JP2012058094A - Image processor and electronic equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress illuminance irregularity and to detect skin areas accurately.SOLUTION: Light source parts 13-1 and 13-2 respectively have first LEDs for emitting light of first wavelength and second LEDs for emitting light of second wavelength longer than the first wavelength. An image pickup part 15 generates a first image on the basis of reflecting light from a subject made incident when the light of the first wavelength is being emitted, and generates a second image on the basis of the reflecting light from the subject made incident when the light of the second wavelength is being emitted. Detection means detects a skin area on the basis of the first and second images generated. The light source parts 13-1 and 13-2 are arranged so that the first LEDs form a point symmetry and the second LEDs form a point symmetry. The present invention is applicable to, for example, a detector for detecting a skin area representing human skin from a picked-up image.

Description

  The present invention relates to an image processing apparatus and an electronic apparatus, and more particularly to an image processing apparatus and an electronic apparatus that can detect, for example, a portion where a skin such as a human hand is exposed based on a photographed image.

  There is a skin detection technique for detecting an area where skin is exposed (hereinafter referred to as a skin area) such as a face or a hand from a captured image obtained by imaging a person (for example, Patent Documents 1 to 4). See).

  In this skin detection technology, a first image obtained by imaging a subject (person) irradiated with an LED (light emitting diode) that outputs light of wavelength λ1 and light of wavelength λ2 different from wavelength λ1 are output. A second image obtained by capturing an image of a subject illuminated by the LED is acquired. And the area | region where the difference of the luminance value of a 1st image and a 2nd image is larger than a predetermined threshold value is detected as a skin area | region.

  The wavelengths λ1 and λ2 are determined depending on the reflection characteristics of human skin. That is, the wavelengths λ1 and λ2 are determined to have different reflectivities when irradiated to human skin and have substantially the same reflectivity when irradiated to other than human skin (for example, hair, clothes, etc.). Yes. Specifically, for example, the wavelength λ1 is 850 nm and the wavelength λ2 is 970 nm.

JP 2006-47067 A Japanese Patent Laid-Open No. 06-123700 JP 05-329163 A JP 2008-27242 A

  In the skin detection technique, an area where the difference between the first image irradiated with light of wavelength λ1 and the second image irradiated with light of wavelength λ2 is larger than a predetermined threshold is defined as a skin area. Detect as.

  Therefore, in the skin detection technology, the illuminance P1 of the light with the wavelength λ1 for the subject and the illuminance P2 of the light with the wavelength λ2 for the subject are constant so that the difference corresponds to the difference in reflectance in the subject. It is necessary to satisfy the relationship.

  Specifically, for example, the relationship that the illuminance difference ΔE obtained by dividing (normalizing) the difference between the illuminance P1 and the illuminance P2 by a predetermined value must be a certain value a or less must be satisfied. The constant value a is determined according to the optical characteristics of the LED, the light receiving characteristics of the imaging unit that captures an image of the subject, and the like.

  If this relationship is not satisfied, the difference between the first image irradiated with light of wavelength λ1 and the second image irradiated with light of wavelength λ2 is due to the difference in reflectance at the subject. In other words, it becomes impossible to distinguish between the LED that emits light with wavelength λ1 and the difference in illuminance between the LED that emits light with wavelength λ2, and the skin region cannot be detected accurately.

  For example, when skin detection is performed by incorporating a detection device used for skin detection in a relatively small electronic device (for example, a mobile phone), the detection device needs to be downsized.

  The present invention has been made in view of such a situation, and in the skin detection technology using a plurality of lights having different wavelengths, the illuminance difference due to the plurality of lights having different wavelengths while miniaturizing a detection device used for skin detection. The skin area can be detected with high accuracy by suppressing the variation of the skin.

  An image processing apparatus according to a first aspect of the present invention is an image processing apparatus that detects a skin region representing human skin from an image, and includes a first light emitting unit that emits light of a first wavelength, and A plurality of irradiating means having a second light emitting section for emitting light of a second wavelength that is longer than the first wavelength, and a subject incident when the light of the first wavelength is emitted; Imaging that generates a first image based on reflected light from a light source and generates a second image based on reflected light from the subject incident when light of the second wavelength is emitted Generation means and detection means for detecting the skin region based on the generated first and second images, wherein the plurality of irradiation means are connected to each other of the first light emitting units in each of the irradiation means. , And the second light emitting parts are both point symmetric or line symmetric. An image processing apparatus which is arranged such that the person.

  When there are two irradiation units, the first light emitting units and the second light emitting units in each of the irradiation units are arranged so that both are point-symmetric, and there are four or more irradiation units. In this case, the first light emitting units and the second light emitting units in each of the irradiation means can be arranged so as to be either point symmetric or line symmetric.

  The imaging generation unit generates the first and second images by imaging the subject within a predetermined imaging range, and directs light emitted from the first and second light emitting units. Directional characteristic changing means for changing the characteristics and irradiating light within the predetermined imaging range can be further provided.

  The directivity changing means may be an anamorphic lens.

  The plurality of irradiating units are configured such that the first light emitting units and the second light emitting units of the irradiating units are either point symmetric or line symmetric with respect to the imaging generation unit. Can be arranged.

The first wavelength λ1 and the second wavelength λ2 satisfy the following relational expression.
640nm ≦ λ1 ≦ 1000nm
900nm ≦ λ2 ≦ 1100nm
Can be.

An illuminance difference ΔE obtained by dividing a difference absolute value between an illuminance P1 when irradiated with the light of the first wavelength and an illuminance P2 when irradiated with the light of the second wavelength by a predetermined value; The illuminance difference a when the luminance values of the first and second images obtained for the subject having the same reflectance with respect to the first and second wavelengths are the same satisfies the following relational expression.
| ΔE-a | ≦ 10
Can be.

  According to the first aspect of the present invention, the first image is generated based on the reflected light from the subject incident when the light having the first wavelength is emitted, and the second image is generated. A second image is generated based on the reflected light from the subject incident when light having a wavelength is emitted, and the skin region is detected based on the generated first and second images. Is done. The plurality of irradiation means having a first light emitting unit that emits light of a first wavelength and a second light emitting unit that emits light of a second wavelength that is longer than the first wavelength. The first light-emitting portions and the second light-emitting portions in each of the irradiating means are arranged so as to be either point-symmetric or line-symmetric.

  An electronic device according to a second aspect of the present invention is an electronic device including an image processing device that detects a skin area representing human skin from an image, and the image processing device emits light of a first wavelength. A plurality of irradiating means having a first light emitting unit that emits light, a second light emitting unit that emits light of a second wavelength that is longer than the first wavelength, and light of the first wavelength The first image is generated based on the reflected light from the subject incident when the light is emitted, and the reflected light from the subject incident when the light of the second wavelength is emitted. An imaging generation unit configured to generate a second image based on the detection unit, and a detection unit configured to detect the skin region based on the generated first and second images. The first light emitting units and the second light emitting units in each of the means Cattle are electronic devices that are arranged so as either a one point symmetry or line symmetry.

  According to the second aspect of the present invention, the image processing device built in the electronic device uses the first reflected light from the subject incident when the light having the first wavelength is emitted. An image is generated, and a second image is generated based on the reflected light from the subject that is incident when the light of the second wavelength is emitted, and the generated first and second images are generated. The skin area is detected on the basis of the image. The plurality of irradiation means having a first light emitting unit that emits light of a first wavelength and a second light emitting unit that emits light of a second wavelength that is longer than the first wavelength. The first light-emitting portions and the second light-emitting portions in each of the irradiating means are arranged so as to be either point-symmetric or line-symmetric.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to detect a skin area | region accurately, reducing the structure used for the detection of a skin area | region.

It is a block diagram which shows the structural example of the detection apparatus to which this invention is applied. It is a figure which shows the structural example of a light source part. It is a figure which shows an example of the reflective characteristic with respect to human skin. It is a figure which shows the example of an external appearance of an anamorphic lens. It is a figure for demonstrating the fall of the detection precision of the skin area | region by illuminance difference. It is a 1st figure which shows an example of the illumination intensity distribution of an expansion imaging range. It is a 1st figure which shows an example of the illumination intensity distribution of an imaging range. It is a 1st figure which shows an example of the illumination intensity distribution on the diagonal in an imaging range. It is a figure which shows arrange | positioning so that it may become point-symmetric when there are two light source parts. It is a figure which shows an example of the arrangement | positioning tried by experiment, when there are two light source parts. It is a figure which shows an example at the time of arrange | positioning two light source parts symmetrically with respect to an imaging part. It is a 2nd figure which shows an example of the illumination intensity distribution of an expansion imaging range. It is a 2nd figure which shows an example of the illumination intensity distribution of an imaging range. It is a 2nd figure which shows an example of the illumination intensity distribution on the diagonal in an imaging range. It is a figure which shows an example at the time of arrange | positioning two light source parts symmetrically with respect to an imaging part. It is a 3rd figure which shows an example of the illumination intensity distribution of an expansion imaging range. It is a 3rd figure which shows an example of the illumination intensity distribution of an imaging range. It is a 3rd figure which shows an example of the illumination intensity distribution on the diagonal in an imaging range. It is a figure which shows arrange | positioning so that it may become either point symmetry or line symmetry in the case where there are four light source parts. It is a figure which shows an example of the arrangement | positioning tried by experiment, when there are four light source parts. It is a figure which shows an example at the time of arrange | positioning four light source parts symmetrically with respect to an imaging part. It is a 4th figure which shows an example of the illumination intensity distribution of an expansion imaging range. It is a 4th figure which shows an example of the illumination intensity distribution of an imaging range. It is a 4th figure which shows an example of the illumination intensity distribution on the diagonal in an imaging range. It is a figure which shows an example at the time of arrange | positioning four light source parts point-symmetrically with respect to the imaging part. It is a 5th figure which shows an example of the illumination intensity distribution of an expansion imaging range. It is a 5th figure which shows an example of the illumination intensity distribution of an imaging range. It is a 5th figure which shows an example of the illumination intensity distribution on the diagonal in an imaging range. It is a figure for demonstrating point symmetry.

Hereinafter, modes for carrying out the invention (hereinafter referred to as embodiments) will be described. The description will be given in the following order.
1. 1st Embodiment (an example in the case of arrange | positioning two light source parts symmetrically)
2. Second embodiment (an example in which four light source units are arranged in either point symmetry or line symmetry)
3. Modified example

<1. First Embodiment>
[Configuration example of detection device]
FIG. 1 shows a configuration example of a detection apparatus according to the first embodiment. The detection apparatus 1 detects a human skin region (for example, a face, a hand, etc.) that is a detection target 21 from a captured image. Further, by devising the arrangement of the two light source units 13-1 and 13-2, uneven illuminance due to the irradiation light from the light source units 13-1 and 13-2 is suppressed.

  The detection device 1 includes a control unit 11, an LED control unit 12, light source units 13-1 and 13-2, an optical filter 14, an imaging unit 15, an imaging control unit 16, and an image processing unit 17.

  The control unit 11 controls the overall operation of each unit of the detection device 1. The LED control unit 12 controls the lighting timing, extinguishing timing, and output level of the light source units 13-1 and 13-2 in accordance with control from the control unit 11.

  The light source unit 13-1 emits (irradiates) light having a peak wavelength of the emission spectrum of λ1 (hereinafter referred to as light of wavelength λ1) under the control of the LED control unit 12. In addition, the light source unit 13-1 emits light whose emission spectrum has a peak wavelength of λ2 (hereinafter referred to as light of wavelength λ2) under the control of the LED control unit 12.

  The light source unit 13-2 is configured in the same manner as the light source unit 13-1, and in accordance with the control of the LED control unit 12, the light of wavelength λ1 or the light of wavelength λ2 is transmitted at the same timing as the light source unit 13-1. Emits light.

  Although details will be described later with reference to FIG. 3, the value of the wavelength λ1 is 640 nm to 1000 nm, and the value of the wavelength λ2 longer than the wavelength λ1 is 900 nm to 1100 nm.

  In the following description, when it is not necessary to distinguish between the light source units 13-1 and 13-2, they are simply referred to as the light source unit 13. Further, the detailed configuration of the light source unit 13 will be described later with reference to FIGS. 2 and 4.

  The optical filter 14 is provided on the front surface of the imaging unit 15 so as to limit light incident on the imaging unit 15, and transmits light from the first wavelength to the second wavelength as its spectral characteristics. It is designed to absorb (block) light.

  The first wavelength and the second wavelength are determined according to the values of the wavelengths λ1 and λ2 so that the optical filter 14 can transmit the light with the wavelength λ1 and the light with the wavelength λ2.

  The imaging unit 15 includes a condensing lens and an imaging device such as a CCD or CMOS, and receives light (reflected light from a subject) that has passed through the optical filter 14 in accordance with control from the imaging control unit 16. To generate an image. Note that an image generated when the light source unit 13-1 emits light of wavelength λ1 is the first image, and is generated when the light source unit 13-2 emits light of wavelength λ2. Let the image be a second image.

  The imaging control unit 16 controls the imaging timing of the imaging unit 15, the gain of luminance amplification, and the like according to the control from the control unit 11. Further, the imaging control unit 16 outputs the first and second images generated by the imaging unit 15 to the image processing unit 17.

  The image processing unit 17 detects the skin area of the subject based on the first image and the second image.

[Configuration of Light Source 13]
Next, a configuration example of the light source unit 13 will be described with reference to FIGS. 2 to 4.

  FIG. 2 shows a configuration example of the light source unit 13.

  The light source unit 13 includes an LED 41 that emits light having a wavelength λ1, an LED 42 that emits light having a wavelength λ2, and an anamorphic lens 43 that covers the LEDs 41 and 42.

  The LEDs 41 and 42 are arranged adjacent to each other around a central axis (indicated by a one-dot chain line in the figure) passing through the lens position where the height of the anamorphic lens 43 is highest. The details of the anamorphic lens 43 will be described later with reference to FIG.

  The light source unit 13 causes the LED 41 and the LED 42 to emit light alternately according to the control from the LED control unit 12. That is, the light source unit 13 alternately performs the process of causing only the LED 41 to emit light as shown in FIG. 2A and the process of causing only the LED 42 to emit light as shown in FIG. 2B.

  Next, the wavelength λ1 of light emitted from the LED 41 and the wavelength λ2 of light emitted from the LED 42 will be described with reference to FIG. FIG. 3 shows reflection characteristics assumed for the human skin region that is the detection target 21.

  As shown in FIG. 3, it is known that a human skin region has a minimum value near a wavelength of 960 nm.

  The value of the wavelength λ1 is 640 nm to 1000 nm, which is larger than the wavelength λ1, so that the difference obtained by subtracting the reflectance at the wavelength λ2 from the reflectance at the wavelength λ1 is relatively large compared to those outside the skin region. The value of the wavelength λ2 on the long wavelength side is set to 900 nm to 1100 nm.

  In the following, it is assumed that λ1 = 850 nm and λ2 = 970 nm. In this case, as shown in FIG. 3, the reflectance at the wavelength λ1 is about 46%, and the reflectance at the wavelength λ2 is about 35%. Therefore, in the skin region, the reflectance at the wavelength λ2 differs from the reflectance at the wavelength λ1 by about 1.3 times (= 46/35).

  On the other hand, the reflectance of the portion other than the skin region is almost the same at both wavelengths λ1 and λ2.

  Therefore, the detection apparatus 1 detects, as a skin region, a region where the reflectances at the wavelengths λ1 and λ2 are greatly different from all the regions on the image obtained by imaging.

  In the first and second embodiments, the light source unit 13 is arranged at a position separated from the imaging unit 15 by 0.6 mm. Further, in the LED 41 and the LED 42 of the light source unit 13, the FWHM (full width at half maximum) is 60 degrees, the light emitting surface chip size is 0.4 × 0.4 (horizontal × vertical) mm, and the light emitting surface chip size ( = 0.4 × 0.4 mm), the amount of emitted light is 1 W. Further, for example, it is assumed that the light emitting surfaces of the LED 41 and the LED 42 are present at positions away from the central axis of the anamorphic lens 43 by 0.2 mm. The light source unit 13 is not limited to the above-described configuration.

  Next, FIG. 4 shows an example of the appearance of the anamorphic lens 43.

  The anamorphic lens 43 efficiently irradiates the irradiation light within the imaging range of the imaging unit 15 by refracting the irradiation light from the LED 41 and the LED 42 (changing the directivity characteristics of the LED 41 and the LED 42). In this case, as compared with the case where the light source unit 13 does not have the anamorphic lens 43, the amount of irradiation light irradiated in the imaging range of the imaging unit 15 increases more than twice. It becomes possible to increase the irradiation efficiency of the irradiation light irradiated inside.

  In the first and second embodiments, the anamorphic lens 43 is made of PMMA (polymethyl methacrylate resin), and the axial thickness (the thickness of the lens portion through which the central axis passes) is 1.16 mm. Shall. In the anamorphic lens 43, the S1 surface (the inner surface where the LED 41 and the LED 42 are present) has a flat shape, and the S2 surface (the outer surface) is an anamorphic aspheric surface. And The anamorphic lens 43 is not limited to the above-described configuration.

  The sag amount Z on the S2 surface of the anamorphic lens 43 is expressed by the following equation (1), for example. Here, the sag amount Z represents the depth from the center position of the anamorphic lens 43 (the position of the lens surface through which the central axis passes and has the highest height) to an arbitrary anamorphic lens surface.

・・・（１）

... (1)

  Here, the sag amount Z on the left side of the expression (1) represents the sag amount at the position (x, y) on the anamorphic lens 43. The position (x, y) is defined by an X axis and a Y axis that are orthogonal to each other at the origin, where the center position of the anamorphic lens 43 is the origin (0, 0).

On the right side of the equation (1), the variable N is 6, for example, and the constants c _x , c _y , α ₂ , β ₂ , α ₄ , β ₄ , α ₆ , β ₆ are respectively c _x <0, c _{The following conditions are satisfied: y} <0, 0 ≦ α ₂ , 0 ≦ β ₂ , α ₄ ≦ 0, β ₄ ≦ 0, α ₆ ≦ 0, β ₆ ≦ 0. Α ₂ represents the aspheric coefficient of the quadratic power clause x ² , α ₄ represents the aspheric coefficient of the _fourth power clause x ⁴ , and α ₆ represents the aspheric coefficient of the ^sixth power clause x ⁶ . Furthermore, β ₂ represents the aspheric coefficient of the ^second power term y ² , β ₄ represents the aspheric coefficient of the _fourth power term y ⁴ , and β ₆ represents the aspheric coefficient of the ^sixth power term y ⁶ .

Further, if the curvature radius in the X-axis direction on the light flux exit surface of the anamorphic lens 43 is R _x , c _x = 1 / R _x , and the curvature radius in the Y-axis direction on the light flux exit surface of the anamorphic lens 43 is R _{If y} , then c _y = 1 / R _y .

Further, in the right side of the equation (1), k _x represents a conic constant in the X direction, k _y represents a conic constant in the Y direction. In the first and second embodiments, for example, R _x = −1.2, R _y = −1.6, α ₂ = 0.15, α ₄ = −0.15625, α ₆ = 0, β ₂ = 0, β ₄ Assume that = -0.3125, β ₆ = 0.

[Detection device operation]
First, the object is irradiated with light having the wavelength λ1 by the LEDs 41 of the light source units 13-1 and 13-2. This irradiation light is reflected by the subject together with the external light, and enters the imaging unit 15 via the optical filter 14. The imaging unit 15 generates a first image by photoelectrically converting incident light and supplies the first image to the imaging control unit 16.

  Next, the subject is irradiated with light of wavelength λ2 by the LEDs 42 of the light source units 13-1 and 13-2. This irradiation light is reflected by the subject together with the external light, and enters the imaging unit 15 via the optical filter 14. The imaging unit 15 generates a second image by photoelectrically converting the incident light and supplies the second image to the imaging control unit 16.

  The imaging control unit 16 supplies the first and second images from the imaging unit 15 to the image processing unit 17.

  The image processing unit 17 calculates a difference S = Y1−Y2 that is a difference between the luminance values Y1 and Y2 of corresponding pixels between the first image and the second image from the imaging control unit 16, and sets the difference S to a predetermined value. It binarizes by comparing with the threshold value, and one area of the binary value (area corresponding to the difference equal to or greater than the predetermined threshold value) is detected as a skin area.

[Illuminance distribution variation]
In order for the image processing unit 17 to accurately detect the skin region based on the difference S, the difference S needs to correspond to the reflectance difference in the subject.

  Here, the difference S corresponds to the difference in the reflectance of the subject (for example, the luminance values Y1 and Y2 obtained when the objects having the same reflectance with respect to the wavelengths λ1 and λ2 are irradiated with light are the same. In order to achieve this, it is necessary to satisfy a certain relationship that the illuminance difference ΔE shown in the following equation (2) is a certain value a.

・・・（２）

... (2)

  In the equation (2), ABS (P1-P2) represents the absolute difference between the illuminance P1 of the light with the wavelength λ1 for the subject and the illuminance P2 of the light with the wavelength λ2 for the subject, and ABS (P1) is Represents the absolute value of illuminance P1.

  In the detection device 1, it is necessary to arrange the light source unit 13 so that the illuminance difference ΔE becomes a constant value a. By the way, it is known from experiments conducted in advance that when the illuminance difference ΔE is a value that is greatly different from the constant value a, the detection accuracy of the skin area is significantly reduced.

  Next, FIG. 5 shows that the detection accuracy of the skin area decreases when the illuminance difference ΔE changes from a constant value a to a significantly different value.

  In FIG. 5, the horizontal axis represents the diagonal position in the imaging range of the imaging unit 15, and the vertical axis represents the illuminance difference ΔE at the position indicated by the horizontal axis.

  As shown in FIG. 5, according to an empirical rule based on an experiment conducted by the present inventor, when the illuminance difference ΔE does not fall within the range of a−Δa to a + Δa, the detection accuracy rapidly increases. It is known that it will decline.

  The units of ΔE, a−Δa, and a + Δa are all percentages (%). Further, a is determined according to the optical characteristics of the LEDs 41 and 42 of the light source unit 13 and the light receiving characteristics of the imaging unit 15.

  Furthermore, Δa is assumed to be an LED having a relatively wide emission spectrum width as the LED 41 and LED 42 of the light source unit 13, and the spectral reflectance spectrum of the reflectance to the skin as shown in FIG. It is calculated assuming Specifically, for example, Δa is about 10%.

  As shown in FIG. 5, in order to detect the skin area with high accuracy, the illuminance difference ΔE must be within the range of a−Δa to a + Δa. That is, it is necessary to satisfy | ΔE−a | ≦ Δa.

  By the way, according to the first embodiment, as shown in FIG. 2, the LEDs 41 and 42 are configured as one light source unit 13, so that compared with the case where the LEDs 41 and 42 are configured separately, respectively. Thus, the detection device 1 can be reduced in size. Therefore, the detection device 1 can be built in a relatively small electronic device (for example, a mobile phone, a PDA (personal digital assistant), a small game machine, or the like).

  In addition, according to the first embodiment, as shown in FIG. 4, the irradiation light rate of irradiation light irradiated in the imaging range is improved, and a detection distance (skin detection is possible) The LED 41 and 42 are provided with an anamorphic lens 43 so that the light source unit 13 is configured so that the distance to the subject can be extended.

  However, in this case, the illuminance distribution in the imaging range is biased (| ΔE−a | ≦ Δa is not satisfied), and skin detection cannot be performed.

  Therefore, in the first embodiment, the number and arrangement of the light source units 13 are devised so as to satisfy | ΔE−a | ≦ Δa so that skin detection can be performed with high accuracy.

  Hereinafter, the number and arrangement of the light source units 13 that satisfy | ΔE−a | ≦ Δa will be described.

  In the following, for the sake of simplicity, for example, when a = 0 and Δa = 10 and | ΔE | ≦ 10 is satisfied, the number and arrangement of the light source units 13 are considered as being capable of accurately detecting a skin region. Shall.

[When there is one light source unit 13]
Next, a case where there is one light source unit 13 will be considered with reference to FIGS.

  When the light source unit 13 is composed of only one, the LED 41 and 42 are offset from the central axis of the anamorphic lens 43, and the LED 41 emits light of wavelength λ1, When the light of wavelength λ2 is irradiated from the LED 42, large illuminance unevenness may occur in the imaging range of the imaging unit 15.

  Next, with reference to FIGS. 6 to 8, the illuminance distribution when the light source 13 emits light of wavelength λ1 and the illuminance distribution when light of wavelength λ2 is irradiated will be described.

  FIG. 6 shows the illuminance distribution in the enlarged imaging range obtained when the angle of view θ of the imaging unit 15 is increased by 1.5 times.

  Note that the angle of view θ of the imaging unit 15 represents the angle of view in the diagonal direction, that is, the angle formed by two line segments respectively extending from the imaging unit 15 to both ends of the diagonal line indicated by the dotted line in FIG. Yes. In this case, the angle of view θ is 65 degrees. Further, the illuminance distribution shown in FIG. 6 represents the illuminance distribution at a position 10 cm away from the imaging unit 15.

  FIG. 6A shows an example of the illuminance distribution obtained when the LED 41 in one light source unit 13 irradiates light of wavelength λ1. FIG. 6B shows an example of the illuminance distribution obtained when the LED 42 in one light source unit 13 irradiates light of wavelength λ2.

  In the illuminance distribution shown in FIGS. 6A and 6B, the higher the illuminance, the darker the color (black). The same applies to FIG. 7 described later.

  Moreover, the rectangle (shown by a black thick line) shown in FIGS. 6A and 6B indicates the imaging range of the imaging unit 15.

  FIG. 7 shows the illuminance distribution of the imaging range at the angle of view θ of the imaging unit 15.

  FIG. 7A shows the illuminance distribution in the imaging range of the imaging unit 15 when the light of wavelength λ1 is irradiated, and FIG. 7B shows the illuminance distribution of the imaging unit 15 when the light of wavelength λ2 is irradiated. The illuminance distribution in the imaging range is shown.

  FIG. 8 shows an illuminance distribution at a position on the diagonal line of the imaging range shown in FIG. 7 (indicated by a dotted line in FIGS. 7A and 7B).

  8A and 8B, the horizontal axis indicates the position on the diagonal line, and the vertical axis indicates the illuminance. The illuminance indicated by the vertical axis indicates the illuminance obtained when the total amount of light emitted from the light source unit 13 at the wavelengths λ1 and λ2 is 1 [W].

When the light source unit 13 emits light with a wavelength λ1 (in this case, the total emission amount of the emitted light with wavelength λ1 is 1 [W]), as shown in FIG. The maximum illuminance is 11.5 [W / m ² ], and the minimum illuminance is 4.3 [W / m ² ]. Further, when the light source unit 13 irradiates light having the wavelength λ1, the irradiation efficiency is about 45%.

  The irradiation efficiency refers to the luminous flux of the irradiation light reaching the imaging range when the luminous flux of the irradiation light emitted from the light source unit 13 (the energy of the light passing through the unit area within the unit time) is 100%. Represents.

When the light source unit 13 emits light having a wavelength λ2 (in this case, the total emission amount of emitted light having a wavelength λ2 is 1 [W]), as shown in FIG. The maximum illuminance is 11.7 [W / m ² ] and the minimum illuminance is 4.1 [W / m ² ]. When the light source unit 13 emits light having a wavelength λ2, the irradiation efficiency is about 45%.

  Further, in FIG. 8, | ΔE | is 50% at the maximum, and | ΔE | ≦ 10 is not satisfied, so that the detection accuracy of the skin region is remarkably lowered.

[When there are two light source units 13]
Next, a case where there are two light source units 13 will be considered with reference to FIGS.

  When the light source unit 13 is composed of two pieces, as shown in FIG. 9, when the LEDs 41 and 42 of the light source unit 13 are arranged so as to be point-symmetric with respect to the imaging unit 15, the most uneven illuminance is obtained. The suppression is known from experiments conducted in advance by the inventors.

  That is, for example, as shown in FIG. 10A, the inventor arranges the LEDs 41 and 42 asymmetrically with respect to the imaging unit 15 with respect to the light source unit 13-1 and the light source unit 13-2. As shown in FIG. 10C, when the LEDs 41 and 42 are arranged in line symmetry, as shown in FIG. 10C, when the LEDs 41 and 42 are arranged in line symmetry and point symmetry, respectively, as shown in FIG. As a result of conducting an experiment on the case where the and 42 are arranged point-symmetrically, etc., as shown in FIG. 10D, the experimental result has been obtained that the illuminance unevenness can be most suppressed when arranged point-symmetrically.

  In FIG. 10, black rectangles indicate the LEDs 41, and gray rectangles indicate the LEDs 42. The same applies to the drawings described later.

[When two light source sections 13 are arranged symmetrically]
Next, with reference to FIG. 11 to FIG. 14, experimental results obtained when arranged in line symmetry will be described.

  FIG. 11 shows an example in which the LEDs 41 and 42 of the light source units 13-1 and 13-2 are arranged line-symmetrically with respect to the imaging unit 15 (center of the lens surface thereof).

  FIG. 11A shows a front view of the light source units 13-1 and 13-2 and the imaging unit 15. FIG. 11B shows a top view of the light source units 13-1 and 13-2 and the imaging unit 15.

  When the LEDs 41 and 42 of the light source units 13-1 and 13-2 are arranged symmetrically with respect to the imaging unit 15, the illuminance distribution of the light with the wavelength λ1 obtained when the LED 41 emits light is shown in FIG. Thru / or the illuminance distribution as shown in FIG. 14A.

  In addition, when the LEDs 41 and 42 of the light source units 13-1 and 13-2 are arranged symmetrically with respect to the imaging unit 15, the illuminance distribution of the light having the wavelength λ2 obtained when the LED 42 emits light is The illuminance distribution is as shown in FIGS. 12B to 14B.

  14A and 14B, the illuminance indicated by the vertical axis is the illuminance obtained when the total amount of light emitted from the light sources 13-1 and 13-2 at the wavelengths λ1 and λ2 is 1 [W]. Is shown. Other than that, FIGS. 12 to 14 are configured in the same manner as the above-described FIGS.

When the light source units 13-1 and 13-2 irradiate light having a wavelength λ1, the maximum illuminance within the imaging range is 21.5 [W / m ² ] and the minimum illuminance is 13.2 [ W / m ² ]. Moreover, when the light source parts 13-1 and 13-2 are irradiating the light of wavelength λ1, the irradiation efficiency is about 46%.

When the light source units 13-1 and 13-2 irradiate light having a wavelength λ2, as illustrated in FIG. 14B, the maximum illuminance within the imaging range is 22.2 [W / m ² ], and the minimum illuminance is 8.8 [ W / m ² ]. Moreover, when the light source parts 13-1 and 13-2 are irradiating the light of wavelength λ2, the irradiation efficiency is about 43%.

  Furthermore, in FIG. 14, | ΔE | is 38% at the maximum, and | ΔE | ≦ 10 is not satisfied, so that the detection accuracy of the skin region is significantly lowered.

[When two light source parts 13 are arranged point-symmetrically]
Next, with reference to FIG. 15 thru | or FIG. 18, the experimental result obtained when arrange | positioning point-symmetrically is demonstrated.

  FIG. 15 shows an example in which the LEDs 41 and 42 of the light source units 13-1 and 13-2 are arranged point-symmetrically with respect to the imaging unit 15.

  FIG. 15A shows a front view of the light source units 13-1 and 13-2 and the imaging unit 15. FIG. 15B shows a top view of the light source units 13-1 and 13-2 and the imaging unit 15.

  When the LEDs 41 and 42 of the light source units 13-1 and 13-2 are arranged point-symmetrically with respect to the imaging unit 15, the illuminance distribution of the light of wavelength λ1 obtained when the LED 41 emits light is shown in FIG. Thru / or the illuminance distribution as shown in FIG. 18A.

  In addition, when the LEDs 41 and 42 of the light source units 13-1 and 13-2 are arranged point-symmetrically with respect to the imaging unit 15, the illuminance distribution of the light with the wavelength λ2 obtained when the LED 42 emits light is The illuminance distribution is as shown in FIGS. 16B to 18B.

  18A and 18B, the illuminance indicated by the vertical axis is the illuminance obtained when the total amount of light emitted from the light sources 13-1 and 13-2 at the wavelengths λ1 and λ2 is 1 [W]. Is shown. Other than that, FIGS. 16 to 18 are configured in the same manner as FIGS. 6 to 8 described above, and thus the description thereof is omitted as appropriate.

When the light source units 13-1 and 13-2 irradiate light having a wavelength λ1, the maximum illuminance within the imaging range is 22.9 [W / m ² ] and the minimum illuminance is 10.4 [ W / m ² ]. Moreover, when the light source parts 13-1 and 13-2 are irradiating the light of wavelength λ1, the irradiation efficiency is about 45%.

When the light source units 13-1 and 13-2 irradiate light having a wavelength λ2, as shown in FIG. 18B, the maximum illuminance within the imaging range is 22.7 [W / m ² ], and the minimum illuminance is 10.6 [ W / m ² ]. Moreover, when the light source parts 13-1 and 13-2 are irradiating the light of wavelength λ2, the irradiation efficiency is about 44%.

  Further, in FIG. 18, | ΔE | is 9% at the maximum, and | ΔE | ≦ 10 is satisfied, so that the skin region can be detected with high accuracy.

  Therefore, in the detection apparatus 1, when two light source units 13 are provided, the LEDs 41 and the LEDs 42 in the two light source units 13 are arranged point-symmetrically. Accordingly, it is possible to detect the skin region with high accuracy by suppressing the uneven illuminance, that is, the increase in the illuminance difference | ΔE |.

  The two light source units 13 are arranged so as to be point-symmetric with respect to the center of the lens in the image capturing unit 15, and at an arbitrary point (for example, a position slightly shifted from the lens center of the image capturing unit 15). On the other hand, it may be arranged so as to be point-symmetric.

<2. Second Embodiment>
[When there are four light source units 13]
Next, with reference to FIGS. 19 to 28, consider the case where the number of the light source units 13 is four.

  When the light source unit 13 is composed of four, as shown in FIG. 19, the LEDs 41 and 42 of the light source unit 13 are arranged so as to be either line symmetric or point symmetric with respect to the imaging unit 15. It has been found from experiments previously conducted by the present inventor that the illuminance unevenness is most suppressed.

  That is, for example, as shown in FIG. 20A, the present inventor assigns the LEDs 41 and 42 to the imaging unit 15 for the four light source units 13-1a, 13-1b, 13-2a, and 13-2b. 20B, when the LEDs 41 and 42 are arranged point-symmetrically as shown in FIG. 20B, the LEDs 41 and 42 are line-symmetrically and point-symmetrical as shown in FIG. 20C. As a result of conducting an experiment on the case of arrangement, etc., as shown in FIG. 20A and FIG. 20B, the experiment result that the illuminance unevenness can be most suppressed when arranged in either line symmetry or point symmetry is obtained. Yes.

  In FIG. 20, the LEDs 41 and 42 are arranged point-symmetrically or line-symmetrically with respect to the imaging unit 15, but the point-symmetrical or line-symmetrical reference is not limited to the imaging unit 15. This will be described later with reference to FIG.

[When four light source parts 13 are arranged in line symmetry]
Next, with reference to FIG. 21 to FIG. 24, experimental results obtained when arranged in line symmetry will be described.

  FIG. 21 illustrates an example in which the LEDs 41 and 42 of the four light source units 13-1a to 13-2b are arranged line-symmetrically with respect to the imaging unit 15.

  FIG. 21A shows a front view of the four light source units 13-1a to 13-2b and the imaging unit 15. FIG. 21B shows a top view of the four light source units 13-1a to 13-2b and the imaging unit 15.

  When the LEDs 41 and 42 of the light source units 13-1a to 13-2b are arranged line-symmetrically with respect to the imaging unit 15, the illuminance distribution of the light with the wavelength λ1 obtained when the LED 41 emits light is shown in FIG. Thru / or the illuminance distribution as shown in FIG. 24A.

  In addition, when the LEDs 41 and 42 of the light source units 13-1a to 13-2b are arranged line-symmetrically with respect to the imaging unit 15, the illuminance distribution of the light having the wavelength λ2 obtained when the LED 42 emits light is The illuminance distribution is as shown in FIGS. 22B to 24B.

  In FIGS. 24A and 24B, the illuminance indicated by the vertical axis is obtained when the total amount of light emitted from the four light sources 13-1a to 13-2b is 1 [W]. The obtained illuminance is shown. In other respects, FIGS. 22 to 24 are configured in the same manner as FIGS. 6 to 8 described above, and thus the description thereof is omitted as appropriate.

When the four light source units 13-1a to 13-2b emit light of wavelength λ1, the maximum illuminance within the imaging range is 43.8 [W / m ² ] as shown in FIG. Is 22.0 [W / m ² ]. In addition, when the light source units 13-1a to 13-2b emit light having the wavelength λ1, the irradiation efficiency is about 45%.

When the light source units 13-1a to 13-2b emit light having the wavelength λ2, the maximum illuminance within the imaging range is 43.1 [W / m ² ] and the minimum illuminance is 21.0 [ W / m ² ]. In addition, when the light source units 13-1a to 13-2b emit light having a wavelength λ2, the irradiation efficiency is about 44%.

  Further, in FIG. 24, | ΔE | is 7% at the maximum, and | ΔE | ≦ 10 is satisfied, so that the skin region can be detected with high accuracy.

[When four light sources 13 are arranged point-symmetrically]
Next, with reference to FIG. 25 to FIG. 28, experimental results obtained when arranged point-symmetrically will be described.

  FIG. 25 shows an example in which the LEDs 41 and 42 of the four light source units 13-1a to 13-2b are arranged point-symmetrically with respect to the imaging unit 15.

  FIG. 25A shows a front view of the four light source units 13-1a to 13-2b and the imaging unit 15. FIG. 25B shows a top view of the four light source units 13-1a to 13-2b and the imaging unit 15.

  When the LEDs 41 and 42 of the four light source units 13-1a to 13-2b are arranged point-symmetrically with respect to the imaging unit 15, the illuminance distribution of the light of wavelength λ1 obtained when the LED 41 emits light is The illuminance distribution is as shown in FIGS. 26A to 28A.

  Further, when the LEDs 41 and 42 of the four light source units 13-1a to 13-2b are arranged point-symmetrically with respect to the imaging unit 15, the illuminance of light having a wavelength λ2 obtained when the LED 42 is caused to emit light The distribution is an illuminance distribution as shown in FIGS. 26B to 28B.

  In FIG. 28A and FIG. 28B, the illuminance indicated by the vertical axis is when the total amount of light emitted from the four light sources 13-1a to 13-2b is 1 [W]. The obtained illuminance is shown. Other than that, FIGS. 26 to 28 are configured in the same manner as FIGS. 6 to 8 described above, and thus the description thereof is omitted as appropriate.

When the light source units 13-1a to 13-2b emit light having a wavelength λ1, the maximum illuminance within the imaging range is 43.4 [W / m ² ] and the minimum illuminance is 21.8 [ W / m ² ]. In addition, when the light source units 13-1a to 13-2b emit light having the wavelength λ1, the irradiation efficiency is about 45%.

When the light source units 13-1a to 13-2b emit light of wavelength λ2, as shown in FIG. 28B, the maximum illuminance within the imaging range is 43.1 [W / m ² ], and the minimum illuminance is 21.1 [ W / m ² ]. In addition, when the light source units 13-1a to 13-2b emit light having a wavelength λ2, the irradiation efficiency is about 45%.

  Further, in FIG. 24, | ΔE | is 3% at the maximum, and | ΔE | ≦ 10 is satisfied, so that the skin region can be detected with high accuracy.

  Therefore, in the detection apparatus 1, when four light source parts 13 are provided, the LED 41 and the LED 42 in each of the four light source parts 13 are arranged in either point symmetry or line symmetry. Accordingly, it is possible to detect the skin region with high accuracy by suppressing the uneven illuminance, that is, the increase in the illuminance difference | ΔE |.

  Note that the point symmetry and the line symmetry are determined based on the imaging unit 15, but the point symmetry and the line symmetry reference are not limited to the imaging unit 15, and the point symmetry and the line symmetry are based on an arbitrary position. Symmetry can be determined.

  Specifically, for example, as shown in FIG. 29A and FIG. 29B, it may be arranged so as to be point-symmetric with respect to a position different from the lens center (shown by a black circle) of the imaging unit 15. . The same applies to line symmetry.

<3. Modification>
In the first and second embodiments, the case where the number of light source units 13 is two or four has been described. However, for example, 2 × n light source units 13 are included in the detection device 1 (n is 3 or more). (Natural number) may be provided so as to be either point-symmetric or line-symmetric. Also in this case, as in the case where the number of the light source units 13 is four, it is possible to suppress the increase in the illuminance difference | ΔE | and detect the skin region with high accuracy.

  In the first and second embodiments, by providing the light source unit 13 with the anamorphic lens 43, the LED 41 and the LED 42 are arranged so that the light from the LED 41 and the LED 42 falls within the imaging range of the imaging unit 15. The radiation efficiency was improved by changing the directivity characteristics of.

  However, what is provided in the light source unit 13 in order to change the directivity is not limited to the anamorphic lens 43.

  That is, for example, in the light source unit 13, instead of the anamorphic lens 43, a spherical lens or an aspherical lens different from the anamorphic lens 43 may be used to improve the irradiation efficiency.

  Further, for example, a prism or a polarizing plate may be used in place of the anamorphic lens 43. That is, as long as it is for improving the irradiation efficiency, any one may be used, and the anamorphic lens 43, the prism and the like may be arbitrarily combined.

  In the above formula (2), the difference absolute value ABS (P1-P2) between the illuminance P1 and the illuminance P2 is normalized (divided) by the absolute value ABS (P1) of the illuminance P1, but in addition, for example, Alternatively, normalization may be performed using the absolute value ABS (P2) of the illuminance P2. That is, as long as the value is based on at least one of the illuminance P1 and the illuminance P2, any value may be used for normalization.

  Moreover, since the detection apparatus 1 mentioned above comprised LED41 and 42 as one light source part 13, compared with the case where LED41 and 42 are comprised separately, the detection apparatus 1 can be reduced in size. Can do. Therefore, the detection device 1 can be configured to be built in a relatively small electronic device (for example, a mobile phone). In this case, in a small electronic device, the skin region is detected by the built-in detection device 1, and processing corresponding to the shape of the detected skin region is performed.

  Specifically, for example, when a user is watching a broadcast program or the like by receiving a broadcast signal based on so-called one-segment broadcasting on a small mobile phone incorporating the detection device 1, When a posture or gesture operation for instructing a change is performed, the built-in detection device 1 detects the user's posture or gesture based on the detected skin area, and in response to the detection result, the channel or the gesture is detected. Volume change is controlled.

  The illuminance in the illuminance distribution described above is received by the light receiving unit and the area of the light receiving unit that receives the irradiated light using, for example, a power meter having sensitivity in the near infrared wavelength range. It can be calculated based on the light of the irradiated light.

  Also, by combining a detector that performs photoelectric conversion (O / E conversion) that converts received light into electrical signals and an oscilloscope, the illuminance corresponding to the received light is calculated from the electrical level. Is possible.

  When the illuminance is calculated by combining a director or the like and an oscilloscope, a relatively accurate illuminance can be calculated by converting the absolute value of the light amount (illuminance) of the irradiation light from the light receiving sensitivity of the detector.

  By using such an illuminance calculation method, the illuminance distribution within the imaging range of the imaging unit 15 can be calculated.

  The present embodiment is not limited to the first and second embodiments described above, and various modifications can be made without departing from the scope of the present invention.

  DESCRIPTION OF SYMBOLS 1 Detection apparatus, 11 Control part, 12 LED control part, 13-1, 13-2, 13-1a, 13-1b, 13-2a, 13-2b Light source part, 14 Optical filter, 15 Imaging part, 16 Imaging control , 17 Image processing unit, 41, 42 LED, 43 Anamorphic lens

Claims (8)

In an image processing apparatus for detecting a skin area representing human skin from an image,
A plurality of irradiation means including a first light emitting unit that emits light of a first wavelength, and a second light emitting unit that emits light of a second wavelength that is longer than the first wavelength;
The first image is generated based on the reflected light from the subject incident when the light of the first wavelength is emitted, and is incident when the light of the second wavelength is emitted. Imaging generation means for generating a second image based on reflected light from the subject;
Detecting means for detecting the skin region based on the generated first and second images, and
The image processing apparatus, wherein the plurality of irradiation units are arranged so that the first light emitting units and the second light emitting units in each of the irradiation units are either point symmetric or line symmetric. When the number of the irradiating means is two, the first light emitting sections and the second light emitting sections in each of the irradiating means are arranged so as to be point-symmetric with each other.
When there are four or more irradiating means, the first light emitting sections and the second light emitting sections in each of the irradiating means are arranged so as to be either point symmetric or line symmetric. The image processing apparatus according to claim 1. The imaging generation unit generates the first and second images by imaging the subject within a predetermined imaging range.
The image processing apparatus according to claim 2, further comprising directivity characteristic changing means for changing the directivity characteristics of light emitted from the first and second light emitting units to irradiate light within the predetermined imaging range. The image processing apparatus according to claim 3, wherein the directivity characteristic changing unit is an anamorphic lens. The plurality of irradiating units are configured such that the first light emitting units and the second light emitting units of the irradiating units are either point symmetric or line symmetric with respect to the imaging generation unit. The image processing apparatus according to claim 1, wherein the image processing apparatus is arranged. The first wavelength λ1 and the second wavelength λ2 satisfy the following relational expression.
640nm ≦ λ1 ≦ 1000nm
900nm ≦ λ2 ≦ 1100nm
The image processing apparatus according to claim 1. An illuminance difference ΔE obtained by dividing a difference absolute value between an illuminance P1 when irradiated with the light of the first wavelength and an illuminance P2 when irradiated with the light of the second wavelength by a predetermined value; The illuminance difference a when the luminance values of the first and second images obtained for the subject having the same reflectance with respect to the first and second wavelengths are the same satisfies the following relational expression.
| ΔE-a | ≦ 10
The image processing apparatus according to claim 1. In an electronic device incorporating an image processing device for detecting a skin area representing human skin from an image,
The image processing apparatus includes:
A plurality of irradiation means including a first light emitting unit that emits light of a first wavelength, and a second light emitting unit that emits light of a second wavelength that is longer than the first wavelength;
The first image is generated based on the reflected light from the subject incident when the light of the first wavelength is emitted, and is incident when the light of the second wavelength is emitted. Imaging generation means for generating a second image based on reflected light from the subject;
Detecting means for detecting the skin region based on the generated first and second images, and
The plurality of irradiating units are arranged such that the first light emitting units and the second light emitting units in each of the irradiating units are either point symmetric or line symmetric.

Images