JP2932277B2 - Color image recording device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color image recording apparatus, and more particularly, to a color image recording apparatus that performs color correction and prints when forming color print image data.

[Conventional technology]

For example, in a thermal transfer type color printer, the color mixing characteristics of the ink film, the recording density characteristics of the recording paper or the thermal head, the misalignment in multicolor printing, and the like are factors that degrade the image quality. Therefore, conventionally, a gradation look-up table and color masking have been used to correct the excess and deficiency of gradation and the color shift due to turbidity and misalignment, respectively. The image quality is evaluated using factors such as color reproducibility and gradation.

Normally, the gradation adjustment is performed by the user selecting the closest one while comparing the look-up table with the print image. Since color shift cannot be corrected only by tone adjustment, color correction by color masking is also necessary. In color masking, several known color data are printed, a color correction coefficient is obtained by a least-squares method from a color of a printed sample and the known color data by a separate chromaticity measuring device, and input using these. The color data is corrected. In a conventional apparatus, for example, Japanese Patent Laid-Open No. 58-2445
As described in No. 7, the color correction coefficient is fixed to a value obtained under specific device, recording paper, and ink conditions, and the color is corrected using this value.

In terms of mechanism, the shift of the printing position that occurs when printing in YMC (yellow, magenta, cyan) sequentially and face-to-face is strictly controlled. For example, a color shift is performed by a mechanism that presses the edge of the recording paper with a belt. It does not adjust the correction coefficient for each product simply by reducing it.

[Problems to be solved by the invention]

The prior art described above does not take into account the correction when the color tone characteristics of the ink film or the like or the recording density characteristics of the recording paper has changed or changed, or the recording density characteristics of each color image recording apparatus, and the user cannot use another recording paper. Or an ink film could not be freely selected and used. Even if used, there is a problem that color reproducibility and gradation are impaired.

Further, when the recording position of the YMC is mechanically shifted and a color shift occurs, there is a problem that color reproducibility is significantly reduced.

An object of the present invention is to obtain a good color image without impairing image quality such as color reproducibility and gradation even if the color tone characteristics of an ink film or the like or the recording density characteristics of a color image recording device or recording paper are changed. An object of the present invention is to provide a color image recording apparatus.

[Means for solving the problem]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a color image recording apparatus which receives a three-color separation signal captured from a color scanner or a color camera or image data from a computer, corrects the image data, and prints the corrected image data. Means for generating color pallet data, reading means for reading a plurality of color samples obtained by printing the color pallet on recording paper to be used using ink to be used, and obtaining three-color separation signals, and reading by the reading means. A color correction matrix calculating unit that obtains a color correction matrix that minimizes a color difference from a target printing characteristic by using a least square method, using the corrected data and the color pallet data corresponding to the data. A color correction unit for correcting input data, wherein the color correction unit It proposes a color image recording apparatus for printing with ink and recording paper.

Before the color correction, Y (yellow), M (magenta), C (cyan) of the printed color palette
The gradation data obtained by reading each gradation sample is passed through several gradation correction conversion tables, and the gradation at which the difference between the corrected gradation density curve and the preset target gradation density curve is minimized A tone correction conversion table selecting unit for obtaining a correction conversion table; and a tone correction unit for performing tone correction on input image data based on the selected tone correction conversion table. A color image recording apparatus for printing using data is proposed.

Further, a means may be provided for obtaining the degree of color mixture from the light source of the reading means or the spectral characteristics of the color sensor and correcting the color mixture of the read data.

When the tone correction unit is arranged after the color correction unit, the tone correction unit creates a tone reverse conversion table of the input / output reverse of the tone correction conversion table, and converts the color palette data into the tone reverse conversion table. Means for converting the gradation according to.

A density curve is obtained by averaging the density data of three colors obtained by reading the gray tone sample of the printed color palette for each tone, and obtaining the target tone density curve and the average density curve for each color. It is also possible to provide a gray balance correction unit that obtains the difference from the difference, multiplies the difference by a certain value, subtracts the difference from the value of the tone correction conversion table, and sets the value subtracted for each color in the tone correction conversion table. is there.

The gray balance correction unit prepares several correction curves in the low density region with respect to the target gradation density curve, and obtains the density of three colors obtained by reading the gray gradation sample of the printed color palette. A density curve is obtained by averaging the data for each gradation, and the sum of the difference between the target gradation density curve and the average density curve is obtained for each color, and one of the correction curves in the low density range is selected based on this sum. And means for setting the value in the gradation correction conversion table.

The color correction unit further includes two or more conversion tables each of which is obtained by multiplying two or more upper and lower three-color image data by a color correction matrix and obtaining data obtained as signed data, It may be configured to include a unit for adding the output of each conversion table and a unit for limiting the addition result to a certain range.

Regarding the reading means, a plurality of color sensors can be provided in the main scanning direction.

A line sensor placed parallel to the main scanning direction or a color sensor movable in the main scanning direction may be included.

These color image correction means can be applied to any of a color thermal printer, a color inkjet printer, and an electrophotographic color printer.

[Action]

In the step of obtaining the correction value of the present invention, some gradation data or color data is generated, and a color pallet is printed in a belt shape in the recording paper feed direction. A reading sensor is installed at a position where the color pallet can be read, and the color pallet is read. A three-color separation signal from the reading sensor is obtained, color mixing is corrected, and further converted to YMC density data. Next, the Y density data of the read yellow tone sample is converted by using several tone correction conversion tables, and the difference between the read Y tone data and the target print density value is calculated. The gradation correction conversion table that sums up and minimizes the difference sum is defined as a Y gradation correction conversion table. If the M and C gradation correction conversion tables are not desired to be the same as yellow, the M and C also obtain the gradation correction conversion table in the same manner as the Y gradation conversion table.

Further, in order to obtain a gray balance, the density data of three colors obtained by reading the gray tone samples of the printed color palette is averaged for each tone. The difference from the average is obtained for each color, the difference is subtracted from the value of the tone correction conversion table obtained above, and a new tone correction conversion table is set for each color.

When only color correction is performed, color correction coefficients are obtained by the least squares method so that the color difference is minimized, using the color data of a large number of samples and the corresponding color pallet data.

When performing color correction after applying gradation correction, for many samples, the color data of the samples is converted using a gradation correction conversion table, and these and color pallet data corresponding to these are used to minimize the color difference. As described above, the color correction coefficient is obtained by the least square method. When the input image data is luminance data, a luminance / density conversion unit may be included in the gradation correction conversion table.

Conversely, when performing gradation correction after performing color correction, the color palette data is converted with the input / output reverse gradation reverse conversion table,
Using the inverse conversion result data and the corresponding sample density data, a color correction coefficient is obtained by the least square method so that the color difference is minimized.

After the correction value is set, if the input image data is luminance data, the image data is subjected to luminance / density conversion, color correction and gradation correction are performed, and output to the recording unit.

 The recording unit performs printing while feeding recording paper.

In the present invention, for example, even when the recording paper or ink is changed, known color data of the color pallet data is output to measure the recording characteristics, and the parameters of the correction system can be optimized. Can be suppressed.

〔Example〕

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

FIG. 1 is a diagram showing a schematic configuration of a thermal transfer type color image recording apparatus as an example of a color image recording apparatus according to the present invention. In the figure, after the recording paper 2 is wound around the rotating drum 1, the thermal head 3 is pushed down, and the rotating drum 1 is rotated in the direction of arrow A. Y (yellow), M (magenta), C (cyan) face-sequential ink film 4
Is transported in the direction of arrow B by the rotation of the rotary drum 1. It is transported in the direction of arrow B by rotation of the rotating drum 1. The rotating drum 1 is driven by a rotating drum drive motor 5. The top sensor 8 detects the leading edge of the recording paper and sends a detection signal to the signal processing circuit 6. The signal processing circuit 6 determines a recording position and outputs a recording signal to the head (in this case, a thermal head) 3. Each time the rotating drum 1 makes one rotation, printing is performed in the order of Y, M, and C. The signal processing circuit 6 fetches RGB (red, green, blue) image data from the outside, corrects the image data, and sends it to the thermal head 3 as recording data. When the recording characteristics and the like of the color image recording apparatus change and it is desired to correct the correction value, color pallet data is generated in the signal processing circuit 6, and data without correction is sent to the thermal head 3 for printing. The printed color sample is read by the reading sensor 7 and sent to the signal processing circuit 6. The signal processing circuit 6 obtains a new correction value using the measured color data. This is stored in a memory or the like and used for subsequent image data correction.

The reading sensor 7 is, as shown in FIG.
Illuminates the color sample printed on the recording paper 2,
A sample image is generated by the imaging lens 10, and a three-color separation signal is obtained by a color sensor 11 having R, G, and B color filters. Note that color filters such as Y (yellow), G (green), and C (cyan) may be used instead of R, G, and B. The three-color separation signal is subjected to analog / digital conversion by the A / D converter 12 and sent to the signal processing circuit 6. The reading sensor 7 may be provided with a color mixing correction function to correct characteristics such as a color filter and illumination, and then sent to the signal processing circuit 6. The color mixture correction is a procedure for obtaining the degree of color mixture from the spectral characteristics of the light source 9 and the color sensor 11 and correcting the color mixture of the read data by linear calculation.

Now, the signal processing circuit 6 will be described with reference to FIG. The signal processing circuit 6 includes a CPU 13, a memory 14, a reading sensor 7 interface 15, an image data input interface 16, a mechanism controller interface 17, a thermal head driver 18, a motor driver 19, a panel switch interface 20, Consists of Only the main motors and sensors that control the mechanism are described. The main switches are a print switch 21 and a test print switch 22.

The operation of the signal processing circuit 6 having such a configuration will be described with reference to the flowchart of FIG. Here, it is assumed that the recording paper and the ink film are changed to other types. Press the test print switch 22 to start test print. The recording paper is fed, and the recording paper 2 is wound around the rotating drum 1. After the top sensor 8 detects the leading end of the recording paper 2, the line signal in the sub-scanning direction is counted, and the rotary drum 1 is rotated to the recording position. This line signal is generated each time the rotating drum 1 rotates and advances by one line pitch. The color pallet data is created from the memory 14 and output to the thermal head 3 without any correction processing. The reading sensor 7 is set to the operating state. The line signal in the sub-scanning direction is counted, and reading is started when the sample reaches the reading position. The reading sensor 7 reads one sample several times. These data are respectively averaged in the signal processing circuit 6 to become three color data. Then, the sample is read while printing in the YMC plane-sequential manner.
FIG. 5 shows how the sample is printed. First, Y for the first color
Y1 to Y16 are printed by changing the ink amount in 16 steps with ink. For example, in the case of printing with a dispersed halftone type 4 × 4 area gradation in the recording unit, Y1 to Y16 are printed by increasing the recording dots one by one in a 4 × 4 matrix.

Subsequently, M1 to M16 are printed in two cases by changing the ink amount in 16 steps with the second color M ink, and the M16 ink shown in FIG.
Steps R1-R16, Y1-Y16 are obtained. Finally, three cases of C1 to C16 are printed with the third color C ink by changing the ink amount in 16 steps, and Bl1 to Bl16 and B1 to B16 as shown in FIG.
Get C16. The read data is stored in the memory 14, and the recording paper 2 is discharged. Then, a correction value is obtained from the read data, the result is stored in a memory or the like, and the test print is completed. Bl represents black, and W represents white.

The printing operation after the correction is as shown in FIG. Pressing the print switch 21 starts printing. The recording paper 2 is fed, and the recording paper 2 is wound around the rotating drum 1. After the top sensor 8 detects the leading end of the recording paper 2, the line signal in the sub-scanning direction is counted, and the rotary drum 1 is rotated to the recording position. Image data is input, and if it is luminance data, it is converted into density data, and this density data is corrected and converted by a gradation correction conversion table. Then, color correction is performed, and these are stored in the memory 14. The data is read from the memory 14 one by one in the order of YMC, output to the thermal head 3, and transferred in the order of YMC. Performs the correction operation three times without storing the operation disqualification in the memory 14.
The image may be transferred in the YMC plane sequence. When the three-color transfer is completed, the sheet is discharged and printing is completed.

Further, the flow of data processing will be described with reference to FIG. The input image data is, for example, 7-bit data. If the input image data is luminance data, the luminance / density conversion unit 23 performs luminance / density conversion. Then, the tone correction unit 24 and the color correction unit 25 execute the tone correction and the color correction, respectively, and output to the printing unit 26. The gradation correction is, for example, a conversion table method. As the conversion table, an optimum one is selected and set from several conversion tables.

In color correction, three-color data of input image data is converted by a color correction matrix. The color correction matrix differs depending on how the color masking equation is established. Input data
If Dr, Dg, Db and the amount of printing ink are y, m, c, the normal color masking equation is In particular, when the recording system is nonlinear, a second-order term is added, and the following masking equation is used.

Next, a procedure for performing a test print and obtaining a correction value will be described with reference to a flowchart of FIG.

(1) The color pallet data 28 is printed through the printing unit 26, and the sample 29 is read by the reading sensor 7. In addition,
In this case, the read data is 7 bits.

(2) The color mixture correction unit 30 corrects the color mixture of the read data,
The luminance / density conversion unit 23 performs luminance / density conversion. Then, the data is stored in the memory 14 of FIG.

(3) The y-density data of the yellow tone samples Y1 to Y16 are taken out of the memory 14 and passed through several tone correction conversion tables prepared in advance in the tone correction unit 24. In a thermal transfer printer, the gradation density curve is generally an S-shaped curve. Therefore, the gradation correction curve is an inverted S-shaped curve. FIG. 9 shows an example of the correction curve used in this embodiment.

(4) The tone correction conversion table selection unit 27 adds up the errors between the respective correction data output from the tone correction conversion table and the target tone density data for each tone correction conversion table. The target gradation density curve is a straight line or a curve close thereto.

(5) The gradation correction conversion table selection unit 27 sets the smallest gradation correction conversion table among the total additions of the errors as the y gradation correction conversion table.

(6) For m and c, similarly to y, a gradation correction conversion table for m and c is set.

In the above example, the tone correction curve is selected based on the 16 data. However, the data is increased from the 16 data by interpolation processing, error calculation is performed, and the tone correction curve is selected. You may.

The procedure for correcting the gray balance (part A in the flowchart in FIG. 8) will be described with reference to the flowchart in FIG.

(1) Extract ymc density data of gray tone samples Bl1 to Bl16.

(2) The gray balance correction unit 31 creates 128 data by interpolation from 16 data for each color.

(3) Then, an average density curve of three colors is obtained. FIG. 11 shows an example of an average density curve and a yellow tone density curve. In this example, yellow is conspicuous in the low density region due to misregistration, and it is necessary to suppress yellow in the low density region.

(4) The gray balance correction unit 31 calculates the difference between the gradation density curve and the average density curve for each color, multiplies the difference by a certain value, and calculates the difference from the gradation correction curve obtained by the gradation correction conversion table selection unit 27. Pull.

(5) Then, the value subtracted for each color is set in the gradation correction conversion table.

If the fact that the gray balance is lost mainly in recording in a low density region is used, the following procedure can be adopted. The twelfth for one gradation correction curve
As shown in the figure, several correction curves in the low density range are prepared. Then, the tone correction curve in the low density range is selected based on the total value of the values obtained by subtracting the average density data from the tone density data for each color. In addition,
The gradation correction curve in the low density range with respect to the total value is associated in advance. Instead of the average density data, a total value may be obtained using tone density data of any of the three colors. No.
FIG. 13 is a flowchart showing the procedure of this alternative.

Next, the procedure for obtaining the color correction matrix (the portion B in the flowchart in FIG. 8) will be described with reference to the flowchart in FIG.

(1) The color data correction and the luminance / density conversion are performed on the read data of the sample 29, the stored color data is taken out, and the gradation correction conversion is performed using the set gradation correction conversion table.

(2) From these data and the corresponding color pallet data 28, the color correction matrix calculator 32 obtains a color correction matrix that minimizes the color difference by using the least squares method.

Specifically, the data after gradation correction obtained by reading the recording sample 29 is set to = (dr, dg, db) n. on the other hand,
The color pallet data is set to T = (C, M, Y) n, and a color correction matrix A is obtained from these according to the following equation. When the equation (2) is used for color correction, a color correction matrix including a quadratic term is obtained. t represents a transposed matrix, and −1
Represents an inverse matrix.

This color correction matrix corrects data for a recorded color sample so that a density error is minimized.

(3) Set the correction coefficient of A in the color correction unit 25.

When correcting an input image only by color correction,
From the data before the tone correction conversion and the corresponding color pallet data, a color correction matrix that minimizes the color difference is obtained using the least squares method.

In the present embodiment, the data processing shown in FIG. 7 is executed by software. However, where high-speed processing is desired, the processing may be realized by hardware. For example, a conversion table such as a ROM or a RAM may be used for luminance density conversion and gradation correction. Also, color correction can be realized by a conversion table. That is, using the color correction matrix obtained by equation (3),
Correction values for all the input data are obtained by equation (1) or (2), and these are written in a conversion table to perform color correction. The negative correction value obtained by the calculation is 0.
And The correction value exceeding the maximum value is limited to the maximum value.

Assuming that each of the three color data is 7-bit data, 21 address lines are required, but there is no single RAM that satisfies these. Therefore, it is considered that color correction is performed on all data by the linear transformation of Equation (1) (there is no quadratic term). When the equation (1) is used, the gradation correction is performed in consideration of the gray balance. FIG.
A circuit is shown in which the input data in the equation (1) is divided into upper and lower computations, and the respective computation results are written in a conversion table to perform color correction. The input data is YMC image data for each pixel.
Entered in 3. In the gradation correction conversion table 33, eight gradation correction tables and four gray balance correction tables are written for each eight. The lower 7 bits of B0 to B6 are input data, and the 3 bits of B7 to B9 are mode select data for selecting eight kinds of gradation correction tables.
Mode select data is also input to the three bits B12 to B12, and gray select data for selecting the gray balance correction curve is input to B13 and B14. The select data can be set for each color. Output data from the gradation correction table 33 is held in the latches 34y, 34m, and 34c. And
The upper three bits are the upper color correction conversion table 35a.
, And the lower 4 bits become the input data of the lower color correction conversion table 35b. Further, a color designation signal 36 is input to the color correction conversion table 35, and the color of the correction value is designated. The upper color correction conversion table 34a has 3
The upper 3 bits of the color input data are extracted and the lower 4 bits are extracted.
Values obtained by putting the data in which the bit is 0 into the expression (1) are written in 8 colors with sign for each of the three colors. In the lower color correction conversion table 35b, the values obtained by putting the lower 4 bits of the input data of the three colors into the expression (1) are written as signed 8-bit data for each of the three colors. Since the value may be negative as a result of the operation of the expression (1), the write data has a sign bit. Writing is
This is performed through address lines and data lines (not shown).

The upper correction value and the lower correction value output from the color correction conversion table 35 are added by the adder 37. If the result is negative, the selector circuit 39 is disabled by the disable signal 38 and 0 is output. On the other hand, if the result exceeds 127, 127 is selected by the select signal 40. Other addition results are output as they are. This selection is made by the selector circuit 39.

FIG. 16 shows a circuit for calculating the input data in equation (1) by dividing the data into upper, middle, and lower three parts, writing the respective calculation results in a conversion table, and performing color correction. The upper color correction conversion table 35c takes out the upper 2 bits of the input data of the three colors, puts the data with the lower 5 bits of 0 into the equation (1), and obtains the value obtained by using the signed 8 bits for each of the three colors. Has been written. In the middle color correction conversion table 35d, the value obtained by taking out the upper 2 bits out of the lower 5 bits of the input data of the three colors and putting the lower 3 bits as 0 into the equation (1) is signed. Each of the three colors is written in 8 bits. In the lower color correction conversion table 35e, a value obtained by putting the lower three bits of the input data of three colors into the expression (1) is a signed 8-bit value of 3 bits.
Each color is written. The input data of the three colors is input to the color correction conversion table 35, divided into upper, middle and lower order, and the color is specified by the color specifying signal 36. As a result, the upper correction value, the middle correction value, and the lower correction value designated for the color are output from the color correction conversion table 35. Thereafter, color correction is performed in the same manner as in FIG. Note that there is no restriction on how to divide the input data, and if the color correction conversion table can handle 9 bits, the above-described color correction processing can be performed on 8-bit input data.

According to the present embodiment, even if an ink film having a different recording density characteristic or a different degree of color mixing or a recording paper of a type different from the designated type is used, or even if a color shift occurs mechanically,
Since the color correction coefficient can be set again, the color reproducibility is not impaired. In addition, the use of the above-described correction circuit allows input data to be corrected at high speed.

FIG. 17 is a diagram showing a signal processing circuit of another embodiment. In this embodiment, tone correction is performed after color correction. The procedure for selecting the gradation correction conversion table in the test print is the same as in the above embodiment. However, the density data of the gradation sample is passed through the color correction unit 25.

Here, a method of obtaining a color correction value, which is a main difference, will be described. FIG. 18 is a flowchart showing the procedure.

(1) The color pallet data 28 is converted through the gradation correction conversion table of the gradation correction unit 24 in reverse. That is, a reverse conversion table for input / output reverse is prepared, and data is converted through this. That is, in the above embodiment, the sample
Although the color correction is performed after the gradation correction of 29, here, the color pallet data 28 is inversely converted to prepare for the next color correction.

(2) The color correction calculation unit 31 obtains a color correction matrix with the minimum color difference from the converted color palette data and the color data of the sample 29 stored in the memory 14 by using the least square method. .

(3) Set the correction coefficient of A in the color correction unit 25.

Also in the present embodiment, when an ink film having a different recording density characteristic or color mixing degree or a recording paper of a different type from the designated one is used, or when a color misregistration occurs mechanically, the color correction coefficient is reset. Since it can be set, color reproducibility is not impaired.

FIGS. 19 and 20 show another form of means for obtaining a three-color separation signal.
It is shown in Fig. 21.

In the example of FIG. 19, a plurality of reading sensors 7 are arranged in the main scanning direction, and a large number of color samples are read simultaneously. Therefore, as shown in FIG. 22, the color palette records two or more rows simultaneously. That is, first, Y1 to Y16 are printed with the first color Y ink while changing the ink amount in 16 steps. Subsequently, with M ink of the second color, the ink amount is changed to 16 levels and M1 to M16 are recorded in two cases, and R1 to R16 and M1 to M16 of 16 levels are obtained. Finally, with the third color C ink, change the ink amount to 16 levels and set C1 to C16 to 4
Record cases, Bl1 to Bl16, B1 to B16, C1 to C16, G1 to G16
Get. While recording these, a plurality of reading sensors 7 read the three-color separation signals. As shown in FIG. 23, the output from each reading sensor 7 is guided to the A / D converter 12 by the multiplexer 41 as a color signal of one color sample. The A / D converted data is sent to the signal processing circuit 6. After that, it is the same as the above embodiment. According to this embodiment, since many color samples can be recorded, the reliability of the color correction coefficient is improved.

In the example of FIG. 20, a line sensor 42 is used as the reading sensor 7, and a large number of color samples are read simultaneously. FIG. 24 shows a block diagram of the reading sensor 7. The line sensor 42 reads a color palette as shown in FIG. 22, and outputs a line start signal 43 in the main scanning direction and a three-color division signal. The three-color separation signal is converted into color data by the A / D converter 12 and then input to the averaging circuit 44. The averaging processing circuit 44 inputs the main scanning direction line start signal 43 and the sub scanning direction line signal 45 from the line sensor 42, averages a plurality of color data from one color sample, and obtains highly reliable color data. Get. That is, since the color measurement area of each reading sensor of the line sensor 42 is small, sufficient color measurement cannot be performed by measuring only one point. In this embodiment, since the color data obtained from a plurality of points are averaged, the reliability is improved. The data from the averaging circuit 44 is sent to the signal processing circuit 6 and thereafter processed in the same manner as in the above embodiment.

According to this embodiment, since many color samples can be read, the reliability of the color correction coefficient is improved.

The example of FIG. 21 has a configuration in which the reading sensor is movable in the main scanning direction and sequentially reads a large number of color samples. The reading sensor 7 moves in the main scanning direction when the guide bar 47 is rotated by the reading sensor scanning motor 46. The reading sensor 7 reads the color palette shown in FIG. 22 in the order of Y, M, C, B1, B, and G.

Also in this embodiment, since a large number of color samples can be read, the reliability of the color correction coefficient is improved.

〔The invention's effect〕

According to the present invention, even if the color tone characteristics of an ink film or the like or the recording density characteristics of a color image recording apparatus or recording paper change, the correction coefficient can be set again, so that image quality such as color reproducibility and gradation is not impaired. And a color image recording apparatus capable of obtaining a good color image.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of a color image recording apparatus according to the present invention, FIG. 2 is a diagram showing a configuration of a reading sensor, FIG. 3 is a block diagram showing a configuration of a signal processing circuit, and FIG. Flowchart showing a test print operation of the circuit,
FIG. 5 is a view showing a state in which a test print is printed, FIG. 6 is a flowchart showing a print operation of a signal processing circuit, FIG. 7 is a block diagram showing a data processing circuit,
8 is a flowchart showing a correction processing procedure, FIG. 9 is a view showing a tone correction curve used in this embodiment, FIG. 10 is a flowchart showing a gray balance correction procedure, and FIG. 11 is a gray balance correction. FIG. 12 is a diagram illustrating a correction curve in gray balance, FIG. 13 is a flowchart illustrating another example of a gray balance correction procedure, FIG. 14 is a flowchart illustrating a color correction procedure, FIG. Is a diagram showing a configuration of a circuit that performs color correction by a conversion table formula,
FIG. 16 is a diagram showing a modification thereof, FIG. 17 is a block diagram showing another embodiment of the data processing circuit, FIG. 18 is a flowchart showing a procedure for obtaining the correction value, FIGS. No.
FIG. 21 is a diagram showing another embodiment of the reading sensor, FIG. 22 is a diagram showing a state of printing a plurality of columns of color pallets in the main scanning direction, FIG. 23 is a diagram showing a circuit configuration of the reading sensor of FIG.
FIG. 24 is a diagram showing a circuit configuration of the reading sensor of FIG. DESCRIPTION OF SYMBOLS 1 ... Rotary drum, 2 ... Recording paper, 3 ... Thermal head, 4 ... Ink film, 5 ... Rotary drum drive motor, 6 ... Signal processing circuit, 7 ... Reading sensor, 8 ...
... Top sensor, 9 ... Light source, 10 ... Imaging lens, 11 ...
... color sensor, 12 ... A / D converter, 13 ... CPU, 14 ...
Memory, 15… Read sensor interface, 16…
... image data input interface, 17 ... mechanical control interface, 18 ... thermal head driver, 19 ... motor driver, 20 ... panel switch interface, 21 ... print switch, 22 ... test print switch, 23 ... Brightness / density conversion unit, 24: gradation correction unit, 25: color correction unit, 26: printing unit, 27: gradation correction conversion table selection unit, 28: color pallet data, 29: sample, 30 …… Color mixture correction section, 31… Gray balance correction section, 32 …… Color correction matrix calculation section, 33…
... gradation correction conversion table, 34 ... latch, 35 ... color correction conversion table, 36 ... color designation signal, 37 ... adder, 38 ...
... Disable signal, 39 ... Selector circuit, 40 ...
Select signal, 41: Multiplexer, 42: Line sensor, 43: Main scan direction line start signal, 44: Average processing circuit, 45: Sub-scan direction line signal, 46: Read sensor scan motor, 47 …… Information bar.

Claims (13)

(57) [Claims] 1. A color image recording apparatus which receives a three-color color separation signal captured from a color scanner or a color camera or image data from a computer, corrects the image data, and prints after correcting the image data. Reading means for reading a plurality of color samples obtained by printing the color pallet on recording paper to be used using ink to be used, and obtaining a three-color separation signal; and reading the data read by the reading means and the data. A color correction matrix operation unit that obtains a color correction matrix that minimizes a color difference from a target recording characteristic using the corresponding color palette data by a least square method, and a color that corrects input data using the correction value. And a recording unit based on the color-corrected image data. Color image recording apparatus characterized by printing with. 2. The color image recording apparatus according to claim 1, wherein a density sample obtained by reading Y (yellow), M (magenta), and C (cyan) tone samples of the printed color pallet. A tone correction conversion table selecting unit that passes data through several tone correction conversion tables and obtains a tone correction conversion table that minimizes the difference between the corrected tone density curve and a preset target tone density curve. A tone correction unit for tone-correcting input image data based on the selected tone correction conversion table, wherein a color image is printed based on the tone-corrected and color-corrected image data. Recording device. 3. The color image recording apparatus according to claim 1, further comprising: means for obtaining a degree of color mixing from a light source of the reading means or a spectral characteristic of a color sensor and correcting color mixing of read data. Color image recording apparatus. 4. A color image recording apparatus according to claim 2, wherein said gradation correction section creates a gradation reverse conversion table which is the input / output reverse of said gradation correction conversion table, and converts the color pallet data into said gradation. A color image recording apparatus, comprising: means for performing tone conversion by an inverse conversion table, and after performing color correction, performing tone correction using the tone correction conversion table. 5. The color image recording apparatus according to claim 2, wherein the density data of three colors obtained by reading a gray tone sample of the printed color pallet is used for each tone. An average density curve is obtained for each color, a difference between the target tone density curve and the average density curve is obtained for each color, this difference is multiplied by a certain value, subtracted from the value of the tone correction conversion table, and A color image recording apparatus comprising a gray balance correction unit for setting a value subtracted every time in a gradation correction conversion table. 6. The color image recording apparatus according to claim 5, wherein the gray balance correction unit prepares some correction curves in a low density region with respect to the target gradation density curve, and performs the printing. A density curve is obtained by averaging the density data of the three colors obtained by reading the gray tone samples of the color palette for each tone, and calculating the difference between the target tone density curve and the average density curve for each color. And a means for selecting one of the correction curves in the low-density region based on the total and setting the value in a gradation correction conversion table. 7. The color image recording apparatus according to claim 1, wherein the color correction unit applies a color correction matrix to two or more upper and lower three-color image data. Two or more conversion tables each of which writes the data obtained by the multiplication as signed data, means for adding the outputs of the conversion tables, and means for limiting the addition result to a certain range. Color image recording device. 8. A color image recording apparatus according to claim 1, wherein said reading means includes a plurality of color sensors provided in a main scanning direction. 9. A color image recording apparatus according to claim 1, wherein said reading means includes a line sensor placed parallel to the main scanning direction. apparatus. 10. The color image recording apparatus according to claim 1, wherein said reading means includes a color sensor movable in a main scanning direction. 11. A color thermal printer according to claim 1, wherein said color ink is a color thermal ink film. 12. A color ink jet printer according to claim 1, further comprising a nozzle for ejecting each of said color inks. 13. An electrophotographic color printer according to claim 1, wherein said color image is formed by color toner.