by a computer in order to compensate for the color change based on the amount deviation is recorded, and the use amount deviation of the recording material set for each element color is compensated. The correction amount is stored, the color mixture order is determined for each dot, and when the color mixture order increases, the correction amount is adjusted to reduce the correction amount compared to the case of a single color. A software recording medium recording a print data correction program, characterized in that the print data is corrected based on the above.