JP2009212824A - Skin area detection imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect an accurate skin area regardless of whether an object is exposed to the sunny side or shade of environmental light in a skin area detection imaging apparatus. <P>SOLUTION: The skin area detection imaging apparatus 1 includes an (S1) LED strobe for applying irradiation light of two different kinds of wavelengths with the same intensity ratio as that of light having the wavelengths in the environmental light, thus fixing the intensity ratio of the irradiation light having the two kinds of wavelengths in an entire portion in an imaging area, and hence setting the intensity ratio of the reflected light of the two kinds of wavelengths in the entire portion of the imaging area to be an intensity ratio that is owned by the object and corresponds to the ratio of reflectivity to the irradiation light of the two kinds of wavelengths. Therefore, a skin area in the imaging area is detected accurately based on the intensity ration of the reflected light having the two kinds of wavelengths from the object regardless of whether the object is exposed to the sunny side or shade of the environmental light (S5). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a skin region detection imaging device, and more particularly to a skin region detection imaging device that detects a skin region of a human body from a captured image of a subject illuminated with light in a near infrared region.

  Human skin regions have different reflectivities for different wavelengths of irradiated light in the near infrared region (eg, skin reflectivity for 850 nm irradiated light and skin reflectivity for 950 nm irradiated light. The ratio is about 1.2: 1.0). Conventionally, it has been proposed to detect a human body in a monitoring camera or the like using this property. For example, the present applicant collects light from a subject and forms two single-eye images A and B on a solid-state imaging device, a rolling shutter device that sequentially reads the two single-eye images, Two LEDs that emit light of different wavelengths (850 nm, 940 nm) in the near-infrared region, and when the single-eye image A is read, the LED that emits light of a wavelength of 850 nm is turned on. An application has been filed for a skin region detection imaging device that turns on an LED that emits light having a wavelength of 940 nm when read (Japanese Patent Application No. 2007-012921). According to this skin region detection imaging device, the difference in brightness is determined by comparing the individual images A and B using the difference in reflectance of the skin region with respect to light of two wavelengths in the near infrared region. The above region is detected as a skin region.

  However, since ambient light such as sunlight is often stronger than irradiation light from the LED, there are cases where the entire imaging area cannot be illuminated with light that matches the spectral characteristics of the LED irradiation light.

  For example, when the intensity ratio of light having a wavelength of 850 nm and light having a wavelength of 950 nm in ambient light is 2: 1, light having an intensity ratio of 1: 1 to a light having a wavelength of 850 nm and light having a wavelength of 950 nm Suppose that an LED strobe that emits light is emitted in a time-sharing manner to perform imaging. Here, ambient light such as sunlight is very powerful compared to the irradiation light from the LED strobe. In addition, there are places in the imaging area that are not exposed to ambient light and are shaded.

  Considering the spectral characteristics of the light (irradiation light) striking the subject in the imaging area when the image is captured, the portion that is shaded by the ambient light (shade) is almost illuminated only by the LED strobe. Since it may be considered, the intensity ratio between the light with a wavelength of 850 nm and the light with a wavelength of 950 nm in the irradiation light to this portion is approximately 1: 1. On the other hand, the irradiation light from the LED strobe hardly affects the portion of the subject in the imaging area where the ambient light is strongly applied. It is considered that the intensity ratio between the light having the wavelength and the light having the wavelength of 950 nm is almost the same value (close to 2: 1) as the intensity ratio in the ambient light.

  Next, consider the spectral characteristics of the reflected light from the subject. The ratio of the reflectance of human skin to light having a wavelength of 850 nm and the reflectance of human skin to light having a wavelength of 950 nm is about 1.2: 1.0. On the other hand, for substances other than human skin, the ratio of reflectance to light with a wavelength of 850 nm and light with a wavelength of 950 nm is about 1.0: 1.0. The spectral characteristic of reflected light is obtained by multiplying the spectral characteristic of incident light and the spectral characteristic of reflectance (the spectral ratio of reflected light (intensity ratio) is the ratio of the spectral ratio of incident light (intensity ratio) to the reflectance). Therefore, for the subject in the imaging area, irradiation light with wavelengths of 850 nm and 950 nm in the case of 4 types of 2 × 2 other than sunlight / shade of ambient light and human skin / skin When the spectral ratio (intensity ratio) of the reflected light with respect to is roughly estimated, it is as shown in FIG. That is, (1) Ambient light, human skin ... 2.4: 1.0 (= 2.4 / 1.0 = 2.4), (2) Ambient light, other than skin ... 2.0: 1.0 (= 2.0 / 1.0 = 2.0), (3) Ambient light shade / human skin ... 1.2: 1.0 (= 1.2) /1.0=1.2), (4) Other than ambient light shade / skin ... 1.0: 1.0 (= 1.0 / 1.0 = 1.0).

  In the skin region detection imaging apparatus proposed in Japanese Patent Application No. 2007-012921, the spectral ratio (intensity ratio) of the reflected light with respect to the irradiation light with the wavelengths of 850 nm and 950 nm is large for the reflected light from human skin, The detection of the skin area is performed with the expectation that the reflected light from the substance will be small. In the above (1) to (4), the intensity ratio (2.0) of (2) which is an area other than the skin This is larger than the strength ratio (1.2) of (3), which is the skin region. Therefore, the skin region detection imaging apparatus proposed in Japanese Patent Application No. 2007-012921 may not be able to accurately detect the skin region.

In the field of imaging devices, compound eye imaging devices having a plurality of optical systems are known (see, for example, Patent Documents 1 to 5). However, the inventions described in Patent Documents 1 to 5 cannot solve the above problem.
JP 2007-295141 A JP 2005-303694 A JP 2007-65335 A Japanese Patent Laying-Open No. 2005-341301 JP 2007-174666 A

  The present invention has been made to solve the above-described problem, and can accurately detect a skin region regardless of whether the subject is in the shade of the ambient light or in the shade. An object of the present invention is to provide a simple skin region detection imaging apparatus.

  In order to achieve the above object, the invention according to claim 1 uses a plurality of optical lenses for condensing light from a subject and light from the subject collected by the plurality of optical lenses in the near infrared region. Different-type image forming means for forming two types of subject images corresponding to irradiation light of two different types of wavelengths, a solid-state imaging device for taking two types of subject images formed by the different-type image forming means, Two types of subject images formed on the solid-state image sensor are obtained by reading out a voltage corresponding to the charge accumulated in each pixel on the solid-state image sensor (hereinafter abbreviated as an accumulated charge voltage) for each reading line. A rolling shutter device for sequentially reading, a storage means for storing the two types of subject images read out during one shutter operation of the rolling shutter device, and the storage means; Based on the stored two types of images, the intensity of the reflected light of the two types of wavelengths from the subject corresponding to the irradiation light of the two types of wavelengths is determined, and the reflected light of these two types of wavelengths is detected. In a skin region detection imaging apparatus including a skin region detection unit that detects a region having an intensity ratio equal to or greater than a predetermined value as a skin region, the different-type image forming unit includes the irradiation light of two different wavelengths, It includes a flash light source that irradiates at the same intensity ratio as the intensity ratio of these wavelengths of ambient light.

  According to a second aspect of the present invention, in the skin region detecting / imaging apparatus according to the first aspect, the different-type image forming unit uses the rolling shutter device to change the emission switching timing of the irradiation light of two types of wavelengths by the flash light source. The image forming apparatus further includes a switching control unit that performs control in accordance with the timing for switching the image to be read.

  According to a third aspect of the present invention, in the skin region detecting / imaging apparatus according to the first aspect, the different-type image forming means is disposed in a condensing path by the plurality of optical lenses, and in the near infrared region for each of the condensing paths. Two types of band-pass filters for selectively transmitting light of two different wavelengths are further included.

  According to a fourth aspect of the present invention, in the skin region detecting / imaging apparatus according to the first aspect, a diffusion plate for taking ambient light into a part of an imaging area (hereinafter referred to as a “partial imaging area”) on the solid-state imaging device. And two kinds of band-passes for selectively transmitting the irradiation light of the two kinds of wavelengths for each of the passage paths, which are disposed in the passage paths of the ambient light captured through the diffusion plate to the partial imaging area. In the partial imaging area, ambient light of two types of wavelengths taken in through the filter, the diffusion plate, and the two types of bandpass filters are received by the partial imaging area and read by the rolling shutter device. And an ambient light intensity ratio detecting unit that determines an intensity ratio of the light of the two types of wavelengths in the ambient light based on the accumulated charge of the pixel, and the different-type image forming unit includes the ambient light intensity Light emission intensity control means for controlling the flash light source to emit light of the two types of wavelengths based on the intensity ratio of the light of the two types of wavelengths in the ambient light detected by the detection means, and 2 by the flash light source It further includes switching control means for controlling the emission switching timing of the irradiation light of various wavelengths in accordance with the timing for switching the image read by the rolling shutter device.

  According to the invention of claim 1, since the flash light source irradiates the irradiation light of two different wavelengths in the near-infrared region at the same intensity ratio as the intensity ratio of the light of these wavelengths in the ambient light, It becomes possible to make the intensity ratio of the irradiation light of the two types of wavelengths constant in all the portions. Here, the intensity ratio of the reflected light of two types of wavelengths is obtained by multiplying the intensity ratio of the irradiated light of the two types of wavelengths by the ratio of the reflectance of the subject with respect to the irradiated light of the two types of wavelengths. Since it is possible to make the intensity ratio of the irradiation light of two types of wavelengths constant in all parts in the imaging area as described above, the above in all parts in the imaging area can be obtained. The intensity ratio of the reflected light of the two types of wavelengths can be determined according to the ratio of the reflectance of the subject to the irradiation light of the two types of wavelengths. Therefore, regardless of whether the subject is in the sun or the shade of ambient light, the skin area in the imaging area is accurately detected based on the intensity ratio of reflected light of two types of wavelengths from the subject. can do.

  Further, two types of subject images read out during one shutter operation of the rolling shutter device are stored as images, and the skin region is detected using these two types of images, so that a short time can be obtained. It is possible to detect the skin area.

  According to the invention of Claims 2 and 3, the effect of the invention of Claim 1 can be obtained accurately.

  According to the invention of claim 4, the intensity ratio of the light of the two types of wavelengths in the environmental light in the imaging area is actually measured, and the flash light source is configured to detect the light of the two types of wavelengths in the actual environmental light. The subject can be irradiated with the same intensity ratio as the intensity ratio.

  Hereinafter, a skin region detection imaging apparatus according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 7. The first embodiment corresponds to claims 1 and 2. As shown in FIGS. 1 to 3, the skin region detection imaging apparatus 1 according to the present embodiment collects light from a subject and forms two images (hereinafter referred to as “upper and lower” images on a solid-state imaging device 2 at a focal position. A lens optical system 3 including two optical lenses for forming A and B), a solid-state image pickup device 2 for picking up these two single-eye images A and B, and a solid-state image pickup device 2. The electronic circuit 4 that electronically processes the two single-eye images A and B to detect the skin region, and two different types in the near-infrared region according to the timing signals SG2 and SG3 from the electronic circuit 4 LED strobe 5 (flash light source) that emits two LEDs 5a and 5b having a wavelength as a central wavelength alternately (by switching in time), a liquid crystal panel that displays an image of the skin area detected by the electronic circuit 4, and the like A display device 6 composed of And an external device 7 such as a personal computer for performing the uptake of the input and the image data of the data. The electronic circuit 4 has a microprocessor (switching control means, skin area detection means) 24 that controls the entire apparatus.

  One of the two LEDs 5a and 5b in the LED strobe 5 is an LED 5a that emits near-infrared light having a center wavelength of 850 nm, and the other is an LED 5b that emits near-infrared light having a center wavelength of 940 nm. The microprocessor 24 applies voltage adjustment circuit 10 so that the LED strobe 5 emits irradiation light of two different wavelengths (850 nm and 940 nm) at the same intensity ratio as the intensity ratio of the light of these wavelengths in the ambient light. To control. Further, the microprocessor 24 switches the switching timing between the near-infrared light emission of the center wavelength of 850 nm from the LED 5a and the near-infrared light emission of the center wavelength of 850 nm from the LED 5b to the timing of switching the image read by the rolling shutter device 19 described later. Match. In the present embodiment, the microprocessor 24 and the LED strobe 5 correspond to different-type image forming means in the claims. Further, the solid-state imaging device 2 captures two types of subject images (single-eye images A and B) formed by these different-type image forming units.

  As shown in FIGS. 1 and 2, the lens optical system 3 is formed on two optical lenses 8 arranged vertically so that the optical axes L are parallel to each other, and a support frame 9 of the optical lens 8. The diaphragm aperture 11, the partition wall 12 disposed between the optical lens 8 and the solid-state image sensor 2 so that the lights emitted from the optical lenses 8 toward the solid-state image sensor 2 do not interfere with each other, and the solid-state image sensor And an optical filter 13 disposed in front of the element 2. The optical filter 13 is a filter that transmits light in the near infrared region.

  The solid-state imaging device 2 is composed of a CMOS (Complementary Metal Oxide Semiconductor) image sensor formed on a substrate 14, and has a large number of unit pixels 15 in the matrix direction (X and Y directions in FIGS. 3 and 4). Yes.

  Individual eye images A and B formed by being condensed on the solid-state imaging device 2 by the optical lenses 8 are respectively represented by circles in FIG. The individual images A and B are converted into analog image information (voltage corresponding to the charge accumulated in the pixel (accumulated charge voltage)) by the solid-state imaging device 2, and the individual images A and B are converted by the rolling shutter device 19 described later. The eye images B are read in order.

  A timing generator (TG) 18 that outputs a timing signal SG4 to the vertical scanning circuit 16 and the horizontal scanning circuit 17 of the solid-state imaging device 2 is provided on the same substrate 14 as the solid-state imaging device 2, and based on the timing signal SG4. Thus, the unit pixels 15 (accumulated charge voltage) of the solid-state imaging device 2 are read in a predetermined order, which will be described in detail later, and the single-eye image A and single-eye image B are read in this order. The timing generator 18, the vertical scanning circuit 16, and the horizontal scanning circuit 17 constitute a rolling shutter device 19.

  Next, the electronic circuit 4 will be described with reference to FIG. The electronic circuit 4 temporarily receives the analog image information output from the solid-state imaging device 2 as a digital signal via the AD converter 21 and the image information captured by the image processor 22. The above-described microprocessor 24 for detecting the skin region by processing the RAM (storage means) 23 to be stored and the image information captured by the image processor 22 according to the processing procedure described later, and the detected skin region image information Is temporarily stored.

  The image processor 22 outputs a control signal to the solid-state imaging device 2 to perform control such as exposure adjustment and gain adjustment, and performs image processing such as gamma correction and white balance correction on the captured image information.

  The microprocessor 24 is connected to the timing generator 18 and outputs a timing signal SG1 for causing the LED strobe 5 to emit light via the voltage adjustment circuit 10 at a predetermined timing based on the horizontal synchronization signal SG5 output from the timing generator 18. Is configured to do. In addition, the timing signal SG1 is used to control the LED 5a and the LED 5b to emit light at the same intensity ratio as the intensity ratio (for example, 2: 1) of the light having the wavelength of 850 nm and the light having the wavelength of 940 nm in the ambient light. Contains control information.

  The RAM 23 is formed on the solid-state image pickup device 2 by the above-described different-type image forming means (the microprocessor 24 and the LED strobe 5), and is read out in two types of single eyes read out in one shutter operation of the rolling shutter device 19. Images A and B are stored as images. Based on the two types of single-eye images A and B stored in the RAM 23, the microprocessor 24 corresponds to two different wavelengths (850 nm) from the subject corresponding to irradiation light of two different types of wavelengths (850 nm and 940 nm). And 940 nm) of the reflected light is determined, and a region where the intensity ratio of the reflected light of these two types of wavelengths is equal to or greater than a predetermined value is detected as a skin region.

  Hereinafter, the procedure for reading the single-eye images A and B on the solid-state image sensor 2 by the rolling shutter device 19 and the switching timing of the light emission of the two LEDs 5a and 5b of the LED strobe 5 will be described with reference to FIG.

  First, a procedure for reading the single-eye images A and B on the solid-state imaging device 2 will be described. The rolling shutter device 19 reads the unit pixel 15 (accumulated charge voltage) in the first row along the row direction (X direction) starting from the origin S in the matrix direction in which the unit pixels 15 are arranged, By sequentially reading the unit pixels 15 in the next row (reading line) away from the origin S in the direction (Y direction), all the unit pixels 15 are finally read, and the individual images A and B are read in this order. Read with. 4, the order in which the unit pixels 15 are read out is the order of arrows Ra, Rb, Rc,. Note that arrows Ra, Rb, Rc,... Are obtained by schematically thinning out the reading lines in the claims, and the actual reading lines are along the X direction on the solid-state imaging device 2 in FIG. It is a line composed of each unit pixel 15.

  The timing generator 18 outputs a horizontal synchronization signal SG5 to the microprocessor 24 every time reading of each row is completed. The microprocessor 24 counts the horizontal synchronization signal SG5 to start and end reading of the individual image A. And the timing for starting and ending the reading of the single-eye image B, and outputting a lighting command signal and an extinguishing command signal to the LED 5a in accordance with the start and end of reading of the single-eye image A. A lighting command signal and a turn-off command signal are output to the LED 5b in accordance with the start and end. Note that the lighting command signal and the extinguishing command signal for the LEDs 5a and 5b are a kind of the timing signal SG1 described above, and the lighting command signal for the LEDs 5a and 5b includes the light emission intensity of the LEDs 5a and 5b (850 nm in ambient light). Control information for controlling the LED 5a and the LED 5b to emit light at the same intensity ratio as the intensity ratio of the light having the wavelength of 940 nm and the light having the wavelength of 940 nm.

  In FIG. 4, the timing of turning on / off the LED 5a and the timing of turning on / off the LED 5b are shown as pulse waveforms Pa and Pb from the top to the bottom, respectively. In the pulse waveforms Pa and Pb, when the time when reading starts from the origin S of the unit pixel 15 is t = 0 and the time when the last unit pixel 15 is read is t = T, The LED 5a is turned on at the time when reading is started (t1), the LED 5a is turned off at the time when reading of the single-eye image A is finished (t2), and the reading of the single-eye image B is started (t3). The LED 5b is turned on and the LED 5b is turned off at the time (t4) when the reading of the single-eye image B is completed. The ratio between the light emission intensity of the LED 5a and the light emission intensity of the LED 5b is the same as the intensity ratio of light having a wavelength of 850 nm and light having a wavelength of 940 nm in the ambient light. For example, when the intensity ratio of the light with the wavelength of 850 nm and the light with the wavelength of 940 nm in the ambient light is 2: 1, the ratio of the intensity of the irradiation light from the LED 5a and the intensity of the irradiation light from the LED 5b is also 2: 1.

  As described in the background art, in the skin region detection imaging apparatus proposed in Japanese Patent Application No. 2007-012921, the intensity ratio of the light with the wavelength of 850 nm and the light with the wavelength of 950 nm in the irradiation light from the LED strobe is Since it is different from the intensity ratio of light of these wavelengths, as shown in FIG. 16, even if the reflected light is from the same part in the subject, the reflected light depends on whether the ambient light is in the sun or in the shade. Are different in intensity ratio between light having a wavelength of 850 nm and light having a wavelength of 950 nm. Therefore, accurate skin region detection may not be performed based on the intensity ratio of light having a wavelength of 850 nm and light having a wavelength of 950 nm included in the reflected light.

  In the present invention, by making the intensity ratio of the light of the wavelength of 850 nm and the light of the wavelength of 950 nm in the irradiation light from the LED strobe 5 the same as the intensity ratio of the light of these wavelengths in the ambient light, Solve the above problems. For example, when the intensity ratio of the light with the wavelength of 850 nm and the light with the wavelength of 940 nm in the ambient light is 2: 1, the ratio of the intensity of the irradiation light from the LED 5a and the intensity of the irradiation light from the LED 5b is also 2: 1.

  As a result, both the sunlight and the shaded part of the ambient light can be illuminated with irradiation light having an intensity ratio of 2: 1 to 850 nm wavelength light and 950 nm wavelength light. Here, in general, the intensity ratio of the reflected light from the object to the irradiation light of different wavelengths is the ratio of the reflectance specific to the object to the irradiation light of these wavelengths in the intensity ratio of the irradiation light of these wavelengths in the irradiation light. Is obtained by multiplying Therefore, as described above, by irradiating light with a wavelength of 850 nm and light with a wavelength of 950 nm with the same intensity ratio in the sunlit part and the shaded part, the ambient light is reflected in the reflected light. Can be made substantially the same as the ratio of the reflectance inherent in the object to the irradiation light of these wavelengths.

  For example, when the intensity ratio of light having a wavelength of 850 nm and light having a wavelength of 940 nm in ambient light is 2: 1, light having a wavelength of 850 nm and light having a wavelength of 950 nm in the irradiation light from the LED strobe 5 2: 1, the ambient light is irradiated with light having a wavelength of 850 nm and light having a wavelength of 950 nm at an intensity ratio of 2: 1 for both the sun and the shade. can do. As a result, the intensity ratio of the light having a wavelength of 850 nm and the light having a wavelength of 950 nm in the reflected light depends on whether the ambient light is a sunlit part or a shaded part, as shown in FIG. First, in the area of human skin, it becomes 2.4: 1.0, and in the area other than human skin, it becomes 2.0: 1.0. Therefore, for example, by determining an area where the intensity ratio of the light having a wavelength of 850 nm and the light having a wavelength of 950 nm in reflected light is larger than 2.2: 1.0 as a skin area, Can be determined.

  In general, the shaded portion of the ambient light is often illuminated with a spectral ratio (light intensity ratio for each frequency component) different from that of the ambient light due to reflection or the like. Therefore, it is necessary to use the LED strobe 5 in order to eliminate the influence of this reflection. Since the reflection is very weak compared to the direct ambient light, it is possible to eliminate the influence of the reflection by irradiating the LED strobe 5.

  Next, the detection procedure of the skin area in the skin area detection imaging apparatus 1 of this embodiment is demonstrated with reference to the flowchart of FIG.

  Prior to the start of imaging, the microprocessor 24 sends the LED 5a to the voltage adjustment circuit 10 so that the light emission intensity ratio between the LED 5a and the LED 5b is the same as the light intensity ratio of the two types of wavelengths (850 nm and 940 nm) in the ambient light. Then, the emission intensity of the LED 5b is set (S1). When the imaging is started, the microprocessor 24 reads an image read out by the rolling shutter device 19 in accordance with the switching timing between the near infrared light emission of the center wavelength of 850 nm by the LED 5a and the near infrared light emission of the center wavelength of 940 nm by the LED 5b. The LED strobe 5 is controlled so as to irradiate the irradiation light of the two types of wavelengths at the same intensity ratio as the intensity ratio of the light of these wavelengths in the environmental light while matching the switching timing. As a result, two types of subject images (single-eye images A and B) corresponding to the irradiation light having the center wavelength of 850 nm and the center wavelength of 940 nm are formed on the solid-state imaging device 2. The single-eye image A is an image of a subject illuminated by near-infrared light having a central wavelength of 850 nm when the LED 5a emits light, and the single-eye image B has a central wavelength of 940 nm when the LED 5b emits light. It is an image of a subject illuminated by near infrared light. The rolling shutter device 19 sequentially reads out the two types of single-eye images A and B formed on the solid-state image sensor 2 by reading out the accumulated charge voltage of each unit pixel 15 on the solid-state image sensor 2 for each reading line. . The microprocessor 24 performs control so that the image processor 22 acquires the image information of the single-eye images A and B (S2) and cuts out each image information into a predetermined rectangular shape (S3). The single-eye images A and B read out in one shutter operation of the rolling shutter device and cut out by the image processor 22 are stored in the RAM 23 as images.

  Specific examples of the single-eye image A and the single-eye image B are shown in FIGS. 7 (a) and 7 (b). For the skin region Ja such as the face of the person J in the subject, the single-eye image A (FIG. 7A) illuminated by the LED 5a is the single-eye image B illuminated by the LED 5b (FIG. 7B). The area Jb other than the skin such as the hair and clothes of the person J has almost the same reflectivity with respect to the near infrared rays, so the single-eye image A illuminated by the LED 5a (FIG. 7A). ) And a single eye image B (FIG. 7B) illuminated by the LED 5b.

  FIG. 8 shows the reflectance characteristics of the skin region for light of each wavelength in the near infrared region. The ratio of the reflectance for near infrared light having a wavelength of 850 nm to the reflectance for near infrared light having a wavelength of 940 nm is about 1.2: 1.0. Note that a region where the wavelength is shorter than 850 nm is a red region of visible light, and in a region where the wavelength is longer than 940 nm, the sensitivity of the solid-state imaging device 2 is drastically lowered.

  Next, based on the single image A and single image B stored in the RAM 23, the microprocessor 24 reflects two types of wavelengths from the subject corresponding to irradiation light of two types of wavelengths of 850 nm and 940 nm. The intensity of light is determined (S4 in FIG. 6), and an area where the intensity ratio of reflected light of these two types of wavelengths is a predetermined value or more is detected as a skin area (S5).

  In the above example, the face of the person J and the hand portion exposed from the clothes are detected as the skin region Ja. The microprocessor 24 displays an image of the detected skin region Ja on the display device 6 (S6). An example of an image displayed on the display device 6 is shown in FIG.

  As described above, according to the skin region detection imaging apparatus 1 of the present embodiment, the LED strobe 5 emits irradiation light of two different wavelengths in the near infrared region, and the intensity ratio of the light of these wavelengths in the ambient light. The two types of wavelengths in all parts of the imaging area, even when there are parts of the daylight of the ambient light and parts that are shaded in the imaging area The intensity ratio of the irradiated light can be made constant. Here, the intensity ratio of the reflected light of two types of wavelengths is obtained by multiplying the intensity ratio of the irradiated light of the two types of wavelengths by the ratio of the reflectance of the subject with respect to the irradiated light of the two types of wavelengths. Since it is possible to make the intensity ratio of the irradiation light of two types of wavelengths constant in all parts in the imaging area as described above, the above in all parts in the imaging area can be obtained. The intensity ratio of the reflected light of the two types of wavelengths can be determined according to the ratio of the reflectance of the subject to the irradiation light of the two types of wavelengths. Therefore, regardless of whether the subject is in the sun or the shade of ambient light, the skin area in the imaging area is accurately detected based on the intensity ratio of reflected light of two types of wavelengths from the subject. can do.

  Also, two types of subject images read out during one shutter operation of the rolling shutter device 19 are stored as images, and a skin region is detected using these two types of images (single-eye images A and B). By doing so, the skin region can be detected in a short time.

  Next, a second embodiment will be described with reference to FIGS. The second embodiment corresponds to claims 1 and 3. The skin region detection imaging device 1 of the second embodiment has a structure similar to that of the skin region detection imaging device 1 of the first embodiment. The difference is that the optical filter 13 of the first embodiment is used instead. For each of the condensing paths 30a and 30b by the two optical lenses 8, band-pass filters 31a and 31b that selectively transmit light of two different wavelengths in the near-infrared region are provided, light emission by the LED 5a, and LED 5b The light emission by the LED 5a and the light emission by the LED 5b are performed at the same time without switching the light emission by. Hereinafter, each difference will be described in detail.

  In the second embodiment, the LED 5a and the LED 5b in the LED strobe 5 are not switched on / off at a predetermined timing, and both the LED 5a and the LED 5b continuously emit light while the subject is being imaged.

  The bandpass filters 31a and 31b are respectively disposed in the condensing paths 30a and 30b unique to the two optical lenses 8, and the bandpass filter 31a is a filter that transmits near-infrared light having a center wavelength of about 850 nm. The pass filter 31b is a filter that transmits near-infrared light having a center wavelength near 940 nm. FIG. 10 shows the transmittance characteristics of the bandpass filter 31a, and FIG. 11 shows the transmittance characteristics of the bandpass filter 31b.

  The single-eye image A formed by near-infrared light selectively transmitted by the bandpass filter 31a becomes an image (FIG. 7A) in which the skin region Ja is expressed relatively brightly, and the bandpass filter 31b. The single-eye image B formed by the near-infrared light selectively transmitted by the above becomes an image (FIG. 7B) in which the skin region Ja is represented relatively dark.

  In the detection procedure of the skin region in the second embodiment, the microprocessor 24 uses the voltage adjustment circuit 10 so that the LED strobe 5 has the same intensity ratio of two types of wavelengths (850 nm and 940 nm) in ambient light. The intensity ratio is controlled so as to irradiate light of these two types of wavelengths simultaneously. Thereafter, as in the first embodiment, the microprocessor 24 acquires image information, cuts out an image of a predetermined shape, determines the intensity of reflected light of two types of wavelengths, detects a skin region, and displays an image. This is executed to detect the skin region Ja and display an image.

  Also in the skin region detection imaging apparatus 1 of the second embodiment, the same effect as in the first aspect can be obtained.

  The bandpass filters 31a and 31b in the second embodiment may be replaced with those including a visible light region as a light transmission region. In this case, since each bandpass filter 31a, 31b also transmits light in the visible light region, the single-eye images A, B themselves can be obtained as normal subject images with normal colors and the like. In addition, the user can display and view the obtained image on the display device 6, and can use the skin region detection imaging device 1 as a monitoring camera device.

  Next, a third embodiment will be described with reference to FIGS. The third embodiment corresponds to claims 1 and 4. FIG. 12 shows a schematic configuration of the skin region detection imaging device 1 according to the third embodiment, and FIG. 13 shows a front surface of the skin region detection imaging device 1. FIG. 14 shows the reading order of each partial imaging area on the solid-state imaging device 2 and the light emission timings of the two LEDs 5a and 5b. The skin region detection imaging device 1 of the third embodiment has a structure similar to that of the skin region detection imaging device 1 of the first embodiment, and the main difference is that two different wavelengths (850 nm) in ambient light. And a means for actually detecting the light intensity ratio of 940 nm) and the microprocessor 24 controls the LED strobe 5 to emit light of two types of wavelengths at the detected intensity ratio. .

  As shown in FIGS. 12 to 14, the skin region detection imaging apparatus 1 according to the third embodiment includes diffusion plates 41 a and 41 b for taking ambient light into the partial imaging areas 2 c and 2 d on the solid-state imaging device 2. The ambient light taken in through the diffusion plates 41a and 41b is arranged in the passages 40a and 40b to the partial imaging areas 2c and 2d, and selectively irradiates light of two different wavelengths for each of the passages 40a and 40b. Two types of band-pass filters 42a and 42b for transmission are provided. The bandpass filter 42a is a filter that transmits near-infrared light having a center wavelength near 850 nm, and the bandpass filter 42b is a filter that transmits near-infrared light having a center wavelength near 940 nm.

  The skin region detection imaging apparatus 1 according to the present embodiment partially captures ambient light having two types of wavelengths (near 850 nm and 940 nm) captured via the diffusion plates 41a and 41b and the two types of bandpass filters 42a and 42b. Based on the accumulated charge voltage of the unit pixel 15 in the partial imaging areas 2c and 2d received by the areas 2c and 2d and read by the rolling shutter device 19, the intensity ratio of light having a wavelength near 850 nm and 940 nm in the ambient light Determine. As shown in FIG. 14, the timing generator 18 is set in advance so that the LED strobe 5 is turned off (turns off) at the timing of imaging the partial imaging areas 2c and 2d. The microprocessor 24 controls the LED strobe 5 to emit light with wavelengths of 850 nm and 940 nm at the intensity ratio of the two types of wavelengths of ambient light detected as described above. The microprocessor 24 corresponds to the ambient light intensity ratio detection means, the emission intensity control means, and the switching control means in claim 4. Note that the partial imaging areas 2a and 2b shown in FIGS. 12 and 14 are imaging areas for imaging the single-eye images A and B, respectively.

  FIG. 15 shows a procedure for detecting a skin region in the third embodiment. First, based on the accumulated charge voltage of the unit pixel 15 in the partial imaging areas 2c and 2d corresponding to the two types of band-pass filters 42a and 42b, the microprocessor 24 uses ambient light having wavelengths near 850 nm and 940 nm. Is determined, and based on this intensity ratio, the light emission intensity (ratio) between the LED 5a that emits light with a central wavelength of 850 nm and the LED 5b that emits light with a central wavelength of 940 nm is determined (S11). Then, the microprocessor 24 sets the light emission intensities of the LEDs 5a and 5b in the voltage adjustment circuit 10 based on the determined intensity (ratio) (S12). Then, when imaging is started, the microprocessor 24 causes the LEDs 5a and 5b to emit light in a time-sharing manner, as shown in FIG. 14, and acquires image information as in the first embodiment (S13), Extraction into an image having a predetermined shape (S14), intensity determination of reflected light of two types of wavelengths (S15), detection of a skin region (S16), display of an image (S17), detection of skin region Ja and image Display.

  As described above, according to the skin region detection imaging device 1 of the third embodiment, the LED strobe 5 is actually measured by measuring the light intensity ratio of the two types of wavelengths in the ambient light in the imaging area. It is possible to irradiate the subject with the same intensity ratio as the intensity ratio of the light of the two types of wavelengths in the actual ambient light.

The figure which shows schematic structure of the skin region detection imaging device which concerns on the 1st Embodiment of this invention. The front view of the same skin region detection imaging device. The front view of the solid-state image sensor in the same skin region detection imaging device. Explanatory drawing which shows the order in which the monocular image in the same skin region detection imaging device is read, and the light emission timing of two LED. The figure which shows the intensity ratio of the reflected light with respect to the irradiation light of the wavelength of 850 nm and 950 nm in the case of four types other than the daytime / shade of environmental light and human skin / skin in the same skin region detection imaging device. The flowchart which shows the detection procedure of the skin area | region in the same skin area | region detection imaging device. (A) is a figure which shows the example of the single eye image of the to-be-photographed object illuminated with near-infrared light whose center wavelength is 850 nm in the same skin region detection imaging device, (b) is illuminated with near-infrared light whose center wavelength is 940 nm The figure which shows the example of the single eye image of the to-be-photographed object, (c) is a figure which shows the example of the detection image of a skin area | region. The figure which shows the reflectance of the skin area | region with respect to the light of each wavelength of a near-infrared area | region. The figure which shows schematic structure of the skin region detection imaging device which concerns on the 2nd Embodiment of this invention. The figure which shows the transmittance | permeability characteristic of the band pass filter which permeate | transmits the near-infrared light whose center wavelength is 850 nm vicinity in the same skin region detection imaging device. The figure which shows the transmittance | permeability characteristic of the band pass filter which permeate | transmits the near infrared light whose center wavelength is 940 nm vicinity in the same skin region detection imaging device. The figure which shows schematic structure of the skin region detection imaging device which concerns on the 3rd Embodiment of this invention. The front view of the same skin region detection imaging device. Explanatory drawing which shows the read-out order of each partial imaging area and the light emission timing of two LED in the same skin region detection imaging device. The flowchart which shows the detection procedure of the skin area | region in the same skin area | region detection imaging device. The figure which shows the intensity | strength ratio of the reflected light with respect to the irradiation light of a wavelength of 850 nm and 950 nm in the case of four types other than the sun / shade of environmental light, and human skin / skin in the skin region detection imaging device of a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Skin region detection imaging device 2 Solid-state image sensor 2c, 2d Partial imaging area 5 LED strobe (different kind image formation means, flash light source)
5a, 5b LED
8 Optical lens 19 Rolling shutter device 23 RAM (storage means)
24 Microprocessor (switching control means, skin area detection means, ambient light intensity ratio detection means, emission intensity control means)
30a, 30b Condensing paths 31a, 31b Band pass filters (different kind of image forming means)
40a, 40b Passing paths 41a, 41b Diffuser plates 42a, 42b Band pass filters A, B Single eye images (two types of images)
Ja skin area

Claims (4)

A plurality of optical lenses that collect light from the subject;
Different-type image forming means for forming two types of subject images corresponding to irradiation light of two different types of wavelengths in the near-infrared region using light from the subject collected by the plurality of optical lenses;
A solid-state imaging device for imaging two types of subject images formed by the different type image forming means;
Two types of subject images formed on the solid-state image sensor are obtained by reading out a voltage corresponding to the charge accumulated in each pixel on the solid-state image sensor (hereinafter abbreviated as an accumulated charge voltage) for each reading line. A rolling shutter device for sequentially reading;
Storage means for storing the two types of subject images read out during one shutter operation of the rolling shutter device as images;
Based on the two types of images stored in the storage unit, the intensity of the reflected light of the two types of wavelengths from the subject corresponding to the irradiation light of the two types of wavelengths is determined, and these two types of wavelengths are determined. In a skin region detection imaging apparatus, comprising: a skin region detection unit that detects a region where the intensity ratio of the reflected light is equal to or greater than a predetermined value as a skin region;
The different type image forming means includes a flash light source that irradiates the irradiation light of the two different wavelengths with the same intensity ratio as the intensity ratio of the light of these wavelengths in the ambient light. Imaging device.   The different-type image forming means further includes switching control means for controlling the emission switching timing of the irradiation light of two types of wavelengths by the flash light source in accordance with the timing of switching the image read by the rolling shutter device. The skin region detection imaging device according to claim 1. The different type image forming means includes:
The optical system further includes two types of band-pass filters that are arranged in a condensing path by the plurality of optical lenses and selectively transmit light of two different wavelengths in the near-infrared region for each of the condensing paths. The skin region detection imaging apparatus according to claim 1. A diffusion plate for taking ambient light into a part of the imaging area on the solid-state imaging device (hereinafter referred to as “partial imaging area”);
Two kinds of band-pass filters which are arranged in the passage way of the ambient light taken through the diffusion plate to the partial imaging area, and selectively transmit the irradiation light of the two kinds of wavelengths for each passage way; ,
Accumulation of pixels in the partial imaging area received by the partial imaging area by receiving ambient light of two types of wavelengths taken in through the diffusion plate and the two types of bandpass filters, and read by the rolling shutter device. An environmental light intensity ratio detecting means for determining an intensity ratio of the light of the two types of wavelengths in the environmental light based on the electric charge;
The different type image forming means includes:
Luminescence intensity control means for controlling the flash light source to emit light of the two types of wavelengths at an intensity ratio of the two types of wavelengths of ambient light detected by the ambient light intensity ratio detection means;
The switching control means for controlling the emission switching timing of the irradiation light of the two types of wavelengths by the flash light source in accordance with the timing for switching the image read by the rolling shutter device. Skin region detection imaging device.

Images