JP2005219321A - Recording system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a recording system capable of performing color misregistration detection with high accuracy and low cost in processing for correcting color misregistration caused by a difference in recording characteristics of individual recording apparatuses.
A test pattern used in a process for correcting color misregistration is composed of a plurality of patch data having different printing ratios of color materials held in a small size, and each patch data is continuously colored. Record the position so that it fluctuates.
[Selection] Figure 6

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information processing apparatus for performing image data correction processing and recording, and more particularly to a recording system comprising a recording apparatus. The present invention relates to a process for correcting a difference in recording characteristics occurring between the two.

  Conventionally, as output devices for recording color images on various recording media, for example, recording apparatuses using various recording systems such as an ink jet system, an electrophotographic system, and a thermal transfer system have been known. A relatively high-quality color image is output, and the recording apparatus is not only used for personal use, but also plays a role as a product of the recorded material itself.

  As described above, the demand for the image quality of the recording apparatus and the reproducibility of the recording result has been increasing year by year, and there are problems such as slight color tone differences and slight density unevenness on the recorded image that were not considered a problem in the past. It is getting seen.

  As a cause of the difference in color tone, for example, there is a difference in recording characteristics between the recording heads. For example, a color recording apparatus generally uses four color materials of cyan (C), magenta (M), yellow (Y), and black (K), and records a full color image by changing the printing ratio of each color. However, the balance of the recording characteristics (reflection density, brightness, saturation, hue, etc.) of the recording head that records each recording color material is not necessarily appropriate for all devices.

  For example, in an ink jet recording apparatus, due to variations in the heat generation amount (film thickness) of the heat generating heater that discharges ink, or variations in the nozzle diameter that discharges ink, discharge between recording heads for each color material or discharge from head to head There is an individual difference in the amount, and the individual difference may cause a color shift (density shift) of each color recording portion. In this case, there arises a problem that a desired image quality cannot be obtained. Furthermore, it is also known that the recording characteristics of each recording head change due to changes over time and usage environments.

  Although the difference or change in recording characteristics for each recording head as described above may be caused by the head structure, it can be said that it is difficult to completely suppress this in the manufacturing process. For this reason, conventionally, as a method for correcting such a difference in color tone, the recording apparatus is provided with a calibration function for correcting various color shifts including γ correction.

  In this calibration, an inspection pattern is actually printed on a predetermined recording medium, color misregistration is inspected based on the printing result, and this is used as correction data for calibration. There are two methods for inspecting color misregistration due to individual differences of such devices, a method of inspecting the above-described inspection pattern using an inspection device such as a scanner, and a method of inspecting by visual inspection.

  Here, an outline of each color misregistration inspection method will be described. For example, Patent Document 1 discloses a method using an input device such as a scanner. In this Patent Document 1, an inspection pattern is printed for each color material of C, M, Y, and K, each inspection pattern is read by a scanner, a colorimeter, a densitometer, and the like, and the read value and each inspection pattern are read. A method of inspecting a deviation from an expected value and correcting a color tone such as a γ value based on the deviation is disclosed. At this time, as an inspection pattern for inspecting color misregistration, a gradation pattern for each element color is printed together with a solid pattern of each element color of C, M, Y, and K. Improve inspection accuracy by inspecting tonal recording characteristics to improve inspection accuracy for color misregistration, and printing patch patterns of secondary and tertiary colors that combine C, M, Y, and K respectively. The method of making it known is known.

  On the other hand, since it is difficult to inspect the absolute value of the recording characteristics of each element color by the visual method, a test pattern for a tertiary color in which only three color materials of C, M, and Y are mixed is printed. From now on, a method for inspecting color misregistration has been adopted. That is, the print ratio of each color material is slightly changed, centering on the print pattern formed by the C, M, Y tertiary colors mixed in the ratio expected to be achromatic if the recording head has a standard discharge amount. By printing a plurality of substantially gray inspection patterns that have been changed one by one and visually selecting a pattern that is closest to the achromatic color from among the plurality of inspection patterns, the recording characteristics of the color materials of the C, M, and Y element colors can be obtained. A method of inspection is disclosed. In other words, the gray pattern uses the fact that the influence of the color having a strong recording characteristic appears due to a slight shift in the balance of the recording characteristics of the respective element colors of C, M, and Y, and is no longer an achromatic color. Even visually, color misregistration can be easily inspected.

  For example, Patent Document 2 discloses a configuration that enables color reproduction faithful to the original color without using a dedicated densitometer. In this patent document 2, a gray patch having component data corresponding to the coordinates of each reference axis is printed while setting a reference axis corresponding to the element color on the paper surface, and it is assumed that the color is achromatic. It is disclosed that the deviation of the output characteristic for each print head unit 31a1 can be calculated backward based on the gray patch component data. Also, if you know the tendency of deviations between element colors, you can print multiple grayscale patterns with different correction levels across all tones, and select one that appears to be achromatic from the whole. It is disclosed that the degree of deviation of output characteristics can be determined.

In the above description, the color misregistration and the detection thereof are described in the case of an ink jet recording head. However, even in an electrophotographic recording apparatus and a thermal transfer recording apparatus, each color recording mechanism is caused by a cause depending on each recording principle. In this case, the color misregistration detection and correction similar to those described above are performed.
Japanese Patent Registration No. 2661917 JP-A-10-278311

  However, the conventional color misregistration detection method described above has the following problems.

  First, the method using an input device such as a scanner is based on the premise that the user or the like possesses the input device in consideration of the general usage environment of the recording apparatus. Not all users necessarily have input devices, and in this case, the method using the scanner or the like is not practical. Even if some input device can be procured, the color data format and the number of pixels that can be obtained by the input device are different, and correction according to color misregistration detection using a wide variety of input devices is extremely difficult. There are many cases.

  Moreover, even if a dedicated input device can be prepared, a heavy burden is imposed on the user accordingly.

  On the other hand, since the visual method does not require a special input device, any user can detect color misregistration.

  However, it is not so easy to select a patch closest to the achromatic color from a plurality of patches with slightly different recording ratios of C, M, and Y.

  For example, JIS (JIS E3305, JIS Z8721, JIS L0600, etc.) and various organizations have specified the color difference (ΔE). For example, the range of the color difference of 3.2 to 6.5 is “the same color at the impression level” The range that can be handled as. This suggests that it is difficult to visually select a patch closest to the achromatic color from patches of such a color difference range.

  Therefore, in order to visually select a pattern close to an achromatic color, a method of comparing a pattern printed with only a K color material as a reference is known.

  However, C.I. M.M. When comparing the recording result of a pattern having a gradation value with each chromatic color of Y with the recording result serving as a reference of the same gradation value using only the K color material, especially when recording with a binary recording apparatus, A relatively large difference occurs in the spatial frequency (dot density). As a result, the visual perception characteristics for the respective areas to be compared and contrasted greatly differ, and color misregistration detection by visual inspection may not be performed properly.

  Even if the K reference area is compared and a patch can be selected from the test area composed of mixed colors of C, M, and Y, the K color material actually used is not necessarily a pure achromatic color. It is known to have a little saturation from coloring.

  Even if the true achromatic color generated from the mixed color of C, M, and Y is visually selected, a false achromatic color with saturation of only K ink is used as a refare, so that an inappropriate patch is selected. It will end up.

  Furthermore, since the preferred achromatic color varies depending on the individual or race, even if a true achromatic color patch can be selected, it cannot be said that the color desired by the user has been reproduced.

  In general, there is a recording apparatus that does not have a K color material and records only C, M, and Y. In this case, it is impossible to use K as a reference.

  For this reason, in the color misregistration detection method by visual observation, there is a demand for an improvement in correction accuracy that does not have a K reference area and also takes into account user preferences.

  As a method for detecting color misregistration by visual inspection, for example, a method as disclosed in Japanese Patent No. 10-2788311 is known, but for color misregistration detection in a recording apparatus or an information processing apparatus having a limited memory. No means for holding the test pattern data with a small memory capacity and no means for correcting the color misregistration by holding the color misregistration correction table with a small memory capacity.

  Furthermore, in order to perform color misregistration detection visually without using a dedicated input device, a means for recording a test pattern that can more easily detect color misregistration is required.

  The present invention has been made to solve the above-described conventional problems, and an object of the present invention is to detect color misregistration by visual inspection in a process for correcting color misregistration caused by a difference in recording characteristics of each recording apparatus. It is an object of the present invention to provide a recording system that can perform recording at high accuracy and at low cost.

  In order to achieve the above object, the present invention is therefore provided on a recording medium using an information processing apparatus that performs image processing of image data and transmits the image data to a recording apparatus, and a recording head that discharges a plurality of types of ink. A recording system comprising a recording device for recording, the recording device comprising: test pattern data holding means for holding test pattern recording data in which a plurality of patch data having different printing ratios of each ink are arranged; and operation of the recording device A test pattern recording unit that records the test pattern by operating a panel or a user interface screen on the information processing apparatus, and selects a patch that appears to be the most preferable achromatic color from the test patterns. Setting means for setting corresponding information in the recording apparatus, and correction corresponding to the information Correction value holding means for holding the correction value, correction value acquisition means for acquiring the correction value by the information processing apparatus, and a correction table in which the information processing apparatus holds a plurality of correction tables corresponding to the correction value information. A holding unit; an image correcting unit that corrects the image data using the correction table corresponding to the acquired correction value information; and a recording device that records the converted image data. And a corrected image recording means.

  As is apparent from the above description, according to the present invention, the test pattern used for the process of correcting the color misregistration with the output characteristics for each of the color materials of a plurality of colors being a predetermined color is held in a small size. The patch data is composed of a plurality of patch data having different printing ratios. Each patch data is arranged so that its color continuously changes, and each patch data is recorded by copying.

As a result, the test pattern can be recorded with a small memory capacity, and the user can easily select the patch that appears visually as the most preferable achromatic color.
As a result, it is possible to determine a color misregistration correction LUT corresponding to the selected patch, and to perform color misregistration correction output γ processing in the image processing step of the image data, and to record it on the recording device. It becomes.

  As a result, in the process of correcting the color misregistration due to the difference in the output characteristics of each recording apparatus, it is possible to detect and correct the color misregistration visually.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

<Overview>
In each embodiment of the present invention, a method for detecting C, M, Y recording characteristics of an ink jet recording apparatus includes arranging a plurality of patches having a mixed color (PCBk) region in which the printing ratio of each color of C, M, Y is changed. The test pattern is recorded by copying a plurality of pieces of data held in block units each having a size smaller than each patch, and a patch having an area closest to the achromatic color is selected from the data.

  The correction for the recording characteristic deviation of the recording head obtained as described above is performed by selecting an output γ correction table corresponding to the selected patch from a plurality of preset output γ tables, In the image processing step, color misregistration correction processing is performed.

  Hereinafter, embodiments of the recording apparatus of the present invention will be described with reference to the drawings. In the embodiments described below, a printer is taken as an example of a recording apparatus using an inkjet recording method.

  FIG. 1 is a block diagram showing the configuration of a recording system according to an embodiment of the present invention.

  In the figure, a host 100 as an information processing apparatus is realized as a personal computer, for example, and is provided between a CPU 10, a memory 11, an external storage device 13, an input unit 12 such as a keyboard, and a printer 200. And an interface for communication. The CPU 10 executes various processes according to a program stored in the memory 11, and in particular performs image processing such as color processing and quantization processing described later, and correction processing for recording characteristics according to the present embodiment. To 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 200 as a recording apparatus via an interface, and can transmit recording data subjected to image processing to the printer 200 for recording.

<Printer configuration>
FIG. 2 is a schematic perspective view showing the mechanical configuration of the printer 200 described above.

  In FIG. 2, reference numeral 1 denotes a recording sheet such as paper or a plastic sheet. When a plurality of sheets are stacked on a cassette or the like, they are separated and supplied one by one by a paper feed roller (not shown) during recording. In the drawing, the first conveying roller pair 3 and the second conveying roller pair 4 which are arranged at a predetermined interval and are driven by individual stepping motors (not shown) are at timings corresponding to scanning of the recording head. It is conveyed by a predetermined amount in the direction of arrow A.

  Reference numeral 5 denotes an ink jet recording head for performing recording by ejecting ink onto the recording sheet 1. The ink supply to the recording head is supplied from an ink cartridge (not shown), and the recording head 5 is driven according to the discharge signal to discharge ink from the ink discharge port. More specifically, an electrothermal conversion element is provided in an ink path corresponding to each ink discharge port of the recording head, and bubbles are generated in the ink by using thermal energy generated by the electrothermal conversion element. Ink is ejected by the pressure of bubbles. The recording head 5 and the ink cartridge are mounted on the carriage 6. The driving force of the carriage motor 23 is transmitted to the carriage 6 via the belt 7 and the pulleys 8a and 8b, so that the carriage 6 can reciprocate along the guide shaft 9 and the recording head can be scanned. Become.

  In the above configuration, the recording head 5 can perform recording by ejecting ink onto the recording sheet 1 in accordance with the ejection signal while scanning in the direction of arrow B in the figure to form ink dots on the sheet 1. . The recording head 5 moves to the home position as necessary and performs a recovery operation by the discharge recovery device 2 to prevent or eliminate clogging of the discharge ports. In synchronization with the scanning of the recording head 5, the conveyance roller pairs 3 and 4 are driven, and the recording sheet 1 is conveyed by one line in the arrow A direction. By repeating this operation, an image or the like can be recorded on the recording sheet 1.

  FIG. 3 is a block diagram showing the control configuration of the printer described above.

  As shown in FIG. 3, this control system is used as a CPU 20a such as a microprocessor, a ROM 20b storing a control program for the CPU 20a and various data, and a work area for the CPU 20a, and various data such as recording data. A control unit 20 having a RAM 20c for temporary storage and the like, an interface 21, an operation panel 22, motors (carriage driving motor 23, paper feed roller driving motor 24, first transport roller pair driving motor 25 A driver 27 for driving the second conveying roller pair driving motor 26) and a driver 28 for driving the recording head 5.

  In the above configuration, the control unit 20 performs processing for inputting / outputting data such as recording data to / from the host 100 via the interface 21 and processing for inputting various information (for example, character pitch, character type, etc.) from the operation panel 22. I do. Further, the control unit 20 outputs ON / OFF signals for driving the motors 23 to 26 via the interface 21, and outputs ejection signals and the like to the driver 28 to eject ink in the recording head. Control the drive.

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

  FIG. 4 is a block diagram showing the configuration of this image processing. The input red (R), green (G), and blue (B) image data of 8 bits (256 gradations) is finally converted into cyan ( C), magenta (M), yellow (Y), and black (K) image processing for outputting as 1-bit, 2-bit, or 4-bit bit image data.

  As shown in FIG. 4, luminance data of 8 bits for each color of R, G, B is first processed by using a three-dimensional look-up table (LUT) 401 and 8 bits or 10 bits for each color of R ′, G ′, B ′. Converted to data. This conversion process from R, G, B data to R ′, G ′, B ′ data is referred to herein as pre-stage color processing, and the color space of the input image represented by the R, G, B luminance data and the printer 200. Color space conversion is performed to correct a reproducible color space difference. The 8-bit data or 10-bit data of each color R ′, G ′, B ′ subjected to the preceding color processing is converted into 10-bit data for each color of C, M, Y, K by the processing using the three-dimensional LUT 402 in the next stage. The This color conversion process is referred to as post-stage color processing, and is a process for color-converting input RGB data represented by luminance signals into output CMYK data for representing density signals. This is because the input data is often created with three additive primary colors (RGB) of a light emitter such as a display. On the other hand, subtractive three primary colors (CMY) that express colors by reflecting light are used in printers. This is because it is used.

  In the above-described three-dimensional LUT used for the pre-stage color process and the post-stage color process, table data is not prepared for every combination of 10-bit data for each color because of memory capacity restrictions. For example, only the data for the points at a predetermined interval among the points on the three-dimensional space represented are prepared. Therefore, conversion of 10-bit bit data at points other than the points at the predetermined interval is performed using interpolation processing. Since this interpolation process is a known technique, its description is omitted.

  The C-, M-, Y-, and K-color 10-bit data subjected to the subsequent color processing is subjected to output γ correction by the one-dimensional LUT 403 for each color. This is a process performed because the number of dots recorded per unit area of the recording medium and the recording characteristics such as reflection density obtained by measuring this do not usually have a linear relationship. Therefore, by performing this output γ correction, it is possible to guarantee a linear relationship between the input gradation level of 10 bits for each of C, M, Y, and K and the density level of the recorded image.

  In general, the output γ correction table is often used for a recording head that exhibits standard recording characteristics. However, as described above, there is generally an individual difference or exists in the recording head with respect to the recording characteristics. Therefore, all the recording heads have only the output γ correction table for the recording head showing the standard recording characteristics. However, a suitable result cannot be obtained.

  For this reason, in this embodiment, as will be described later, 10-bit data for each color of C, M, Y, and K subjected to output γ correction is subjected to color misregistration correction output γ by the color misregistration correction one-dimensional LUT 404. Correction is applied.

  This correction is performed by acquiring information related to color misregistration caused by the combination of the recording characteristics of the C, M, and Y colors, and setting an output γ correction table for color misregistration correction that is optimal for the information.

  For example, when the recording characteristics of a recording head for recording a color material of C is larger than the balance of recording characteristics of a recording head that exhibits standard recording characteristics when the balance of the recording characteristics of C, M, and Y of a certain recording head is larger. Is a table in which the one-dimensional LUT for correcting C is a value with a lower output value than the input value. As a result, in this output γ correction for color misregistration correction, correction is performed so that the same color tone as that of a recording head exhibiting standard recording characteristics can be reproduced even when a recording head that outputs C color material with a high intensity is used. Made.

  After the above output γ correction, a binarization process 405 is performed. Since the printer 200 of the present embodiment is a binary recording apparatus, the 8-bit data for each of the C, M, Y, and K colors obtained as described above is quantized into 1-bit data for each of the C, M, Y, and K colors. It becomes.

  In this embodiment, an error diffusion method is used as a binarization method. Since the quantization method using the error diffusion method itself is a known technique, its description is omitted here. In addition to the error diffusion method, a dither method may be used as the binarization means.

<Color shift detection method>
Next, a color misregistration detection method and a correction method based thereon according to the present embodiment will be described.

  FIG. 5 is a flowchart showing color misregistration detection and correction value setting procedures based on the color misregistration information performed in the recording apparatus printer 200.

  This process is started when the user selects this mode on the operation panel of the printing apparatus printer 200 to be corrected. First, in step S110, the printer 200 is caused to record a detection pattern for detecting color misregistration.

  Details of the detection pattern data are shown in FIG. In FIG. 6, each frame indicates a patch recorded according to each combination of C, M, and Y colors, and each of the three numbers in each frame is a recording data value of C, M, and Y from the top in 10 bits. It represents a gradation value.

  In such a patch, the test pattern is composed of 19 patches having different C, M, and Y combinations for the gradation value.

  Each patch is composed of a combination of three levels of gradations of C, M, and Y colors 476, 512, and 548, but the same relative ratio, for example, C, M, and Y gradations are mixed colors of each color 476, and Since patches composed of mixed colors of the respective colors 512 and 548 have the same color, patches other than one mixed color (here, patches of the respective colors 512) are not included in the test pattern.

  At this time, in order to obtain the gradation difference of all patches so that the color misregistration can be easily understood, the patch to be included in the test pattern employs a patch having a higher gradation value or a patch having a lower gradation value as much as possible.

  For example, the mixed colors of C, M, and Y are 548, 548, and 512, and the mixed colors of 512, 512, and 476 have the same color, but the mixed colors of 548, 548, and 512 having a high absolute density are used. Adopt patches for test patterns.

  In addition, it is an array having continuity of colors with adjacent patches. For example, in this case, the C gradation value increases or decreases in the vertical direction, the M gradation value increases or decreases in the horizontal direction, and the Y gradation value increases or decreases in the diagonally right direction.

  Thereby, it is possible to realize an array of patches having continuity from red to green from the lower left to the upper right.

  As described above, the test pattern in which patches of the same color are not formed and the patches are arranged in a continuous color is used, so that the user can accurately select the patch that is closest to the achromatic color without worrying. Make it possible.

  Each patch data of the test pattern is composed of 256 × 256 dots in terms of 600 dpi as indicated by 701 in FIG. 7, and each of the data of 4 × 64 dots in the vertical direction and four in the horizontal direction as indicated by 702 in FIG. , It is recorded by duplicating in total 16 pieces.

In this case, for example, when 288 KB is required when the patch data is held in a size of 256 × 256 dots, the patch data is held down to 18 KB by holding it in a size of 64 × 64 dots, and can be held in a 1/16 size.
This makes it possible to greatly reduce the test pattern data capacity in a recording apparatus having a limited memory capacity.

  Note that the generation of test pattern data by duplication as described above is not limited to 16 duplications of 1/16 size data, and even if there are four duplications of 1/4 size data, 1/8 size data It is obvious that the present invention is not limited by the size of data or the number of replicas.

  After selecting the patch of the color closest to the achromatic color based on the recording of the test pattern (step S110) and the user's visual judgment (step S120) in the test pattern, the selected patch number is input in step S130. Process.

  That is, the patch number input by the user via the operation panel of the printing apparatus printer is stored in a predetermined memory area of the printing apparatus (step S140).

  Here, as long as the test pattern of the present embodiment has no deviation in the discharge amount of each print head that discharges each color ink, the center patch P9 (C = M = Y = 512) shown in FIG. 6 is the most. It is configured to be selected as a patch close to an achromatic color. In other words, in the image processing of FIG. 4 described above, the output value obtained by the output γ correction LUT 403 is mounted on a recording head having a recording characteristic (discharge amount) such that the patch P9 has a color closest to an achromatic color. This is an LUT that is set when the density balance achieved for each color is optimal.

  However, when a patch other than the patch P9 is selected as having the test area closest to the achromatic color in the test pattern shown in FIG. 6, the recording apparatus to which the test pattern is recorded is C, M, Y. The balance of the recording characteristics between the recording heads is shifted (that is, the color is shifted).

  In the present embodiment, there are 19 patches that can be selected as shown in FIG. 6, and the extent to which the balance of the recording characteristics (recording characteristics) of the recording heads is shifted is determined from the test area as the most preferable achromatic color. Judgment can be made by selecting a visible patch.

  In step S150, according to the patch number information input in step S130, a color misregistration correction output γ correction LUT that is actually used in image processing is determined from the above three output γ correction LUTs for each color. This is stored in a predetermined memory area of the recording apparatus as a color misregistration correction value for each color (step S160).

<Color misregistration correction value acquisition method / correction LUT determination method>
FIG. 8 is a flowchart showing a procedure for acquiring a color misregistration correction value and specifying a color misregistration correction processing LUT performed in the host 100.

This process is started by selecting this mode on the GUI of the host 100 in step S210. First, in step S220, a color misregistration correction value for each color is acquired from the memory of the printing apparatus printer 200 to be corrected.
In step S230, the acquired color misregistration correction value is stored in the memory of the information processing apparatus.

  On the other hand, in this embodiment, three types of one-dimensional LUTs (output γ correction tables) shown in FIG. 9 are used to perform color misregistration correction output γ correction so as to optimize the balance of recording characteristics in accordance with the selected patch. ) Is prepared in advance.

  In step S240, a color misregistration correction LUT for each color corresponding to the color misregistration correction value for each color is determined.

  FIG. 10 shows the test pattern patch No. The relationship diagram of (setting value), color misregistration correction value, and color misregistration correction output γ correction one-dimensional LUT is shown.

  For example, the patch P0 (patch No. 0) shown in FIG. 6 is generated with 10 bits and gradation values of C: 476, M: 476, Y: 548, and this patch is a color close to the most preferable achromatic color. When the setting value is set to 0, the color misregistration correction value is stored in the recording apparatus as C: 0, C: 0, C: 2. Then, the information processing apparatus acquires the color misregistration correction value, and C: Table0, M: Table0, and Y: Table2 are set as the color misregistration correction output γ correction one-dimensional LUT.

  For example, patch P4 (patch No. 4) shown in FIG. 6 is generated with gradation values of C: 476, M: 476, and Y: 512, but when the set value is 4, color misregistration correction is performed. The value is stored in the recording device as C: 1, C: 1, C: 2 instead of C: 0, C: 0, C: 1 as a value, and C: Table0 as an output γ correction one-dimensional LUT for color misregistration correction , M: Table0, Y: Table2 are set.

  C: 0, C: 0, C: 1 and C: 1, C: 1, C: 2 have the same balance of the printing ratio of each color of C, M, and Y, so that image data can be obtained even at the same printing ratio. Can be corrected in a higher density direction.

  With the above processing, the color misregistration detection and correction LUT determination processing is completed.

  Next, a second embodiment of the present invention will be described with reference to the drawings.

  In the first embodiment, the test pattern data is stored in the memory of the printer 200 shown in FIG. 1, but it may be stored in the memory of the host 100 shown in FIG.

  A color misregistration detection method and a correction method based thereon will be described in the present embodiment.

<Color shift detection method / color shift correction value acquisition method / correction LUT determination method>
FIG. 11 is a flowchart showing color misregistration detection, correction value setting, and correction processing procedures performed in the information processing apparatus 100 shown in FIG.

  This process is started when the user selects this mode on the GUI of the host 100 shown in FIG. First, in step S310, the printer 200 is caused to record a detection pattern for detecting color misregistration.

  After the above test pattern recording (step S310) and the user's visual judgment in this test pattern (step S320), the patch closest to the achromatic color is selected, and then the selected patch number is input in step S330. Process.

  That is, the patch number input by the user via the GUI of the host 100 shown in FIG. 1 is stored in a predetermined memory area of the information processing apparatus host 100 (step S340).

  In step S350, according to the patch number information input in step S330, a color misregistration correction output γ correction LUT that is actually used in image processing is determined from the above three output γ correction LUTs for each color. This is stored in a predetermined memory area of the information processing apparatus as a color misregistration correction value for each color (step S360).

  In step S370, a color misregistration correction LUT for each color corresponding to the color misregistration correction value for each color is determined.

  With the above processing, the color misregistration detection and correction LUT determination processing is completed.

  Since the configuration and operational effects other than the color misregistration detection and correction LUT determination method are the same as those in the first embodiment, detailed description thereof will be omitted.

  Next, Embodiment 3 of the present invention will be described with reference to the drawings.

  The color misregistration correction LUT described in the first and second embodiments corrects when the C, M, and Y recording characteristics are out of balance as compared with a head having standard recording characteristics. Correction is performed so that the discharge amounts of other colors are lowered in accordance with the head of the color having the largest recording characteristic (the discharge amount is large) among C, M, and Y of the target head.

  This is because, in the case of a head having a recording characteristic smaller than that of a standard head, since the maximum amount of ejection of the standard head cannot be output by a head having a small recording characteristic, correction is made so that the colors match relatively. It is.

  However, as a result, when image data is recorded, there may be a case where the absolute density is lower than that of a head having standard recording characteristics.

  If the absolute density is low, the impression of the recorded result may be worsened.

  In the case of general image data, it is composed of data consisting of a large number of gradation values, and the portion that requires the maximum amount of ejection from each head when recording is limited.

  Further, an image having a high gradation value has a feature that a color shift due to variations due to the recording characteristics of the recording head is felt little.

  From this point, in this embodiment, color misregistration correction is performed using a color misregistration correction LUT that realizes a recording result in which the absolute density is not lowered as much as possible.

  In the present embodiment, three types of one-dimensional LUTs (output γ correction tables) shown in FIG. 12 are used to perform color misregistration correction output γ correction so as to optimize the balance of recording characteristics in accordance with the selected patch. Prepared in advance.

  This is because the correction value 0 with the lowest gradation value is matched with the ejection characteristics of a standard head, and the correction value 1 and the correction value 2 linearly fluctuate up to a value close to the maximum gradation value, and then the maximum It is assumed that the table has a curve that draws the gradation value.

  Since the configuration and operational effects other than the color misregistration correction LUT are the same as those in the first and second embodiments, detailed description thereof will be omitted.

1 is a block diagram illustrating a recording system according to an embodiment of the present invention. 1 is a perspective view showing a mechanism of a main part of an ink jet printer in a recording system to which the present invention can be applied. It is a block diagram which shows the control structure of an inkjet printer. It is a block diagram for demonstrating the procedure of the image processing in the recording system which can apply this invention. It is a flowchart which shows the process sequence of the color misregistration detection and correction value setting in one Example of this invention. It is a figure explaining the test pattern for the color shift detection which concerns on one Example of this invention. It is a figure explaining the patch data comprised by the test pattern for the color shift detection which concerns on one Example of this invention. 6 is a flowchart illustrating a procedure for acquiring a color misregistration correction value and a color misregistration correction process according to an embodiment of the present invention. FIG. 6 is a diagram illustrating an output γ correction one-dimensional LUT for color misregistration correction according to an embodiment of the present invention. FIG. 7 is a diagram illustrating a relationship between a color misregistration detection setting value, a color misregistration correction value, and a color misregistration correction LUT according to an embodiment of the present invention. 6 is a flowchart showing a procedure for determining a color misregistration correction value, setting a correction value, and determining a correction LUT according to an embodiment of the present invention. It is a figure explaining the output γ correction one-dimensional LUT for color misregistration correction according to the embodiment of the present invention.

Explanation of symbols

10 CPU
11 Memory 12 Input Unit 13 External Storage Device 100 Host 200 Printer 402 3D LUT
403 One-dimensional LUT
404 One-dimensional LUT for color misregistration correction

Claims (9)

An information processing apparatus that performs image processing on image data and transmits the image data to a recording apparatus, and a recording system that records on a recording medium using a recording head that discharges a plurality of types of ink,
The recording apparatus includes test pattern data holding means for holding test pattern recording data in which a plurality of patch data having different printing ratios of the respective inks are arranged;
Test pattern recording means for recording the test pattern by operating an operation panel of the recording apparatus or a user interface screen on the information processing apparatus;
From the test pattern, select a patch that appears as the most preferable achromatic color,
Setting means for setting information corresponding to the selected patch in the recording device;
Correction value holding means for holding a correction value corresponding to the information;
Correction value acquisition means for acquiring the correction value by the information processing apparatus;
A correction table holding means for holding a plurality of correction tables corresponding to each of the correction value information;
Image correction means for correcting the image data using the correction table corresponding to the acquired correction value information;
A correction image recording means for recording the converted image data by the recording device;
A recording system comprising:   In the image correcting means, the image data is changed from data represented by R (red) G (green) B (blue) to data represented by C (cyan) M (magenta) Y (yellow) K (black). The recording system according to claim 1, wherein after the conversion, the multi-value data for each color corresponding to the correction value information is corrected by a one-dimensional lookup table (LUT).   The recording system according to claim 1, wherein the one-dimensional LUT includes a linearly varying curve.   The recording system according to claim 1, wherein the patch data is recorded in a gradation value range of 30% to 70% as a density at which a color can be easily recognized.   2. The recording system according to claim 1, wherein the test pattern data includes the patch data having different printing ratios within a range of variation in recording characteristics of the recording head and not including the same printing ratio.   2. The recording system according to claim 1, wherein the test pattern data is arranged such that adjacent patches have color tone continuity.   The recording system according to claim 1, wherein the one-dimensional LUT includes a curve that does not change a maximum gradation value when correcting image data.   2. The recording system according to claim 1, wherein the test pattern data is recorded by duplicating each of the patch data held in the recording apparatus with a predetermined size.   The color correction is performed in the image correction unit using the one-dimensional LUT that corrects the density higher with respect to the printing ratio of each color of the selected patch data. Recording system.

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