JPH08107508A - Device and method for processing image - Google Patents

Abstract

PURPOSE: To precisely estimate a color reproducing range by providing a setting means for setting the color reproducing range at the value of the reference axis of an output means based on sample data converted by a converting means. CONSTITUTION: A host 401 transmits pattern data 202 to a color printer 101 based on a ROM 201 where the data showing a sample color are stored. The color printer 101 outputs RGB data stored in a memory 205 to an image processing circuit 208 based on the control of a CPU 212. Then, the image data provided with the changes of 16 gradations in respective axial directions with RGB signals, for example, are applied based on the value at the reference axis of the pattern data and color samples in 4096 colors are outputted to paper sheets 211. Therefore, since the samples of mixed colors are used, in comparison with the estimation of the color reproducing range while using only a single color, even the ranges to be reproduced by mixing colors can be estimated and the exact color reproducing range of the printer 101 can be estimated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing apparatus and method relating to color signal processing such as a color scanner device and a color printer.

[0002]

2. Description of the Related Art In an apparatus that handles colors, such as a color scanner apparatus, a color display apparatus, and a color printer, the range of colors reproduced by each device (color reproduction area) is generally greatly different. Therefore, colors that can be reproduced on one device cannot be reproduced on another device.

As a conventional method for predicting which color can be reproduced and which cannot be reproduced, for example, eight preset reference colors (Red, Green,
Blue, Yellow, Magenta, Cyan,
A method for prediction based on Black, White) has been proposed. This is a method in which a dodecahedron having coordinate points of 8 colors existing in a uniform color space as vertices is considered as shown in FIG. 13 and the reproduction range is estimated with the surface as a boundary.

[0004]

However, when an existing color printer is taken as an example and its color reproduction area is actually plotted, it is found that the color reproduction area also has a distorted curved surface as shown in FIG. . Therefore, the method of estimating the color reproduction area on each plane having the vertexes of the coordinate points of the above eight colors has a problem that the determination accuracy becomes poor.

The present invention has been made in view of the above points, and an object of the first invention of the present application is to accurately estimate a color reproduction range.

It is an object of the second invention of the present application to supplement the insufficient sample data so that the color reproduction range can be accurately estimated regardless of the first sample data.

An object of the third invention of the present application is to accurately determine the color reproduction range based on the output sample color of the mixed color.

[0008]

In order to achieve the above object, the image processing apparatus of the first invention of the present application is a sample obtained by reading the sample color output by the output means based on the data indicating the sample color. Input means for inputting data, conversion means for converting the sample data into data on a plane having an arbitrary reference axis value based on the value on the reference axis of the sample data input by the input means, and conversion by the conversion means Setting means for setting the color reproduction range at the value of the reference axis of the output means based on the sampled data.

The image processing apparatus of the second invention of the present application obtains the first sample output means for outputting the first sample based on the sample data indicating the sample color, and the sample output by the output means for reading. And a second sample output means for outputting a second sample containing a sample different from the sample based on the sample measurement data.

The image processing apparatus of the third invention of the present application is an input means for reading the sample color of the mixed color outputted by the output means on the basis of the data showing the sample color and inputting the sample data, and the sample color of the inputted mixed color. It is characterized by comprising an estimating means for estimating the color reproduction range of the output means on the basis of sample data indicating

[0011]

【Example】

(Embodiment 1) As a first embodiment of the present invention, an example of estimating a color reproduction area of a color printer will be described below.

Description of System Configuration FIG. 1 is a conceptual diagram showing a system in which a sample color is output to a sheet 211 in order to obtain color characteristic data of the color printer 101 and the colorimeter 301 measures the sample color. .

FIG. 2 is a block diagram showing the main configuration of each machine in the schematic diagram of the system shown in FIG.

When a mode for estimating the color reproduction range of the printer is selected by the operation unit such as a keyboard (not shown) for the host 401, the host 401 causes the CPU 200 to obtain a program and color characteristic data corresponding to the selected mode. The color patch data 202 is transmitted to the color printer apparatus 101 based on the ROM 201 in which the data indicating the sample color is stored.

Further, the color sample paper 2 from the colorimeter 301
When the result of measuring the color of each sample output by the color printer apparatus 101 is received at 11, the CPU 2
00 estimates the color reproduction range of the color printer apparatus 101 based on the received sample data, and sends the estimation result to the color printer apparatus 101.

The color printer device 101 includes a host 40
The data from No. 1 is received, and the normal process or the sample color output process is performed based on the received data.

First, the normal processing mode will be described.
When the result of receiving the received data from the host through the interface 204 and analyzing by the CPU 212 is the normal processing mode, the received RGB data is stored in the memory 2
Each of the RGB components is stored in the memory 205 in 05 and output to the selector 206. Selector 206 is CPU 212
Output to the color space compression circuit 207 under the control of. The color space compression circuit performs color space compression processing on the RGB data input based on the color reproduction range data 214 stored in the RAM 213 and the program stored in the ROM 215, and outputs it to the image processing circuit 208. The image processing circuit 208 performs luminance density conversion, masking processing, U
Performs CR processing, blackening processing, etc., and executes the line buffer 20.
Output to 9. The line buffer 209 prints 25
The CMYK data input in synchronization with the image formation at 0 is output to the print 250.

Next, in the sample color output processing mode, the RG stored in the memory 205 is the same as in the normal processing mode.
The B data is output to the image processing circuit 208 under the control of the CPU 212, and thereafter, the same processing as in the normal processing mode is performed and the color patch is output to the color sample paper 211.

The color space compression process is a process for converting input data that cannot be faithfully reproduced outside the color reproduction range of the printer device into data within the color reproduction range of the printer device because it is output faithfully based on the input data. Yes, for example, in FIG.
There are color space compression methods as shown in (1) and (2).

FIG. 4A shows a color space compression method in which the color reproduction range is faithfully reproduced and the input data outside the color reproduction range is compressed to the outermost edge of the color reproduction range having the same brightness and the same hue. .

In FIG. 4B, the color reproduction range is faithfully reproduced, and the input data outside the color reproduction range is converted into the data within the color reproduction range having the smallest color difference.

Further, the color reproduction range data 214 used in the color space compression processing is updated with the data showing the color reproduction range estimated and obtained by the host 401.

Therefore, the color reproduction range data 214 is
The data corresponds to a change in the color reproduction range due to a change over time of the color printer apparatus 101 or an environment change, and accurately indicates the color reproduction range of the color printer apparatus 101 at that time.

Therefore, since the color space compression processing is performed based on accurate color reproduction range data, it is possible to perform highly accurate color space compression that effectively uses the color reproduction range.

The colorimeter 301 measures the color sample paper 211 and sends the color measurement result of each color patch to the host 401.

Description of Color Processing Device Device (Color Printer Device) FIG. 3 is a schematic configuration diagram of the color printer device 101 to which the present invention is applied.

In the figure, 120 to 123 are color ink cartridges, and the cartridge 120 has yellow (Y) ink.
Color ink, magenta (M) in the cartridge 121
Color ink, the cartridge 122 is filled with cyan (C) color ink, and the cartridge 123 is filled with black (K) color ink. An independent pipe extends from each ink cartridge and has a pressure pump 116.
Is connected to Each ink is sent from the pressure pump 116 to the print head 112 at a constant pressure. The paper 211 is the color printer device 10.
The sheet is fed from the rear surface of the sheet No. 1 and is fixed by the sheet platen 111 and the front guide roller 115. The operation of the printer device is performed by pressing a key button on the control panel 118, and the control board 119 controls all operations of the color printer device 101.

In order to print to the color printer device, a print control command and print data may be sent via an interface (not shown). For example, when RGB colors are designated by a color designation command, the control board 119 converts the YMCK data via an internal color processing device and then drives the print head 112 to print the data on the paper 211.

The color reproduction range reproduced by the color printer 101 is the ink characteristics of each of YMCK and the paper 211.
And the color processing method in the control board 119.

Description of Method for Obtaining Color Characteristic Data of Color Printer Device A method for obtaining color characteristic data of the color printer device 101 using the procedure shown in FIG. 4 will be described below.

The work proceeds according to the procedure described in [1] to [3].

[1] Output of Color Sample First, image data having a change of 16 gradations in each axis direction by RGB signals is given to the color printer device 101 connected to the host computer 401 based on the pattern data 202. , 4096 color samples on paper 21
Output to 1.

[2] Color measurement of color sample Next, the paper 211 on which the color sample is printed is measured with a colorimeter 30.
The tristimulus value XYZ is set to 1 for each color and recorded as color characteristic data and transmitted to the host 401.

In the present embodiment, for the sake of convenience, each color sample is numbered (in the order of measurement) with sample points 1, 2, 3, ... Sample point 4096.

[3] Plotting of Measurement Data In this embodiment, in order to determine the color reproduction area in the uniform color space, the measured XYZ values are converted into CIE1976 Lab values.

FIG. 14 is a plot of the data obtained by the measurement on the spatial coordinates, and shows the distribution characteristics of the colors output by the color printer device of the present embodiment. There are three coordinate axes in the uniform color space, namely the L axis, the a axis, and the b axis.

Therefore, in the present invention, since the mixed color sample is used as shown in the above [1], the range that can be reproduced by the mixed color is compared with the estimation using the color reproduction range using only a single color. Can even be estimated,
It is possible to accurately estimate the color reproduction range of the color printer apparatus 101.

In the present invention, the pattern data 202, that is, the data showing the sample color is shown by the RGB signal.
For example, YMC signal, YMCK signal, XYZ signal, L ^* a ^*
Other signal formats such as b ^* signal may be used.

In the present invention, the coordinate axes used for plotting the measurement data are not limited to the L-axis, the a-axis, and the b-axis, but for example, the Y-axis,
Other coordinate axes such as the I axis, the Q axis, the L axis, the U axis, and the V axis may be used.

Next, a method of estimating the color reproduction range using the color characteristic data obtained by the above method will be described.

The work proceeds according to the procedure described in.

In order to capture an overview of objects in space, consider one slide axis and a plurality of plane coordinate systems orthogonal to the slide axis. Here, the plane represented by this plane coordinate system will be referred to as a slice plane hereinafter.

The slide axis can be arbitrarily defined in the space, but in this embodiment, the L axis, which is one of the coordinate axes, is the slide axis, that is, the reference coordinate. Therefore, the slice plane for this is a plane parallel to both the a-axis and the b-axis.

Sticking Sample Points to Slice Plane Next, sample points scattered in space are stuck to the slice plane. Here, the slice planes are treated as the same plane in order from the sample point having the lowest L value and only a predetermined number of sample points are collected. For example, if the number of samples is 729 and it is divided into 6 slice planes, the next smallest sample point from the smallest L value sample point is picked up (in ascending order), and the first slice at the 121st sample point. A plane s1 is formed. Next slice plane s
2 picks up from 122nd to 242nd. Figure 5
[Fig. 4] is a distribution diagram showing a state of six actual slice planes (s1 to s6) formed by repeating such processing.

Therefore, since the number of sample points in each slice plane becomes uniform, it is possible to accurately estimate the color reproduction range in all planes.

Introduction of Polar Coordinates on Slice Plane Next, a polar coordinate system is introduced on the slice plane. FIG. 6 shows the movement of the coordinate origin and conversion to the polar coordinate system by taking the slice plane s3 as an example.

First, with respect to all the points stuck on the slice plane s3, the center point (Xc) is the average of the coordinates of all the points (Xc =
Calculated from (1 / n) * Σp). Further, as shown in FIG. 6 (1), it may be obtained by appropriately plotting the coordinates. When the central coordinates are obtained, mapping is performed so that the central coordinates are the origin, as shown in FIG. 6 (2).

Next, a polar coordinate system will be defined. When the straight line connecting the origin and the sample point coincides with the boundary line between the quadrant I and the quadrant IV, θ = 0 is set, and the polar coordinate system is defined counterclockwise starting from this point. In the polar coordinate system, the position of the point is determined by the angle θ and the length L.

By calculating the center point as described above and mapping so that the center coordinates are at the origin, the calculation used to estimate the color reproduction thereafter, the calculation used to determine the inside and outside of the area, and the color space The calculation used for compression becomes simpler,
The time required for each processing can be shortened.

Definition of Function for Returning Positions of Points on Outer Perimeter FIG. 7 shows how to find the positions of points on the outer perimeter and grasp the appearance of all points on s3. In FIG. 7 (1),
The outer peripheral line that surrounds all points has nine points (k1, k2, ...,
k9). The sample points plotted in the polar coordinate system in FIG. 6B are used to determine these points. A method of drawing a rough outline from the plotted points on the coordinate plane to obtain each vertex is also conceivable, but well-known convex surface generation algorithms such as convex surface estimation method may be applied. . Detailed description of these will be omitted because it departs from the spirit of the present invention, but in any case, s3 as shown in FIG.
Find the vertices that define the perimeter that surrounds the top point. Once these vertex groups are obtained, the values between the vertices are filled in by linear interpolation as shown in FIG. 7C to calculate data up to the required resolution. These filled and obtained values are referred to as B1, B2, ..., Bn and are referred to as border area values.

Creation of Border Table After the above-mentioned group of vertices on the outer peripheral line is obtained, a border table is created based on it. FIG. 8 shows a structure of a border table corresponding to six slice planes in the Lab space and a part of the table data in an enlarged manner.

In the table data, one record corresponds to each slice plane, and a tag for identifying each slice plane is provided at the head of each record. The elements in the record are Tag, Lb, Lu, Xc, Yc, followed by B.
, B2, ..., Bn. The meaning of each is
Tag = identifier, Lb = lower limit luminance of slice plane, Lu
= Upper limit brightness of slice plane, Xc = X coordinate of center point, Y
c = Y coordinate of center point, B1, B2, ..., Bn = border area value.

By the above processing, the color reproduction range of the color printer 101 is interpolated by using the color reproduction range for each luminance stored in the border table, so that the color reproduction range can be shown accurately and easily.

The brightness of the slice plane to which the sample points are attached in the work may be set to an arbitrary value in advance or may be obtained from the obtained sample points.

Next, a method of judging whether or not the input data is within the area by using the border table by using the judgment subroutine function will be described with reference to FIG.

When the process is started, the input value is delivered in step S101. Step S102
Then, it is determined which slice plane L is closest to.
If it is determined that L is not close to any slice plane, the value of L of the input data is out of the area, so step S10.
8, the process proceeds to step S103 in other cases. In step S103, the record corresponding to the input value L is retrieved from the border table. Step S104
Then, the X coordinate of the center point recorded in the record (= X
c) and Y coordinate (= Yc) move origin (Xx = zA-X
c, Yy = zB-Yc), and then maps to a polar coordinate system. The distance d from the origin on polar coordinates is SQRT (Xx ^ 2
+ Yy ^ 2). The rotation angle θ is ArcSin (X
x / d). In step S105, the border area value dT corresponding to the obtained θ is read. In step S106, the magnitude relationship between the values d and dT is determined. Here, if d <dT, the process proceeds to step S107; otherwise, the process proceeds to step S108. In step S107, the in-area code indicating that it is in the area is assigned to the return value, and in the step S108, the out-of-area code indicating that it is outside the area is assigned to the return value, and the processing of this function ends.

(Second Embodiment) A second embodiment of the present application will be described below with reference to the drawings.

The second embodiment of the present application aims to more accurately estimate the outer ring of the region to be discriminated by increasing the sample points in the region roughly distributed in space as a result of plotting the measurement data. To do.

The description of the same parts in the system configuration and procedure as those in the embodiment will be omitted. FIG. 10 is a schematic flowchart showing the processing of this embodiment. First, in step S110, color patch samples that are even in the input space are prepared and output. Next, step S1
At 20, the color patch sample is measured. Next, the values measured in step S130 are mapped to a uniform color space (Lab space) and then attached to the slice plane.

In the present embodiment, each sample point is attached to the slice plane having the shortest distance. The slice planes are evenly prepared on the L axis, and are set so that the L values are even at 10 intervals (25 <L <35, 35 <L <45, ... 75 <
L <85). FIG. 11 shows the state of sample points actually attached to six slice planes.

In step S140, the number of sample points attached in each slice plane is counted to determine whether or not a desired number is present. If the number of sample points is small, the process proceeds to step S160, and if not, the process proceeds to step S150. In step S160, based on the sample points on the slice plane, the input data is regenerated so as to increase the sample points, and then step S1
The process proceeds to step 10 and the sample output and color measurement are repeated again.
In step S150, area estimation is performed by interpolation, and in step S170 border area data is generated from the result of the estimation, and the processing ends.

Therefore, when the pattern data indicating the color sample output from the host 401 is an RGB signal and a change of 16 gradations is given in each axial direction, the RGB signal is a uniform color space signal of the L ^* a ^* b ^* signal. However, it is possible to solve the problem that the number of sample points included in the L value of a certain interval is small and becomes rough, and it is possible to generate border area data with high accuracy.

Next, an example of processing for obtaining input data near a rough area will be described.

FIG. 12 shows the processing in step S160 in FIG.

In step S1210, initialization processing is performed. Here, a pointer or the like indicating a sample attached to the plane is set. In step S1220, it is determined whether or not all the sample points have been referenced, and if there are sample points that have not been referenced yet, the flow advances to step S1231.

In step S1231, a random number is generated,
In step S1232, the displacement in the R direction is determined based on this random number. Similarly, a random number is generated in step S1233, a displacement in the G direction is determined based on this random number in step S1234, a random number is generated in step S1235, and a displacement in the B direction is determined based on this random number in step S1236. In step S1237, step S12
It is determined whether the RGB values determined in 31 to 1236 are correct values, and if correct, the process proceeds to step S1238, and if not, the process proceeds to step S1239. Step S12
At 38, additional registration processing of sample points is performed. After moving the pointer to the next sample point in step S1239, the process returns to step S1220.

Further, as another processing for obtaining the input data in the vicinity of the rough area, the RG is generated based on the RGB data indicating the sampling points of the rough area generated by the host 401.
The additional registration of the sample points may be performed so that the vicinity of the B data is supplemented.

Although the obtained color reproduction range is used in the color space compression processing in the above-described embodiment, the present invention is not limited to this. For example, is the input image data within the color reproduction range? It may be used for the color reproduction range check process of determining whether or not and notifying the user. By using the data showing the color reproduction range obtained by the method of the present invention for this color reproduction range check processing, it is possible to obtain an effect that an accurate determination can be made based on the accurate color reproduction range of the output device. To be

Further, although the above-described embodiment shows the method performed by the system using the three devices of the host 401, the color printer 101, and the colorimeter 301, the present invention is not limited to this, and, for example, the input means. Alternatively, a color copier having an image processing means and an output means may be used alone.

Although the color printer 101 is used as the output device in the above embodiment, other output devices such as a monitor may be used.

The present invention may also be achieved by supplying a program to a system or device.

[0072]

As described above, according to the first aspect of the present invention, the color reproduction range can be accurately estimated.

According to the second aspect of the present invention, the color reproduction range can be accurately estimated by supplementing the insufficient sample data regardless of the first sample data.

Furthermore, according to the third aspect of the present invention, the color reproduction range can be accurately determined based on the output mixed sample colors.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an example of an image processing apparatus according to the present invention.

FIG. 2 is a block diagram showing an example of an image processing apparatus according to the present invention.

FIG. 3 is a configuration diagram showing an example of an image output apparatus according to the present invention.

FIG. 4 is a diagram showing an example of color space compression according to the present invention.

FIG. 5 is a conceptual diagram showing how sample points in a uniform color space are pasted on a slice plane in the first embodiment of the present application.

FIG. 6 is a diagram showing an example of a concept of mapping points in a slice plane to a polar coordinate system according to the present invention.

FIG. 7 is a diagram showing an example of a concept of mapping vertices on an outer peripheral line to a polar coordinate system according to the present invention.

FIG. 8 is a diagram showing an example of a concept of a border table according to the present invention.

FIG. 9 is a diagram showing an example of a procedure of a color reproduction area determination function according to the present invention.

FIG. 10 is a diagram showing an example of sample point replenishment processing in the second embodiment of the present application.

FIG. 11 is a conceptual diagram showing how sample points in a uniform color space are pasted on a slice plane in the second embodiment of the present application.

FIG. 12 is a diagram showing a flowchart showing a process for obtaining an input value near a rough region in the second embodiment of the present application.

FIG. 13 is a diagram showing a color reproduction area by an octahedron.

FIG. 14 is a diagram showing an actual color distribution of a color output device.

[Explanation of symbols]

 101 color printer 211 color sample paper 301 colorimeter 401 host

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location H04N 1/46 H04N 1/46 Z

Claims (16)

[Claims] 1. An input unit for inputting sample data obtained by reading a sample color output by an output unit on the basis of data indicating a sample color, and based on a value on a reference axis of the sample data input by the input unit, Converting means for converting the sample data into data on a plane having an arbitrary reference axis value; and setting means for setting a color reproduction range at the reference axis value of the output means based on the sample data converted by the converting means. An image processing apparatus comprising: 2. The conversion means regards sample data up to an arbitrary number in ascending order from a value with a small value on the reference axis as one area, and converts the sample data into data on a plane of the value of the arbitrary reference axis. The image processing apparatus according to claim 1, wherein the image processing apparatus performs conversion. 3. The conversion means converts the sample data input by the input means into data on a plane closest to a preset plane of a plurality of reference axis values. 1. The image processing device according to 1. 4. A determination means for determining whether or not the number of sample data on each plane converted by the conversion means exceeds a predetermined number, and a generation for generating new sample data based on the result of the determination means. And means.
The image processing device described. 5. The image processing apparatus according to claim 1, further comprising a color space compression unit that performs a color space compression process based on the color reproduction range set by the setting unit. 6. The image processing apparatus according to claim 1, further comprising a determination unit that determines whether or not the input data is within the color reproduction range based on the color reproduction range set by the setting unit. 7. A first sample output means for outputting a first sample based on sample data indicating a sample color, and a sample output by the output means is read,
An image comprising: an input unit for inputting the obtained sample measurement data; and a second sample output unit for outputting a second sample containing a sample different from the sample based on the sample measurement data. Processing equipment. 8. The second sample output means is a determination means for determining whether or not to replenish the sample data based on the sample measurement data input by the input means, and a new sample based on the result of the determination means. The image processing apparatus according to claim 7, further comprising a second sample output unit that generates and outputs data. 9. The image processing apparatus according to claim 8, wherein the determination unit makes a determination based on the number of the sample measurement data existing in an arbitrary area. 10. The image processing apparatus according to claim 7, further comprising a detection unit that detects the output characteristic of the output unit based on the first and second sample data. 11. Input means for reading the sample color of the mixed color output by the output means on the basis of the data indicating the sample color and inputting the sample data, and the output means on the basis of the sample data indicating the input sample color of the mixed color. An image processing apparatus, comprising: an estimation unit that estimates the color reproduction range of the image. 12. A storage unit that stores the color reproduction range of the output unit in advance, and the storage unit stores the color reproduction range of the output unit stored in advance in the color reproduction range estimated by the estimation unit. The image processing apparatus according to claim 11, further comprising update means for updating. 13. The image processing apparatus according to claim 11, further comprising an input unit for inputting image data representing a document, and an image output unit for outputting an image based on the image data input by the input unit. . 14. The value of an arbitrary reference axis is read based on the value of the sample axis input from the input means by reading the sample color output from the output means based on the data indicating the sample color The image processing method is characterized in that the color reproduction range at the value of the reference axis of the output means is set based on the sample data converted by the conversion means. 15. A first sample is output based on sample data indicating a sample color, and the sample output by said output means is read,
An image processing method, wherein the obtained sample measurement data is input, and a second sample including a sample different from the sample is output based on the sample measurement data. 16. The color reproduction of the output means based on the sample color indicating the mixed color sample color read by the output means on the basis of the data indicating the sample color and inputting the sample data. An image processing method characterized by estimating a range.