Multiband colorimetry system

Abstract

To provide a multiband colorimetry system that easily performs multiband photographing in a low cost, and detects color information of a photogenic subject with high accuracy.SOLUTION: A subject 142 performing commercial photographing is installed to front of a background cloth 140, and a color chart 144 is arranged to a neighbor. Then, a white LED light source 132, a RLED light source 134, a GLED light source 136, and a BLED light source 138 are turned on and off sequentially by a lighting control part 124, the six subjects 142 and an image of the color chart 144 are imaged by an imaging part 110 by a consecutive shoot mode. Then, image components of a R band, a G band, and a B band are obtained from the image obtained by the white LED light source 132, and components of the R band, the G band, and the B band are obtained from the RLED light source 134, the GLED light source 136, and the BLED light source 138. From the image components of those six bands, accurate color information of the subject 142 corrected by color chart information is detected.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a multiband colorimetry system that acquires color information of a subject with high accuracy using a multiband image capturing device capable of capturing images in four or more bands each with different spectral characteristics. [Background technology]

[0002] Conventionally, so-called RGB cameras using three bands, red, green, and blue, have been widely used to capture images of a subject, but in recent years, in order to detect the color information of the subject with high accuracy, a method has been proposed in which the spectral information of the subject is acquired and recorded as an image using a multiband camera capable of capturing images in four or more bands. Examples of such image capturing devices with four or more bands include those described in the following patent documents.

[0003] First, the "image processing system" described in Patent Document 1 below uses a monochrome imager and multiple LED light sources that have narrow-band emission spectra and different peak wavelengths. By sequentially lighting up six types of LED light sources, it is possible to easily capture a multiband image. In addition, by using six bands instead of three RGB bands, it is possible to estimate the spectral spectrum of the subject and detect the color information of the subject with high accuracy.

[0004] Next, the "image processing system" of the following Patent Document 2 uses a special comb-shaped optical filter as shown in Figures 5 and 6 in the document to capture an RGB image with narrow-band spectral characteristics in addition to a conventional standard RGB image, and by using these, estimates the spectral spectrum of the subject with high accuracy and accurately reproduces the color of the subject. Since the standard RGB image is captured in one shot, an RGB image for monitor display can be obtained without delay, unlike the above-mentioned Patent Document 1. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication WO2004 / 012461 [Patent Document 2] Patent No. 4118916 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the method of Patent Document 1, since an RGB image signal that can be displayed on a monitor cannot be directly obtained, in order to observe and check the captured image on a monitor during shooting, it is necessary to convert the obtained 6-band image data into RGB image data for display. Therefore, since the signal conversion is performed after shooting the 6-band, there is a drawback that a time delay occurs, making framing and focusing difficult. Furthermore, compared to normal white LED light sources, LED light sources having a narrow emission spectrum are expensive because they are specialized and are used for few purposes.

[0007] In addition, the method of Patent Document 1 uses two imagers as shown in FIG. 1 of the same publication, making the imaging device very expensive. On the other hand, the same publication also proposes a method of obtaining six bands using strobe light as shown in FIG. 23, as a configuration that can be realized with a single camera, and this configuration has the advantage that the entire device can be made smaller and less expensive. However, strobe light sources generally have large variations in light emission. Standard RGB images can be captured with stable illumination from ambient light, but RGB images with narrow-band spectral characteristics are captured with strobe light, which has variations in light emission brightness, and therefore stable color reproduction performance cannot be obtained.

[0008] In addition, in all of the above patent documents, a dedicated imaging device is required to obtain a multiband image, such as using a dedicated optical filter or using multiple image sensors, which makes the device very expensive compared to commercially available digital cameras. In addition, there are also problems such as a time delay in confirming the subject image being captured and difficulty in framing and focusing.

[0009] The present invention has been made in view of the above points, and has an object to easily perform multiband photography. Another object is to detect color information of a subject with high accuracy. [Means for solving the problem]

[0010] The multiband colorimetric system of the present invention comprises: An imaging means having a continuous shooting function, a light source means for illuminating an object with a white light source and a plurality of narrowband light sources having different bands; a multiband image generating means for illuminating a subject with the light source and obtaining a plurality of images by continuous shooting with the imaging means; A color conversion method to obtain color information of the subject from the multiband image obtained by the above method, The present invention is characterized by comprising:

[0011] According to one of the main forms, the imaging means captures a color chart having color characteristics similar to those of the subject in the same image as the subject to obtain the multiband image, and uses image information of the color chart to correct light emission variations of the light source means.

[0012] According to another aspect, the method is characterized in that the image unevenness of the multiband image of the subject is corrected for each band by using a reference plate image obtained by capturing an image of a reference plate having a uniform brightness distribution. Alternatively, the method is characterized in that at least two of the narrowband light sources are caused to emit light simultaneously.

[0013] According to another embodiment, the narrowband light source includes a light source having spectral sensitivities in R, G, and B bands, and the multiband image generating means obtains images of the spectral sensitivities of the R, G, and B bands from an image of the subject obtained by the white light source, and obtains images of the spectral sensitivities of the R, G, and B bands of the subject obtained by the narrowband light source, and obtains color information of the subject from these two sets of images of the R, G, and B bands by the color conversion means.

[0014] According to yet another aspect, the color conversion means detects color information of any one of XYZ information, Lab information, spectral information, and color reproduction image from the generated multiband image. The above and other objects, features, and advantages of the present invention will become apparent from the following detailed description and the accompanying drawings. Effect of the Invention

[0015] According to the present invention, a multiband image including a standard RGB image and a narrowband image can be easily obtained by sequentially irradiating white light and narrowband light and taking continuous shots using a digital camera capable of continuous shooting. In addition, by placing a color chart that is similar to the color of the subject near the subject and photographing this color chart in the same screen as the subject, it is possible to correct the light emission variation of the lighting and detect the color information of the subject with high accuracy. [Brief description of the drawings]

[0016] [Figure 1] 1 shows a configuration of a first embodiment of the present invention. [Diagram 2] 3 shows the spectrum of illumination light in the first embodiment. [Diagram 3] 1 shows the spectrum of an image captured in Example 1. [Figure 4] 4 shows an imaging sequence in the first embodiment. [Diagram 5] 4 shows another imaging sequence in the first embodiment. [Figure 6] 2 shows a configuration of a second embodiment of the present invention. [Figure 7] 1 shows the appearance of the lighting unit in the second embodiment. [Figure 8] 11 shows details of the color measurement processing unit in the second embodiment. [Figure 9] 11 shows an imaging sequence in the second embodiment. [Figure 10] An example of color measurement in the second embodiment will be described. [Figure 11] 1 shows the spectrum of an image taken in Example 2. [Figure 12]11 shows another imaging sequence in the second embodiment. [Figure 13] 13 shows a spectrum of an image captured in another sequence according to the second embodiment. [Figure 14] 4 shows the change in spectrum when the temperature is changed in the above embodiment. [Figure 15] 3 shows a configuration of a third embodiment of the present invention. [Figure 16] 13 shows an example of color measurement of a dental crown in the third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] The best mode for carrying out the present invention will now be described in detail with reference to examples. EXAMPLES

[0018] First, a first embodiment of the present invention will be described with reference to FIGS. 1 to 6. In this embodiment, a case where a product image to be published in a catalog or the like is photographed in a studio will be described. Clothing, shoes, hats, and the like are sold at online shops. A purchaser refers to a screen of a personal computer or smartphone, trusts the color of the product displayed, and orders the product he or she wants. However, if the color of the actual product delivered is different from the desired color, this may cause the product to be returned or exchanged. This is because the conventional RGB camera that photographed the product could not detect subtle color differences and could not accurately display colors faithful to the actual product on the screen. The purchaser will have to go through the extra trouble of returning or exchanging the product, and the seller will have to deal with complaints and pay shipping fees. In this embodiment, the product, which is the subject, is photographed using multiband photography to detect color information with high accuracy, thereby achieving accurate color reproduction of the product on the screen.

[0019] <Configuration> Fig. 1 shows the configuration of the photographing system 100 of this embodiment. In the figure, the photographing system 100 is mainly composed of an imaging unit 110, a light source unit 130, and a color measurement processing unit 150. Among these, the imaging unit 110 is a commercially available RGB camera such as a single-lens digital camera, and is equipped with an imaging optical system 112 such as an interchangeable lens, an image sensor 114, a shutter button 116, an image memory 118 such as an SD card, and a photographing signal output unit 120. When the shutter button 116 is pressed, an image of a subject 142 is captured and recorded in the image memory 118 as an RGB image. The subject 142 is placed in front of a background cloth 140 together with a color chart 144. The color chart 144 is a sheet-like object made of a single color and is placed near the subject 142, and the focal length and shooting distance of the imaging optical system 112 are adjusted so that the subject 142 and the color chart 144 are captured simultaneously.

[0020] The photographing signal output unit 120 is, for example, an external strobe attachment unit called a hot shoe, and is configured to output a photographing trigger signal to an illumination control unit 124 when the shutter button 116 is pressed.

[0021] The lighting control unit 124 controls turning on and off each light source implemented in the light source unit in response to the received trigger signal. The lighting control unit 124 also has a power button 126, which, when turned on, starts up the lighting control unit 124 and turns on the light source unit 130.

[0022] The light source unit 130 includes a white LED light source 132 having an emission spectrum covering almost the entire R, G, and B bands of the image sensor, and M types of narrowband LED light sources (M=3 in this embodiment) including RLED 134, GLED 136, and BLED 138, each of which has a peak wavelength of its emission spectrum in one of the R, G, or B bands.

[0023] Next, the colorimetry processing unit 150 includes a multiband image generating unit 152, a color conversion information recording unit 154, and a color conversion processing unit 160, and is implemented as software on a personal computer. The multiband image generating unit 152 selects necessary bands, as described below, from a plurality of captured images captured by the imaging unit 110 and recorded in the image memory 118, and generates an N-band multiband image. The color conversion information recording unit 154 records information necessary for conversion processing in the color conversion processing unit 160, and in this embodiment, A, a color chart image taken in advance, b, the color transformation coefficients created at that time, has been recorded.

[0024] The color conversion processing unit 160 calculates color information of a display image, etc., using the color chart images and color conversion coefficients recorded in the color conversion information recording unit 154. The color information is, for example, XYZ information, Lab information, spectral information, color reproduction image, etc., and is calculated or created by an XYZ calculation unit 162, a Lab calculation unit 164, a spectral calculation unit 166, and a color reproduction image creation unit 168, respectively. a, XYZ calculation unit 162: Using the color conversion coefficients recorded in the color conversion information recording unit 154, calculates the XYZ tristimulus values ​​of each pixel or a specified area, and outputs them as XYZ information. The XYZ tristimulus values ​​are the coordinates of the CIE XYZ color space, which is a unified display standard for colors established by the International Commission on Illumination (CIE) in 1931. In order to achieve accurate color reproduction, it is necessary to correctly calculate the XYZ tristimulus values ​​of the subject. b,Lab calculation unit 164: Calculates the Lab value of each pixel or a specified area from the XYZ tristimulus values ​​and outputs it as Lab information. The Lab value is a coordinate value in the Lab color space, where L represents brightness, a represents the red direction, -a represents the green direction, b represents the yellow direction, and -b represents the blue direction. It is a nonlinear compression of the coordinates in the CIE1931 color space, where L represents brightness, a represents redness, and b represents the yellow intensity. c) Spectrum calculation unit 166: Using the color conversion coefficients recorded in the color conversion information recording unit 154, calculates the spectral reflectance spectrum of each pixel or a predetermined region, and outputs it as spectral information. d. The color reproduction image creation unit 168 uses the XYZ tristimulus values ​​to calculate the image signal value of the sRGB standard for each pixel and creates a color reproduction image. sRGB is one of the standard color space standards, and is supported by general information devices such as personal computers, displays, and printers. When images and videos are exchanged between devices, the standard absorbs differences in characteristics due to models and devices and maintains the same color tone. Accurate color reproduction is possible by displaying the image signal of the sRGB standard on a monitor that supports sRGB.

[0025] The display image converted by the color conversion processing unit 160 is in a standard RGB image format, and is output and displayed on a display 170 such as a personal computer.

[0026] Next, Fig. 2(A) shows normalized spectral sensitivity of each band of an RGB image captured by the imaging unit 110. The horizontal axis is wavelength, and each RGB band covers the visible light range. The spectral sensitivity of each RGB band can be calculated from the spectral transmittance of the lens of the imaging optical system 112 and the spectral sensitivity of the image sensor 114. Fig. 2(B) shows the emission spectrum of the narrowband LED light sources 134-138 of the light source unit 130. While the white LED light source 132 emits light in the entire visible light range, the peak wavelengths of the narrowband LED light sources RLED 134, GLED 136, and BLED 138 are within the half-width of the RGB band, and further, the half-width of the narrowband LED light sources 134-138 is equal to or less than the half-width of the RGB band to which they belong.

[0027] These can be expressed by the following formula. If the peak wavelengths of the RLED 134, GLED 136, and BLED 138 are λ1, λ2, and λ3, the half-widths are h1, h2, and h3, respectively, and the wavelengths at the half-widths of the RGB bands are r1, r2, g1, g2, b1, and b2, respectively, then: b1<λ1 <b2,h1<(b2-b1) g1<λ2 <g2,h2<(g2-g1) r1<λ3 <r2,h3<(r2-r1) It becomes.

[0028] By selecting and using the R band for the image irradiated by the RLED 134, the G band for the image irradiated by the GLED 136, and the B band for the image irradiated by the BLED 138, a higher signal value can be obtained than when using other color bands, and an image with a high S / N ratio can be obtained. In addition, by making the half-width smaller than the half-width of the selected RGB band, an RGB image with narrowband characteristics compared to standard RGB can be obtained. It has been experimentally confirmed that high color information can be obtained by setting the half-width of the narrowband LED light sources 134-138 to approximately 1 / 2 to 1 / 3 of the half-width of the selected band.

[0029] FIG. 3 shows the spectral sensitivity of an image obtained when photographing with each light source of the light source unit 130. FIG. 3(A) shows the spectral sensitivity of each RGB band when the white LED light source 132 is used. If the white LED light source 132 provides flat illumination over the entire visible light range, the spectral sensitivity will have a shape similar to that of FIG. 2(A). On the other hand, in the case of the narrowband LED light sources 134-138, only one band that has the highest photographing intensity can be obtained as a valid signal when irradiated with each LED light source. Therefore, the R LED 134 uses the R band signal, the G LED 136 uses the G band signal, and the B LED 138 uses the B band signal. The obtained spectral sensitivity is as shown in FIG. 3(D), (C), and (B), respectively. In this way, a total of six bands, including three RGB bands photographed with illumination by the white LED light source 132 and narrowband images photographed with illumination by the narrowband LED light sources 134-138, can be obtained as multiband images, and accurate color information can be obtained from these multiband images.

[0030] Next, an example of an imaging sequence in this embodiment is shown in Fig. 4. The horizontal axis in this figure is time, and shows the trigger signal, exposure time, and light emission timing of each light source. Fig. 4(A) shows the trigger signal output from the imaging unit 110 to the illumination control unit 124, and the trigger signals that are generated and output sequentially are called trigger signal 1, trigger signal 2, .... In this embodiment, the trigger signal is output six times.

[0031] Figure (B) shows the exposure period of the image sensor 114. The slanted vertical lines indicate the period during which the shutter curtain is moving, and the period when the shutter curtain is fully open consists of only the upper and lower horizontal lines. As shown in Figures (C) to (F), each of the LED light sources 132 to 138 is turned on by a trigger signal and turned off after a lapse of a predetermined time t1 to t4 seconds. In this case, if t < T (total shutter open time), it is controlled to turn on only during the period when the shutter is safely open and not to turn on during the movement period of the shutter curtain, so uniform exposure can be achieved. Note that since the light emission intensities of the LED light sources 132 to 138 are different, the brightness of the obtained image can be adjusted by adjusting the lighting times t1 to t5. With the trigger signal 6, a non-emitting image in which the LED light sources 132 to 138 do not emit light is captured. This is for capturing an image of ambient light, and by subtracting this non-emitting image from the image irradiated with the LED light sources 132 to 138, the influence of ambient light can be removed.

[0032] Note that the white LED light source 132 is turned on when the power button 126 of the lighting control unit 124 is turned on. Therefore, the white LED light source 132 irradiates the subject 142, and framing and focusing can be performed during the period until the first trigger signal 1 is input from the imaging unit 110 (see Figure 4(G)). Then, when the shutter button 116 is half-pressed, focus lock is applied and the exposure operation starts. Also, after the exposure is completed in the non-emitting state, the white LED light source 132 is turned on and returns to the initial state.

[0033] <Operation> Next, the operation and movement of this embodiment will be described. As shown in Figure 1, a subject 142 for product photography is placed in front of the background cloth 140, and a color chart 144 is placed nearby. After fixing the imaging unit 110 with a tripod 122 or the like, turn on the power of the imaging unit 110 (not shown), a. Set the exposure to "manual", the focus to "auto", and the recording mode to "RAW data", respectively. The reason for setting to "RAW data" is that since the captured image is not data-compressed, the highest-quality image can be obtained. b. Set the shooting mode to "continuous shooting mode". This "continuous shooting mode" is, for example, bracket shooting. In this bracket shooting, a specified number of images are shot continuously while changing the conditions. In this embodiment, it is set to shoot six images continuously.

[0034] Next, the power button 126 of the lighting control unit 124 is turned ON to light up the white LED light source 132. At this time, it is preferable to turn off the lights in the studio room, as this is less susceptible to the effects of ambient light. Next, the photographer performs framing and focusing while looking at the subject 142 reflected in the LCD finder or LCD monitor of the imaging unit 110. In framing, the positions of the subject 142 and the color chart 144 and the zoom of the imaging optical system 112 are changed so that the subject 142 and the color chart 144 are within the same angle of view. Since the subject is illuminated by the white LED light source 132, the subject image can be confirmed in the LCD finder or LCD monitor in the same color as the real thing, making framing and focusing easy.

[0035] In this way, when preparations for shooting are complete, the shutter button 116 begins to be pressed. When the shutter button 116 is half-pressed, focus lock is applied. Then, when the shutter button 116 is fully pressed, shooting trigger signals 1 to 6 are output in sequence. As a result, the white LED light source 132, RLED light source 134, GLED light source 136, and BLED light source 138 are turned on and off in sequence in the sequence shown in FIG. (1) An image in which part of the subject 142 is illuminated with white light at trigger signal 1. (2) An image in which the entire area of ​​the subject 142 is illuminated by the white LED light source 132 upon trigger signal 2. (3) Image in which the entire area of ​​the subject 142 is illuminated by the RLED light source 134 upon trigger signal 3. (4) Image of the subject 142 illuminated by the GLED light source 136 at trigger signal 4 (5) Image of the subject 142 illuminated by the BLED light source 138 at trigger signal 5 (6) Image of subject 142 captured without flash upon trigger signal 6 That is, in this embodiment, six images of the subject 142 and the color chart 144 are captured with one shutter press, and the captured images are output from the imaging unit 110 to the color measurement processing unit 150.

[0036] The image captured with trigger signal 1 cannot be used because the white LED light source 132 is non-uniformly illuminated. For this reason, the multiband image generating unit 152 of the color measurement processing unit 150 (1) Trigger signal 2: R band of the image captured by the white LED light source 132 ⇒ band 1 (2) G band of the image captured by the white LED light source 132 with trigger signal 2 ⇒ band 2 (3) Trigger signal 2: B band of the image captured by the white LED light source 132 ⇒ band 3 (4) Trigger signal 3: R band of the image captured by the RLED light source 134 ⇒ band 4 (5) G band of the image captured by the GLED light source 136 with trigger signal 4 ⇒ band 5 (6) B band of the image captured by the BLED light source 138 with trigger signal 5 ⇒ band 6 A 6-band multiband image is created by selecting bands as shown in the figure. In other words, if M types of narrowband LED light sources (M=3 in this embodiment) are used, an N-band (N=3+M) multiband image is created.

[0037] In this selection of bands, the band that provides the highest imaging intensity when the subject 142 is illuminated with each LED light is selected. In an image captured by illuminating with the RLED light source 134, the peak wavelength of the RLED light source 136 is close to the peak position of the R band, so that when the emission luminance of each of the LED light sources 134 to 138 is the same, the R band provides the highest signal value compared to the G band and B band. Similarly, the G band is selected for an image captured by illuminating with the GLED light source 136, and the B band is selected for an image captured by illuminating with the BLED light source 138. Note that when generating this multiband image, the non-emission image is subtracted to remove the influence of ambient light, and the multiband image information after the removal is output to the color conversion processing unit 160.

[0038] On the other hand, the image information of the color chart 144 pre-recorded in the color conversion information recording unit 154 and the color conversion coefficients created at that time are output to the color conversion processing unit 160. a,The luminance value of the color chart area in the multiband image is compared with the luminance value of the color chart image recorded in advance, and the luminance of the multiband image is corrected; b. Furthermore, color information is calculated using the color transformation coefficients.

[0039] As described above, the color information includes XYZ information, Lab information, spectral information, color reproduction image, etc., and is calculated or created by XYZ calculation unit 162, Lab calculation unit 164, spectral calculation unit 166, and color reproduction image creation unit 168, respectively. The image is of the sRGB standard, as will be described in detail later. By using an sRGB standard display 170, an image reproduced in colors faithful to those of subject 142 is displayed on display 170.

[0040] <Effects> As described above, according to this embodiment, in the studio product photography, by performing multiband photography of 6 bands, the color information of the subject 142 can be detected with high accuracy, and accurate color reproduction can be realized on the display 170. As a result, it is expected that complaints and returns regarding colors in online shopping can be reduced. In addition, a commercially available digital camera can be used as the imaging unit 110, and multiband photography can be realized at low cost. In multiband photography, since photography is first performed using the white LED light source 132, preparation for photography can be performed with a standard RGB image, and framing and focusing are easy and convenient. Furthermore, by using the luminance value of the color chart 144 photographed in advance and the luminance value of the color chart 144 actually photographed, the light emission variation of the illumination light source can be corrected, and the color information of the subject 142 can be detected with high accuracy.

[0041] It is also possible to use another trigger signal to capture a white image last. In this way, after a series of continuous shots is completed, the last captured image of the white LED light source 132 is displayed for a certain period of time on the LCD monitor of the imaging unit 110, so that the photographer can know that the shooting has been completed successfully.

[0042] <Modification> Fig. 5 shows a shooting sequence of a modification of the first embodiment. As shown in the figure, in the above embodiment, the trigger signal was output a total of six times, and six images were shot. If the continuous shooting speed is 20 fps, shooting took 6 / 20 = 0.3 seconds, but it is desirable to shorten the shooting time as much as possible. In the above embodiment, the images were saved as RAW data to improve image quality, but since RAW images are not compressed and require a large memory capacity, it is desirable to save as few images as possible. Therefore, as a modification, an example in which the shooting trigger is output five times, one less time, will be described.

[0043] As shown in FIG. 5, the white LED light source 132 is not turned off by the trigger signal 1, but goes into exposure, and is turned off t1 seconds after the trigger signal 1 is received. The narrowband LED light sources 134 to 138 are the same as those in the above embodiment. The white LED light source 132 is turned on before exposure, and exposure starts when the shutter curtain opens. For this reason, by turning on the white LED light source 132 until the shutter curtain is completely closed, uniform exposure can be achieved on the screen. Although time errors are likely to occur in the opening and closing of the shutter curtain, some fluctuations can be corrected by brightness correction using the color chart 144. According to this modification, the number of exposures can be reduced, which enables the shooting time to be shortened and the storage capacity to be reduced. EXAMPLES

[0044] Next, a second embodiment will be described with reference to Figs. 6 to 14. This embodiment is an example in which the present invention is applied to color inspection. Dedicated color scales for color inspection are used in the color inspection of industrial products, the grading of food based on the color, and the determination of the growth level of plants based on the color. For example, in rice cultivation, the following seven-color color scale is used for managing top dressing. https: / / www.zennoh.or.jp / members / pdf / gijyutu_2-06.pdf In addition, when making crowns (dentures) in dentistry, a color scale called a shade guide is used, as shown below. https: / / smileteeth.jp / column / orthodontics_beginner / shade_guide /

[0045] However, there are problems with the judgment of these color scales, such as differences due to personal differences caused by differences in people's experience, and differences in the lighting of the observation location can cause colors to appear differently and judgments to differ. In addition, conventional RGB cameras cannot accurately detect color information, making it difficult to make correct judgments. In the dental example, if a judgment is made incorrectly using the color scale, a crown will have to be remade, resulting in unnecessary costs. In this embodiment, multiband photography is applied to the judgment of such a color scale to make good color judgments.

[0046] <Configuration> The configuration of this embodiment is shown in Fig. 6. The same reference numerals are used for the same or corresponding parts to the first embodiment. The biggest difference from the first embodiment is the use of an illumination unit 210 in which the light source section 130 and the color chart 144 are integrated. This illumination unit 210 has a detachable section 212, and can be detachably attached to the imaging section 110. For example, interchangeable lenses for digital cameras have thread grooves for attaching filters so that various filters can be attached, and the illumination unit 210 is attached by utilizing these thread grooves. Alternatively, the illumination unit 210 may be attached by sandwiching a filter frame from the left and right like a lens cap.

[0047] The lighting unit 210 has a measurement window 220 for measuring the subject on the front, where the subject 142 is placed and photographed. The subject 142 is not necessarily flat, so some ambient light enters from the outside, but it is slight, and the effects of this ambient light can be removed by bias correction, which will be described later. The photographing signal output section 120 is a so-called hot shoe, which is a mechanism for attaching an external strobe, and the lighting control section 124 is connected to it. Figure 7(A) shows an image photographed with the lighting unit 210 attached. There is a measurement window 220 near the center of the screen, and the screen is configured so that a color chart 144 is reflected at the bottom.

[0048] Next, the color measurement processing unit 500 has a configuration shown in detail in FIG. 8. In the figure, the bias correction unit 512 of the multiband image generation unit 510 removes the influence of ambient light by subtracting an image captured without emitting light from an image captured by irradiating the illumination light source. If there is fixed pattern noise in the image sensor 114, this also has the effect of removing this noise. The demosaicing processing unit 514 is a processing unit that generates an RGB image. The image sensor of a commercially available digital camera is usually composed of an on-chip filter with RGB transmission characteristics and a monochrome sensor, so that the signal captured for each pixel is one of R, G, and B. This demosaicing processing is a process for obtaining R, G, and B values ​​for all pixels. In the band selection unit 516, as described in the above embodiment, an appropriate band according to the illumination is selected from the RGB image obtained by the demosaicing processing unit 514, and a multiband image is generated.

[0049] Next, the color conversion processing unit 520 will be described. The spectral characteristics of the image sensor 114 of the imaging unit 110, the spectral characteristics of the imaging optical system 112, and the emission spectrum of each LED of the light source unit 130 built in the lighting unit 210 are different for each individual due to manufacturing variations. In order to accurately detect color information, color conversion processing is required according to the characteristics of the imaging unit 110, the lighting unit 210, and the light source unit 130. The color conversion information recording unit 530 records information such as parameters and images related to color conversion. In this embodiment, as described later, an image of a reference plate with a color chart 144 placed nearby and color conversion coefficients calculated when the reference plate was photographed in advance are recorded as color conversion information. These color conversion information are configured to be recorded for each combination of the imaging unit 110 and the lighting unit 210, and the required color conversion information is output when an imaging unit ID, which is the serial number of the imaging unit 110, and a lighting unit ID, which is the serial number of the lighting unit 210, are input.

[0050] Next, image unevenness correction will be described. It is difficult to make the light quantity distribution of the irradiating light source unit 130 uniform, and illumination unevenness occurs depending on the position. In particular, since multiple light sources are used, this illumination unevenness differs for each light source. Also, in the imaging optical system 112, shading occurs, in which the brightness of the captured image becomes darker in the periphery compared to the vicinity of the optical axis. Therefore, the brightness of the captured image becomes non-uniform, and even when a subject 142 with a uniform brightness distribution is captured, brightness unevenness that differs for each light source occurs. This is corrected by the image unevenness correction unit 522.

[0051] To correct this image unevenness, a reference plate with a uniform brightness distribution, such as a standard white plate, is photographed in advance with each light source and stored in the color conversion information recording unit 530, and the image unevenness is corrected using the images. Fig. 7(B) shows an image obtained by photographing the reference plate 222. The image of this reference plate 222 is recorded in the color conversion information recording unit 530, and the image unevenness is corrected for each band using this image.

[0052] The region extraction unit 524 extracts images of the subject region hre and the color chart region pre, as shown in FIG. 7(C). The subject region hre to be extracted is preferably slightly smaller than the measurement window 220, as shown by the dotted line, in consideration of the influence of the positional deviation of the lighting unit 210 itself. Similarly, the color chart region pre is preferably smaller in size than the color chart 144. Moreover, since uneven illumination is likely to occur in the vertical direction, it is preferable to set the region horizontally. In addition, since the lighting unit 210 can be detached from the imaging unit 110, it is not necessarily attached to the same position when attached. That is, the image is formed with a positional deviation on the image sensor 114. In this case, the region is shifted from the image of the reference plate 222 captured, and a positional deviation may occur between the images of FIG. 7(A) and FIG. 7(B). Therefore, the amount of this positional deviation may be detected in advance, and the region may be extracted taking this deviation into consideration before the region is extracted.

[0053] Next, the luminance correction unit 526 corrects the light emission variation of the white LED light source 132 and narrowband LED light sources 134-138 of the light source unit 130. The luminance correction coefficient C(k) (k=1 to N, N is the number of bands) for each band calculated by the luminance correction coefficient calculation unit 528 is multiplied by the subject area image. The luminance correction coefficient calculation unit 528 extracts an image of the color chart area from a reference plate image captured in advance (color chart area pre in FIG. 7(B)), averages this image for each band, and calculates it as Vpre(k). k represents the band and is an integer between 1 and N (N=6 in this embodiment). Similarly, the image of the color chart area pre obtained by the area extraction unit 524 is averaged for each band, and the obtained value is V(k), and the luminance correction coefficient C(k) is given by C(k)=Vpre(k) / V(k) (k=1~N) It is calculated as follows.

[0054] Next, the color information calculation unit 540 calculates various color information from the luminance-corrected multiband image. As described above, the color information includes XYZ information, Lab information, spectrum information, and color reproduction image. First, the XYZ calculation unit 542 uses the color conversion coefficients recorded in the color conversion information recording unit 530 to obtain XYZ tristimulus values ​​of each pixel or a predetermined area, and outputs them as XYZ information. The XYZ tristimulus values ​​are the coordinates of the CIE·XYZ color space, which is a unified display standard for colors established by the International Commission on Illumination (CIE) in 1931. In order to achieve accurate color reproduction, it is necessary to correctly obtain the XYZ tristimulus values ​​of the subject.

[0055] The Lab calculation unit 544 calculates the Lab value of each pixel or a predetermined area from the XYZ tristimulus values ​​and outputs it as Lab information. The Lab value is a coordinate value in the Lab color space, https: / / ja.wikipedia.org / wiki / CIE_1931_%E8%89%B2%E7%A9%BA%E9%96%93 It is a nonlinear compression of the coordinates, where L represents brightness, a represents redness, and b represents yellowness.

[0056] The spectrum calculation section 546 uses the color conversion coefficients recorded in the color conversion information recording section 530 to calculate the spectral reflectance spectrum of each pixel or a predetermined region, and outputs it as spectral information.

[0057] The color reproduction image creation unit 548 uses the XYZ tristimulus values ​​to calculate image signal values ​​of the sRGB standard for each pixel and creates a color reproduction image. sRGB is one of the standard color space standards, and is supported by general information devices such as personal computers, displays, monitors, and printers. When images or videos are exchanged between devices, the standard absorbs differences in characteristics due to models and devices and maintains the same color tone. Accurate color reproduction is possible by displaying image signals of the sRGB standard on a display that supports sRGB.

[0058] A color scale information recording unit 560 has Lab values ​​corresponding to each color scale recorded in advance, and a color judgment unit 562 compares the Lab values ​​obtained from the Lab calculation unit 544 with the Lab values ​​recorded in the color scale information recording unit 560 to select the closest color scale and output it as color judgment information. Then, color information such as XYZ information, Lab information, spectral information, and color reproduction image is all output to a display 170 that complies with the sRGB standard.

[0059] <Function> Next, the function of this embodiment will be described using an example of measuring the color of a person's teeth. The photographer attaches the lighting unit 210 to the imaging section 110. Then, as in the above-mentioned embodiment 1, the photographer turns on the power of the imaging section 110 (not shown), sets the exposure to "manual", the focus to "automatic", the recording mode to "RAW data", and the shooting mode to "continuous shooting mode". In this embodiment, it is set to shoot three images continuously. Next, the power button 126 of the lighting control section 124 is turned on to start the framing and focusing operations. The photographer brings the tip of the lighting unit 210 close to the tooth whose color is to be measured, and moves the imaging section 110 and the lighting unit 210 to a position as shown in FIG. 7(C). Since the subject is illuminated by the white LED light source 132, the subject image can be confirmed in the LCD finder or LCD monitor in the same color as the real thing, and framing and focusing can be easily performed. It is to be noted that a cap or the like may be attached to the tip of the lighting unit 210. The patient's teeth do not come into direct contact with the lighting unit 210, which is more hygienic.

[0060] 9 is a timing chart of this embodiment. As in the first embodiment, three types of narrowband light, RLED 134, GLED 136, and BLED 138, are used, and these narrowband LED light sources 134 to 138 emit light simultaneously. From the image captured in this way, a bias correction unit 512 subtracts a non-emission image, and a demosaicing processing unit 514 generates all pixels of the image of each band.

[0061] In the band selection unit 516, (1) Trigger signal 1: R band of the image captured by the white LED light source 132 ⇒ band 1 (2) Trigger signal 1: G band of the image captured by the white LED light source 132 ⇒ band 2 (3) Trigger signal 1: B band of the image captured by the white LED light source 132 ⇒ band 3 (4) R band of the image taken by irradiating RLED, GLED, and BLED simultaneously with trigger signal 2 ⇒ band 4 (5) G band of the image taken by irradiating RLED, GLED, and BLED simultaneously with trigger signal 2 ⇒ Band 5 (6) B band of the image captured by irradiating RLED, GLED, and BLED simultaneously with trigger signal 2 ⇒ band 6 This generates a multiband image.

[0062] Next, the image unevenness correction unit 522 uses the reference plate image read out from the color conversion information recording unit 530 to correct image unevenness caused by illumination unevenness of the illumination light source and shading of the imaging optical system 112. From the image in which image unevenness has been corrected, the region extraction unit 524 extracts the subject region hre and the color chart region pre as shown in Fig. 7(C). Then, the color chart region pre is also extracted from the reference plate image as shown in Fig. 7(B), and the brightness correction coefficient calculation unit 528 calculates a brightness correction coefficient C(k). Based on this brightness correction coefficient C(k), the brightness correction unit 526 performs brightness correction for each band on the multiband image of the subject region hre.

[0063] Furthermore, using the color conversion coefficients read out from the color conversion information recording unit 530, the XYZ calculation unit 542 calculates XYZ stimulus values ​​for each pixel, and the color reproduction image creation unit 548 uses these XYZ tristimulus values ​​to calculate image signal values ​​of the sRGB standard for each pixel, and outputs them to the display 170 as an sRGB image.

[0064] On the other hand, the Lab calculation unit 544 calculates the Lab value of each pixel or a predetermined area from the XYZ tristimulus values ​​and outputs it as Lab information. The color judgment unit 562 compares the Lab value obtained from the Lab calculation unit 544 with the Lab value recorded in the color scale information recording unit 560, selects the color scale closest to the Lab value recorded in the color scale information recording unit 560, and outputs it as color judgment information. In the case of human teeth, a shade guide is used as the color scale. For example, the shade guide "classic" by VITA has a color scale of 16 colors. Therefore, the color judgment unit 562 outputs the shade guide number having the closest Lab value among these 16 colors as color judgment information.

[0065] FIG. 10 shows an example of display on the display 170. FIG. 10(A) shows a color reproduction image, FIG. 10(B) shows spectrum information, FIG. 10(C) shows colorimetric information of XYZ tristimulus values ​​and Lab values, and FIG. 10(D) shows color judgment information. In this example, a predetermined area is set in the color reproduction image, and the spectrum information, colorimetric information, and color judgment information are calculated for the data obtained by averaging the predetermined area. For the color judgment information, the shade guide with the closest Lab value is shown as the first candidate, the second closest shade guide as the second candidate, and the third closest shade guide as the third candidate. In FIG. 10, ΔE is the difference between the Lab values, which is the Euclidean distance in the Lab space. The predetermined area in FIG. 10(A) may be set by selecting it with a mouse of a personal computer, or by specifying the position coordinates x, y in the image, or by recognizing the shape of the tooth and setting it near the center.

[0066] <Effects> As described above, according to this embodiment, the color scale can be judged stably and accurately without being affected by personal differences due to differences in experience or differences in the lighting of the observation location. In addition, only three images are taken, which is half the number of images compared to the above-mentioned embodiment 1, and the shooting time can be shortened and the memory capacity for storing the captured images can be significantly reduced. In addition, the display 170 can display an image with accurate color reproduction according to the sRGB standard, color measurement information such as Lab information and XYZ information, and color judgment information of the color scale on the same screen, so that a crown maker such as a dental technician can efficiently make a crown while viewing the image and numerical information at the same time.

[0067] In this embodiment, the color space displayed on the display 170 is the sRGB standard, but other color spaces, such as the Adobe (registered trademark) RGB standard, which has a wider color space, may be used. Furthermore, although the color judgment unit selects three or more types of color scales in ascending order of ΔE, they may be displayed in ascending order using ΔL (difference in brightness L), Δa (difference in redness a), or Δb (difference in yellow intensity b).

[0068] <Modification 1> In the case of the second embodiment, the three types of LED light sources, RLED134, GLED136, and LED3138, emit light simultaneously, so that the spectral sensitivity of each RGB band has a small peak (crosstalk) in addition to the main wavelength peak, as shown in Fig. 11. In this case, if the emission intensities of RLED134, GLED136, and BLED138 vary, luminance correction using the color chip 144 is ineffective. Therefore, as shown in Fig. 12, the GLED136, which is a light source having a peak wavelength in the G band, is not emitted simultaneously with the other light sources, a, Trigger signal 1 emits white LED light source 132, b. Trigger signal 2 lights up RLED134 and BLED138 simultaneously. c, GLED136 lights up with trigger signal 3, Furthermore, the peak wavelength of the RLED 134 is set as short as possible, and the peak wavelength of the BLED 138 is set as long as possible. FIG. 13(A) shows this state. The dotted line in the figure is the optical spectrum in the second embodiment shown in FIG. 11(A), but in this embodiment, the peak wavelength is shifted as shown by the solid line in FIG. 13(A). In this way, as shown in FIGS. 13(B) to (D), the crosstalk shown in FIGS. 11(B) to (D) hardly appears. Therefore, it is possible to perform shooting with reduced influence of crosstalk, and even if the emission intensity of each narrowband LED light source 134 to 138 varies, the luminance correction can be performed well, and color information can be detected with high accuracy.

[0069] <Modification 2> Next, a description will be given of Modification 2. The emission spectrum of an LED light source is determined by the band gap (Eg) of the LED portion. Wavelength = Planck constant * speed of light / Eg Since the band gap Eg is a function of temperature, the temperature of the LED rises at the timing (time) of light emission, and the emitted wavelength changes. In other words, the emitted wavelength changes depending on the ambient temperature of the subject being photographed. Figure 14(A) shows this, with the wavelength of the emitted LED changing (shifting) from a solid line to a dotted line relative to the spectrum of the subject. It is unlikely that the temperature will be exactly the same when the reference board is photographed in advance and when the subject is photographed, so the image will actually show a signal value that differs from the expected signal value.

[0070] In this case, if the color chip 144 has similar color characteristics (i.e., similar spectral reflectance) as the subject 142 photographing the color chip 144, the signal value V(k) obtained by photographing the color chip 144 will also change in the same way, and the wavelength change (wavelength shift) can be corrected by processing by the luminance correction unit 526. In this sense, it is very effective to select a lighting unit 210 with color characteristics close to those of the subject 142. Here, color characteristics close to the subject 142 desirably have the same shape of spectral reflectance as the subject 142, but since it is generally difficult to select such a color chip 144, it is more practical to select a similar color.

[0071] However, there is generally a certain degree of variation in the color of the subject 142 to be measured, and it is difficult to select a single color chip 144 that has characteristics close to those of the subject 142. Therefore, as shown in Fig. 14(B), multiple color chips 144A, 142B, and 142C may be provided, and these may be photographed and selected during processing. EXAMPLES

[0072] Next, a third embodiment will be described with reference to Fig. 15 and Fig. 16. In this embodiment, a system 600 is described in which the obtained tooth color information is shared between a dental clinic and a dental laboratory using the cloud.

[0073] <Configuration> Fig. 15 shows the configuration of this embodiment, and a dental clinic 610 and a dental laboratory 630 exchange various data using a cloud 620. An imaging unit 610A for photographing the patient's teeth and a lighting unit 610B are provided in the dental clinic 610. In addition, an image recording unit 610C for recording the photographed image of the patient's teeth, a transmission operation unit 610D for transmitting data to the cloud, and an information input unit 610E for inputting ID numbers of the imaging unit 610A and the lighting unit 610B, information on the patient and clinic, etc. are provided as functions of clinic software 612. The clinic software 612 is installed and executed on a personal computer or the like installed in the dental clinic 610, but may be implemented on the cloud as a Web application.

[0074] Next, the dental laboratory 630 is provided with an imaging unit 630F for photographing the created crown, a lighting unit 630E, and a measurement box 630G. In addition, an image recording unit 630A for recording the photographed image of the created crown and the ID number of the imaging unit 630F and the lighting unit 630E, a transmission / reception operation unit 630B for transmitting and receiving data to the cloud 620, an information input unit 630C for inputting information on the patient and the dental laboratory, and an information display unit 630D for displaying information received from the cloud 620 are provided as functions of the dental laboratory software 632. The dental laboratory software 632 is installed and executed on a personal computer or the like installed in the dental laboratory 630, but may be implemented on the cloud as a Web application.

[0075] Next, the cloud 620 is provided with a color measurement processing unit 620A, an information recording unit 620B, and a comparison evaluation unit 620C. These are also executed by executing the cloud software. The color measurement processing unit 620A performs the same processing as the color measurement processing unit 500 of the second embodiment. The information recording unit 620B records the patient information and clinic information sent from the dental clinic 610, the laboratory information requested for production, the patient information and clinic information and laboratory information sent from the dental laboratory 630, and the color information calculated by the color measurement processing unit 620A. The comparison evaluation unit 620C compares the color information of the patient's teeth photographed and obtained at the dental clinic 610 with the color information of the crown produced at the dental laboratory 630. For example, the difference in Lab value ΔE, the difference in brightness ΔL, the difference in redness Δa, and the difference in yellow Δb are calculated as the difference in the Lab color space. The comparison result is displayed on the information display unit 630D of the dental laboratory 630.

[0076] <Function> Next, the function of this embodiment will be described. In the dental clinic 610, the lighting unit 610B is attached to the imaging unit 610A. Then, the power supply of the imaging unit 610A and the power supply of the lighting control are turned on to capture the color of the patient's teeth. The tooth to be captured is, for example, the tooth next to the tooth for which a crown is to be created. Next, the clinic software 612 is started, and the captured image is recorded in the image recording unit 610C. Then, from the information input unit 610E, information required for crown production, such as patient information, the serial number (ID) of the imaging unit 610A and the lighting unit 610B used for capturing the image, and the name of the dental laboratory where the crown is to be produced, is input. When the input is completed, the transmission operation unit 610D is operated to transmit the information to the cloud 620.

[0077] In the cloud 620, color measurement processing unit 620A calculates color information from information on the captured image, imaging unit ID, and lighting unit ID, and records it in information recording unit 620B. In addition, patient information, clinic information, and dental laboratory information are also recorded in information recording unit 620B, and the information is notified to dental laboratory 630 designated by dental clinic 610.

[0078] When the dental laboratory 630 starts up the laboratory software 632, it receives a notification from the dental clinic 610 and knows that an order for the production of a crown has been placed. Next, the color information of the patient's teeth and patient information photographed at the dental clinic 610 are displayed on the information display unit 630D, and the crown is produced based on that information. When the production of the crown is complete, the lighting unit 630E is attached to the imaging unit 630F, the power supply of the imaging unit 630F and the power supply of the lighting control are turned on, and the color of the produced crown is photographed. A dedicated measurement box 630G is used for this photography, and the crown is placed in it and measured, allowing the measurement to be performed in an environment similar to that inside the oral cavity.

[0079] The captured image is then recorded in the image recording section 630A. Next, necessary information such as patient information, serial numbers (IDs) of the imaging section 630F and the lighting unit 630E, and the name of the dental clinic that made the request is input from the information input section 630C. When the input is complete, the transmission / reception operation section 630B is operated to transmit the information to the cloud 620.

[0080] In the cloud 620, the color measurement processing unit 620A calculates color information from the captured image, image capture unit ID, and lighting unit ID information, and records it in the information recording unit 620B. Furthermore, the comparative evaluation unit 620C compares the color information of the patient's teeth with the color information of the manufactured crown. Fig. 16 shows an example of comparative display of information on the position P1 of the patient's teeth and the position P2 of the manufactured crown. As described above, the Lab value is a numerical value that represents brightness and color, ΔL indicates the difference in the brightness L value, Δa indicates the difference in the redness a value, and Δb indicates the difference in the yellowness b value.

[0081] In the example of FIG. 1C, since ΔL is small, the produced crown is darker, since the a values ​​are almost the same, the redness is almost the same, and since the b value is -2.1, it can be seen that the crown is more blue than yellow. ΔE represents the color difference taking into account all of these Lab values. It is generally said that when ΔE is greater than 3, people perceive the colors as different. In the example of FIG. 1C, ΔE=3.5, and the human eye perceives the colors as different, so the crown needs to be remade. In this way, the dental technician refers to the values ​​of ΔE, ΔL, Δa, and Δb, adjusts the type of porcelain, the compounding ratio, the thickness to be applied, etc., when producing the crown, and produces the crown again. When ΔE<3, it is judged to be completed, and this crown is sent by mail or the like to the dental clinic 610.

[0082] <Effects> As described above, according to this embodiment, the dental clinic 610 can easily request the dental laboratory 630 to make a crown by simply sending the captured image to the cloud 620. In addition, since only crowns that meet the condition of ΔE<3 are sent from the dental laboratory 630, remaking can be almost eliminated and the cost of remaking can be reduced.

[0083] On the other hand, the dental laboratory 630 can check the color information of the patient's teeth and the color information of the produced crown through images and numerical values, and can produce the crown without trial and error, thereby shortening the production time and, as a result, reducing production costs.

[0084] <Other Examples> The present invention has many examples, and can be modified in various ways based on the above disclosure. For example, the following are also included. (1) In the above embodiment, three types of narrowband light sources, R LED 134, G LED 136, and B LED 138, were used as narrowband light sources, but the number of types is not limited to R, G, and B, and any M number of types may be used. M may be 1 to 2, or 4 or more. When M types of narrowband light sources are used, the number of bands in the captured multiband image is N=3+M. Furthermore, some types of narrowband light sources have low emission intensity. In that case, multiple light sources of the same type may be used. (2) In the above embodiment, the recording mode of the captured image is set to RAW data, but it may be RAW image + JPEG image. RAW images have unique and different formats for each camera manufacturer, so they cannot be easily displayed on a general personal computer. However, by using RAW image + JPEG image, although the recording capacity increases slightly, image data in JPEG format can also be obtained, so the captured image can be displayed without demosaicing. This has the advantage that the captured image can be easily confirmed using commercially available image display software, which is particularly effective in developing the multiband imaging device of the present invention. (3) The system configuration shown in the above embodiment is merely an example, and may be applied to various known systems that provide similar functions. (4) In the above embodiment, the present invention is applied to photographing objects and manufacturing dental crowns, but it can be applied to accurate color reproduction of various images. (5) The above embodiment is applied to RGB since it is assumed that the color will be displayed on a display. However, in the case of printing pamphlets or catalogs, the embodiment may be applied to RYB or CMYK. [Industrial Applicability]

[0085] According to the present invention, a multiband image including a standard RGB image and a narrowband image can be easily obtained by sequentially irradiating white light and narrowband light with a digital camera capable of continuous shooting and taking continuous shots. By placing a color chart approximating the subject color near the subject and photographing this color chart on the same screen as the subject, variations in the light emission of the lighting can be corrected and the color information of the subject can be detected with high accuracy. This is suitable for color adjustment of product images on a display or color adjustment of crowns in dental technician work. [Explanation of symbols]

[0086] 100: Shooting system 110: Imaging unit 112: Imaging optical system 114: Image sensor 116: Shutter button 118: Image memory 120: Shooting signal output section 122: Tripod 124: Lighting control unit 126: Power button 130: Light source section 132: White LED light source 134~138: Narrowband LED light source 140: Background cloth 142:Subject 144,144A,144B,144C: ​​Color chart 150: Color measurement processing unit 152: Multiband image generator 154: Color conversion information recording unit 160: Color conversion processing unit 162:XYZ calculation part 164:Lab calculation part 166: Spectral calculation unit 168: Color reproduction image creation section 170: Display 210: Lighting unit 212: Detachable part 220: Measurement window 222: Reference board 500: Color measurement processing unit 510: Multiband image generator 512: Bias correction unit 514: Demosaicing processing unit 516: Band selection section 520: Color conversion processing unit 522: Image unevenness correction unit 524: Area extraction part 526: Brightness correction section 528: Luminance correction coefficient calculation unit 530: Color conversion information recording unit 540: Color information calculation section 542:XYZ operation section 544:Lab calculation part 546: Spectral calculation unit 548: Color Reproduction Image Creation Department 560: Color scale information recording unit 562: Color judgment section 600: System 610:Dental clinic 610A: Imaging unit 610B: Lighting unit 610C: Image recording unit 610D: Transmission operation unit 610E: Information input section 612: Clinic software 620: Cloud 620A: Color measurement processing unit 620B: Information recording section 620C: Comparative Evaluation Section 630: Dental laboratory 630A: Image recording section 630B: Transmitting and receiving operation section 630C: Information input section 630D: Information display section 630E: Lighting unit 630F: Imaging unit 630G: Measurement box 632: Laboratory software

Claims

1. an imaging section having an imaging optical system, an image sensor section for acquiring images with three spectral sensitivities of R band, G band, and B band, a shutter button for starting imaging, an imaging signal output section for outputting an imaging trigger signal to the outside at the start of exposure, and an image memory for recording the captured image, and which issues the imaging trigger signal when the shutter button is pressed; a light source unit including a white light source having an emission spectrum in almost all wavelength ranges of the spectral sensitivity ranges of the R band, the G band, and the B band of the imaging unit, and M types of narrow band light sources having a peak wavelength within a wavelength range of a half width of a band in which the highest signal value is obtained in the R band, the G band, and the B band when emitting light, and having an emission spectrum with a half width narrower than the half width of the band; a light source control unit that controls turning on or off the light source of the light source unit in response to a photography trigger signal; a multiband image generator that captures a plurality of images by first irradiating the image with a white light source, then with multiple narrowband light sources, either sequentially or simultaneously, and generates an N-band (N=3+M) image from the image captured by irradiating the image with the white light source and the image captured by irradiating the image with the narrowband light sources; a color conversion processing unit that detects color information of any one of XYZ information, Lab information, spectral information, and color reproduction image from the generated multiband image; A multi-band color measurement system comprising:

2. A color chart with color characteristics similar to that of the subject is placed near the subject and captured in the same image as the subject.

2. The multiband colorimetric system according to claim 1, further comprising a luminance correction unit which corrects for variations in light emission from the light source unit based on luminance information of the color chart area of ​​the captured image.

3. 3. The multiband colorimetric system according to claim 2, further comprising an illumination unit having a built-in light source section and a color chart, a measurement window for photographing an object, and a detachable section for attaching to and detaching from the photographing section.

4. 2. The multiband colorimetric system according to claim 1, wherein a narrowband light source that provides the highest signal value in the G band when the narrowband light source emits light is not emitted simultaneously with other narrowband light sources.

5. a color conversion information recording unit that records a reference plate image obtained by photographing a reference subject and color conversion information for color conversion created at that time; an image unevenness correction unit that corrects image unevenness of a multiband image for each band by using the reference plate image; 2. The multiband colorimetric system according to claim 1, further comprising:

6. a color scale information recording section in which color information of the color scale is recorded; a color determining unit that determines a color scale from the color information obtained by the color conversion processing unit; 2. The multiband colorimetric system according to claim 1, further comprising:

7. 2. The multiband colorimetric system according to claim 1, further comprising a comparison evaluation unit that compares color information calculated from images taken at different locations and calculates the difference in color information between the images as a difference in Lab color space.

Images