JP7362121B2 - Color/texture measuring device and method - Google Patents

Description

The present invention relates to a color/texture measuring device and method for measuring textures such as gloss, luster, and metallic feel.

Recently, there has been an increasing need to quantify metallicity, gloss, etc. as measurement targets at the same time as color. Examples include metallic paint, the color and luster of hair and food, and the color and luster of glossy building materials. Under these circumstances, color is currently quantified using a spectrophotometer, and gloss is quantified using a gloss meter. Since the human eye evaluates gloss at the same time as color, it is desirable to have a method that can quantify this from the same perspective. For example, the glossiness of marble-like ceramics in kitchens, condominiums, or hotels may become a problem after construction. In reality, there is a demand for simultaneous measurement of color, gloss, and luster for building materials. Color is measured using a spectrophotometer that measures the surface by shining a light on it, and luster and luster are measured using a gloss meter and a gloss meter that measure the surface by shining a light on it, and it is common to measure this in conjunction with a spectrophotometer that measures the color by shining a light on the surface. It is. There is also Patent Document 1 that evaluates color and texture by image processing.

Japanese Patent Application Publication No. 2016-194449

Regarding luster and gloss, there is a need for a new evaluation method that is similar to the sense of appearance, but conventional techniques have not yet achieved sufficient evaluation. For example, in the field of building materials, if only some of the tiles on a wall made of tiles lack luster, even though most of the tiles are glossy and shiny, some of them lack luster. Parts of the wall are lifted up, creating an imbalance in the entire wall surface. In Patent Document 1, it is possible to measure the metallic feel to some extent, but there is a risk that differences in texture due to the particle size, number of particles, etc. of materials that produce luster or luster, such as aluminum flakes, may not be ascertained. etc., are uniform, so it is difficult to evaluate the detailed glossiness that feels close to the appearance.

The present invention provides an outer shell, an indirect illumination section provided along a lower end of the outer shell for indirectly illuminating an inner wall surface of the outer shell, and an indirect illumination section provided on a ceiling of the outer shell to cover the inner wall surface of the outer shell. a direct illumination unit that directly illuminates the object to be measured at a predetermined angle; a colorimeter that is installed on the ceiling and that images the object; It includes an illumination image and a color/texture calculation unit that calculates color and texture based on the illumination image and the direct illumination image.

As shown in FIG. 4, the color/texture calculation unit images the object to be measured with the colorimeter under the direct illumination, and calculates the first brightness Ld(x , y); and a first brightness calculation unit that calculates a second brightness Lr(x, of the brightness of the direct illumination image calculated by the second brightness calculation unit that calculates y) and the first brightness calculation unit, a threshold value T for the brightness corresponding to the specular reflection component and the brightness corresponding to the diffuse reflection component. and a threshold calculation unit that calculates the direct illumination image by dividing pixels having brightness corresponding to the specular reflection component of the direct illumination image and pixels having brightness corresponding to the diffuse reflection component of the direct illumination image, using the threshold T, An integral value or average value Mean (LdT (x, y)) of the brightness LdT (x, y) corresponding to the diffuse reflection component of the illumination image and an integral value or average value Mean (LdT (x, y)) of the second brightness LrT (x, y) (LrT(x,y)), and based on the ratio, the second lightness LrT(x,y) is set to the lightness LdT(x,y) corresponding to the diffuse reflection component of the direct illumination image. a brightness adjustment section that calculates an adjusted brightness Lr ₁ T (x, y) adjusted according to the first brightness Ld (x, This is a high-resolution color/texture measurement device that includes a difference calculation unit that calculates the difference between the color and the adjusted brightness Lr ₁ T(x, y). (x, y) is position (coordinate) information for specifying a pixel.

The three-band visual sensitivity value for direct lighting is i, the three-band visual sensitivity value for indirect lighting is j, the L value for direct lighting is d, the L value for indirect lighting is r, the L value is less than or equal to the threshold T of direct lighting, or The L value of the indirect illumination corresponding to is given the suffix T. (x, y) indicates the position of a pixel in the image sensor 53 as a combination of integers (x = 1 to s, y = 1 to t, s is the total number of pixels in one row of the image sensor 53, t is the total number of pixels in one column) number of pixels). Mean (LdT (x, y)) = Σ (LdT (x, y)) / nT, Mean (LrT (x, y)) = Σ (LrT (x, y)) / nT, nT is the total below the threshold It is the number of pixels.

Extracting specular reflection components using a threshold using only direct illumination without using indirect illumination is only applicable in limited cases and is therefore not a subject of the present invention. In general, gloss is localized in various parts such as differences in brightness, uneven building materials, hair, etc. Furthermore, gloss is localized and not large as in frozen grilled rice balls. To handle cases where the specular reflection component does not appear, it is appropriate to use the indirect illumination image in a completely matte state for extracting and quantifying the specular reflection component. Approximately, it is possible to extract the specular reflection component using a threshold using only a direct illumination image without using an indirect illumination image, as long as it is a large and glossy object with a simple shape such as a flat plate. .

The brightness of the XYZ color system of the "first brightness calculation unit" and the "second brightness calculation unit" is determined from the three-band visual sensitivity values S ₁ i, S ₂ i, S ₃ i measured by a colorimeter. For example, the tristimulus values are converted to XYZ, Lab is calculated from the tristimulus values XYZ, and the brightness L is determined. The exposure time for imaging may be the same or different for indirect illumination and direct illumination.

Examples of the "direct lighting section" and "indirect lighting section" include LEDs, lamps, artificial sun lamps, and the like. One to several lighting units can be arranged in parallel.

"Specular reflection component" and "diffuse reflection component" are JIS Z8722:2000 Color measurement method - Reflection and transmission object color Explanation Solution 5, https://www.konicaminolta.jp/instruments/knowledge/color/section4/02. Please refer to the description of html etc.

"Lightness" is basically a measured value in the XYZ color system. The "XYZ color system" was defined by CIE in 1931 at the same time as the RGB color system to prevent negative values from appearing in simple linear conversion.

Examples of the "object to be measured" include vehicles, building materials, electrical products, hair, and foods. Examples of vehicles include automobiles, two-wheeled vehicles, bicycles, rickshaws, sleds, handcarts, carts, horse-drawn carriages, and ryakas.

A "colorimeter" is a device that measures the chromaticity distribution of an object two-dimensionally. Examples include PPLB-400 and PPLB-600 manufactured by Papa Lab Co., Ltd., which can display graphs showing changes in color difference ΔE within the measurement range and Lab values. By obtaining the color difference ΔE from the starting point, it is possible to verify and inspect differences in color development, color unevenness, etc. in the object to be measured. In the case of the Lab system, it is possible to read how the color is changing from the graph changes in the L value, a value, and b value.

A "colorimeter" images an object divided into three channels using three specific standardized sensitivities (S ₁ (λ), S ₂ (λ), S ₃ (λ)) shown in Figure 6. Things are exemplified. Any type of optical filter, dichroic mirror, dichroic prism, etc. set to obtain these spectral sensitivities can be used.

The spectral sensitivity (S ₁ (λ), S ₂ (λ), S ₃ (λ)) of the "colorimeter" is a mountain shape with a single peak that does not have a negative value from the CIE XYZ spectral sensitivity, and each An example is an equivalent conversion based on the conditions that the peak values of the spectral sensitivity curves are equal and the overlap of the spectral sensitivity curves is minimized. For example, the curve of spectral sensitivity _S1 has a peak wavelength of 582 nm, a half width of 523 to 629 nm, and a 1/10 width of 491 to 663 nm. The spectral sensitivity S ₂ curve has a peak wavelength of 543 nm, a half width of 506 to 589 nm, and a 1/10 width of 464 to 632 nm. The curve of spectral sensitivity _S3 has a peak wavelength of 446 nm, a half width of 423 to 478 nm, and a 1/10 width of 409 to 508 nm.

The "control unit" is an appropriate control device such as a so-called personal computer or a controller.

The "XYZ color system" includes, for example, CIE color systems such as Yxy, XYZ, Lab, and Luv, and is a concept that includes a two-dimensional chromaticity diagram or a three-dimensional color space.

The xyY color system (also referred to as the Yxy color system) was established to express absolute hues from the XYZ color system, since it is difficult to understand the relationship between numerical values and colors in the XYZ color system. .

The Luv color system is one of the uniform color spaces established by CIE in 1976, and CIELuv is based on the wavelength of light and improves the uniformity of wavelength intervals in the xy chromaticity diagram of the XYZ color system. In Japan, it is specified in JIS Z8518.

The Lab color system includes CIE Lab, etc., and is derived from the XYZ color system to measure color differences due to differences in perception and equipment, and is specified in JIS Z 8729 in Japan.

The "XYZ color system" includes a color space defined by two-dimensional coordinates and three-dimensional coordinates. Typical examples of color spaces include configuration examples such as an XYZ color space and a Lab color space. In the case of a two-dimensional color space, for example, the Yxy color space or the Luv color space, an xy chromaticity diagram (xy chromaticity values (plane) normalized in the Yxy color space), which is a two-dimensional plane, or a uv chromaticity diagram , u'v' chromaticity diagram. This corresponds to an xy chromaticity histogram distribution or a Luv chromaticity histogram distribution expressed as the density of pixels in a two-dimensional chromaticity diagram on a plane. Examples of three-dimensional color spaces include XYZ color space and Lab color space, which are three-dimensional spaces. This corresponds to an XYZ color space histogram expressed as the density of pixels on a three-dimensional color space, a Lab color space histogram distribution, or the like.

In contrast to the separation of colors and textures in the two-dimensional xy chromaticity plane, uv chromaticity diagram, and u'v' chromaticity diagram, other XYZ color spaces and Lab color spaces, etc., separate colors and textures on a three-dimensional color space. This results in a separation of textures. The xy chromaticity histogram is distinguished and defined as an XYZ color space histogram, a Lab color space histogram, and the like.

It is preferable that the threshold calculation unit creates a brightness histogram that is a distribution of the number of pixels indicating brightness, and calculates the threshold from the brightness histogram.

An XYZ brightness histogram and a Lab brightness histogram are exemplified.

In the brightness adjustment section, it is preferable that the brightness index is an integral value or an average value of brightness of each pixel.

The present invention can be applied with or without adjusting the exposure time (re-shooting). Adjusting the exposure time is a process necessary to further improve the S/N (signal-to-noise ratio) of the image element 53 that captures the image. If a sufficient S/N can be obtained without adjusting the exposure time, calculation alone may be sufficient. When adjusting the exposure time, the second brightness calculation unit images the object under indirect illumination with the colorimeter at the first exposure time, and calculates the captured indirect illumination image using the XYZ color system. The brightness is calculated, and the second brightness calculation unit calculates a brightness value such that the maximum value of the brightness of the direct illumination image and the maximum value of the second brightness of the indirect illumination image calculated by the first brightness calculation unit are the same. It is preferable to set two exposure times tr'.

Preferably, in the brightness adjustment section, the pixels are stored separately by binarizing the brightness corresponding to the specular reflection component and the brightness corresponding to the diffuse reflection component.

Another invention provides an outer shell, an indirect illumination section provided along a lower end of the outer shell and indirectly illuminating an inner wall surface of the outer shell, and a ceiling section of the outer shell. , a direct illumination unit that directly illuminates the object to be measured at a predetermined angle; a colorimeter provided on the ceiling that takes an image of the object; and a colorimeter that switches between the indirect illumination and the direct illumination, Using a high-resolution color/texture measurement device that includes an indirect lighting image and a color/texture calculation unit that calculates color and texture based on the direct lighting image, a first lightness calculation step of capturing an image of the object to be measured and calculating a first lightness Ld(x,y) of an XYZ color system for the captured direct illumination image; a second lightness calculation step of capturing an image of an object and calculating a second lightness Lr(x,y) of an XYZ color system for the captured indirect lighting image; and the direct illumination calculated by the first lightness calculation step . A threshold calculation step of calculating a threshold value T for a brightness corresponding to a specular reflection component and a brightness corresponding to a diffuse reflection component among the brightness of the image, and a brightness corresponding to the specular reflection component of the directly illuminated image using the threshold T. and pixels having a brightness corresponding to the diffuse reflection component of the direct illumination image, and an integral value or an average value Mean of the first brightness LdT (x, y) corresponding to the diffuse reflection component of the direct illumination image. (LdT (x, y)) and the integral value or average value Mean (LrT (x, y)) of the second lightness LrT (x, y) is calculated, and based on the ratio, the a brightness adjustment step of calculating an adjusted brightness Lr ₁ (x, y) in which the second brightness LrT (x, y) is adjusted to match the first brightness LdT (x, y) corresponding to the diffuse reflection component of the direct illumination image; , a difference calculation step of calculating a difference between the brightness LdT (x, y) of the XYZ color system of the direct illumination image calculated in the first brightness calculation step and the adjusted brightness Lr ₁ T (x, y); This is a high-resolution color and texture measurement method that includes

The present invention makes it possible to establish a detailed and accurate evaluation method that can correspond to surface unevenness, brightness distribution, gloss distribution, etc., which is similar to the visual sense, regarding glossiness, glossiness, etc. For example, in-line measurement allows accurate gloss measurement.

1 is a front view showing the configuration of a high-resolution color/texture measuring device 1 according to Embodiment 1 of the present invention. (a) is a plan view of the high-resolution color/texture measuring device 1 according to the first embodiment of the present invention, and (b) is a perspective view thereof. FIG. 2 is a schematic diagram of a color/texture calculation unit 60 of the high resolution color/texture measuring device 1 according to the first embodiment of the present invention. FIG. 2 is an explanatory diagram schematically showing a calculation method of the high-resolution color/texture measuring device 1 according to the first embodiment of the present invention. FIG. 6 is an explanatory diagram schematically showing a modification of the calculation method of the high-resolution color/texture measuring device 1 according to the first embodiment of the present invention. This is a function indicating the spectral sensitivity of the two-dimensional colorimeter 5 of the XYZ color system in Embodiment 1 of the present invention. This is a specific example of a method for acquiring image information according to three spectral sensitivities (S ₁ (λ), S ₂ (λ), and S ₃ (λ)) in Embodiment 1 of the present invention. (a) is an explanatory diagram when using a dichroic mirror. (b) is an explanatory diagram when using a filter turret. (c) is an explanatory diagram when optical filters 52a, 52b, and 52c are microscopically attached to an image sensor 53. 1 is a block diagram showing a circuit configuration of a control section of a high-resolution color/texture measuring device 1 according to Embodiment 1 of the present invention. FIG. 3 is a flowchart showing high-resolution color/texture measurement processing according to the first embodiment of the present invention. 7 is a flowchart showing a modification of the high-resolution color/texture measurement process according to the first embodiment of the present invention. FIG. 3 is a graph of a direct illumination histogram. (a) is a front view of a high-resolution color/texture measuring device 201 according to Embodiment 2 of the present invention, and (b) is a bottom view.

A high-resolution color/texture measuring device 1 according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 11. As shown in FIGS. 1 and 2, this high-resolution color/texture measuring device 1 has an entrance 2A and an exit 2B, a conveyor 2C passes through the entrance 2A and the exit 2B, a lower end 2D, an inner wall 2E, and a ceiling 2F, a tunnel-shaped outer shell 2 having a recess 2G, and a light shielding wall 2H, an indirect illumination section 3 provided along the lower end 2D and providing indirect illumination to the inner wall 2E, and a ceiling section of the outer shell. A direct illumination unit 4 provided on the 2F and directly illuminating the object M to be measured at a predetermined angle θ, a two-dimensional colorimeter 5 provided on the ceiling 2F and capturing an image of the object M, and the indirect illumination. and a control unit 6 having a color/texture calculation unit 60 that switches the direct illumination and performs color and texture calculations based on the indirect illumination image acquired by the two-dimensional colorimeter and the direct illumination image. , and a display section 7. The inner wall surface of the inner wall 2E is coated with white barium sulfate, which is often used in integrating spheres. The angle of the optical axis of the two-dimensional colorimeter 5 is 15° from the vertical direction. Set the angle to approach condition C and condition D described in JIS Z8722 Explanation 5.

The color/texture calculation section 60 will be explained with reference to FIGS. 3 and 4. The color/texture calculation unit 60 images the object M under direct illumination with the two-dimensional colorimeter 5 for an exposure time td, and calculates a first brightness Ld (x, y ), the object M is imaged with the two-dimensional colorimeter 5 under indirect illumination for an exposure time tr, and the second brightness of the XYZ color system is calculated for the indirect illumination image. A second brightness calculation unit 60B that calculates Lr(x,y), and a threshold calculation unit that calculates a threshold value T for the brightness corresponding to the specular reflection component and the brightness corresponding to the diffuse reflection component among the brightness of the direct illumination image. 60C and a threshold T, pixels having a brightness corresponding to the specular reflection component of the direct illumination image and pixels having brightness corresponding to the diffuse reflection component of the direct illumination image are separated, and pixels corresponding to the diffuse reflection component of the direct illumination image are separated. Mean(LdT(x,y)) of the lightness LdT(x,y) (in this embodiment, the average value) and the index of the second lightness LrT(x,y) at the corresponding pixel of the indirect illumination image (Mean(LdT(x,y))) In the embodiment, the ratio with Mean (Lr ₁ T (x, y)) is calculated, and based on the ratio, the second brightness Lr (x, y) is the brightness indicating the diffuse reflection component of direct illumination. A brightness adjustment unit 60D that calculates the adjusted brightness Lr ₁ T (x, y) adjusted according to LdT (x, y), the brightness LdT (x, y) of the XYZ color system of the direct illumination image, and the adjusted brightness. It includes a difference calculation unit 60E that calculates the difference between Lr ₁ T(x, y). The lightness is the Lab L value calculated from the measured values of the XYZ color system.

In this embodiment, indirect illumination may be re-photographed. A second exposure time tr' is set by correcting the first exposure time tr so that the maximum values of Ld (x, y) and Lr (x, y) match, and the second exposure time tr' is set using a two-dimensional colorimeter 5 under indirect illumination. A brightness adjustment section is provided that images the object to be measured at the second exposure time tr' and calculates the adjusted brightness Lr ₁ (x,y) of the XYZ color system for the indirect illumination image.

In the embodiment of the present invention, gloss may be localized in various parts such as building materials with differences in brightness or unevenness, hair, etc. Furthermore, gloss may be localized in various parts such as frozen grilled rice balls. The main purpose is to handle cases where the reflection is not very large, and it is necessary to use the indirect illumination image in a completely matte state in order to extract and quantify the specular reflection component.

The outer shell 2 has a semicylindrical or semicylindrical cross section. The image may be taken while the object M to be measured is being conveyed by the conveyor 2C inside the outer shell 2, or the object M may be stopped at a predetermined location and the object M may be imaged. If the conveyance speed of the conveyor 2C is set to be slow, there will be no problem in position correction.

The illumination sources of the indirect illumination section 3 and the direct illumination section 4 employ xenon lamps (simulated sunlight), and are arranged linearly parallel to the conveyance direction of the conveyor 2. The lighting section is equipped with a Fresnel lens assembly in addition to a xenon lamp. In addition to xenon lamps, LED artificial solar lamps may also be used. The illumination source is a highly directional, high color rendering LED. Color rendering is an index of how colors appear. The higher the color rendering, the more vivid and beautiful the colors will look. The directivity angle represents the angle at which the light of the LED spreads. Highly directional, high color rendering LEDs are manufactured by pasting a viewing angle limiting film (https://www.shinpoly.co.jp/product/automotive/vcf/n-vcf.html) in front of the LED's light emitting surface. Achieves high directivity with limited angles.

The spectral sensitivity of the two-dimensional colorimeter 5 satisfies the router condition, and the spectral sensitivity (S ₁ (λ), S ₂ (λ), S ₃ (λ)) is as shown in FIG. From the color function, it is a mountain shape with no negative values and a single peak, and it is an equivalent conversion based on the conditions that the peak values of each spectral sensitivity curve are equal, and the overlap of the spectral sensitivity curves is minimized. . Specifically, the spectral sensitivities (S ₁ (λ), S ₂ (λ), S ₃ (λ)) have the following characteristics.
Note Peak wavelength Half width 1/10 width S ₁ 582 nm 523 to 629 nm 491 to 663 nm
S ₂ 543nm 506-589nm 464-632nm
S ₃ 446nm 423~478nm 409~508nm

It is also possible to treat the peak wavelength of the above-mentioned spectral sensitivity _S1 as 580±4 nm, the peak wavelength of spectral sensitivity _S2 as 543±3 nm, and the peak wavelength of spectral sensitivity _S3 as 446±7 nm.

The three spectral sensitivities (S ₁ (λ), S ₂ (λ), and S ₃ (λ)) are obtained using the following Equation 1. For details regarding the spectral sensitivity itself, please refer to JP-A No. 2005-257827.

The high resolution of the two-dimensional colorimeter 5 is 4K resolution, 8K resolution or higher. The 2D colorimeter 5 has 8 million pixels at normal 4K resolution, and can support up to 12 million pixels. 4K resolution refers to a screen resolution of around 4,000 x 2,000 x 4,000 x 2,000. For example, the specifications of the 2D colorimeter 5 include an effective frequency value of approximately 8 million pixels, an effective area of 9.93 mm x 8.7 mm, an image size of 3.45 μm x 3.45 μm, a video output of 12 bits, a GigE interface for the 2D colorimeter 5, and a frame rate. 30 frames/sec, shutter speed 1/15,600sec to 1/15sec, integration time up to 3 seconds, S/N ratio 60DB or more, lens mount F mount, operating temperature 0℃ to 40℃, operating humidity 20% to 80%. Illustrated.

As shown in FIG. 7, the two-dimensional colorimeter 5 includes a photographic lens 51, three optical filters 52a, 52b, 52c (or 52a', 52c') arranged behind the photographic lens 51, and an optical filter. It includes an image sensor 53 (CCD, CMOS, etc.) disposed behind 52a, 52b, 52c (or 52a', 52c'). The three spectral sensitivities (S ₁ (λ), S ₂ (λ), S ₃ (λ)) of the two-dimensional colorimeter 5 are the spectral transmittances of the optical filters 52a, 52b, 52c (or 52a', 52c'). and the spectral sensitivity of the image sensor 53. The arrangement relationship between the optical filters 52a, 52b, 52c and the image sensor 53 in FIG. 7 is only shown schematically. Specific examples of methods for acquiring image information according to three spectral sensitivities (S ₁ (λ), S ₂ (λ), S ₃ (λ)) are given below, but in the first embodiment, other methods are adopted. You can also do that.

The method shown in FIG. 7(a) uses a dichroic mirror. A dichroic mirror 52c' reflects light of a specific wavelength, and another dichroic mirror 52a' reflects light of another specific wavelength for the remaining light that passes through the dichroic mirror 52c' to separate the lights, and the image sensors 53a and 53b , 53c are read out in parallel. Dichroic mirror 52a' corresponds to optical filters 52a and 52b, and dichroic mirror 52c' corresponds to optical filter 52c. Of the light incident from the photographing lens 51, the dichroic mirror 52c' reflects the light according to the spectral sensitivity _S3 , and transmits the remaining light. The light reflected by the dichroic mirror 52c' is reflected by the reflecting mirror 56 to obtain the spectral sensitivity _S3 from the image sensor 53c. On the other hand, the light transmitted through _the dichroic mirror 52c' is reflected at the dichroic mirror 52a', and the remaining light according to the spectral sensitivity _S2 is transmitted. The image is captured to obtain spectral sensitivities S ₁ and S ₂ . Instead of the dichroic mirror, a dichroic prism having similar characteristics may be used to separate the light into three parts, and the imaging elements 53a, 53b, and 53c may be bonded to positions through which each light passes.

FIG. 7(b) shows a method using a filter turret 57. Optical filters 52a, 52b, and 52c are provided on a filter turret 57 whose rotational axis is in the same direction as the incident light from the photographing lens 51, and these are mechanically rotated. Spectral sensitivities S ₁ , S ₂ and S ₃ are obtained.

The method shown in FIG. 7C is a method in which optical filters 52a, 52b, and 52c are microscopically attached to an image sensor 53. Optical filters 52a, 52b, and 52c on the image sensor 53 are provided in a Bayer array type. In this arrangement, the optical filter 52b is provided in half of the area on the image sensor 53 divided into a grid, and the optical filter 52a and the optical filter 52c are equally arranged in the remaining half area. That is, the arrangement amount is optical filter 52a:optical filter 52b:optical filter 52c=1:2:1. In the first embodiment, the arrangement of the optical filters 52a, 52b, and 52c may be other than the Bayer arrangement. Since the individual optical filters 52a, 52b, and 52c are very fine, they are attached to the image sensor 53 by printing. The present invention does not have any meaning in this arrangement, but rather in attaching a filter having characteristics of spectral sensitivity (S ₁ (λ), S ₂ (λ), S ₃ (λ)) to the image sensor.

The control section 6 that controls color/texture calculations will be explained with reference to FIG. The control section 6 includes a CPU 61, a RAM 62, a ROM 63, a counter 64, a timer 65, and an input/output interface 68 interconnected by a bus 69. The input/output interface 68 is connected to the conveyor 2C, the indirect lighting section 3, the direct lighting section 4, the two-dimensional colorimeter 5, the display section 7, and the like. The CPU 61 performs initial settings or predetermined calculations upon receiving input signals, and control signals are sent to them.

The CPU 61 generates control signals to be output to each section, and performs color/texture control by outputting the control signals under program control. The RAM 62 is used to temporarily read and write data such as color and texture control. Programs such as color and texture control are stored in the ROM 63 in a read-only manner. Internal calculations of the CPU 61 are performed using 64-bit floating point numbers. There are no problems such as overflow during calculations. Instead of program control, it can also be implemented by hardware control such as LSI logic.

The counter 64 functions as a counting unit that indicates count values and cumulative values such as threshold T, number of pixels, brightness L, brightness histogram, etc., and after the power is turned on, the initial values of the count value and cumulative value of the counter 64 are set. is set to "0" and counts and increments by referring to various input signals.

The timer 65 performs time calculation processing such as the first exposure time tr and the second exposure time tr'.

The display section 7 is connected to the control section 6, receives the image signal processed by the control section 6, and displays the image on the screen. The control unit 6 or the display unit 7 is appropriately equipped with input means (not shown) and the like. Input means include a keyboard, a mouse, a touch panel provided on the display section 7, and the like.

A specific example of the operation of the high-resolution color/texture measuring device 1 will be described with reference to FIGS. 4, 9, etc.

When the two-dimensional colorimeter 5, control unit 6, and display unit 7 are powered on, they are initialized as shown in FIG. are set to the first exposure times td and tr, the indirect illumination and the direct illumination are turned ON/OFF, the object M is imaged with the two-dimensional colorimeter 5 in response to each lighting, and each direct illumination is Three-band visual sensitivity values S ₁ i, S ₂ i, S ₃ i (i = 1 to n: n is the total number of pixels) and indirect lighting three-band visual sensitivity values S ₁ j, S ₂ j, S ₃ j ( j=1 to n: where n is the total number of pixels) is obtained (S1).

Corresponding XiYiZi and XjYjZj are calculated from the three-band visual sensitivity values S ₁ i, S ₂ i, S ₃ i and S ₁ j, S ₂ j, S ₃ j obtained in S1, and XiYiZi, Lab values are calculated from XjYjZj, respectively, and are set as direct illumination Ld(x,y) and indirect illumination Lr(x,y) (S2).

The threshold calculation unit 60C creates a brightness histogram of the direct illumination image (S3). As shown in FIG. 11, the horizontal axis is Ld(x,y), the vertical axis is the number of pixels, and the brightness histogram of the direct illumination image is created by integrating the number of pixels belonging to each brightness on the horizontal axis.

As shown in FIG. 11, when a histogram of the distribution of the number of pixels with respect to the L value is taken, two peaks are formed: a diffuse reflection component and a regular reflection component. In the case of a target with high reflectance, the number of pixels for the specular reflection component is large, so the number of pixels for the diffuse reflection component is small. In the case of a target with low reflectance, the number of pixels for the specular reflection component is small, so the number of pixels for the diffuse reflection component is large. If all or most of the reflected components are diffuse reflection components, this processing is meaningless, so there is no need to measure the glossiness. Since it is a glossy feeling, the lightness L is processed, but as the final result, the average of each of the L value, a value, and b value may be calculated. It is also possible to measure the L value of the glossy feel, and the a value and b value of the glossy area. Although not shown, the indirect illumination brightness histogram has one peak of the diffuse reflection component. With indirect lighting, light gathers from all directions, so if you use only indirect lighting, there will be no specular reflection component, and only diffuse reflection components.

The threshold calculation unit 60C calculates the threshold T shown in FIG. 11 from the direct illumination brightness histogram created in S6 using the method of Ohtsu et al. (S4).

At 60D, the brightness adjustment unit calculates the average value of LdT(x,y) of pixels having a value equal to or lower than the threshold T in the direct illumination image, and the LrT(x,x) of the pixel corresponding to LdT(x,y) in the indirect illumination image. , y) and calculate the ratio. An integral value may be used instead of the average value. These average values or integrated values are referred to as indexes in the present invention. Using this index ratio, the index of the second brightness LrT (x, y) of the indirect illumination image is aligned with the index of the brightness LdT (x, y) of the direct illumination image, according to the calculation formula example shown at the bottom of Fig. 4. , the adjusted brightness Lr ₁ T(x,y) of the indirect illumination image is calculated (S8). The subscript "1" is a suffix indicating that the ratio has been corrected.

Although the index is an average value, it may be replaced with an integral value. When calculating the threshold value T, etc., the direct illumination brightness is binarized in advance, for example, a flag is set to 0 or 1, and if the pixel has a brightness corresponding to the specular reflection component of the direct illumination, it is set to "1", and the direct illumination brightness is set to "1". In the case of a pixel having a brightness corresponding to a diffuse reflection component, "0" is set, a flag and an L value are stored as a set, and the specular reflection component and the diffuse component are distinguished.

When the difference ΔF=LdT(x,y)−Lr ₁ T(x,y) is calculated for all pixels, the L value of the specular reflection component is extracted as shown in FIG. 4 (S6) and is returned. The L value of the specular reflection component, the index (average value or integral value) of the L value, etc. serve as an index indicating the glossiness. By calculating the difference ΔF, the diffuse reflection component is canceled. Although there is a possibility that a diffuse reflection component remains, the numerical value is small, so it does not affect the gloss evaluation.

Regarding tristimulus values XYZ, Lab, brightness histogram creation, etc., please also refer to Patent Document 1, JP 2019-20311, JP 2018-141687, JP 2018-115877, etc.

Since FIG. 5 shows a modification of the embodiment of FIG. 4, the differences will be mainly explained, and the explanation will be used for common processing. Common processes will be explained with reference to the explanation of added S2-1 to S2-3. In the second brightness calculation unit 60B, the first exposure is performed so that the maximum value of the first brightness Ld (x, y) of the direct illumination image matches the maximum value of the second brightness Lr (x, y) of the indirect illumination image. The time tr is adjusted to set the second exposure time tr' (S2-1). The indirect illumination is turned on, the direct illumination is turned off, and the object to be measured M is imaged again using the second exposure time tr' extended in S3 (S2-2).

The second brightness calculation unit 60B recalculates the adjusted brightness Lr ₂ T(x,y) of the indirect illumination image by Lab recalculation using the calculation formula example shown in the lower part of FIG. 5 (S5).

S1, S2, S3 to S6 perform the same processing as in FIG. When the difference ΔF=LdT(x,y)−Lr ₂ T(x,y) is calculated for all pixels, the L value of the specular reflection component is extracted as shown in FIG. 5 (S6) and is returned. The subscript "1" is a suffix indicating that the L value is obtained by retaking the image at the second exposure time tr', and the subscript "2" is a ratio correction.

According to the high-resolution color/texture measuring device of the embodiment of the present invention, it is possible to establish a new detailed evaluation method of luster and luster that is close to the sense of appearance. For example, in the field of building materials, it is possible to eliminate the situation where only some of the tiles on a wall made of tiles lack gloss, and the entire wall surface has a well-balanced gloss. Accurate gloss can be measured even with in-line measurement. For example, the metallic feel is related to the particle size and particle distribution of the metallic component, which can also be measured in consideration of these factors. For example, mixing aluminum flakes with paint creates a metallic feel. Mixing a large amount of flakes into the paint will increase the sparkle. Increase the grain size of the frame to give it a rugged feel. Even if the density decreases, the metallic feeling becomes stronger. Sometimes a large amount of fine grains of flakes are mixed in. It looks slightly different to the human eye, such as a lumpy feel. Since the metallic feel can be precisely quantified by the size of the flake particles and the amount of flakes mixed, it is possible to precisely control the metallic feeling.

A high-resolution color/texture measuring device 201 according to a second embodiment will be described with reference to the drawings. Basically, the explanation will be used for common configurations, and different configurations will be explained with reference to FIG. 12 and the like. The part numbers are basically in the 200s, corresponding to the first embodiment. Embodiment 2 will be described in detail below.

Embodiment 2 uses a hemispherical dome for the outer shell because it is based on off-line measurements rather than in-line measurements. It can be applied to the luster of hair, food, etc. The high-resolution color/texture measurement device 201 includes a dome-shaped housing 202, one or more indirect illumination units 203 having LEDs that illuminate hair, etc., a direct illumination unit 204, and images the hair and the like as a target object. It includes a two-dimensional colorimeter 205, a control unit 206 that performs on/off of lighting power, color/texture calculations, etc. and connects to the two-dimensional colorimeter 205, a display unit 207, and a grip unit 208. .

As shown in FIG. 12, the dome-shaped housing 202 includes a circular opening 202A, a lower end 202D, a dome-shaped (for example, hemispherical) inner wall 202E, an arc-shaped ceiling 202F, an annular recess 202G, and an annular light-shielding portion. A mounting part 202K is provided for fixing the two-dimensional colorimeter 205 at an angle with respect to the central vertical axis of the wall 202H and the ceiling part 202F. The reason why the position of the mounting portion 202K is shifted from the center is to prevent the lens from directly imprinting on the image when the object is shiny. The angle (angle tilted from the center) is, for example, 10° to 30°.

As shown in FIG. 12, the indirect illumination units 203 are distributed in an annular manner around the inner periphery of the inner wall of the dome-shaped housing 202, and serve as indirect illumination that irradiates light onto the upper inner wall surface. Embodiment 2 is an off-line application, and when it is applied to hair, food, etc., a ring-shaped indirect illumination section 203 is arranged.

As shown in FIG. 12, the grip part 208 is formed in the shape of a grip that can be held by hand, and allows the object to be imaged to be imaged manually. An imaging button (not shown) of the two-dimensional colorimeter 205 is provided near it.

The object can be measured in a wide range of fields such as building materials, hair, cosmetics, food (frozen foods such as grilled rice balls, persimmon seeds, etc.), automobiles, and electrical appliances, and can measure textures such as gloss, shine, and illuminance along with color.

The embodiments of the present invention are not limited to the above-described embodiments, and modifications and the like can be made without departing from the technical idea of the present invention, and these modifications and equivalents are also included in the present invention. It goes without saying that it is included in the technical scope of , and can take various forms as long as it belongs to the technical scope. For example, regarding the method of acquiring an image according to three spectral sensitivities (S ₁ (λ), S ₂ (λ), S ₃ (λ)) and the method of calculating the L value as brightness, the methods listed in this embodiment are as follows. These are merely specific examples, and the technical idea of the present invention may be implemented by other methods without being limited to these.

1 High-resolution color/texture measuring device 2 Outer shell 2A Entrance 2B Exit 2C Conveyor 2D Lower end 2E Inner wall 2F Ceiling 2G Recess 2H Light shielding wall 3 Indirect light source M Object to be measured θ Angle 4 Direct illumination unit 5 Two-dimensional colorimeter 6 Control section 7 Display section

Claims (5)

an outer shell body;
an indirect lighting section provided along the lower end of the outer shell and indirectly illuminating the inner wall surface of the outer shell;
a direct illumination section that is provided on the ceiling of the outer shell and directly illuminates the object to be measured at a predetermined angle;
a colorimeter that is installed on the ceiling and captures an image of the object to be measured;
a color/texture calculation unit that switches between the indirect lighting and the direct lighting and calculates color and texture based on the indirect lighting image acquired by the colorimeter and the direct lighting image;
a first brightness calculation unit in which the color/texture calculation unit images the object to be measured with the colorimeter under the direct illumination, and calculates brightness in an XYZ color system for the captured direct illumination image;
a second brightness calculation unit that images the object to be measured with the colorimeter under the indirect illumination and calculates a second brightness in an XYZ color system for the captured indirect illumination image;
A threshold calculation unit that calculates a threshold value for a brightness corresponding to a specular reflection component and a brightness corresponding to a diffuse reflection component among the brightness of the direct illumination image calculated by the first brightness calculation unit;
The threshold value separates pixels having brightness corresponding to the specular reflection component of the direct illumination image and pixels having brightness corresponding to the diffuse reflection component of the direct illumination image, and pixels having brightness corresponding to the diffuse reflection component of the direct illumination image. Calculating the ratio between the integral value or average value of brightness and the integral value or average value of the second brightness, and adjusting the brightness corresponding to the diffuse reflection component of the direct illumination image based on the ratio. a brightness adjustment section that calculates brightness;
a difference calculation unit that calculates a difference between the brightness of the XYZ color system of the direct illumination image calculated by the first brightness calculation unit and the adjusted brightness;
High-resolution color/texture measurement device. 2. The high-resolution color/texture measuring device according to claim 1, wherein the threshold calculation section creates a brightness histogram that is a distribution of the number of pixels indicating brightness, and calculates the threshold from the brightness histogram. 3. The high-resolution color/texture measuring device according to claim 1, wherein the brightness adjustment section stores the pixels separately by binarizing the brightness corresponding to the specular reflection component and the brightness corresponding to the diffuse reflection component. In the second brightness calculation unit, image the object under indirect illumination with the colorimeter at a first exposure time, and calculate the brightness of the captured indirect illumination image in an XYZ color system;
The second exposure time is set so that the maximum value of the first brightness of the direct illumination image and the maximum value of the second brightness of the indirect illumination image calculated by the first brightness calculation section are the same, and the second exposure time is set again. The high-resolution color/texture measuring device according to any one of claims 1 to 3 , wherein the second brightness is recalculated by capturing an image of an object. an outer shell body;
an indirect lighting section provided along the lower end of the outer shell and indirectly illuminating the inner wall surface of the outer shell;
a direct illumination section that is provided on the ceiling of the outer shell and directly illuminates the object to be measured at a predetermined angle;
a colorimeter that is installed on the ceiling and captures an image of the object to be measured;
A high-resolution color/texture calculation unit that switches between the indirect lighting and the direct lighting and calculates color and texture based on the indirect lighting image acquired by the colorimeter and the direct lighting image. Using a measuring device,
a first brightness calculation step of capturing an image of the object to be measured with the colorimeter under the direct illumination, and calculating the brightness of the captured direct illumination image in an XYZ color system;
a second brightness calculation step of capturing an image of the object to be measured with the colorimeter at a second exposure time under the indirect illumination, and calculating a second brightness in an XYZ color system for the captured indirect illumination image;
A threshold calculation step of calculating a threshold value for a brightness corresponding to a specular reflection component and a brightness corresponding to a diffuse reflection component among the first brightness of the direct illumination image calculated in the first brightness calculation step;
The threshold value separates pixels having brightness corresponding to the specular reflection component of the direct illumination image and pixels having brightness corresponding to the diffuse reflection component of the direct illumination image, and pixels having brightness corresponding to the diffuse reflection component of the direct illumination image. The ratio between the integrated value or average value of brightness and the integrated value or average value of the second brightness was calculated, and the brightness was adjusted based on the ratio to match the brightness corresponding to the diffuse reflection component of the direct illumination image. a brightness adjustment step for calculating the adjusted brightness;
a difference calculation unit step that calculates a difference between the brightness of the XYZ color system of the direct illumination image calculated in the first brightness calculation step and the adjusted brightness;
High-resolution color and texture measurement methods including.

Images