JP2002120388A - Method of correcting color shift, color recorder and memory medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To adequately correct a balance of an output characteristic of a recording head, to simplify an operation of a user, to dispense with a memory capacity for holding a correction table, and to obtain a high quality image by making an ejection characteristic of each head uniform. SOLUTION: Two kinds of test patterns consisting of a plurality of mixture color patches in dark gray color obtained by varying mixture rates of a plurality of colorants in chromatic colors are printed. A characteristic of an input/ output signal of a recorder is estimated to be corrected based on the two mixture color patches selected from the printed two kinds of test patterns.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color misregistration correction method for correcting a color balance of an ink jet printing system capable of obtaining a high-quality image on a recording material, a color recording apparatus, and a storage storing a program. Regarding the medium.
Note that the present invention can be applied to all devices using a recording medium such as paper, cloth, nonwoven fabric, and OHP paper.
Office equipment such as a printer, a copier, and a facsimile can be used.

[0002]

2. Description of the Related Art With the spread of office automation equipment, opportunities for outputting color images are increasing. As a color image output device, for example, recording devices using various recording methods such as an ink jet method, an electrophotographic method, and a thermal transfer method are known. In recent years, these apparatuses have been capable of outputting a relatively high-quality photographic color image. Is being done.

In these recording apparatuses, three chromatic color materials of cyan (C), magenta (M), and yellow (Y) are generally used, or achromatic black (K) is added thereto. A color image is recorded using color materials.In this case, the output characteristics (reflection density, lightness, saturation, hue, etc.) between the color heads are not properly balanced, and color deviation (desired May differ from color). For example, in an ink jet type recording head, a variation in the calorific value (film thickness) of a heating heater that generates thermal energy for discharging ink, and a variation in size or shape of a discharge port for discharging ink are caused. In some cases, there is an individual difference in the ejection amount for each print head, and as a result, the output characteristics may be unbalanced among the print heads for each color as described above. Note that such individual differences are not limited to those inherent in the recording head as described above, and it is also known that such individual differences occur due to, for example, changes over time of individual recording heads.

On the other hand, a process of detecting color misregistration due to such individual differences and correcting the output characteristics of the recording head based on the detection result is performed by a personal computer or the like as a host of the recording device or a recording device. May be done by itself. As the correction method, there are generally known two methods for detecting color misregistration, mainly in the case of using an input device such as a scanner and in the case of visual observation by a human. The outline of these two correction methods will be briefly described below.

In a method using an input device such as a scanner,
For example, as described in Japanese Patent No. 2661917, a patch pattern is recorded using a recording head for each of C, M, Y, and K color materials to be corrected. Then, by reading this patch pattern with a scanner, the read value is obtained.
A deviation between (a value indicating an output characteristic) and an expected value indicated by the print data of the patch pattern is detected, and a color deviation is corrected based on the deviation. As a patch pattern in this case,
There are a solid pattern of each color of C, M, Y, and K, a patch pattern for forming a gradation for each of the above colors, and the like.
The gradation forming pattern can also detect the output characteristics regarding the halftone, thereby improving the detection accuracy of the color misregistration. Further, C, M, Y, K
Is also known, which records a patch pattern of a secondary color and a tertiary color, each of which is combined to improve the detection correction accuracy.

On the other hand, in the visual method, it is not easy to detect the absolute value of the output characteristic for each head of each color as in the method using the above-described device. Therefore, C,
A detection method using a patch pattern of a tertiary color recorded by mixing three color materials of M and Y is adopted. That is, a patch pattern printed at a printing (mixing) ratio of three color materials, which is expected to be achromatic when printed using a print head having an average or a non-biased discharge amount,
By recording a plurality of almost gray patch patterns in which the recording ratio of each color material is slightly changed, a user or the like visually selects a pattern closest to an achromatic color from among the plurality of patch patterns to obtain C, The one that has the optimum balance of output characteristics between the M and Y color recording heads is detected. Then, the output characteristics of each recording head are corrected by the correction data corresponding to the detected patch. In other words, the color misregistration detection method utilizes the fact that a slight deviation in the output characteristics of the C, M, and Y recording heads causes, for example, the effect of a color having a large change in the output characteristics to appear and the patch is not achromatic. Things.

In the above description, color misregistration and its detection have been described in the case of an ink jet type recording head. However, even in an electrophotographic type or thermal transfer type recording apparatus, there is a problem that depends on each recording principle or the like. The output characteristics of each color recording head may vary, and in this case, the same color shift detection and correction as described above are performed.

[0008]

However, the above-mentioned conventional color shift detecting method has the following disadvantages.

In the method for adjusting the head output characteristics described above,
A plurality of correction tables are provided in the apparatus, and an appropriate correction table is selected from among the plurality of correction tables to perform correction. Although it is common to use a γ curve as the correction table, the γ curve is different from the output characteristic of the ink jet printing apparatus.
At other gradations, the color may shift.

Here, the relationship between the input and output signals of the ink jet recording apparatus will be described with reference to FIGS. First, FIG. 10 shows the results of measuring the relationship between the number of print dots (gradation of an input signal) and the optical reflection density using three types of recording heads having different ejection amounts per dot.

Line 1-2 shows the output characteristics of the print head with a standard discharge amount, and line 1-1 shows the output characteristics of the print head with a smaller discharge amount. -3 indicates the output characteristic of the print head having a larger discharge amount.

Looking at these characteristics in general, each characteristic has two inflection points. Output characteristics 1
1, the inflection points of the output characteristics 1-2 are 2A and 2B, and the inflection points of the output characteristics 1-3 are 3A and 3B.
B.

As a reason for such a change, a recording characteristic unique to an ink jet printer can be considered.

First, in the low gradation area from the point 0 to 1A, 2A and 3A, as shown in FIG. 11A, the recording dots do not overlap at all on the recording medium. In this area, since the recording dots do not overlap each other, the density increases in proportion to the number of recording dots. Further, in this region, the difference in the ejection amount is directly perceived as a density difference.

Next, between each inflection point, 1A-1B,
The areas 2A-2B and 3A-3B are areas where the ejected dots begin to overlap on the recording medium, as shown in FIG. The state of the dots on the recording medium at this time will be described with reference to FIG.

FIG. 12 is a schematic diagram showing a state in which three recording dots are superimposed and recorded on a recording medium. FIG.
, The area 2-0 is an area without dots, and the density is also the density of the recording medium itself. The area 2-1 is an area in which dots do not overlap, and the average density of this area is 1. The reason why the density is averaged is that the density differs between the center and the periphery of the dot. The area 2-2 is an area where two dots overlap, but in this area, the average density of this area does not increase to 2 because the ink permeates deep into the recording medium. Similarly, the average density of the area 2-3 where the three dots overlap does not increase to three. Of course, depending on the type of ink and the type of recording medium, the density also increases only up to about 1.5 in the area 2-3. For these reasons, the relationship between the number of dots and the density is no longer a simple proportional relationship in the region between the inflection points.

Finally, after the inflection point 1B, after 2B, 3B
In the subsequent high gradation area, as shown in FIG. 11C, since ink almost overlaps on the recording medium, it takes time to penetrate. For this reason, in this area, the ink overflows for a short time, and the ink flows to a larger area than the normal recording dots. For this reason, in this high gradation area, the amount of ejected ink and the density change in a substantially proportional relationship.

FIG. 13 shows the input / output characteristics 1-1 of the print head having a small discharge amount and the large discharge amount when the input / output characteristics 1-2 of the print head having a standard discharge amount are γ = 1. 1 shows the input / output characteristics 1-3 of the recording head. For reference, FIG. 13 shows γ curves of γ = 0.8 and γ = 1.2.

As can be seen from FIG. 13, the input / output characteristics of the recording head are different from the γ curve. As described above, since the input / output characteristics of the recording head cannot be completely corrected only by the gamma curve, in the related art, measurement is performed for each of a plurality of gradations, and a different correction curve (correction table) is used for each gradation. In this case, a method of re-correction is adopted.

However, in the conventional method, the processing becomes complicated and processing time is required. The number of correction tables is increased, and a huge memory capacity is required. The recording medium may have different input / output characteristics. In consideration of this, there are problems that the number of correction tables is further increased, an enormous memory capacity is required, and cost increases cannot be avoided.

The present invention has been made in order to solve such a problem, and a method for correcting color misregistration which can make the ejection characteristics of each recording head uniform and obtain high image quality with simple means and at low cost. It is an object of the present invention to provide a color recording device and a storage medium.

[0022]

According to one embodiment of the present invention, there is provided a color shift correction method for correcting a color shift of a color printing apparatus which performs printing using a plurality of color materials. Correspondingly, a first step of outputting two types of test patterns consisting of a plurality of mixed patches of dark gray in which the mixing ratio of a plurality of chromatic color materials is changed, and selecting from the two types of test patterns Estimating the characteristics of the input / output signals of the color printing apparatus based on the two mixed color patches thus obtained,
And a second step of correcting.

According to another aspect of the present invention, in a color recording apparatus which performs recording using a plurality of color materials, a mixing ratio of a plurality of chromatic color materials is determined in accordance with two input signal values. A first means for outputting two kinds of test patterns composed of a plurality of changed dark gray mixed color patches; and a color recording apparatus of the color printing apparatus based on two mixed color patches selected from the two kinds of test patterns. A second means for estimating and correcting the characteristics of the input / output signal.

According to this configuration, it is sufficient to provide two test patterns composed of mixed color patches near two inflection points, so that the user's labor for correction is simplified. In addition, since input / output characteristics are estimated from two inflection points and correction is performed, it is possible to perform color misregistration correction according to the characteristics of each recording device without requiring memory capacity for the correction table. Becomes

[0025]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

<Overview> In the present embodiment, two types of test patterns (colored chromatic colors) having gradations near two input values at which the input / output characteristics of a print head of a standard ejection amount are inflection points at inflection points. A plurality of PCBk patches in which the mixture ratio of color materials C, M, and Y (color balance, printing ratio) is changed) are printed, and a patch closest to an achromatic color is visually checked by the user from each test pattern. The ejection characteristics of the ink jet recording apparatus are detected based on the selection.

The selected test pattern (PCB
(k patches), and corrects the ejection characteristic deviation of the recording head by replacing the selected coefficient with an output γ table used for image processing correction. .

<Overall Configuration> FIG. 2 is a block diagram showing the configuration of an image processing system according to an embodiment of the present invention.

In FIG. 1, a host computer 100 as an information processing apparatus is realized as, for example, a personal computer, and includes a CPU 10 and a memory 1.
1, an external storage device 13, and an input unit 12 such as a keyboard.
And an interface 14 for communication with the printer 200. The CPU 10 executes various processes in accordance with programs stored in the memory 11, and in particular, executes image processing such as color processing and quantization processing, which will be described later, and further executes output characteristic correction processing according to the present embodiment. I do. These programs are stored in the external storage device 13 or supplied from an external device. The host 100 is connected to a printer 20 as a recording device via an interface.
0, and can transmit print data subjected to image processing to the printer 200 to perform printing.

<Printer Configuration> FIG. 3 is a schematic perspective view showing the mechanical configuration of the printer 200 described above.

In FIG. 3, a recording medium 1 such as paper or a plastic sheet is supplied one by one by a paper feeding roller (not shown), and a first conveying roller pair 3 and a second conveying roller which are arranged at a predetermined interval. The sheet is conveyed by a predetermined amount in the direction of arrow A by the roller pair 4. These roller pairs 3 and 4 are driven by a stepping motor.

The carriage 6 is loaded with an ink jet recording head 5 and an ink tank (not shown). In this case, the recording head 5 is for color recording and includes yellow (Y), magenta (M), cyan (C),
Four heads 5a, 5b, 5 corresponding to black (K)
c, 5d. A carriage motor 23 is connected to the carriage 6 via a belt 7 and pulleys 8a and 8b. The carriage 6 is configured to scan back and forth in the direction of arrow B along the guide shaft 9 using the carriage motor 23 as a drive source. Have been.

In each of the recording heads 5a, 5b, 5c, and 5d, a plurality of nozzles are arranged in a row (in this case, one row) in a direction parallel to the paper transport direction A. Ink droplets are ejected. In this case, a method is used in which an electrothermal converter as a thermal energy source is provided for each nozzle, and the electrothermal converter is driven to cause film boiling in the ink to discharge the ink. I am trying to do it.

According to this configuration, the recording head 5 ejects ink to the recording sheet 1 in accordance with the ejection signal while moving in the direction of arrow B to form an ink image on the recording sheet 1. When the recording head 5 returns to the home position,
The head recovery device 2 provided at the home position eliminates clogging of nozzles of the recording head 5 and the like. The recovery device 2 is driven at an appropriate timing as needed. After one band of recording is completed by the scanning of the recording head 5, a predetermined amount of paper feed (pitch transport) is performed by the transport roller pairs 3 and 4. By repeating such an operation, recording is performed on the recording sheet 1.

FIG. 4 is a block diagram showing a control configuration of the above-described printer.

As shown in FIG. 4, the control system includes a CPU 20a such as a microprocessor, and a ROM 20 storing control programs for the CPU 20a and various data.
b, a control unit 20 having a RAM 20c and the like which is used as a work area of the CPU 20a and temporarily stores various data such as print data, an interface 21, an operation panel 22, various motors (a motor 23 for driving a carriage, A driver 27 for driving the paper roller driving motor 24, the first conveying roller pair driving motor 25, the second conveying roller pair driving motor 26), and a driver 28 for driving the recording head 5; I have.

In the above configuration, the control unit 20 performs processing for inputting and outputting data such as recording data with the host 100 via the interface 21 and various information (for example, character pitch, character type, etc.) from the operation panel 22. Is input. Further, the control unit 20 includes the interface 2
1 for driving each of the motors 23 to 26 through
An N, OFF signal is output, and an ejection signal or the like is output to the driver 28 to control driving of the print head for ink ejection.

<Image Processing> Next, image processing when the host 100 generates print data used by the above-described printer will be described.

FIG. 5 is a block diagram showing the configuration of this image processing. Red (R), green (G),
Finally, the image data of each 8 bits (256 gradations) of blue (B) is finally output as 1-bit bit image data of each of cyan (C), magenta (M), yellow (Y), and black (K). FIG.

As shown in FIG. 5, 8-bit luminance data of R, G, and B are first processed by using a three-dimensional lookup table (LUT) 501 to obtain R ', G',
It is converted into each 8-bit data of B '. This R, G, B
The conversion process from the data to the R ', G', B 'data is referred to herein as pre-stage color processing, in which the input image color space represented by the R, G, B luminance data and the color space reproducible by the printer 200 are used. The color space conversion for correcting the difference is performed. Each of the R ', G', and B '8
The bit data is converted into C, M, Y, and K 8-bit data by a process using the three-dimensional LUT 502 at the next stage. This color conversion processing is called post-stage color processing, and is a process of performing color conversion from input RGB data represented by a luminance signal to output CMYK data represented by a density signal. This is because input data is often created in three primary colors (RGB) of a light-emitting body such as a display, while a subtractive three primary colors (CMY) that express colors by light reflection in a printer or the like. This is because it is used.

The three-dimensional LU used for the preceding-stage color processing
3D LUT 502 used for T501 and post-stage color processing
In this example, data is held discretely due to the limitation of the memory capacity, and a value between the held data is obtained by using an interpolation process. Since this interpolation processing is a known technique, the description is omitted here.

The 8-bit data of each color of C, M, Y, K subjected to the second-stage color processing is a one-dimensional LUT 503 of each color.
Output gamma correction. Normally, there is no linear relationship between the number of dots printed per unit area of a printing medium and output characteristics such as reflection density obtained by measuring the number of dots. Then, by performing output γ correction, C, M,
The linear relationship between the input gray level of each of Y and K of 8 bits and the density level of an image recorded by the input gray level is guaranteed.

In general, the output γ correction table is often created for a recording head showing an average output characteristic. However, as described above, printheads generally have individual differences in output characteristics, and accordingly, the optimum value of the γ correction parameter differs accordingly. For this reason,
In the present embodiment, as described later, information relating to color misregistration is acquired, and the output γ correction table is updated based on the acquired information. For example, when the output characteristic of a recording head that records cyan (C) color material becomes larger than an expected value, C γ
The one-dimensional LUT related to the correction is changed so that the output value becomes a lower value with respect to the input value. As a result, in the γ correction after updating the table, the correction is performed so that the tone reproduction is performed as expected even if a recording head that outputs the C color material more strongly is used.

After the above output γ correction, binarization processing 504 is performed.
I do. Since the printer 200 of this embodiment is a binary recording device, each of C, M, Y, and K obtained as described above is used.
The bit data is quantized into 1-bit data of C, M, Y, and K, respectively.

In this embodiment, a photographic halftone image is
The error diffusion method is used as a binarization method, because the binarization is realized by expressing the gradation change smoothly by the binary recording system printer 200. Since the quantization method using this error diffusion method is a known technique itself, its description is omitted here.

<Detection and Correction of Color Misregistration> Next, detection of color misregistration and correction based on the color misregistration in this embodiment will be described.

FIG. 1 is a flowchart showing a procedure for detecting a color shift performed by the host 100 and performing correction based on the color shift information.

This processing is performed by a UI (user interface) by a printer driver operating on the host 100.
It is activated when the user selects the color misregistration detection correction mode on the screen. When the color misregistration detection / correction mode is selected, the host 100 causes the printer 200 to be corrected to record a detection pattern for detecting color misregistration (step S110). That is, as shown in FIG. 6 and FIG. 7, two kinds of preset detection pattern data of individual difference information are subjected to the above-described image processing to obtain bit image data, which is represented by the bit image data. The recording data of the detection pattern is transferred to the printer 200 via the interface 14. In the image processing for recording the detection pattern, the output γ correction is performed using an LUT having a linear γ characteristic with a default input / output conversion relationship.

The details of the above two types of detection patterns will be described with reference to FIGS.

In FIG. 6 and FIG. 7, each frame indicates a patch recorded by each combination of each color (C, M, Y, K), and three numbers in the upper part US of each frame are C,
The numbers represent the gradation values that are the recording data values of M and Y, and one number in the lower part DS of each frame represents the gradation value that is the recording data value of K. And the upper and lower two parts U
By arranging 5 × 5 patches composed of S and DS in the vertical and horizontal directions, one type of test pattern is formed. In the vertical direction, the gradation value of M is changed in five steps, and in the horizontal direction, the gradation value of C is changed in five steps.

In each patch, the upper part US is a "test area" for visually judging the color by the user.
Recording is performed using a mixed color (PCBk) of each of the C, M, and Y color materials. On the other hand, the lower part DS is an achromatic “reference area” serving as a reference for comparison, and is recorded using only an achromatic K color material.

After the two types of detection patterns shown in FIGS. 6 and 7 are printed, the user visually judges these two types of detection patterns, and selects a patch closest to an achromatic color one by one from each of the detection patterns. select. Then, the user inputs two patch numbers corresponding to the selected two patches via the UI screen of the printer driver (Step S).
120).

Here, with the C, M, and Y color materials in the present embodiment, if the recording head has a standard ejection amount characteristic, the middle patch 33A from the test pattern of FIG.
(C = M = Y = 80) is determined to be the most achromatic color,
From the test pattern of FIG. 7, the middle patch 33B (C
= M = Y = 150) is determined to be the most achromatic color. Therefore the default output γLUT
Reference numeral 503 denotes a state where a recording head that determines that these patches 33A and 33B are most achromatic is mounted.
The balance between the chromatic colors is set to be optimal. However, if another patch in the test pattern is selected, the target printing apparatus is out of balance in the output characteristics of the C, M, and Y print heads (ie, is out of color). .

Next, input signal values (gradation values) used in the two types of test patterns shown in FIGS. 6 and 7 will be described with reference to FIGS.

FIG. 8 shows the input / output characteristics of the recording head where the ink ejection amount is a standard value (solid line), the input / output characteristics of the recording head where the ink ejection amount is the maximum value of the tolerance (dotted line), and the ink ejection amount is the tolerance. Shows the input / output characteristics (broken line) of the recording head, which is the minimum value of.

The gradation value of the middle patch 33A of the test pattern shown in FIG. 6 is determined by using the input / output characteristics (dotted line) of the recording head where the ink ejection amount is the maximum value of the tolerance. That is, when the input value of the input / output characteristics indicated by the dotted line is increased, the input value corresponding to the point A (inflection point) at which the input / output characteristics lose linearity is set as the tone value of the patch 33A. If the input value is larger than the point A, in a print head having a large ejection amount, the ejected ink overlaps on the recording medium, and the difference in the ejection amount becomes difficult to reflect on the printing density on the recording medium. I will. Further, even if the input value is smaller than this point, as is apparent from the graph, the difference in the ejection amount becomes difficult to reflect on the print density on the recording medium.

Next, the gradation value of the middle patch 33B of the test pattern shown in FIG. 7 is determined using the input / output characteristics (broken line) of the recording head in which the ink ejection amount has the minimum tolerance. That is, when the input value of the input / output characteristic indicated by the broken line is decreased from the larger one, the input value corresponding to the point B (inflection point) at which the input / output characteristic loses linearity is set to the above-mentioned patch
The gradation value is 3B. If the input value is smaller than the point B, the printhead having a small ejection amount does not sufficiently overlap the ejected ink on the recording medium.
It is difficult for the difference in the ejection amount to be reflected on the print density on the recording medium. Also, even if the input value is larger than this point,
As is clear from the graph, it is difficult for the difference in the ejection amount to reflect on the print density on the recording medium.

Then, the two points A,
By setting the input value of B as the center value of the two types of test patterns, and changing C and M in five steps from this center value,
Two types of test patterns composed of 5 × 5 patches are set.

Then, these two types of test patterns are printed, and a patch closest to an achromatic color is selected one by one from these two types of detection patterns by visual judgment of the user, and the corresponding two patches are selected. The user inputs two patch numbers via the UI screen of the printer driver (step S120).

Next, a procedure for creating a correction table based on a selected patch will be described.

FIG. 9 shows a graph (solid line) of the input / output characteristics of the cyan ink (C) of the recording head whose ink ejection amount is the standard value, and patches 31A to 35A in which only the input value of cyan (C) is changed. , 31B to 35B are plotted.

For example, when the patches selected by the user are the patch 31A and the patch 31B, the input / output characteristic of cyan (C) of the recording head can be predicted as shown by a broken line 11-1. In order to correct the input / output characteristics of the recording head, a dotted line 11-2 which is an inverse conversion of the broken line 11-1 is used.
Can be realized by multiplying the input value by a coefficient shown in (1) as a correction coefficient.

Next, the procedure for calculating the correction coefficient will be described.

In this correction, the input / output relationship of the recording apparatus is estimated from the selected patch by function approximation, and the output γ table is corrected using a function obtained by inversely converting the function.

From the recording characteristics of the ink jet printer described above, the area lower than the input value α selected from one of the test patterns shown in FIG. 6 and the area lower than the input value β selected from the other test pattern shown in FIG. In high areas,
Since the number of dots of the ejected ink and the recording density recorded on the recording medium are substantially proportional to each other, linear interpolation is performed.

As this linear interpolation method, for example, a simple DDA is used. Of course, any other linear interpolation method may be used.

On the other hand, in an area between the input value α and the input value β, the number of dots of the ejected ink and the recording density recorded on the recording medium are not in a proportional relationship, and therefore, in this area, a curve-like interpolation is executed. For this curve interpolation, for example, a Bezier curve is used. Of course, any other curve interpolation method may be used, such as using an nth-order curve whose input value is a factor.

A correction curve is calculated by the above-described interpolation processing (step S130).

Then, the output γ table is updated based on the correction curve thus calculated (step S).
140). Through the above processing, the detection and updating of the color shift (correction of the γ correction table) are completed.

In the present embodiment, since the test pattern data shown in FIGS. 6 and 7 has 8-bit information for each of C, M, Y, and K, this multi-valued data is stored in the default one-dimensional data. The data is converted by the LUT (output γ conversion processing), binarized, and output to the printing apparatus as print information. However, it goes without saying that the binarization processing may be performed directly without going through the one-dimensional LUT.
Further, apart from the above-described image processing routine for performing image processing during normal recording, test pattern data is stored in C,
A separate routine for converting into 1-bit recording data for each color of M, Y, and K may be provided. . Further, in the present embodiment, the processing is performed on the host side, but it is of course possible to adopt a configuration in which the processing is performed on the recording apparatus side.

As described above, according to the present embodiment,
Since it is sufficient to provide two types of test patterns composed of mixed color patches near the two inflection points, the user's labor for correction is simplified. In addition, since input / output characteristics are estimated from two inflection points and correction is performed, it is possible to perform color misregistration correction according to the characteristics of each recording device without requiring memory capacity for the correction table. Becomes

[Other Embodiments] As described above, the present invention is applied to a system composed of a plurality of devices (for example, a host computer, an interface device, a reader, a printer, etc.), but is applied to one device (for example, a copying machine). , A facsimile machine).

Also, the functions of the above-described embodiment are implemented in an apparatus connected to the various devices or a computer in the system so as to operate various devices so as to realize the functions shown in FIG. Supplies the software program code for performing the
The invention implemented by operating the various devices according to the program stored in U) is also included in the scope of the present invention.

In this case, the program code of the software implements the functions of the above-described embodiment, and the program code itself and means for supplying the program code to the computer, for example, the program code The stored storage medium constitutes the present invention.

As a storage medium for storing the program code, for example, a floppy (registered trademark) disk, hard disk, optical disk, magneto-optical disk, CD-R
An OM, a magnetic tape, a nonvolatile memory card, a ROM, or the like can be used.

When the computer executes the supplied program code, not only the functions of the above-described embodiment are realized, but also the OS (Operating System) running on the computer, or another program. Needless to say, the program code is included in the embodiment of the present invention even when the functions of the above-described embodiment are realized in cooperation with application software or the like.

Further, the supplied program code is stored in a memory provided in a function expansion board of the computer or a function expansion unit connected to the computer, and then stored in the function expansion board or the function storage unit based on the instruction of the program code. It is needless to say that the present invention includes a case where a provided CPU or the like performs part or all of the actual processing, and the processing realizes the functions of the above-described embodiments.

[0078]

As described above, according to the present invention,
Printing two types of test patterns consisting of a plurality of dark gray mixed color patches in which the mixing ratio of chromatic color materials is changed,
Since the characteristics of the input / output signals of the printing apparatus are estimated and corrected based on two mixed color patches selected from the two types of printed test patterns, a color shift caused by a shift in the balance of each element color. Can be detected without using a special measuring device, and since the correction value is calculated by the correction operation, there is no need to have a correction table in advance, and a large memory space for the correction table is not required. Was. The correction is performed according to the output characteristics of the ink jet printer, and the correction accuracy is improved.

[Brief description of the drawings]

FIG. 1 is a flowchart illustrating an embodiment of a color misregistration detection and correction procedure according to the present invention.

FIG. 2 is a block diagram illustrating an image processing system according to an embodiment of the present invention.

FIG. 3 is a perspective view showing a mechanism of a main part of an ink jet printer in the image processing system.

FIG. 4 is a block diagram illustrating a control configuration of the printer.

FIG. 5 is a block diagram illustrating a procedure of image processing in the printer.

FIG. 6 is a diagram illustrating one test pattern for detecting color misregistration according to an embodiment of the present invention.

FIG. 7 is a diagram illustrating another test pattern for detecting a color shift according to an embodiment of the present invention.

FIG. 8 is a diagram illustrating input / output characteristics of three types of print heads having different ejection amounts.

FIG. 9 is a diagram for explaining boundaries for correcting different input / output characteristics.

FIG. 10 is a diagram illustrating the relationship between the number of print dots of three print heads having different ink ejection amounts and the optical reflection density on a printed medium.

FIG. 11 is a diagram illustrating the relationship between the state of ink and the density on a recording medium.

FIG. 12 is a diagram illustrating the relationship between the state of ink and the density on a recording medium.

FIG. 13 is a diagram illustrating input / output characteristics of an inkjet recording head.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Recording sheet 2 Ink recovery apparatus 3 1st conveyance roller 4 2nd conveyance roller 5 Recording head 6 Carriage 7 Belt 8a, 8b Pulley 9 Guide shaft 10 CPU 12 Input part 13 External storage device 14 Interface 20 Control part 20a CPU 20b ROM 20c RAM 21 interface 22 operation panel 23 carriage motor 24 paper feed motor 25, 26 transport roller drive motor 27, 28 driver 100 host 200 printer 501 color space conversion processing 502 color conversion processing 503 output γ processing 504 binarization processing

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) H04N 1/46 H04N 1/46 Z 5C079 (72) Inventor Masao Kato 3-30-2 Shimomaruko, Ota-ku, Tokyo KYA Within Non Co., Ltd. (72) Inventor Daigoro Kanematsu 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Minoko Kato 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. Of which F-term (reference) 2C056 EA11 EB27 EB47 EC76 EC80 EE02 2C061 AP03 AP04 AQ05 AR01 AS11 AS13 KK25 KK32 2C262 AA02 AA24 AA26 AB17 BA09 BA20 BB03 BB36 BC01 BC03 BC10 BC13 EA12 FA13 5C074 AAFF BB33 PP39 PQ12 PQ23 TT05 5C079 HB03 KA04 KA12 KA15 LA10 LA24 LA31 LB01 MA10 MA11 NA01 NA10 NA27 PA01 PA02 PA03

Claims (13)

[Claims] 1. A color misregistration correction method for correcting color misregistration of a color recording apparatus that performs recording using a plurality of color materials, comprising: a plurality of chromatic color materials corresponding to two input signal values. A first step of outputting two types of test patterns consisting of a plurality of dark gray mixed color patches having a different mixture ratio, and a step of outputting the two types of mixed color patches selected from the two types of test patterns. A second step of estimating and correcting the characteristics of the input / output signals of the color recording apparatus. 2. One of the two test patterns is a plurality of mixed signals centered on an input signal value corresponding to the vicinity of one of the two inflection points of the input / output characteristics of the color printing apparatus. The other of the two types of test patterns includes a plurality of test patterns centered on an input signal value corresponding to the vicinity of the other inflection point of the two inflection points of the input / output characteristics of the color printing apparatus. 2. The color shift correction method according to claim 1, wherein the color shift correction method comprises a mixed color patch. 3. The method according to claim 2, wherein in the second step, a range having an input signal value smaller than the one input signal value having a small signal value and a range having an input signal value larger than the other input signal value having a large signal value are included. 3. The color shift correction method according to claim 1, wherein a linear correction is performed, and a curve correction is performed in a region between the two input signal values. 4. The color misregistration correction method according to claim 3, wherein the curvilinear correction is performed using a Bezier curve. 5. The color misregistration correction method according to claim 3, wherein the curvilinear correction is performed using an n-order curve having an input value as a factor. 6. A mixed color patch of the test pattern, wherein an achromatic color is recorded and a reference patch serving as a reference for comparing the mixed color patches is arranged adjacently. 6. The color misregistration correction method according to any one of 1 to 5. 7. A color recording apparatus which performs recording using a plurality of color materials, wherein a plurality of dark gray colors in which a mixture ratio of a plurality of chromatic color materials is changed corresponding to two input signal values. First means for outputting two types of test patterns composed of mixed color patches; and estimating characteristics of input / output signals of the color printing apparatus based on two mixed color patches selected from the two types of test patterns. And a second means for correcting. 8. One of the two test patterns is a plurality of mixed signals centered on an input signal value corresponding to the vicinity of one of the two inflection points of the input / output characteristics of the color printing apparatus. The other of the two types of test patterns includes a plurality of test patterns centered on an input signal value corresponding to the vicinity of the other inflection point of the two inflection points of the input / output characteristics of the color printing apparatus. The color recording apparatus according to claim 7, comprising a mixed color patch. 9. The method according to claim 1, wherein the second means includes a range having an input signal value smaller than the one input signal value having a small signal value and a range having an input signal value larger than the other input signal value having a large signal value. 9. The color printing apparatus according to claim 7, wherein a linear correction is performed, and a curve correction is performed in a region between the two input signal values. 10. The color printing apparatus according to claim 9, wherein the curvilinear correction is performed using a Bezier curve. 11. The color printing apparatus according to claim 9, wherein the curvilinear correction is performed using an n-order curve having an input value as a factor. 12. The mixed color patch of the test pattern, wherein achromatic recording is performed, and a reference patch serving as a reference for comparison of the mixed color patch is arranged adjacently. 12. The color recording apparatus according to any one of 7 to 11. 13. A storage medium storing a program readable by an information processing apparatus, the program comprising: a color misregistration correction process for correcting a color misregistration of a color recording apparatus that performs recording using a plurality of color materials. And a first process of outputting two types of test patterns including a plurality of dark gray mixed color patches in which a mixing ratio of a plurality of chromatic color materials is changed according to two input signal values. And a second process for estimating and correcting the characteristics of the input / output signals of the color printing apparatus based on two mixed color patches selected from the two types of test patterns. Medium.