JPH10153484A - Color measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To display measurement result such as the color difference from a reference color so as to be easy to understand by displaying stored reference colors, a measured color in photographing a subject to be measured, and colors showing the color difference direction of pigment data together with the color difference data. SOLUTION: The image signal of a subject to be measured photographed by a color CCD camera 58 according to a shutter speed regulation signal from an image processing device 70 is inputted to an image processing part 72 as a signal each of RGB colors through an image signal interface 71. The preliminary measured measurement data by a white reference plate A, the measurement data by a plurality of colored reference plates, and the color data of the colored reference plates are stored in a white reference data memory 73 and a colored reference data memory 74, and the image processing part 72 compares the inputted RGB image signals with each reference data to calculate XYZ color specification value (color difference value), and further converts tit into L*a*b* color specification value. When a convergence error is present, it is displayed on a monitor 80 together with its numerical value, the color in the color difference direction, and the color of the colored reference plate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color measuring device for measuring the color of an object and displaying the measurement result.

[0002]

2. Description of the Related Art In order to specify and display the color of an object, Munsell display based on three attributes of hue, lightness and saturation and color difference from a standard color are used. The device is designed to express sexuality.

[0003] In many products such as an automobile body, not only the number of colors, but also a uniform and balanced coating as a whole is required. This is because if the paint color is partially changed, the commercial value of the paint color is reduced. Therefore, a color measuring device based on the above-described color expression technique has been developed and used for determining the paint color of an automobile body or the like.

As such a color measuring device, for example, Japanese Patent Application Laid-Open No. 7-55,569 discloses a method in which an object to be measured is illuminated, its reflected light is photographed by a camera, and the photographed reflected light is white or a reference light. There has been disclosed an apparatus for displaying on a monitor how much the color deviates from the color as an expression of a numerical value or an intuitive word.

[0005]

In the apparatus described in the above publication, the color difference between the measured color and the reference color is determined by the XYZ colorimetric values according to the CIE standard or other L * a * b.
* Although it is displayed as a color specification value, such a color specification value is thought to be able to represent the human visual sense numerically as much as possible. It takes considerable skill to determine if there is. On the other hand, in the above-mentioned publication, the state of the color is replaced with an intuitive word and displayed. However, even when such expressions are used, there are many individual differences and sensational issues regarding the colors recognized from the words, and it is sometimes difficult to understand.

Accordingly, an object of the present invention is to provide a color measuring device capable of displaying a measurement result of a color difference or the like more easily.

[0007]

According to the first aspect of the present invention, there is provided a photographing means for photographing a color image of a sample and outputting RGB signals of the photographed image.
A color measuring apparatus comprising: a conversion unit that receives the RGB signal as input and converts the RGB value into a predetermined colorimetric value; and a display unit that displays color data based on the colorimetric value. A standard color data storage unit for storing color data obtained by the conversion unit when the standard plate is photographed by the photographing unit as color data; and a color of the reference colored standard plate photographed by the photographing unit. Standard color storage means for storing the color data, and color data stored in the standard color data storage means and colorimetric values obtained when the measurement object is photographed by the photographing means, and color difference data of the measurement object is calculated. The color difference calculation means to be obtained and the reference color stored in the standard color storage means together with the color difference data obtained by the color difference calculation means, the measurement when the object to be measured is photographed. And a color measuring device and having a data output means for the color indicating the color difference direction of the color difference data is displayed and output on the display means.

According to a second aspect of the present invention, in the color measuring device according to the first aspect, the color values obtained by the conversion means are coordinate values on a specific color system diagram. The color difference calculating means obtains a position vector of the measured color from the coordinate values of the colored standard plate and the coordinate values of the measurement object,
A color measuring device for calculating color difference data from the direction and magnitude of the vector.

According to a third aspect of the present invention, in the color measuring device according to the first aspect, the photographing means irradiates the sample with light at a predetermined angle, and irradiates the sample with light. A mirror that reflects light reflected from the sample at a plurality of spatial positions, and captures light reflected from the mirror,
A color measuring device comprising: an image photographing unit that outputs an RGB signal.

According to a fourth aspect of the present invention, in the color measuring device according to the third aspect, the color difference data is obtained for each reflection point at a plurality of spatial positions by the mirror. It is a measuring device.

[0011]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
An embodiment of the present invention will be described.

FIG. 1 is a block diagram showing the configuration of a color measuring apparatus to which the present invention is applied. This device includes a light source 5 described later.
The image processing device 70 is connected to a measuring head 50 which is a photographing means including the color CCD camera 2 and a color CCD camera 58, and an output of the image processing device 70 is displayed on a monitor 80 which is a display means.

The image processing unit 70 has an image processing unit 72 connected to the measuring head 50 and the monitor 80 via a video signal interface 71. In particular, the image processing unit 70 outputs a shutter speed adjustment signal for the color CCD camera 58. Sent out, the color CCD camera 58
Returns signals of R (red), G (green), and B (blue).

Further, a white standard data memory 73 and a colored standard data memory 74 are connected to the image processing section 72. As will be described later, the memories 73 and 74 store measurement data of a white standard plate measured in advance, measurement data of a plurality of colored standard plates, and color data of the colored standard plates. Therefore, the colored standard data memory 74 functions as a standard color data storage unit and a standard color storage unit.

As will be described later in detail, the image processing section 72 has a memory for color conversion therein and has an XY
A conversion matrix from the Z color system to the L * a * b * color system is stored, and an RGB image signal input via the image interface 71 is compared with each standard data to calculate an XYZ color value. Then, the calculation result is further converted into L * a * b * color specification values, and the difference between the measurement result of the colored standard plate and the measurement result of the measurement object is calculated.
The color in the color difference direction and the color of the colored standard plate are displayed on the monitor 80. Therefore, the image processing unit 72 functions as a conversion unit, a color difference calculation unit, and a data output unit.

As shown in FIG. 2, the measuring head 50 includes a light source 52, mirror sets 61 and 62, and a condenser lens 5.
9 and the like are provided.

The light source 52 reflects and condenses the light from the bulb 53 with a reflector 54 and outputs it as parallel light by a light projecting lens 55. This light source 52 is fixed to the casing 51 of the measuring head 50, and its parallel light is incident on the sample S at an incident angle of 45 °.
Is reflected by the light transmitting mirror 56 also supported by the casing 51. Therefore, the light source 52 and the light transmitting mirror function as irradiation means.

A color CCD camera 58 is attached to the casing 51 so that the condenser lens 59 is aligned with a normal line h passing through the center P of the sample window 57. In the vicinity of the sample window 57, two mirror sets 61 and 62 surrounding the normal h are set.

The lower mirror set 61 is a sample S of the irradiation light.
The reflected light having a reflection angle of 30 ° with respect to the surface is reflected toward the condenser lens 59, and the upper mirror set 62 reflects the reflected light having a reflection angle of 70 ° with respect to the sample surface toward the condenser lens. As shown in FIG. 3, each of the mirror sets 61 and 62 has eight flat mirrors 61a and 62a arranged at equal intervals in the circumferential direction around the normal h. Thus, the color CCD camera 58 has the mirror set 6
The color CCD camera 58 collects light from a total of 17 measurement points, including eight 30 ° reflected lights by 1 and eight 70 ° reflected lights by the mirror set 62 and 90 ° reflected light on the normal line.
It is taken in. The mirror sets 61 and 6
By changing the angle of each of the two mirrors, any reflected light from the sample S can be measured.

The color CCD camera 58 functions as an image photographing means, and an image forming portion corresponding to each of the above-mentioned measurement points is determined. A plurality of light receiving elements for each of R, G, and B corresponding to each of the measurement points are provided. For example, a total of 10 dots of 10 dots each
It is composed of 0 pixels. This color CCD camera 5
As shown in FIG. 4, the video captured by the camera 8 is an image obtained by capturing the reflection by each of the mirror sets.

In FIG. 2, reference numeral 64 denotes a spacer extending from the casing 51 for determining the position of the surface of the measurement sample S. Further, supporting members 65, 66, 67 for supporting the light transmitting mirror 56 and the mirror sets 61, 62 on the casing 51 are provided. In particular, the supporting member 67 is provided with the light emitted from the light transmitting mirror 56 and the lower mirror set. It is arranged at a circumferential position that does not block the light beam reflected from 61.

By photographing the reflected light from the sample surface S at a plurality of points as described above, the difference in the color tone of the sample surface S with respect to the light source direction such as the difference between the highlight side and the shade side with respect to the light source direction. Can be measured at once. The highlight side and the shade side are, as shown in FIG. 16, the regular reflection when viewed from the side opposite to the light source is the highlight side, and the shade side when viewed from the same direction as the light source.

The measuring operation of the color measuring apparatus having the above configuration is as follows.
First, the procedure is performed from the setting of the shutter speed in the procedure of the flowchart shown in FIG.

First, the photographing shutter speed is initialized by the image processing device 70 (S1). Here, a sufficiently low speed is set as an initial setting.

Then, a photographing command signal is sent to the color CCD camera 58 of the measuring head with this shutter speed, and the reflected light from the surface of the measuring sample S is photographed (S
2). The video signal of the image captured by the color CCD camera 58 is stored in the internal RAM 72 as reflected light intensity information for each of R, G, and B colors (S3). The reflected light intensity information at this time is 256 from 0 to 255 according to the intensity level.
It is represented by the numerical value of the stage.

Next, the calculation unit 73 obtains the reflected light intensity for each of R, G, and B at each of the 17 measurement points (S
4). Here, the reflected light intensity is obtained as an average value of, for example, R at one measurement point, received by the CCD of 100 pixels. Similarly, G and B are obtained for each measurement point.

When the reflected light intensity at each measurement point is obtained in this way, the measurement points each having a value of 200 or less in each of R, G, and B are extracted. As the data of the extracted measurement points, the numbers of the measurement points, R, G, B
The respective reflected light intensities and the shutter speed used for photographing are stored (S5).

Next, all the measurement points have a reflected light intensity of 20.
It is checked whether or not it is extracted as satisfying the condition of 0 or less (S6). Until the extraction of all measurement points is completed, the shutter speed is reset to a higher speed in step S7 so that the obtained RGB values become smaller, and steps S2 to S6 are repeated. This is to use the measured value in the region where the dynamic range of the light receiving element as the sensor in the color CCD camera 58 is the highest.
5 is set to be in a region of about 80%.

Next, when all the measurement points have been extracted assuming that the condition of the reflected light intensity of 200 or less is satisfied, each of R, G,
The measured value of B is calibrated based on a predetermined reference shutter speed (S8). For example, when the reference shutter speed is set to 1/500 (sec), the reflected light intensity at the measurement point measured at a shutter speed of 1/250 is そ の of that, and conversely, the shutter speed is 1
The reflected light intensity at the measurement point measured at / 1000 is twice as large.

After setting the above shutter speed, the process proceeds to actual color measurement (S9).

The procedure of color measurement will be described. FIG.
6 is a flowchart illustrating a procedure of color measurement.

First, a white standard plate and a colored standard plate are measured before the color of the object to be measured is measured. For this, first, a white standard plate is measured by the measuring head 50 (S11). The measured data is used at each measurement point (17 points in the present embodiment as described above), and the measured values, that is, the RGB values and the known XYZ values, which are input as images, are used as white standard data as an image processing device. It is stored in the white standard data memory 73 in 70 (S12).

Next, the same measurement is performed on the colored standard plate (S13), and the measured value is used as the colored standard data together with the normal XYZ values of the colored standard plate and the colored standard plate in the image processing device 70. The data is stored in the data memory 74 (S14). At this time, the actually measured color of the colored standard plate is also stored in the colored standard data memory 74 as image data.

It is confirmed whether or not all the colored standard data of a plurality of arbitrarily designated colored standard plates are prepared according to the color of the object to be measured (S15). Here, the colored standard plate is
It is desirable to prepare a plurality corresponding to each hue.

When all the necessary colored standard data are prepared, a conversion parameter from RGB values to XYZ values for each hue is calculated from the colored standard data (S1).
6). The determined conversion parameters are also stored in the colored standard data memory 74. If it is determined in step S15 that all the necessary colored standard data are not present, the process returns to step S13, and the colored standard plates are sequentially replaced to obtain colored standard data.

In the calculation of the conversion parameters (S16), the area is divided for each hue, and a conversion formula suitable for each area is calculated and set. This is because L * a * b shown in FIG.
* In the color system chromaticity diagram, each hue is divided into a fan shape centering on achromatic "white" represented near a * = 0 and b * = 0. FIG. 7 shows the position of each color on the L * a * b * color system chromaticity diagram.

Here, when the conversion formula is expressed by the general formula X = a1.R + b1.G + c1.BY = a2.R + b2.G + c2.BZ = a3.R + b3.G + c3.B, it is 3 from the color data of one color. Are obtained from the three color data, the conversion parameters of a1 to c3 are 3
The original simultaneous linear equation is solved, and by solving this, a1
To c3 are determined. Therefore, for example, take three points for each area such as white, green, yellow, etc.
Based on the RGB values of these three points and the known XYZ values, RGB
Obtain a conversion parameter from the value to the XYZ value.

This is shown in a subroutine flowchart as shown in FIG. That is, the step S11
Based on the RGB values of the white standard plate and the colored standard plate obtained in steps S15 to S15, using a conversion matrix stored in a color system conversion memory, a known XYZ
Convert the value to an L * a * b * value and convert the a * b * value to L *
The position of the color in the a * b * color system chromaticity diagram is determined (S51). Next, it is divided into fan-shaped regions requiring "white" (a * = 0, b * = 0) based on the position of each color in the L * a * b * color system chromaticity diagram (S52). And
For each of the fan-shaped regions including “white”, three known XY points
The above simultaneous equations are solved from the Z value and the RGB values, and the conversion parameters a1 to c3 are obtained (S53).

Thereafter, returning to the flow chart of the color measurement shown in FIG. 6, the color measurement of the object to be measured after step S17 is performed.

In the measurement of the object to be measured, first, the object is measured (photographed) by the above-described measuring device (S1).
7). Then, RGB signals are extracted from the measured image, and the RGB values are compared with the previously stored white standard data to determine a difference in the brightness component of the measurement object (S18).

Next, conversion parameters corresponding to the color of the object to be measured are read out from the standard data memory 74 with colors, and the RGB values are converted into XYZ colorimetric values using this (S19). Then, a color conversion matrix is read from the color system conversion memory, and the XYZ color value is set to L using this.
It is converted to * a * b * color values (S20).

As will be described later, the converted L * a * b * color values are expressed as color differences with respect to a reference color (measured value of a colored standard plate) on the L * a * b * color system chromaticity diagram. , The numerical value, the color indicating the direction of the color shift, and the reference color itself are displayed (measurement / measurement result display, S21).

Hereinafter, the display of the measurement result will be described.

In order to display the measurement result, it is necessary to obtain the color shift from the reference color as a numerical value. Therefore, first, as shown in FIG. 9, the color difference vector D obtained by subtracting the position of the measured color from the position of the reference color on the L * a * b * color system chromaticity diagram is used to calculate the brightness component in the vertical direction. Vector L
And a chroma component vector C in the radial direction from the central achromatic axis (0 to L *) and a hue component vector H in the rotational direction about the achromatic axis. Here, as the reference color, a value measured by the above-described colored standard plate is used.

Next, a color difference from the reference color is obtained from the lightness, chroma and color components thus decomposed.
First, as shown in FIG.
Is expressed as a numerical value by the length of the vector L, with the upward direction (white direction) as (+). Further, as for the saturation, even the color is expressed by setting the direction in which the direction of the vector C is outward to (+).

Next, regarding the hue, this cannot be determined only by the color difference vector. Therefore, as shown in FIG.
The a * b * color system chromaticity diagram is divided into representative hues, for example, red, yellow, green, and blue spectral color directions centering on the achromatic color origin. And the name of each dividing line is red dividing line,
A yellow dividing line, a green dividing line, and a blue dividing line are used.

As shown in FIG. 12, the coordinates of the measured color and the coordinates of the reference color (measured value of the colored standard plate) on the L * a * b * color system chromaticity diagram as described above. When the hue component vector H in the rotation direction of the color difference vector D is extracted as the color difference vector D using the positional shift, this becomes the hue difference. A hue shift is represented by a dividing line extending from the hue component vector H in the rotation direction. That is, in the example shown in FIG. 12, the hue component vector H becomes “yellow” because it goes to the yellow dividing line.

Further, as shown in FIG. 13, when the hue component vector in the rotation direction straddles the division line, the hue is expressed by the division line ahead. That is, in the example shown in FIG. 13A, the hue vector is “greenish” because the hue vector extends to the green division line over the yellow division line. In the example shown in FIG. Since the tip is on the yellow dividing line, it is described as being shifted to “yellow”.

FIG. 14 shows the expression of the shift of the color shift by the hue vector in each area on the L * a * b * color system chromaticity diagram obtained in this manner. And
The length of the hue component vector of this shift expression is the color shift amount (numerical value).

The brightness, chroma, and hue difference obtained in this manner are displayed on the monitor 80 as numerical values for each of a plurality of measurement points (17 points in the present embodiment). For the hue difference, the color itself in the color direction is displayed together with its numerical value, and the reference color is also displayed together with the color of the measurement result. For example, in the above example, regarding the hue difference, the color in the color direction having the difference is red (r) if reddish, yellow (y) if yellowish, and green (g) if greenish. If it is bluish, blue (b) is displayed together with the color shift amount.

FIG. 15 shows an example of actual display on the monitor screen 81. Here, numerical values of lightness (brightness), saturation (even), and hue difference (hue) with respect to the measured reference color are displayed for each measurement point (17 points), and the background of the hue direction is used as a background. Displays colors (r, y, g, b, etc.)
Further, a color 90 photographed in the implementation for each measurement point is displayed around it, and a reference color (color of a colored standard plate corresponding to the measurement object) 95 and a current measurement color 96 are displayed in the left corner. Things. The display of the current measurement color 96 shown in the left corner may be switched and displayed for each specific measurement point. In this case, the color for each measurement point when the colored standard plate is measured is also displayed for the reference color. As a display example, in addition to this, for example, the numerical value itself may be slightly bolded and the numerical value itself may be displayed in a color indicating the color direction.

As described above, the actual measurement color is displayed by displaying the reference color and the color indicating the direction of the color misregistration on the monitor, instead of simply expressing the measurement result by numerical values or sensory words. It is possible to visually check how much the color differs from the reference color. Therefore, even if the monitor is small, it is easier to understand than a display using only numerical values, and it is possible to cope with a reduction in the size of an apparatus in which a monitor is provided in a measuring head, for example.

[0053]

According to the present invention described above, the following effects can be obtained for each claim.

According to the first and second aspects of the present invention,
The color difference data is displayed together with its numerical value, the color of the object to be measured, the reference color, and the color in the color difference direction of the color difference data. Will be better understood visually. In addition, since the color measurement result can be recognized even if the screen of the display means is small, the color measurement result can be accurately recognized even if the screen of the display means is small as compared with the display using only character display. Therefore, the size of the device can be reduced.

According to the third and fourth aspects of the present invention, an image of the object to be measured is photographed by photographing means provided with mirrors for reflecting the reflected light from the object to be measured at a plurality of spatial positions. Therefore, in addition to the effects of the first and second aspects, it is possible to obtain color difference data of the object to be measured when viewed from a plurality of directions at a time, thereby improving measurement efficiency.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a color measuring device to which the present invention is applied.

FIG. 2 is a drawing showing details of the measuring head shown in FIG. 1;

FIG. 3 is a view showing an arrangement of a mirror set shown in FIG. 1;

FIG. 4 is a drawing showing an example of a reflected light image by the apparatus shown in FIG.

FIG. 5 is a flowchart showing a measuring procedure by the color measuring device.

FIG. 6 is a flowchart showing a color measuring procedure by the color measuring device.

FIG. 7 is a diagram showing an example of a color position in an L * a * b * color system chromaticity diagram.

FIG. 8 is a subroutine flowchart showing a procedure of parameter calculation shown in FIG. 6;

FIG. 9 is a drawing for explaining a color difference vector.

FIG. 10 is a diagram for explaining the expression of a color difference component in a direction.

FIG. 11 is a diagram for describing division of a region by hue.

FIG. 12 is a diagram for explaining a calculation of a hue difference.

FIG. 13 is a diagram for explaining a calculation of a hue difference.

FIG. 14 is a drawing showing an example of expressing the hue of a hue difference.

FIG. 15 is a diagram showing a display example of a measurement result obtained by the measurement device.

FIG. 16 is a diagram for explaining a highlight side and a shade side.

[Explanation of symbols]

 Reference Signs List 50 measuring head 51 casing 52 light source 53 bulb 54 reflector 55 light transmitting lens 56 light transmitting mirror 57 sample window 58 color CCD camera 59 condenser lens 61, 62 mirror set 61a, 62a Flat mirror 64 Spacer 65, 66, 67 Support member 70 Image processing device 71 Video signal interface 72 Image processing unit 73 White standard data memory 74 Standard data memory with color 80 Monitor

Claims (4)

[Claims] 1. A photographing means for photographing a color image of a sample and outputting RGB signals of the photographed image; a converting means for receiving the RGB signals as input and converting the RGB values into predetermined colorimetric values; Display means for displaying color data based on colorimetric values, wherein the color data obtained by the conversion means when the color standard plate serving as a reference is photographed by the photographing means is represented by color data. A standard color data storage unit that stores the color of the reference colored standard plate photographed by the photographing unit; a color data stored in the standard color data storage unit and measurement Color difference calculation means for comparing colorimetric values obtained when the object is photographed by the photographing means to obtain color difference data of the measurement object; and color difference data obtained by the color difference calculation means. Data output means for outputting the reference color stored in the standard color storage means, the measured color when the object to be measured is photographed, and the color indicating the color difference direction of the color difference data to the display means for display. And a color measuring device. 2. The colorimetric value obtained by the conversion unit is a coordinate value on a specific color system diagram, and the color difference calculating unit is configured to calculate the color difference value from a coordinate value of a colored standard plate and a coordinate value of an object to be measured. 2. The color measuring apparatus according to claim 1, wherein a position vector of the measured color is obtained, and color difference data is calculated from a direction and a magnitude of the vector. 3. An imaging device, comprising: an irradiating unit configured to irradiate a sample with light at a predetermined angle; a mirror configured to reflect light irradiated from the irradiating unit and reflected from the sample at a plurality of spatial positions; 2. The color measuring apparatus according to claim 1, further comprising: image photographing means for photographing the reflected light and outputting RGB signals. 4. The color measuring apparatus according to claim 3, wherein the color difference data is obtained for each reflection point at a plurality of spatial positions by the mirror.