JP2003298843A - Image recording apparatus and gradation correction data creation method - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To eliminate the complexity of gradation correction processing when using a plurality of screen patterns, and to generate accurate gradation correction data using gradation patterns with a small number of steps. SOLUTION: A predetermined screen pattern having a plurality of screen patterns each having a plurality of gradations and different gradation characteristics is recorded on one sheet of paper (ST102), and the recorded predetermined screen pattern is imaged. Reading is performed by the reading unit (ST103). Interpolation data indicating gradation characteristics is created based on the read signal of the predetermined screen pattern (ST105), and gradation correction data is created based on the interpolation data (ST106). In the step of creating the interpolation data (ST105), the patches of a plurality of gradations are classified into a plurality of groups including overlapping gradations, and the interpolation data for each group is obtained from the read data of the patches configured for each group. Calculating and combining the interpolated data for all groups.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to an image recording apparatus such as a copying machine that records an image corresponding to the original image on a sheet, and particularly to signal processing for faithfully recording a halftone on the original.

[0002]

2. Description of the Related Art When an image recording apparatus such as a copying machine or a printer records a halftone, there is a problem that the density of the halftone varies from machine to machine or changes with time. In order to solve this problem, a gradation pattern of multiple stages is recorded in advance, this is optically read by a scanner or the like, the gradation characteristics of the recording device are calculated, and correction data is created based on this. Every time, a means for performing gradation correction using this correction data at the time of image recording has been used. Further, the interpolation data is obtained by approximating with one high-order function based on the read values of the gradation patterns of a plurality of stages, and the interpolation data is created based on this approximation function.

[0003]

SUMMARY OF THE INVENTION Multiple original modes and P
The types of screen patterns are increasing due to the addition of printer functions to PCs. It is necessary to perform gradation correction for each screen pattern, but if gradation correction is performed for various screen patterns recorded on a plurality of sheets, the operation becomes time-consuming and complicated.

By outputting a plurality of screen patterns on one sheet, the above-mentioned complication can be solved, but the number of patches per screen pattern is reduced due to the limitation of the sheet size, which may adversely affect the correction accuracy. .

When the gradation characteristics for all gradation areas are approximated by a high-order polynomial, for example, a high order of 8th order or higher is required, the amount of calculation becomes enormous, the error due to digit cancellation is large, and the correction accuracy is high. There was a problem such as a drop.

Therefore, an object of the present invention is to eliminate the complexity of gradation correction processing when a plurality of screen patterns are used and to create accurate gradation correction data using a gradation pattern with a small number of steps. And

[0007]

In order to achieve the above object, a gradation correction data creating method according to an embodiment of the present invention is directed to a plurality of screen patterns each having a plurality of gradations and different gradation characteristics. Recording a predetermined screen pattern having the following on a sheet of paper using the image recording unit,
The step of reading the recorded predetermined screen pattern with an image reading unit and providing a read signal of the predetermined screen pattern, and creating interpolation data indicating gradation characteristics based on the read signal of the predetermined screen pattern And a step of creating the gradation correction data based on the interpolation data.

The predetermined screen pattern includes a plurality of patches having a plurality of gradations different from each other, and the step of creating the interpolation data classifies the plurality of patches into a plurality of groups including gradation overlaps, Calculating interpolation data for each group from the read data of the patch formed for each group, and synthesizing the interpolation data for all groups.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail with reference to the drawings. The following description is an embodiment of the present invention and does not limit the apparatus and method of the present invention.

<First Embodiment> FIG. 1 is a block diagram showing the arrangement of an image forming apparatus according to an embodiment of the present invention.

The image input unit 101 optically reads a document image and outputs it as an RGB signal 151. The signal integration unit 102 integrates the read RGB signals 151 within a designated area. The color conversion unit 103 converts the RGB signal 151 into a CMY signal 152 representing the density of each color of the printer.
The image area identifying unit 104 uses the RGB signal 151 and the CMY signal 15
2 is input, the character area, the gradation area, etc. are identified using the information such as the edge structure, the saturation, and the density.
53 is output. The filter unit 105 uses the CMY signal 152
Filter on. Further, the filter unit 105 switches the characteristics of the filter according to the image area signal 153 output from the image area identification unit 104.

The blacking processing unit 106 adds a black plate (K plate) signal to the CMY signal 154 output from the filter unit 105 and outputs a CMYK signal 155. The calculation method for the black version is GCR (gray component remova)
l) A method or the like is selected by the identification signal 153. When the identification result is the black character area, the black one color process is selected to clearly express the black character, and in the other areas, GCR is selected to enhance the gradation reproducibility and the color reproducibility.

The tone correction unit 107 gamma-corrects the signal value using the LUT so that the tone characteristics of the tone processing unit 108 and the image recording unit 109 become linear with respect to the value of the signal 155, and the CMYK signal 156. Is output. Gradation processing unit 108
Outputs a recording signal 157 by subjecting the CMYK signal 156 to screen processing for area modulation. In the test mode, the pattern generation unit 112 outputs gradation patterns, which will be described later, corresponding to various image areas and screen patterns.

The image recording unit 109 records an image on the paper according to the image signal 157. The interface unit 110 is connected to an external general-purpose computer or a dedicated RIP machine, inputs an image signal 158 from the outside, and supplies it to the gradation correction unit.

Next, gradation correction and gradation processing according to the present invention will be described.

Since electrophotographic recording tends to be unstable if density is expressed for each pixel, gradation is often expressed by the area modulation method. The area modulation method includes a method using a regular pattern repetition and a method using an irregular pattern, and the regular pattern is called a screen. Here, the screen generally indicates a set of regular patterns.

As shown in FIG. 2 (a), the screen pattern is composed of parallel lines at equal intervals, and a parallel line pattern in which the thickness of the parallel lines is used to express light and shade, and regular dots as shown in FIG. 2 (b). There is a halftone dot pattern that is configured by a two-dimensional periodic structure of (1) and expresses shading depending on the size of dots, or a method of switching between lines and halftone dots according to the density. Further, as a method of using an irregular pattern, error diffusion, blue noise mask, etc. are known.

In the example of the parallel line pattern shown in FIG. 2A, signal values of horizontal 3 pixels are added, and a line image having a width corresponding to the added value is formed at the center of the 3 pixels. Furthermore, FIG.
In the case of (a), the pattern is shifted by one pixel for every two scanning lines. The resulting gradation image is an image composed of a plurality of diagonal lines.

In the example of the halftone dot pattern shown in FIG. 2B, the signal values of four horizontal pixels are added, and an image having a width corresponding to the added value is formed in the central portion of the four pixels. Furthermore, FIG.
In the case of (b), the pattern is shifted by two pixels for every two scanning lines. The gradation image obtained as a result is an image composed of independent points.

The present embodiment will be described below by taking the case of using the parallel line method as the screen processing as an example.

Image quality characteristics such as gradation reproducibility and resolution change depending on the density of the screen pattern. In the case of the parallel line method, if the density is increased (the distance between adjacent parallel lines is decreased), the resolution is increased and even a fine portion of the image can be expressed, but the gradation stability, that is, the gradation reproducibility is deteriorated. on the other hand,
When the density is decreased (the interval is increased), the resolution is decreased and the texture of lines is visible, but the gradation stability is improved.

A high-density screen is suitable for recording images such as characters and line drawings, and a low-density screen is suitable for recording gradation images such as photographs.
Therefore, when the screen patterns having different densities are switched between the character area and the photograph area, both areas are reproduced well.

A screen pattern suitable for the original image can be obtained by allowing the user to specify the original mode according to the type of the original and changing the density between the case of recording a photographic image and the case of recording a character image. Can be used.

As a signal processing method for generating such a screen, there are methods such as a multi-value dither method and a direct pattern selection method. Screen processing can be performed by performing table reference and calculation according to these methods.

In electrophotographic recording, the recording section generally has a characteristic that the input image signal value and the output image density are non-linear.
Furthermore, the characteristics also fluctuate due to environmental conditions such as temperature and humidity and variations between aircraft. The relationship between the input image signal value and the density of the output image (printed image) in the gradation process is called the gradation characteristic. The gradation correction unit 107 corrects (gamma correction) the non-linearity, the temporal variability, and the variation between the bodies. The gradation correction unit 107 is composed of an LUT and converts a signal so as to reproduce a linear density according to an input image signal.

Since the gradation characteristics differ depending on the screen pattern used, it is necessary to have a correction table corresponding to each screen pattern. In the case of color, since the gradation characteristics differ for each recording color, it is necessary to have a correction table for each recording color.

FIG. 3 shows the detailed configurations of the gradation correction unit 107 and the gradation processing unit 108 according to this embodiment.

In the normal original mode, screen patterns having different densities are used for the photograph area and the character area. Therefore, the gradation correction unit 107 has a correction table 121a and a first gradation correction unit 122a for the photo area, and has a correction table 121b and a second gradation correction unit 122b for the character area. CPUs in these tables
You can set a screen pattern independent of.

The gradation processing section 108 has a screen pattern 123a and a first gradation processing section 124a for the photograph area, and a screen pattern 123b and a first gradation processing section for the character area.
It has a gradation processing unit 124b. Two gradation processing units 12
The outputs of 4a and 124b are selected by the signal selection unit 125 according to the identification signal.

Further, since the screen pattern is also changed depending on the recording color, gradation correction and gradation processing are performed for the photographic area and the character area for each of the four recording colors of CMYK.

The gradation correction unit 107 corrects the density characteristic (gamma correction). The correction is performed using a LUT (lookup table). Since the gradation characteristics are different for each screen pattern, this embodiment has a total of eight CMYK color × 2 correction tables.

FIG. 4 is a flow chart showing the operation in the test mode according to this embodiment.

The pattern generation section 112 generates a predetermined screen pattern composed of a plurality of gradation patches as gradation test pattern data (ST101). Each patch is, for example, a 10 mm square uniform gradation pattern. The gradation test pattern data generated by the pattern generation unit 112 is screen-processed by the gradation processing unit 108,
The image is recorded on one sheet by the image recording unit 109 (ST
102).

Since it is difficult in space to record all the gradation patches by the image recording unit 109 on one sheet,
As a gradation test pattern, patches of a predetermined number of gradation values, which are thinned out of all gradation values, are recorded. The characteristics of all gradation values are calculated by the interpolation processing described later.

An example of the gradation test pattern of this embodiment is shown in FIG.

The black bar 401 is for position detection and is used for specifying the position of the patch. Below the black bar 401, the screen patch area 402 for the photo area is arranged in 8 columns and 10 rows, and the screen area for character area 403 is arranged below it in 8 rows and 10 rows.

C1, C2, ... C20 are patches for the photographic area of C (cyan) color, C1 is the lowest density (white),
C20 is the highest density (solid) patch. Similarly M
1 to M20, Y1 to Y20, and K1 to K20 are M (magenta), Y (yellow), and K (black) patches for photography, respectively. Similarly, C21 to C40, M21 to M40,
Y21 to Y40 and K21 to K40 are C, M, Y, and K character area patches, and are C21, M21, Y21, and K2.
1 is the lowest density (white), C40, M40, Y40, K40
Is the highest density (solid).

The image input unit 101 reads the gradation test pattern recorded on the paper (ST103). Signal integration unit 1
02 integrates a plurality of pixel signals. That is, the signal integration unit 1
In the input image area 02, the pixel signal values of the area corresponding to each patch are integrated. The CPU 111 reads the integrated value.

The CPU 111 performs the following calculation to create a gradation correction table. Here, the cyan photo area pattern will be described. The reading values of the 20 patches C1 to C20 for the cyan photographic area are YC1 to YC20. Among the RGB signals, the R signal which is the complementary color component of cyan is used. Here, the R signal is used in the image input unit 10.
This is because of the R, G, and B component light receiving elements of 1, the R component light receiving element has the highest sensitivity to cyan and a high signal S / N is obtained.

The CPU 111 standardizes by the following equation (ST104).

ZCi = (YCi−YC1) / (YC20−YC1) ZCi is 1 when YCi has the maximum density (YC20) and 0 when YCi has the minimum density (YC1). Thus each YCi
Is standardized to ZCi. This ZCi is called an area ratio.

FIG. 6 is an explanatory diagram of creating a gamma correction table.

Signal 1 when recording patches C1 to C20
The value of 56 is XC1 to XC20. FIG. 6A shows the area ratio ZCi for the signal values XC1 to XC20. That is, FIG. 6A shows a read value YCi (YC1 to YC2 when reading each patch recorded with the signal values XC1 to XC20).
It is the figure which normalized 0) and represented it by area ratio ZCi. Figure 6
From the point sequence 501 shown in FIG.
11 calculates a continuous approximation function such as the curve shown by 502 in FIG. 6B by regression calculation (ST105). C
The PU 111 further uses the approximation function 502 as shown in FIG.
The inverse function 503 of is calculated, and this is the gradation correction table (ST106).

Similarly to the above, the CPU 111 sequentially creates the MYK gradation correction table of the photographic screen and the CMYK gradation correction table of the character area screen (ST.
107). It is necessary to calculate these gradation correction tables a plurality of times (eight times in the case of this embodiment), but recording and reading of the gradation test pattern are performed in step ST102.
And like ST103, it only needs to be done once.

Next, details of the method of calculating the approximation function in step ST105 will be described.

First, as shown in FIG. 7A, C1 to C20 are allowed to overlap and are divided into the following 17 groups A1 to A17.

A1: C1 to C4 A2: C2 to C5 A3: C3 to C6 ... A7: C17 to C20 An approximate function Fi is set for each group Ai. calculate. For example, an Nth degree polynomial is used for the calculation of the approximation function. In the present embodiment, the quadratic function that minimizes the sum of squares of the approximation error is used by using the least squares method.

For example, in group A1, (XC1, ZC
1) to (XC4, ZC4) from four points E = Σ (F1 (XCj) −ZCj) ^ 2 1 ≦ j ≦ 4 * X ^ 2 represents the square of X.

A quadratic function F1 that minimizes is calculated. The curve in FIG. 7B shows the quadratic function F1. Similarly, the approximate functions (F2 to F17) of the group A2 and thereafter are also obtained.

Since the approximate functions calculated in this way are discontinuous, the weighted synthesis is performed in the overlapping region between the groups, and the result is used as the final approximate function F (x). For example, in the case of XC1 ≦ x ≦ XC2 F (x) = F1 (x) In the case of XC2 ≦ x ≦ XC3 F (x) = ((XC3-
x) ・ F1 (x) + (x−XC2) ・ F2 (x)) / (XC
3-XC2) In the case of XC3 ≦ x ≦ XC4 F (x) = ((XC4-
x) ・ F1 (x) + (x−XC3) ・ F2 (x)) / (XC
4-XC3) (In this case, the component of F3 is not included in order to simplify the formula, but of course F3 may be included.) The same applies to the following. Since the interpolation is performed by the polynomial, there is a problem that a high order of 8 or more is required, the amount of calculation becomes enormous, the error due to digit cancellation is large, and the correction accuracy is deteriorated. However, by using the interval division as described above, it is possible to perform highly accurate interpolation with simple calculation.

As described above, according to the first embodiment of the present invention, even when screen patterns having different gradation characteristics for photographs and characters are used, one gradation test pattern is output (printed). You can create a gradation correction table with. or,
The gradation correction table can be created by reading the gradation test pattern once. This reduces the complexity of the gradation correction operation. Further, by dividing the patch data into groups and obtaining the interpolation function, high correction accuracy can be obtained with a small amount of calculation.

<Second Embodiment> Next, a second embodiment of the present invention will be described. The block configuration is similar to that of the first embodiment. In this embodiment, the screen pattern used in the printer and the screen pattern used in the copying machine are different from each other. Therefore, the number of screen patterns and correction tables is doubled as compared with the first embodiment.

The gradation test pattern of this embodiment is shown in FIG. This gradation test pattern is roughly divided into left and right, and the screen pattern patch 7 for the printer is on the left side.
02, screen pattern patch 7 for the copier on the right
Place 03.

The calculation of the interpolation function of this embodiment is the same as that of the first embodiment, but the method of segmentation is different. Depending on the screen pattern, there may be a case where a gradation characteristic having a long flat region is obtained as shown in FIG. In such a case, one section is lengthened in the flat portion (group A1 in FIG. 9) to suppress sudden data fluctuation.

According to this embodiment, even if screen patterns having different gradation characteristics are used in the printer mode and the copying machine mode, the gradation correction table can be created by outputting one gradation pattern. This reduces the complexity of the gradation correction operation. Further, by dividing the patch data into groups to obtain the interpolation function and further increasing the group size in the portion where the gradation is flat, high correction accuracy can be obtained with a small amount of calculation.

<Third Embodiment> Next, a second embodiment of the present invention will be described. The block configuration is similar to that of the first embodiment. In this embodiment, a plurality of original modes (character photograph, character, photographic paper photograph, print photograph) are provided, and different screen patterns are used according to the original mode.

The structure of the gradation pattern is shown in FIG. The screen pattern corresponding to the four original modes is set to the upper left (90
2), upper right (903), lower left (904), lower right (90
It is located in 5). Further, since many types of patterns are arranged, the number of patches in one pattern is as small as 10. Therefore, the document mode is set to 4 as in the present embodiment.
For the type, 40 gradation patches are set for each color. That is, 160 gradation patches are set as a whole in the patch shown in FIG. For simplicity of explanation, only cyan will be described below.

In this embodiment, since the number of patches (the number of gradations) is small, the approximation accuracy may decrease. In order to prevent this, gradation correction data is created using measured values of different screen patterns.

FIG. 11 shows the method of calculating the approximation function of this embodiment.
Will be described with reference to.

In this embodiment, ten gradation patches are recorded for each original mode. The screen pattern patches of the first original mode are C1 to C10, the screen pattern patches of the second original mode are C11 to C20, and the patches corresponding to the third and fourth original modes are C21.
To C30 and C31 to C40. Assuming that the signal value for outputting the patch Ci is XCi, in the present embodiment, as shown in FIG.
As shown in (a) to 11 (d) and the following equation, the densities of the patches of the corresponding density ranks are sequentially shifted and set in each mode.

XC1 <XC11 <XC21 <XC31 <
XC2 <XC12 <... Also, standard gradation characteristics G1 (x), G2 (x), G3 (x), G4 of the respective screen patterns are prepared in advance.
(X) is measured and stored. FIG. 11A shows the standard gradation characteristic G1 (x) of the first screen pattern, the patch signal values XC1, XC2, ... And the patch area ratios ZC1, ZC2 ,.

Next, a value obtained by subtracting the standard gradation characteristic G1 (x) from the area ratios ZC1, ZC2, ... Is calculated, and this is calculated as QC1,
QC2, ... These represent variations from standard gradation characteristics. FIG. 11E corresponds to XC1 to XC3. Variations QC1 to QC3 are shown.

Similarly, the variations in the second, third, and fourth screen patterns are calculated as shown in FIGS. 11 (f) to 11 (h). Figure 1 shows these fluctuations superimposed on each other.
It becomes like 1 (i). From these point sequences, the approximation function G5
By calculating (x) and adding the standard gradation characteristics of each screen pattern to the obtained approximation function G5 (x),
An approximate function of the screen pattern is obtained.

The variation data shown in FIGS. 11E to 11H are data relating to different screen patterns, but since they are data of the same color component, the correlation is extremely strong. Therefore, the approximation function G5 (x) is calculated from these data.
If is calculated, the approximation calculation is performed using substantially four times the data, and the correction accuracy is improved. Further, by increasing the weight of the data from the screen patterns calculated when obtaining the approximate function, the correction accuracy can be improved even when the correlation between the screen patterns is small.

As described above, according to the third embodiment, even when screen patterns having different gradation characteristics are used in a plurality of original modes, the gradation correction table can be created by outputting one gradation pattern. . This reduces the complexity of the gradation correction operation.

Further, by creating the gradation correction data by using the gradation data of the pattern other than the corresponding screen pattern, it is possible to obtain a high correction accuracy with a small number of patches.

[0067]

According to the present invention, even when screen patterns having different gradation characteristics are used, a gradation correction table for each screen pattern can be created by outputting one gradation pattern. The complexity of the operation of is reduced.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing an example of a screen pattern.

FIG. 3 is a block diagram showing a detailed configuration of a gradation correction unit and a gradation processing unit.

FIG. 4 is a flowchart showing an operation in a test mode according to this embodiment.

FIG. 5 is a diagram showing a configuration example of a gradation pattern.

FIG. 6 is a diagram for explaining the creation of a gamma correction table.

FIG. 7 is a diagram for explaining a calculation method of an interpolation function.

FIG. 8 is a diagram showing a second configuration example of a gradation pattern.

FIG. 9 is a diagram for explaining a long gradation characteristic of a flat portion.

FIG. 10 is a diagram showing a third configuration example of a gradation pattern.

FIG. 11 is a diagram for explaining another calculation method of the interpolation function.

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) H04N 5/91 B41J 3/00 A 5C077 F term (reference) 2C262 AA24 AA26 AB07 AB19 BB01 BB27 BC15 EA06 EA07 2H027 DA09 DB01 EA18 EB04 EC03 5B057 AA11 BA02 CA01 CA02 CA07 CA12 CA16 CB01 CB02 CB08 CB12 CB16 CC01 CE11 CH07 CH08 5C052 AA11 AB02 DD04 FA03 FB01 FC00 FD02 FD11 FE01 5C053 FA04 KA04 LA03 5C077 LL04 LL08 Q15Q23 MP02 MP02

Claims (13)

[Claims] 1. An image reading section for optically reading an image and outputting an image signal, a gradation correction processing section for correcting the image signal using gradation correction data, and a gradation correction processing section for correcting the image signal according to the corrected image signal. A method of creating the gradation correction data in an image recording apparatus having an image recording unit for recording an image, comprising: providing the image recording unit with a predetermined screen pattern having a plurality of gradations and a plurality of types of screen patterns. Recording on one sheet of paper using the same, reading the recorded predetermined screen pattern by the image reading unit, and providing a read signal of the predetermined screen pattern, and a read signal of the predetermined screen pattern Based on the step of creating interpolation data indicating gradation characteristics, and creating the gradation correction data based on the interpolation data. Gradation correction data creation method characterized by comprising the step, the. 2. The gradation correction data creating method according to claim 1, wherein the predetermined screen pattern has a plurality of gradations and a plurality of screen patterns corresponding to a plurality of original modes. 3. The number of times of reading the predetermined screen pattern required to create the gradation correction data is 1
3. The gradation correction data creation method according to claim 1, wherein the gradation correction data creation is performed once. 4. The predetermined screen pattern includes a plurality of patches having a plurality of gradations different from each other, and the step of creating the interpolation data classifies the plurality of patches into a plurality of groups including gradation overlaps. Then, from the read data of the patch configured for each group,
4. The gradation correction data creating method according to claim 1, further comprising a step of calculating interpolation data for each group and synthesizing the interpolation data of all groups. 5. The gradation correction data creation according to claim 4, wherein the number of gradations included in each group is set independently for each group according to the value of the read data of the patch. Method. 6. The predetermined screen pattern includes a plurality of patches having a plurality of gradations different from each other, and the step of creating the interpolation data corresponds to a first screen pattern of the plurality of kinds of screen patterns. 3. The gradation according to claim 1, further comprising the step of creating interpolation data corresponding to the first screen pattern by referring to the read data corresponding to the second screen pattern and the read data corresponding to the second screen pattern. Correction data creation method. 7. The predetermined screen pattern includes a plurality of patches having a plurality of gradations different from each other, and the step of creating the interpolation data includes a value of read data of the patch corresponding to the plurality of types of screen patterns. And the step of creating interpolation data corresponding to each screen pattern based on a difference between the standard gradation characteristic value of each screen pattern and the standard gradation characteristic value of each screen pattern. Method. 8. The step of creating the interpolation data comprises:
8. The gradation correction data creating method according to claim 1, further comprising the step of creating the interpolation data from the read data using a polynomial approximation method. 9. An image reading unit that optically reads an image and outputs an image signal; a gradation correction processing unit that corrects the image signal output from the reading unit using gradation correction data; An image recording device for recording an image in accordance with the generated image signal, wherein the gradation correction processing unit has a predetermined screen having a plurality of gradations and a plurality of types of screen patterns. Pattern generating means for generating a pattern, recording means for recording the predetermined screen pattern generated by the pattern generating means on one sheet of paper using the image recording section, and the recorded predetermined screen pattern Pattern reading means for reading with the image reading unit and providing a read signal for the predetermined screen pattern; and reading the predetermined screen pattern It is characterized by comprising: interpolation data creating means for creating interpolation data indicating gradation characteristics based on a signal; and correction data creating means for creating the gradation correction data based on the interpolation data. Image recording device. 10. An image interface unit for inputting an image signal from outside is provided, wherein the gradation correction processing unit corrects an image signal provided from the image reading unit or the image interface unit. Claim 9
The image recording apparatus described. 11. The predetermined screen pattern includes a plurality of patches having a plurality of gradations different from each other, and the interpolation data creating unit classifies the plurality of patches into a plurality of groups including gradation overlaps, 10. The image recording apparatus according to claim 9, wherein interpolation data is calculated for each group from the read data of the patch formed for each group, and the interpolation data for all groups are combined. 12. The predetermined screen pattern includes a plurality of patches having a plurality of gradations different from each other, and the interpolation data creating means reads the first screen pattern of the plurality of types of screen patterns. The image recording apparatus according to claim 9, wherein the interpolation data corresponding to the first screen pattern is created by referring to the data and the read data corresponding to the second screen pattern. 13. The predetermined screen pattern includes a plurality of patches having a plurality of gradations different from each other, and the interpolation data creating means has a value of read data of the patch corresponding to the plurality of types of screen patterns, 10. The image recording apparatus according to claim 9, wherein the interpolation data corresponding to each screen pattern is created based on the difference between the standard gradation characteristic value of each screen pattern.