JP4831962B2 - Imaging device - Google Patents

Description

  The present invention relates to a photographing apparatus that measures an input image using spectral spectrum information of a subject.

  Conventionally, color management has been performed in many fields such as the industrial field, food field, and medical field. For example, in the industrial field, color management is performed on the colors of manufactured products, and colorimeters such as spectrometers and colorimeters are used to check whether the products are finished in a standard color. ing. In the medical field, for example, in dermatology, color management for skin color is performed. Digital cameras are often used to record changes in skin color.

  In recent years, digital cameras have been increased in the number of pixels and the cost thereof, and accordingly, the field of use in color management has expanded. For example, digital cameras are being used in the dental field and the like.

  Digital cameras have the advantage of being able to easily acquire an image of the affected area and confirming the image immediately after imaging, but the accuracy of color correction is low. However, there is a problem that the color of the captured image is different. The accuracy of color correction in a digital camera decreases due to various causes. In particular, a decrease in white balance detection accuracy has a great influence on color correction accuracy.

Therefore, in Patent Document 1, a proposal for improving the accuracy of white balance correction has been made. In this proposal, white balance correction accuracy is improved by using information of a colorimetric sensor when photographing with a digital camera. That is, in Patent Document 1, a colorimetric sensor is installed in almost the same direction as an area photographed by a digital camera, and the signal value of the digital camera is corrected based on the obtained RGB value of the colorimetric sensor. It is. In this case, the RGB values of the image data captured by the digital camera are averaged over the entire screen for each RGB and compared with the colorimetric sensor.
JP 2003-125422 A

  By the way, in the dermatology and the medical field for dentistry, there is a high demand for obtaining an accurate color only for the affected part in the image. However, in Patent Document 1, since the object is simply to adjust the white balance of the entire screen, it is not always possible to acquire an accurate color for the affected area.

  In view of this, a method of improving the colorimetric accuracy by photographing using four or more light sources that emit light of different colors is also conceivable.

  However, when the number of light sources is increased, there is a disadvantage that the power consumption increases accordingly. In particular, when the photographing apparatus for color measurement is configured to be portable, there is a problem that various problems occur due to an increase in power consumption.

  The present invention has been made in view of such problems, and an object of the present invention is to provide an imaging apparatus capable of performing high-precision color measurement without increasing power consumption.

An imaging apparatus according to the present invention is an imaging apparatus for imaging a subject, and includes a color filter array, a color image imaging unit for capturing a color image of the subject, and light sources having different spectral characteristics of four or more colors. Then, in the multiband shooting mode by the illuminating means for illuminating the subject and the color image capturing means, all kinds of light sources are sequentially selected to emit light, and a moving image is captured by the color image capturing means. In the multiband shooting standby mode for viewing , there is provided illumination control means for simultaneously selecting and emitting only some types of light sources among the light sources.

  According to the present invention, there is an effect that highly accurate color correction can be performed on a captured image without increasing power consumption.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing a photographing apparatus according to an embodiment of the present invention. FIG. 2 is a perspective view showing the appearance of the apparatus. FIG. 1 schematically shows the internal circuit configuration of the photographing apparatus according to the present embodiment, and schematically shows the state of being placed on the cradle 72.

  This embodiment is suitable when the object to be imaged is a face including teeth, all jaws, and teeth. By using the imaging apparatus according to the present embodiment, it is possible to construct a system for measuring a tooth and calculating a shade number that is a number of a crown color chart.

  FIG. 3 is an explanatory diagram showing a configuration of a tooth measurement system performed for tooth restoration, tooth whitening, and the like.

  In FIG. 3, the tooth measurement system is configured by a camera unit 69 that is an imaging device, a cradle 72, and a personal computer (PC) 68 that constitutes an image processing unit.

  The camera unit 69 is an illumination type multiband camera. The cradle 72 is configured so that the camera unit 69 can be placed, and the camera unit 69 can be charged. As shown in FIG. 1, the cradle 72 includes a reference plate 110 for calibrating the camera unit 69 and a micro for confirming whether the camera unit 69 is mounted on the cradle 72 at a normal position. A switch 111, a power switch 102 for turning on / off the power of the charging unit, a power lamp (not shown) that is turned on / off in conjunction with the ON / OFF of the power switch 102, and the camera unit 69 are mounted in a normal position. It is comprised by the mounting lamp 104 which lights when it is carried out.

  The cradle 72 is, for example, a desktop type, and the camera unit 69 is attached to a predetermined position of the cradle 72 so that power can be supplied to the camera unit 69 via the charging contact 100 of the camera unit 69. It has become.

  The mounting lamp 104 lights green when the cradle 72 is mounted at the normal position of the camera unit 69, and flashes red when the cradle 72 is not mounted. Further, the cradle 72 is provided with a power connection connector 105 so that an AC adapter 106 is connected thereto. When the charging capacity of the lithium battery 99 is reduced and the yellow or red of the charging LED 95 is lit, the lithium battery 99 is charged when the camera unit 69 is placed on the cradle 72. ing.

  The cradle 72 and the PC 68 are connected to each other by a USB2 standard cable or the like. The PC 68 receives an image captured by the camera unit 69 via the cradle 72 and a cable. The PC 68 performs predetermined image processing on the input captured image and calculates a shade number based on the captured image. Further, the PC 68 can execute programs for performing various processes relating to color chart inspection, displaying and taking in information to the operator, and the like.

  In FIG. 1, the camera unit 69 includes an illumination unit 70, an imaging unit 73, and a control unit 71. The illumination unit 70 indicated by a bold line is detachably provided on the distal end side of the camera unit 69, and exchanges signals with the control unit 71 and supplies power through an illumination unit contact (not shown). . Although not shown, it may be fixed without being attached or detached.

  The illumination unit 70 stores LED illumination units 70a and 70b composed of a plurality of types of LEDs having different spectral characteristics of emitted light, an illumination optical system 74 for illuminating the subject, and LED information. An LED memory 75 and a temperature sensor 76 for measuring the temperature in the vicinity of the LED are included. Note that the LED illumination units 70a and 70b are configured by, for example, a total of 28 LEDs in which four each of seven types of LEDs are arranged in this embodiment. The center wavelengths of the LEDs are 450 nm, 465 nm, 505 nm, 525 nm, 575 nm, 605 nm, and 630 nm, respectively. The illumination optical system 74 is for irradiating the subject surface with the LED light, and is configured to irradiate the LED light substantially uniformly.

  The imaging unit 73 includes a photographic lens 16, an RGB imaging device 5, a signal processing unit 17 that performs analog processing for performing gain correction, offset correction, and the like, and an AD converter (A / D) 18. The focus lever 79 is for manually changing the focus, and is provided with a position detection contact 80 of the focus lever 79.

  In FIG. 1, a control unit 71 is configured in a portion excluding the illumination unit 70 and the imaging unit 73 in the camera unit 69. A camera control CPU 81 in the control unit 71 is a CPU for performing camera control. The camera control CPU 81 is connected to the local bus 82 and the LCD controller 87, and controls the imaging unit 73 and also takes a color image taken by the imaging unit 73. It is connected to a composite output terminal 85 for outputting a signal to an external monitor. The camera control CPU 81 constitutes an illumination control means.

  The LED driver 83 is for controlling the light emission of the LED illumination units 70a and 70b, and the data I / F 84 is an interface for receiving the contents of the LED memory 75 of the illumination unit 70 and the information of the temperature sensor 76. The communication I / F controller 97 is a controller for controlling a communication I / F such as USB 2, and 98 is a communication I / F connection contact for the connection.

  The lithium battery 99 is used to supply power to the entire camera unit 69 and is connected to a charging contact 100 that is a contact for charging. The image memory 89 is for temporarily storing image data captured by the imaging unit 73.

  The LED illumination units 70a and 70b use seven types of LEDs, and the image memory 89 has a capacity capable of storing at least seven types of spectral images and one RGB color image. The LCD monitor 86 is a monitor for displaying an image being captured by the camera or an image that has been captured.

  The LCD monitor 86 is configured to display an image superimposed on the image pattern stored in the overlay memory 88 as necessary. The image pattern is, for example, a horizontal line that captures the entire tooth horizontally, a cross line that intersects the horizontal line, or the like. The operation unit I / F 90 exchanges signals with first to third function buttons disposed on the camera unit 69 and an output unit (not shown) for information transmission.

  Note that the first function button 91 has a function of switching to the RGB shooting mode, for example. The second function button 92 functions as a shutter button. Further, the third function button 93 has a function of switching to the multiband shooting standby mode. Each of the first to third function buttons also has a function of switching to a mode other than these operation modes.

  Further, the camera unit 69 is provided with a charging LED 95 for notifying the state of the battery, an alarm buzzer 96 for notifying the danger at the time of photographing, and the like.

  These first to third function buttons 91 to 93 and the LCD monitor 86 are disposed on the back side of the housing of the camera unit 69. FIG. 2 shows the external appearance of the camera unit 69 mainly on the back side.

  The camera unit 69 has a substantially L-shaped body part for displaying an image or gripped by the user, and a contact part applied to the mouth of the subject via the contact cap 260, for example. It has an integrally configured shape.

  An LCD monitor 86 is provided at the upper back of the main body of the camera unit 69, and a charging LED 95 is provided at the lower right of the LCD monitor 86. Further, on the lower side of the LCD monitor 86, a first function button 91, a second function button 92, and a third function are sequentially arranged from the left to the right along the lower side of the rectangular LCD monitor 86. Function buttons 93 are provided. Information on the functions performed by these function buttons 91, 92, 93 is displayed at positions corresponding to the function buttons 91, 92, 93 on the lower side in the LCD monitor 86. Therefore, even if the function of each function button 91, 92, 93 changes according to the operating state, it is possible to easily understand what function the button is used for.

  Further, a focus lever 79 is disposed on the upper surface side of the contact portion of the camera unit 69 so as to be partially operable. Further, on both side surfaces of the contact portion of the camera unit 69, hook portions 260a for attaching a later-described contact cap 260 having elasticity formed of styrene-based elastomer or the like are provided.

  In the present embodiment, normal RGB color photographing is possible in the RGB photographing mode. In order to enable color photographing with a single-plate image sensor, the RGB image sensor 5 includes a color filter.

  FIG. 4 is an explanatory diagram showing a specific configuration for RGB color photography. The photographing lens 16 forms a subject optical image on the incident surface of the RGB image sensor 5. A color filter array 5 b is disposed on the incident surface side of the RGB imaging element 5. The color filter array 5b has R (red), G (green), and B (blue) color filters arranged in a checkered pattern. The color filter array 5b converts the incident light into RGB color light for each pixel and forms an image on the incident surface of the RGB imaging device 5. In this way, a color image signal is obtained from the RGB imaging device 5.

  By sequentially outputting image signals from the RGB image sensor 5 by the camera control CPU 81, a moving image obtained by RGB photographing can be displayed on the display screen of the LCD monitor 86. In addition, when the second function button (shutter button) is pressed in the RGB shooting mode, the camera control CPU 81 captures a still image at the shutter button pressing timing and stores it in the image memory 89 and the LCD monitor 86. It can be displayed on the display screen.

  In this embodiment, an RGB color image can be obtained even in the multiband shooting standby mode. In the multiband shooting standby mode, the camera control CPU 81 controls the LED driver 83 to cause one or more LEDs of the LED illumination units 70a and 70b to emit light. The light emitted from the LED is reflected by the subject, and the reflected light forms an image on the incident surface of the RGB imaging device 5 via the photographing lens 16 and the color filter array 5b. In this way, even in the multiband shooting standby mode, the image signals from the RGB imaging device 5 are sequentially output to display a moving image (live image) by shooting using LED light emission on the display screen of the LCD monitor 86. be able to.

  By the way, in the multiband shooting standby mode, it is necessary to cause the LED to emit light, which increases power consumption. Therefore, in the present embodiment, the camera control CPU 81 controls the LED driver 83 to individually control the light emission of each LED of the LED illumination units 70a and 70b, for example, only three types of seven types of LEDs. Is made to emit light.

  FIG. 5 is a diagram illustrating characteristics λ1 to λ7 of the seven types of LEDs (hereinafter referred to as LEDs λ1 to λ7) of the LED illumination units 70a and 70b. As described above, the center frequencies of the characteristics λ1 to λ7 are 450 nm, 465 nm, 505 nm, 525 nm, 575 nm, 605 nm, and 630 nm, respectively. Among these LEDs λ1 to λ7, the LED with the lowest luminous efficiency is LED λ5 having a central wavelength of 575 nm. Further, LEDs having relatively high luminous efficiency are LEDs λ2, λ4, and λ7 having center frequencies of 465 nm, 525 nm, and 630 nm. The emission bands of the LEDs λ1 and λ2 are included in the wavelength range of approximately B (blue) light, the emission bands of the LEDs λ3 to λ5 are included in the wavelength range of approximately G (green) light, and the emission bands of the LEDs λ6 and λ7 are It is included in the wavelength range of approximately R (red) color light.

  Therefore, in the present embodiment, the camera control CPU 81 selectively emits three types of LEDs λ2, λ4, and λ7 that include RGB three primary colors and have excellent light emission efficiency in the multiband shooting standby mode. ing. Even in this case, it is possible to irradiate the subject with white light.

  In the multiband shooting standby mode, each LED emits light for a relatively long time, so that power consumption is likely to increase and the temperature rises greatly. For this reason, the change in LED characteristics becomes large. However, in the present embodiment, only a few types of LEDs emit light in the multiband shooting standby mode, so that power consumption can be reduced, temperature rise is suppressed, and LED characteristics are stabilized. It is also possible.

  If there is no need to consider power consumption, the camera control CPU 81 may cause all LEDs λ1 to λ7 to emit light simultaneously. When the color reproducibility of the live image in the multiband shooting standby mode is not particularly problematic, the camera control CPU 81 may emit only one or two types of LEDs among all the LEDs. Furthermore, if the brightness is sufficient, only some of the LEDs may be caused to emit light for each selected type.

  In the present embodiment, when the second function button (shutter button) is pressed in the multiband shooting standby mode, the camera control CPU 81 shifts to the multiband shooting mode. In the multiband shooting mode, the camera control CPU 81 sequentially turns on seven types of LEDs.

The camera control CPU 81 captures an image signal for each color of the LEDs that emit light sequentially. In this case, the camera control CPU 81 captures a signal for each pixel of the color filter array 5b corresponding to the emission color of the LED. That is, a spectral image is captured for each light emission of each LED. The camera control CPU 81 can store the seven types of captured spectral images in the image memory 89.

  Next, the operation of the embodiment configured as described above will be described with reference to FIGS. In the present embodiment, whitening (bleaching) or denture construction in a dental clinic is taken as an example.

  Three imaging modes are executed for tooth measurement in the dental clinic. Each photographing mode will be described with reference to FIGS.

  As the photographing mode, as shown in FIG. 6, facial photographing that is photographing of the entire face, full jaw photographing that is photographing of the entire upper and lower teeth shown in FIG. 7, and photographing of one or two teeth shown in FIG. There are three types of tooth photography to be performed. The RGB shooting mode described above is adopted as an operation mode in facial photography and full jaw photography. In addition, a multiband imaging mode is employed for tooth imaging. The above-described multiband imaging standby mode is employed when the apparatus is aligned for preparation for tooth imaging.

  The operation mode is changed by pressing the first to third function buttons. The operation at the time of tooth measurement shown in FIGS. 6 to 8 will be described.

(RGB shooting)
First, in step S1 in FIG. 9, the initial mode is set. The RGB mode is selected as the initial mode. The photographer lifts and removes the camera unit 69 from the cradle 72 and sets the photographing mode to the “RGB photographing mode”. The RGB image sensor 5 sequentially takes images and displays the images on the LCD monitor 86. At the time of this photographing, the LED illumination units 70a and 70b are turned off, and photographing using external light is performed as shown in FIG.

  Thereafter, in steps S2, S6, and S3, it is determined whether or not the first to third function buttons have been pressed. When the first function button is pressed, the RGB shooting mode is set (step S5), and when the third function button is pressed, the multiband shooting standby mode is set (step S4).

  The photographer (dentist or dental hygienist) adjusts the position of the subject (face or whole jaw) while viewing the image on the LCD monitor 86, and then focuses using the focus lever 79. At this time, the camera control CPU 81 controls the electronic shutter speed of the RGB imaging device 5 so as to achieve proper exposure. When the shutter button, which is the second function button, is pressed, the process proceeds from step S6 to step S7 to determine the operation mode. In this case, since the RGB shooting mode is selected, RGB shooting is performed in step S9. The captured image is stored in the image memory 89. At this time, incidental information such as the RGB image mode is also stored together.

(Multiband shooting)
Next, the photographer performs tooth photography. In this case, as shown in FIG. 10, a contact cap 260 is attached to the tip of the contact portion of the camera unit 69. The photographer brings the contact cap 260 into contact with the periphery of the tooth to be examined by the subject. In this case, in order to stabilize the power consumption at the time of transition to the multiband shooting mode, and since the external light is blocked by the contact cap 260, the photographer presses the third function button to perform the multiband shooting. Switch to standby mode. If the camera control CPU 81 detects in step S3 that the third function button has been pressed, it sets a multiband shooting standby mode in step S4.

  That is, the camera control CPU 81 controls the LED driver 83 to emit only the LEDs λ2, λ4, and λ7 among the seven types of LEDs. Thereby, white light by illumination light from these LEDs is irradiated around the teeth of the subject, and the reflected light forms an image on the incident surface of the RGB imaging element 5 via the imaging lens 16 and the color filter array 5b. . In this way, the RGB imaging device 5 performs RGB photographing using the illumination light of the three types of LEDs, and a live image is displayed on the LCD monitor 86. Current is supplied to several types of LEDs in the multiband shooting standby mode, and it is possible to stabilize the light emission of the LEDs during multiband shooting.

  The photographer positions the contact cap 260 while viewing the display on the LCD monitor 86. When the imaging range is determined, the photographer presses the second function button that is a shutter button. As a result, the camera control CPU 81 shifts from steps S6 and S7 to step S8 to execute multiband shooting.

  FIG. 11 is a flowchart showing a single-tooth image photographing process by multiband photographing.

  At the time of multiband shooting, the camera control CPU 81 first causes one of the seven types of LEDs to emit light in step S11 of FIG. Then, the teeth are imaged under illumination with one emitted primary color (step S12).

  Thereafter, it is determined whether or not the LEDs of all the primary colors (seven primary colors in the above-described example) are caused to emit light (step S13). Select (step S14). Thereafter, the process returns to step S11, the newly selected primary color LED is caused to emit light, and the tooth is imaged in step S12.

  In this way, if it is determined in step S13 that all primary color LEDs have been made to emit light, then the teeth are imaged without emitting the LEDs (single-tooth background imaging) (step S15). The camera control CPU 81 stores each image obtained by imaging in the image memory 89. The multiband captured image thus obtained is transferred to the PC 68, and the shade number of the shade guide is calculated.

  As described above, in this embodiment, the multi-band shooting is performed in the multi-band shooting standby mode because the LED light emission in the multi-band shooting is stabilized and the external light is limited immediately before the multi-band shooting. Illumination using the LED to be used is performed. In this case, three types of LEDs that emit light of three primary colors among the LEDs are selected, and LEDs having excellent luminous efficiency are selected to emit light. Thereby, power consumption can be significantly reduced. Moreover, the temperature rise of LED and its vicinity can also be suppressed, LED characteristics can be stabilized, and the effect that calibration is made easy is also acquired.

  In the above-described embodiment, in the multiband shooting standby mode, LEDs with high luminous efficiency are selectively used among narrowband LEDs corresponding to RGB primary color light. However, since the reflected light from the subject enters the incident surface of the RGB imaging device 5 via the color filter array 5b, it is better to consider not only the LED characteristics but also the color characteristics of the color filter array 5b. Conceivable.

  For example, the product of each LED output and the output of the color filter array 5b may be integrated to select the LED that provides the largest value. That is, for LEDs λ1 and λ2, the output when each reflected light passes through the B filter of the color filter array 5b, and for LEDs λ3 to λ5, the output when each reflected light passes through the G filter of the color filter array 5b, LED λ6, For λ7, the output when each reflected light passes through the R filter of the color filter array 5b is obtained. The filter output corresponding to each LED is large, and three types of LEDs corresponding to the three primary colors of RGB are selected.

  Furthermore, selection considering white balance is also possible. That is, three types of LEDs are selected so that a good white balance can be obtained by obtaining the filter output corresponding to each LED for the RGB three axes and considering the balance of the three axes. In this case, although there is a possibility that the power consumption is slightly increased, a live image excellent in white balance can be obtained even in the multiband shooting standby mode.

  Furthermore, you may select three types of LED which has a center wavelength close | similar to the center wavelength of each RGB color filter of the color filter array 5b. One or more types of LEDs may be selected by combining the above selection conditions. In any case, it is possible to reduce power consumption compared to the case where all types of LEDs emit light.

1 is a block diagram illustrating a photographing apparatus according to an embodiment of the present invention. The perspective view which shows the external appearance of an apparatus. Explanatory drawing which shows the structure of the tooth measurement system performed by tooth whitening etc. after tooth restoration. Explanatory drawing which shows the specific structure for RGB color imaging | photography. The figure which shows the characteristic (lambda) 1- (lambda) 7 of seven types of LED of LED illumination part 70a, 70b. Explanatory drawing for demonstrating operation | movement of embodiment. Explanatory drawing for demonstrating operation | movement of embodiment. Explanatory drawing for demonstrating operation | movement of embodiment. 6 is a flowchart for explaining the operation of the embodiment. Explanatory drawing for demonstrating operation | movement of embodiment. 6 is a flowchart for explaining the operation of the embodiment.

Explanation of symbols

    DESCRIPTION OF SYMBOLS 5 ... RGB image pick-up element, 69 ... Camera unit, 70 ... Illumination unit, 70a, 70b ... LED illumination part, 71 ... Control unit, 81 ... Camera control CPU, 83 ... LED driver, 86 ... LCD monitor.

      Agent Patent Attorney Susumu Ito

Claims (5)

In a photographing device for photographing a subject,
A color image imaging means for capturing a color image of the subject, having a color filter array;
Illuminating means for illuminating the subject having light sources having different spectral characteristics of four or more colors;
In the multiband shooting mode by the color image pickup means, all types of light sources are sequentially selected to emit light, and in the multiband shooting standby mode for viewing moving images by the color image pickup means, the light source And an illumination control means for simultaneously selecting and emitting only some types of light sources. The illumination control means is a light source that emits light so that each product of the output of each light source and the output from each filter corresponding to the spectral characteristics of each light source in the color filter array has the largest value. The photographing apparatus according to claim 1, wherein the photographing apparatus is selected. The photographing apparatus according to claim 1, wherein the illumination control unit selects a light source that emits light based on white balance in the multiband photographing mode . The photographing apparatus according to claim 2 , wherein the color filter array is a color filter array in which three primary color filters are arranged in an array. 5. The photographing apparatus according to claim 4 , wherein the illumination control unit selects a light source to emit light so as to include at least one light source having a spectral characteristic corresponding to each primary color filter of the color filter array.

Images