JPH08114503A - Colorimetry device - Google Patents

Abstract

PURPOSE: To provide a colorimetry device capable of taking an accurate quantitative measurement of the color of an object. CONSTITUTION: A colorimetry device structurally comprises an integrating sphere 1, a specimen holding means 9 for holding a specimen S in the sphere 1, an illuminating means 7 for entering illuminating light into the sphere 1 through its entrance window, an image input means 2 for sensing the signal light image of the specimen S given out of the photometric window of the sphere 1, a storage means 3 for storing three primary R, G, B color images taken in by the input means 2, a display means 5 for displaying the image of the specimen S from the primary R, G, B color images stored in the storage means 3, an analytic range specifying means 6 for specifying an analytic range of the image of the specimen S displayed by the display means 5 and an image arithmetic means 4 for developing the brightness value of the specified analytic image range into its corresponding chromaticity coordinates from the brightness value of the analytic image range and the brightness value of the remaining image portion beyond the range.

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 capable of analyzing an image of a test object and quantitatively measuring its color.

[0002]

2. Description of the Related Art Conventionally, in the field of color measurement, various measuring methods have been considered in order to quantitatively measure the color of an object. For example, the transmittance in the blue wavelength range, which is the complementary color of yellow, is measured from the reflected light or transmitted light (referred to as measurement light) of the test object, and the fluctuation of the transmittance with respect to the change in yellowness is relatively small for red. There is a color measuring method in which the wavelength range is measured, the difference in transmittance between the red wavelength range and the blue wavelength range is obtained, and only the yellowness of the test object is measured with the transmittance in the red wavelength range as a reference.

Further, the measurement light from the object to be measured is spectrally separated by a diffraction grating, and from the light quantity of each spectrum, the light quantity B in the blue wavelength range, the light quantity R in the red wavelength range, and the light quantity G in the green wavelength range.
Is calculated, and the tristimulus values X, Y, and Z are calculated from the respective light intensity values to measure the color of the test object.

[0004]

However, the above-mentioned color measuring method has the following problems. In the method that uses the difference in transmittance between the red wavelength range and the blue wavelength range, the measurement light is converted into the difference between the blue transmittance and the red transmittance, so it is not possible to obtain accurate color coordinates and the green There is a problem that the colors are judged to be the same even if the wavelengths have different transmittances.

The method of spectrally splitting the measuring light by using the diffraction grating is as follows when the light amount values R, G, B are developed in the xy chromaticity diagram.
The measured values (color coordinate values) change due to changes in the spectrum and changes in the amount of light due to deterioration of the light source. In order to interpolate the change, it is necessary to reset the white balance of the light source at each measurement and normalize the reference position (white: x = 0.333, y = 0.333) on the chromaticity diagram. However, there is a drawback in that the reference position cannot be accurately normalized because there is a time difference between the color measurement of the test object and the reference value measurement for normalization.

Further, in the conventional color measuring method, since the point sensor or the line sensor is used as the light receiving device, it is not possible to display the real image of the object to be inspected, and it is possible to observe the outer shape with only one light receiving device. Color measurements could not be performed in parallel.

The present invention has been made in view of the above circumstances, and can accurately and quantitatively measure the color of an object to be inspected.
Moreover, it is an object of the present invention to provide a color measuring device capable of observing the external shape of a test object.

[0008]

The present invention has taken the following means in order to achieve the above object. The present invention corresponding to claim 1 is a color measuring device for quantitatively measuring a color of an object to be inspected, wherein an integrating sphere having an entrance window and a photometric window and an object to be inspected which holds the object to be inspected within the integrating sphere. Specimen holding means, illuminating means for making illumination light incident through the entrance window of the integrating sphere, and an image of the specimen to be emitted from the photometric window of the integrating sphere, and R, G, B primary colors of the specimen. Image input means for capturing an image, storage means for storing the R, G, B primary color images captured by the image input means, and the subject to be inspected from the R, G, B primary color images stored in the storage means. Display means for displaying an image of an object, analysis range designating means for designating an analysis range in the object image displayed on the display means, luminance value of the analysis range designated by the analysis range designating means, and the analysis From the brightness value outside the range, expand the brightness value in the analysis range to chromaticity coordinates. It has a configuration comprising an image operation means.

According to a second aspect of the present invention, the image calculation means creates a histogram relating to the color of the object from the image data in the analysis range, and the reference white color for reference is obtained from the image data outside the analysis range. Create a histogram and average ± 3 for each of those histograms
It is characterized in that the average luminance value is calculated in the range of σ, and the luminance value in the analysis range is expanded to chromaticity coordinates based on the average luminance value.

According to a third aspect of the present invention, in the color measuring device having the above structure, an aperture is formed in a photographing optical system for forming an image of light emitted from the photometric window of the integrating sphere on the image pickup device of the image input means. A diaphragm is provided.

[0011]

The present invention has the following effects by taking the above measures. According to the present invention corresponding to claim 1, the illumination light enters from the entrance window of the integrating sphere, is diffusely reflected, and the object held by the object holding means is uniformly illuminated in the integrating sphere. It The object image is picked up by the light emitted from the photometric window of the integrating sphere, and the R, G, B primary color images are stored in the storage means.

On the other hand, the object image is displayed on the display means by using the R, G, B primary color images stored in the storage means, and the analysis range of the displayed object image is designated by the analysis range designating means. To be done. Then, the image calculation means develops the luminance value of the analysis range into the chromaticity coordinates from the luminance value of the analysis range designated by the analysis range designation means and the luminance value other than the analysis range.

According to the present invention corresponding to claim 2, a histogram relating to the color of the object is created from the image data in the analysis range by the image calculation means, and the reference white color for reference is obtained from the image data outside the analysis range. A histogram of is created. Then, for each of the histograms, the average luminance value is calculated within the range of the average value ± 3σ, and the luminance value of the analysis range is developed on the chromaticity coordinate based on the average luminance value.

According to the present invention corresponding to claim 3, the light beam diameter of the light emitted from the photometric window of the integrating sphere and entering the image pickup device of the image input means can be narrowed by the aperture stop. By narrowing the light beam diameter with the aperture stop in the photographing optical system, the depth of focus of the photographing optical system becomes deep and the variation in the measured values can be suppressed.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of a color measuring device according to a first embodiment of the present invention. In the color measuring device of this embodiment, an integrating sphere 1 for illuminating a sample S as an object to be inspected with completely diffused light, a CCD camera 2 as an image input device for capturing an image of the sample S, and the CCD camera 2 are used for input. An image analysis device 3 capable of storing image data, an image calculation device 4 for processing the image data stored in the image analysis device 3 and quantitatively measuring the image data, C
A monitor 5 for displaying an image input by the CD camera 2 and a pointing device 6 connected to the arithmetic unit 4 are provided.

The integrating sphere 1 includes a lighting device mounting portion 1a and a CCD.
The camera mounting portion 1b and the sample holding device mounting portion 1c are provided. A lighting device 7 including a light source including a halogen lamp 7a is connected to the lighting device mounting portion 1a via a light projecting tube. The CCD camera 2 is connected to the CCD camera mounting portion 1b. Image pickup device 2a of CCD camera 2 and CC
The imaging lens 8 is arranged on the optical path between the D camera mounting portion 1b. The image of the sample is picked up by the imaging lens 2 by the imaging lens 8.
Image on a. The integrating sphere 1 is mounted on the sample holder mounting portion 1c.
A sample holding device 9 that holds the sample S in a predetermined posture inside and is painted in a standard white color is attached except for the sample holding portion. The CCD camera mounting portion 1b and the sample holding device mounting portion 1c are provided at positions facing each other.
The lighting device mounting portion 1a is provided at a position forming an angle of 90 degrees with them. Further, a light shielding plate 1d is arranged between the illumination device mounting portion 1a and the CCD camera mounting portion 1b in the integrating sphere 1 to prevent the illumination light incident from the illumination device 7 from directly entering the CCD camera mounting portion 1b. It is set up.
As the CCD camera 2, a color single plate type of RGB primary color filter is used.

The image analysis device 3 is connected to the video output terminal of the CCD camera 2. The image analysis device 3 has a CC
Memories 3a to 3c for storing R, G, and B image signals input from the D camera 2 are provided.

The image calculation device 4 operates based on the function of combining the R, G, and B image signals stored in the image analysis device 3 and displaying them on the monitor 5, and based on the flowchart shown in FIG. It has a function to quantitatively measure the color of.

Next, the operation of the present embodiment configured as described above will be described with reference to FIG. Lighting device 7
The illumination light emitted from the halogen lamp 7a enters the integrating sphere 1 through the opening of the illuminating device mounting portion 1a, and is multiple-reflected by the inner wall of the integrating sphere 1 to become completely diffused light. The sample S held by the sample holding device 9 in the integrating sphere 1 is illuminated from all directions by this diffused light.

The image of the sample S illuminated in this manner is formed on the image pickup device 2a of the CCD camera 2 by the image forming lens 8. The CCD camera 2 captures an image of the sample S formed on the image sensor 2a and outputs R, G, and B signals.
These R, G and B signals are A / D converted and then stored in the corresponding memories 3a to 3c of the image analysis device 3.

When the image calculation device 4 is given a quantitative measurement instruction, the memory 3 of the image analysis device 3 operates as described above.
The monochrome image data or the RGB combined image stored in a to 3c is displayed on the monitor 5 (step S1).

Here, the operator uses the pointing device 6 to specify the analysis range for the image calculation device 4. That is, the coordinates representing the outline of the sample image displayed on the monitor 5 are designated and input.

In the image calculation device 4, if the analysis range is instructed from the pointing device 6 (step S
2) judge the address on the memories 3a to 3c in which the image data of the designated analysis range is stored, R,
Read each G and B. R of the read analysis range,
A histogram is created for each of the G and B signals (step S3). Further, in order to set the area outside the analysis range in the same image as the reference white color, the image signals (Rn, Gn, Bn) of the area outside the analysis range are read and the histograms of Rn, Gn, Bn are similarly obtained. Create (step S4).

Here, if the analysis range is colored uniformly, the histogram has a normal distribution. In this normal distribution, it can be determined that the value is out of the range of the average value ± 3σ (99.7%). For example, a low output due to a defect of the image pickup element 2a of the CCD camera 2 or a saturated output due to surface reflection of the sample S causes an abnormal value.

In order to eliminate these abnormal values, first the provisional average luminance value (the average luminance value obtained from the entire histogram) is calculated (step S5), and the range of the provisional average value ± 3σ is determined from the histogram (step S6). , And then R, G, B, and Rn, Gn, B within the range of provisional average value ± 3σ
The average luminance value of n is calculated (step 7). Next, the average luminance values of R, G and B obtained in step S7 are substituted into the following equation (1) to obtain tristimulus values X, Y and Z (step S8).

[0026]

[Equation 1] Further, Rn, Gn, and Bn obtained in step S7 are substituted into the equation (1) to obtain the white reference (Rn, Gn, Bn) of 3
Stimulation values Xn, Yn, Zn are obtained. And step S
Tristimulus values X, Y, Z obtained in 8 and white reference tristimulus values X
Substituting n, Yn and Zn into the equation (2), the lightness index L and the perceptual chromaticity indexes a ^* and b ^* in the color system are obtained (step S9).

L = 116 × (Y / Yn) ¹ / 3−16 a ^* = 500 × {(X / Xn) ¹ / 3− (Y / Yn) ^1/3 } b ^* = 200 × {(Y / Yn) ¹ / 3- (Z / Zn) ^1/3 } (2) As described above, the color of the sample S has tristimulus values X, Y, Z,
Quantitative measurement is performed in the states of the lightness index L and the perceived chromaticity indexes a ^* and b ^* .

As described above, according to this embodiment, since the range of color measurement is designated for the image of the sample S displayed on the monitor 5, the entire image of the sample S can be visually observed, and at the same time, 3
Since the primary color image is taken in and the signals in the analysis range and the range used for the white reference are taken out from the same image, there is no measurement error due to temporal variation, and highly accurate quantitative measurement is possible.

According to this embodiment, since the sample S is arranged and illuminated in the integrating sphere 1, it is possible to create an ideal illumination state in which no illumination unevenness occurs, and it is not affected by the setting state of the sample S. Color measurement of samples of various shapes is possible.

According to this embodiment, since the average luminance values of R, G, B and Rn, Gn, Bn are calculated within the range of the provisional average value ± 3σ, the output of the defective portion of the CCD element is calculated. It is possible to eliminate the saturated output of the CCD and CCD device, and more accurate color measurement is possible.

According to this embodiment, the light source 7a of the illumination device 7 is
Since a halogen lamp or the like that does not cause ripples is used, a stable light amount can be supplied, the reproducibility of measured values is good, and minute color differences can be accurately measured.

In the above embodiment, the example in which the halogen lamp 7a is used as the light source of the illuminating device 7 has been described, but the same effect can be expected with a xenon lamp, for example. In that case, since it is not necessary to correct the color temperature of the illumination light and color measurement can be performed including the autofluorescence of the sample, it is possible to perform evaluation that is very close to the sense of the human eye. Further, the CCD camera 2 does not have to be a single-plate type, and for example, a 3-plate type can also be used. Further, the light blocking plate 1d is provided on the integrating sphere 1.
Although the example including is described, it can be removed if necessary.

Next, a second embodiment of the present invention will be described. FIG. 3 shows the configuration of the color measuring device according to the second embodiment. In this embodiment, the CCD camera mounting portion 1b and the CCD
An aperture stop 11 is provided in a photographic optical system 10 formed between the camera 2 and the imaging lens 8 arranged therein.
Others are the same as those in the first embodiment described above, and the constituent elements having the same functions are designated by the same reference numerals. Aperture stop 1
1 is composed of a fixed diaphragm, and its numerical aperture is NA =
It is set to 0.05. The aperture stop 11 is arranged in the photographing optical system 10 between the image forming lens 8 and the image pickup device 2 a of the CCD camera 2.

In the present embodiment configured as described above, the illumination light emitted from the halogen lamp 7a of the illumination device 7 enters the integrating sphere 1 through the opening of the illumination device mounting portion 1a. The illumination light, which has been multiple-reflected by the inner wall of the integrating sphere 1 and becomes a completely diffused light, is incident from all directions by the sample S held by the sample holding device 9 in the integrating sphere 1.

The measuring light from the sample S illuminated in the integrating sphere 1 in this way enters the photographic optical system 10 from the CCD camera mounting portion 1b, and the imaging lens 8 causes the image pickup element 2a of the CCD camera 2 to move. Imaged above. At this time, the light that enters the imaging element 2a from the imaging lens 8 is narrowed down by the aperture stop 11 so that the light beam diameter becomes small. The CCD camera 2 picks up the image of the sample S formed on the image pickup element 2 a, converts it into video signals of R, G, and B colors and sends it to the image analysis device 3. Subsequent processing is the same as in the first embodiment described above.

According to this embodiment, as in the first embodiment described above, the entire image of the sample S can be visually observed and accurate color measurement can be performed. According to this embodiment, the imaging lens 8
Since the light incident on the image pickup device 2a is narrowed down by the aperture stop 11, the depth of focus of the photographing optical system 10 becomes deeper,
Accurate color measurement is possible even if the sample S is thick or the sample S has various shapes.

As the aperture diaphragm 11 is narrowed down, the depth of focus becomes deeper and the present effect becomes larger. However, if the aperture is too narrowed, the brightness of the image is lowered and the S / N is deteriorated, and the stability of the data is rather deteriorated. Be done. For example, when a 100 W halogen lamp is used as the light source and a normal color CCD is used as the image sensor, the numerical aperture NA is preferably about 0.05 to 0.03.
Note that the numerical aperture can be further reduced by using a cooled CCD or the like as the image pickup element or by improving the S / N ratio by making the light source brighter.

Here, a comparative example in which the numerical aperture of the photographing optical system 10 is made small (this embodiment) and other cases will be described with reference to FIGS. 4 and 5 are images obtained when the numerical aperture of the photographing optical system 10 is NA = 0.28 (FIG. 4) and NA = 0.03 (FIG. 5), respectively, and the sample is moved back and forth from the focus position. The degree of change in the luminance value of the element 2a is shown. The sign of the amount of deviation from the in-focus position is + in the direction away from the taking optical system 10.

In the comparative examples shown in FIGS. 4 and 5, when the numerical aperture is made small as shown in FIG. 5, the amount of change in the luminance value is small even if the focus position is changed, but as shown in FIG. It is shown that when the value is large, the change amount of the brightness value with respect to the change of the focus position is large. From this, it is proved that a more stable measurement result can be obtained by reducing the numerical aperture as in this embodiment. In particular, it can be an effective means when the sample S has a complicated shape, the sample S is transparent and has a thickness, and when it is a polyhedral object.

6 and 7, the numerical apertures of the photographing optical system 10 are NA = 0.28 (FIG. 6) and NA = 0.03, respectively.
(FIG. 7) shows how the luminance value changes when the sample S is tilted from the horizontal position. In the integrating sphere 1, the sample S
Since the incident light with respect to is a complete diffused illumination from all directions, the sign of the tilt angle has no particular meaning and is arbitrarily set.

In the comparative examples shown in FIGS. 6 and 7, when the numerical aperture is reduced as shown in FIG. 7, the amount of change in the luminance value when the inclination of the sample S is changed is small, but as shown in FIG. It is shown that when the numerical aperture is large, the amount of change in the luminance value with respect to the change in the inclination of the sample S is large. From this, it is proved that the measurement result more stable with respect to the inclination of the sample can be obtained by reducing the numerical aperture as in the present embodiment. In particular, when the sample S has a complicated shape or is a polyhedral object, it can be an effective means.

Although the above description has been given based on the embodiments, the present invention includes the following inventions. (1) An integrating sphere having an entrance window and a photometric window, an object holding means for holding an object to be tested in the integrating sphere, an illuminating means for entering illumination light from an entrance window of the integrating sphere, Image input means for picking up an image of an object to be inspected emitted from the photometric window of the integrating sphere and taking in R, G, B primary color images of the object, and R, G, B taken in by the image input means. Storage means for storing the primary color image, display means for displaying the image of the test object from the R, G, B primary color images stored in the storage means, and analysis of the test object image displayed on the display means Image calculation for expanding the brightness value of the analysis range into chromaticity coordinates from the analysis range specifying means for specifying the range, the brightness value of the analysis range specified by the analysis range specifying means, and the brightness value other than the analysis range. Means between the entrance window and the photometric window inside the integrating sphere. Disposing a light shielding plate.

According to the present invention having such a structure, the light shielding plate provided between the entrance window of the integrating sphere and the photometric window prevents the illumination light entering from the entrance window from directly entering the photometric window. To be done. (2) An integrating sphere having an entrance window and a photometric window, an object holding means for holding an object to be inspected in the integrating sphere, an illuminating means for entering illumination light from the entrance window of the integrating sphere, Image input means for picking up an image of an object to be inspected emitted from the photometric window of the integrating sphere and taking in R, G, B primary color images of the object, and R, G, B taken in by the image input means. Storage means for storing the primary color image, and R, G, B stored in the storage means
Display means for displaying an image of the inspection object from the primary color image,
From the analysis range designating means for designating an analysis range in the object image displayed on the display means, the brightness value of the analysis range specified by the analysis range designating means and the brightness value other than the analysis range, the analysis is performed. And an image calculation means for expanding the brightness value in the range into chromaticity coordinates, and an aperture stop is provided in the photographing optical system for forming the light emitted from the photometric window of the integrating sphere on the image sensor of the image input means. The aperture stop reduces the numerical aperture of the photographic optical system.

According to the present invention having such a configuration, the focal depth of the photographic optical system becomes deep and the dispersion of the measured values can be suppressed by narrowing the light beam diameter by the aperture stop in the photographic optical system. The present invention is not limited to the above embodiments, and various modifications can be made without departing from the gist of the present invention.

[0045]

As described above in detail, according to the present invention, it is possible to provide a color measuring apparatus capable of accurately quantitatively measuring the color of a test object and observing the external shape of the test object. According to the present invention, since the numerical aperture is reduced by providing the aperture stop in the photographing optical system, it is possible to reduce the variation in the measurement values due to the tilt caused when focusing or mounting the sample, and it is possible to improve the measurement accuracy. Can be provided.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a color measuring device according to a first embodiment of the present invention.

FIG. 2 is an operation explanatory view of the color measuring device according to the first embodiment.

FIG. 3 is a configuration diagram of a color measuring device according to a second embodiment of the present invention.

FIG. 4 is a diagram showing how the luminance value changes when the sample is moved back and forth from the in-focus position of the photographic optical system with a numerical aperture set to NA = 0.28.

FIG. 5 is a diagram showing how the luminance value changes when the sample is moved back and forth from the in-focus position of the photographing optical system with the numerical aperture NA = 0.03.

FIG. 6 is a diagram showing how the luminance value changes when the sample is tilted in a photographic optical system in which the numerical aperture is set to NA = 0.28.

FIG. 7 is a diagram showing how the luminance value changes when the sample is tilted in a photographing optical system with a numerical aperture set to NA = 0.03.

[Explanation of symbols]

1 ... Integrating sphere, 2 ... CCD camera, 3 ... Image analysis device, 4
Image processing device, 5 ... Monitor, 6 ... Pointing device, 7 ... Illumination device, 8 ... Imaging lens, 9 ... Sample holding device, 10 ... Photographing optical system, 11 ... Aperture stop, S ... Sample.

Claims (3)

[Claims] 1. A color measuring device for quantitatively measuring a color of an object to be inspected, comprising: an integrating sphere having an entrance window and a photometric window; and an object holding means for holding an object to be inspected in the integrating sphere. An image of an R, G, B primary color image of an object to be inspected which is obtained by illuminating means for injecting illumination light from an entrance window of the integrating sphere and an image of the object to be inspected emitted from the photometric window of the integrating sphere. Input means, storage means for storing the R, G, B primary color images captured by the image input means, and an image of the test object is displayed from the R, G, B primary color images stored in the storage means. Display means, an analysis range designating means for designating an analysis range in the object image displayed on the display means, a brightness value of the analysis range specified by the analysis range designating means, and a brightness value other than the analysis range. From this, an image calculation for expanding the luminance value of the analysis range into chromaticity coordinates Color measuring apparatus characterized by comprising a stage. 2. The image calculation means creates a histogram relating to the color of the object from the image data in the analysis range, creates a reference white histogram for reference from the image data outside the analysis range, The color measuring device according to claim 1, wherein an average luminance value is calculated for each of the average values ± 3σ, and the luminance value in the analysis range is developed into chromaticity coordinates based on the average luminance value. 3. An aperture stop is provided in a photographing optical system for forming an image of the light emitted from the photometric window of the integrating sphere on the image pickup device of the image input means. The color measuring device described in 1.