JP2012000147A - Image processing apparatus, image processing method, program and electronic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To precisely detect a skin region while suppressing electric power consumption.SOLUTION: A light source group 23 has a plurality of irradiating parts for irradiating a body to be photographed with a light of a first wavelength in respectively different directional characteristics. A light source group 24 has a plurality of irradiating parts for irradiating the body to be photographed with a light of a second wavelength being longer wavelength than the first wavelength in respectively different directional characteristics. An LED controlling part 22 controls light outputs of respective irradiating parts of the light source groups 23 and 24 in accordance with the distance to the body to be photographed, and an image photographing part 26 forms a first image obtained by photographing the body to be photographed when the light of the first wavelength irradiates the body to be photographed, and forms a second image obtained by photographing the body to be photographed when the light of the second wavelength irradiates the body to be photographed. An image processing part 28 detects a skin region based on the result of comparison between the difference of the first image and the second image and the threshold value to be compared with difference. The present invention can be applied, for example, to a detecting apparatus for detecting the movement of a hand of a human being or the like.

Description

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

  There is a skin detection technique for detecting a region where skin is exposed (hereinafter referred to as a skin region) such as a face or a hand from a captured image obtained by capturing a subject (for example, a person) (for example, (See Patent Documents 1 to 3).

  In this skin detection technique, a first image obtained by imaging a subject irradiated with an LED (light emitting diode) that outputs light having a wavelength λ1 and an LED that outputs light having a wavelength λ2 different from the wavelength λ1 are irradiated. And a second image obtained by capturing an image of the subject in the state. 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 reflectivity when irradiated to human skin is different, and the reflectivity when irradiated to other than human skin (for example, hair, clothes, etc.) is determined to be substantially equal. Specifically, for example, the wavelength λ1 is 870 nm and the wavelength λ2 is 950 nm.

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

  In the skin detection technology, for example, when the distance to the subject is 0.05 [m], when using each directional characteristic LED that irradiates the range where the subject exists, the distance to the subject is 5 [m]. In this case, in addition to the range where the subject is present, light is also irradiated to a range where the subject is not present and irradiation is not necessary.

  For this reason, in the skin detection technology, light is emitted with a light output necessary for skin detection even in a range where irradiation is not required, so the amount of irradiation light increases and the power consumption of each LED increases. .

  The present invention has been made in view of such a situation, and makes it possible to accurately detect a skin region while suppressing power consumption.

  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 irradiates a subject with light having a first wavelength with different directivity characteristics. And a second light emitting unit having a plurality of irradiating units that irradiate the subject with light having a second wavelength that is longer than the first wavelength with different directivity characteristics. Means, irradiation control means for controlling the light output of each of the first and second light emitting means according to the distance to the subject, and the subject is irradiated with light of the first wavelength. Generating a first image obtained by imaging the subject while the second object is captured, and obtaining a second image obtained by imaging the subject when the subject is irradiated with light of the second wavelength. Imaging generation means for generating and the first image And the difference between the second image and, based on a result of comparison between the threshold value to be compared with the difference, an image processing apparatus including a detection means for detecting the skin region.

  In the irradiation control unit, when the distance to the subject is less than a predetermined distance, the light output of the irradiation unit with high directivity among the irradiation units of the first and second light emitting units is reduced, and When the light output of the irradiating unit having low directivity is controlled to be large and the distance to the subject is equal to or greater than the predetermined distance, the directivity of each of the irradiating units of the first and second light emitting means It is possible to control so that the light output of the irradiation unit having a high directivity increases and the light output of the irradiation unit having low directivity characteristics decreases.

  In the imaging region imaged by the imaging generation means, a detection target region for irradiating with a light output necessary for detecting the skin region is determined in advance according to the distance to the subject, The distance to the subject is not less than the predetermined distance determined based on at least one of the horizontal half width of the detection target area or the vertical half width of the detection target area and the half angle of view of the imaging generation unit It is possible to further provide determination means for determining whether or not.

  Distance calculation means for calculating the distance to the subject can be further provided, and the irradiation control means can provide each of the irradiation units of the first and second light emitting means according to the calculated distance to the subject. The light output can be controlled.

  In the first and second light emitting means, at least one of an irradiation unit whose half-value half angle is greater than or equal to a half field angle of the imaging generation unit, or an irradiation unit whose half-value half angle is less than or equal to the half field angle of the imaging generation unit is provided. Can have.

The first wavelength λ1 and the second wavelength λ2 satisfy the relationship of the following equation: 630 [nm] ≦ λ1 ≦ 1000 [nm]
900 [nm] ≦ λ2 ≦ 1100 [nm]
Can be.

  An image processing method according to a first aspect of the present invention is an image processing method of an image processing device that detects a skin region representing human skin from an image, and the image processing device has first directivity characteristics different from each other. A first light emitting unit having a plurality of irradiating units for irradiating the subject with light having a wavelength of λ, and irradiating the subject with light having a second wavelength that is longer than the first wavelength with different directivity characteristics A second light-emitting unit having a plurality of irradiation units; an irradiation control unit; an imaging generation unit; and a detection unit. The first light-emitting unit irradiates the subject with light having the first wavelength. The second light emitting unit irradiates the subject with light of the second wavelength, and the irradiation control unit irradiates each of the first and second light emitting units according to the distance to the subject. Controlling the light output of the imaging unit, the imaging generation means Generating a first image obtained by imaging the subject when the subject is irradiated with light of a wavelength of the subject, and the subject when the subject is irradiated with light of the second wavelength. A second image obtained by imaging the image is generated, and the detection means is based on a comparison result between a difference between the first image and the second image and a threshold value compared with the difference. An image processing method including the step of detecting the skin region.

  A program 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 a plurality of irradiations that irradiate a subject with light of a first wavelength with different directivity characteristics. A first light emitting unit having a plurality of irradiation units, and a second light emitting unit having a plurality of irradiation units that irradiate the subject with light having a second wavelength that is longer than the first wavelength with different directivity characteristics Generating a first image obtained by imaging the subject when the subject is irradiated with light of the first wavelength, and irradiating the subject with light of the second wavelength A computer of an image processing apparatus including an imaging generation unit that generates a second image obtained by imaging the subject at times, depending on the distance to the subject, each of the first and second light emitting units Controls the light output of the irradiation unit For controlling the skin region based on a comparison result between a difference between the first image and the second image and a threshold value compared with the difference. It is a program.

  According to the first aspect of the present invention, the light output of the irradiation unit of each of the first and second light emitting means is controlled according to the distance to the subject, and the first image and the second image are controlled. The skin region is detected based on a comparison result between a difference from the image and a threshold value compared with the difference.

  An electronic apparatus according to a second aspect of the present invention is an electronic apparatus that detects a skin region representing human skin from an image, and a plurality of irradiations that irradiate a subject with light having a first wavelength with different directivity characteristics. A first light emitting unit having a plurality of irradiation units, and a second light emitting unit having a plurality of irradiation units that irradiate the subject with light having a second wavelength that is longer than the first wavelength with different directivity characteristics Irradiating control means for controlling the light output of each of the first and second light emitting means according to the distance to the subject, and when the subject is irradiated with light of the first wavelength. Generating a first image obtained by imaging the subject, and generating a second image obtained by imaging the subject when the subject is irradiated with light of the second wavelength. An imaging generation unit; the first image; The detection means for detecting the skin area based on a comparison result between the difference between the second image and the threshold value to be compared with the difference, and execution of executing a predetermined process based on the detected skin area And an electronic device.

  According to the second aspect of the present invention, the light output of each of the irradiation units of the first and second light emitting means is controlled according to the distance to the subject, and the light of the first wavelength is emitted from the subject. A first image obtained by imaging the subject when the subject is irradiated is generated, and obtained by imaging the subject when the subject is irradiated with light of the second wavelength A second image is generated, and based on a comparison result between the difference between the first image and the second image and a threshold value compared with the difference, the skin region is detected, and the detected A predetermined process is executed based on the skin region.

  According to the present invention, it is possible to accurately detect a skin region while suppressing power consumption by a light source.

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 an example of the spectral reflection characteristic with respect to human skin. It is a figure for demonstrating the imaging range of an imaging part. It is a figure which shows an example of directivity. It is a figure which shows an example of the illumination intensity distribution in a short distance. It is a figure which shows an example of the illumination distribution in a long distance. It is a flowchart for demonstrating the skin detection process which a detection apparatus performs. It is a block diagram which shows the structural example of a computer.

Hereinafter, modes for carrying out the invention (hereinafter referred to as the present embodiment) will be described. The description will be given in the following order.
1. This embodiment (an example of using LEDs with different directivity characteristics according to the distance to the subject)
2. Modified example

<1. Embodiment>
[Configuration Example of Detection Device 1]
FIG. 1 shows a configuration example of a detection apparatus 1 according to the present embodiment. For example, the detection device 1 illuminates light efficiently by turning on an LED corresponding to a distance to the detection target 41 (hereinafter referred to as a subject distance) among a plurality of LEDs having different directivity characteristics. Thus, a human skin region (for example, a face, a hand, etc.) as the detection object 41 can be accurately detected from the captured image.

  The detection device 1 includes a controller 21, an LED control unit 22, a light source group 23, a light source group 24, an optical filter 25, an imaging unit 26, an imaging control unit 27, an image processing unit 28, and a distance calculation unit 29.

  For example, the controller 21 can detect a condition that the luminance value of the subject on the first and second images (described later) obtained by imaging by the imaging unit 26 is 1/5 or more of the saturation level (skin area can be detected) The operation of each part of the detection apparatus 1 is controlled in a unified manner so that the above-mentioned conditions are satisfied.

  That is, for example, the brightness value of the first and second images decreases as the distance to the subject increases. If the luminance value of the subject on the first and second images becomes too small, it will be buried in noise and the skin area will not be detected. Further, even if the luminance values of the subjects on the first and second images become too large and become saturated (overexposed), the skin area cannot be detected.

  Therefore, the controller 21 responds to the subject distance so that the condition that the skin area can be detected satisfies the condition that the luminance value of the subject on the first and second images is 1/5 or more of the saturation level. Thus, the operation of each part of the detection apparatus 1 is controlled. This condition is obtained from an empirical rule based on the result of actual measurement of each image sensor by the present inventor.

  The LED control unit 22 controls lighting timing, extinguishing timing, and light output level of the light source groups 23 and 24 according to control from the controller 21.

  The light source group 23 includes a sub-light source group 23-1 configured by each bullet-type LED and a sub-light source group 23-2 configured by each LED having a flat emission surface. The light source group 24 includes a sub-light source group 24-1 configured by each bullet-type LED and a sub-light source group 24-2 configured by each LED having a flat emission surface. The bullet-type LED has higher directivity than an LED with a flat emission surface.

  The light source group 23 emits light having a peak wavelength of the emission spectrum of λ1 (hereinafter referred to as light of wavelength λ1) in accordance with control from the LED control unit 22. That is, for example, the light source group 23 emits light so that the light output of the sub-light source group 23-1 having high directivity characteristics increases as the subject distance increases, and the directivity characteristics increase as the subject distance decreases. Light is emitted so that the light output of the sub-light source group 23-2 having a low value becomes large.

  The light source group 24 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 22. That is, for example, the light source group 24 emits light so that the light output of the sub-light source group 24-1 having high directivity characteristics increases as the subject distance increases, and the directivity characteristics increase as the subject distance decreases. Light is emitted so that the light output of the sub-light source group 24-2 having a low value becomes large.

  Specific values of the wavelengths λ1 and λ2 will be described later with reference to FIG.

  The optical filter 25 is provided on the front surface of the imaging unit 26 so as to limit light incident on the imaging unit 26. For example, the optical filter 25 has a short wavelength side than the wavelength λ1 and a longer wavelength side than the wavelength λ2 as its spectral characteristics. Are transmitted, and light having a wavelength of λ1 or more and a wavelength of λ2 or less is transmitted.

  The imaging unit 26 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 25 in accordance with control from the imaging control unit 27. To generate an image. An image generated when the light source group 23 emits light is referred to as a first image, and an image generated when the light source group 24 emits light is referred to as a second image.

  The imaging unit 26 supplies the generated first and second images to the imaging control unit 27.

  The imaging control unit 27 controls the imaging timing, imaging time (exposure time), gain of luminance value amplification, and the like of the imaging unit 26 in accordance with control from the controller 21. In addition, the imaging control unit 27 outputs the first and second images supplied from the imaging unit 26 to the image processing unit 28.

  The image processing unit 28 calculates a reflectance difference detection signal S = Y1-Y2 that is the difference between the luminance values Y1 and Y2 of the corresponding pixels of the first and second images from the imaging control unit 27, and reflects the reflectance. The difference detection signal S is binarized by comparing it with a predetermined threshold value.

  Then, the image processing unit 28 selects one of the binary regions (corresponding reflectance difference detection signal S is equal to or greater than a predetermined threshold) among all regions on the binarized skin image obtained by the binarization. Area) is detected as a skin area. In addition, the image processing unit 28 supplies the binarized skin image to the distance calculation unit 29.

  Note that the image processing unit 28 may perform binarization after dividing (normalizing) the calculated reflectance difference detection signal S by, for example, the luminance value Y1 or Y2.

  The distance calculation unit 29 uses the fact that the size of the skin area of the subject (for example, the area and width of the skin area) increases as the subject distance is shorter, and the binarized skin image from the image processing unit 28 is used. The subject distance is calculated based on the size of the upper skin area and supplied to the controller 21.

  Thereby, the controller 21 controls, for example, the LED control unit 22 based on the subject distance from the distance calculation unit 29, and each of the sub light source group 23-1 and the sub light source group 23-2 constituting the light source group 23. The optical output and the optical output of each of the auxiliary light source group 24-1 and auxiliary light source group 24-2 constituting the light source group 24 are controlled.

  The distance calculation unit 29 calculates the subject distance based on the size of the skin area on the binarized skin image from the image processing unit 28. However, any calculation is possible as long as the subject distance can be calculated. It may be calculated by a method.

  Specifically, for example, the distance calculation unit 29 replaces the binarized skin image from the image processing unit 28 with a laser range finder that measures the subject distance by irradiating the detection target 41 with a laser, or a different parallax. The subject distance may be measured by using a stereo camera or the like that measures the subject distance using two cameras provided with.

[Spectral reflection characteristics for skin]
Next, FIG. 2 shows spectral reflection characteristics with respect to human skin.

  This spectral reflection characteristic has generality regardless of the color of human skin (difference in race) or the state (sunburn, etc.).

  In FIG. 2, the horizontal axis indicates the wavelength of the irradiation light irradiated on the human skin, and the vertical axis indicates the reflectance of the irradiation light irradiated on the human skin.

  This is peculiar to human skin. For objects other than human skin (for example, hair and clothes), the change in reflectance is moderate in the vicinity of 630 to 1100 [nm]. Many.

  The combination of wavelengths λ1 and λ2 is a combination in which the difference in reflectance with respect to human skin is relatively large, and the combination in which the difference in reflectance with respect to portions other than human skin is relatively small.

  Specifically, for example, in the above-described spectral reflection characteristics, as a combination of the wavelengths λ1 and λ2, the wavelength λ1 is 630 [nm] or more and 1000 [nm] or less, and the wavelength λ2 is 900 [nm] or more. And a combination in which the wavelength λ1 is shorter than the wavelength λ2 (wavelength λ1 <wavelength λ2) (more preferably, the wavelength λ1 + 40 [nm] <wavelength λ2) is employed. .

[Imaging range of the imaging unit 26]
Next, the imaging range of the imaging unit 26 will be described with reference to FIG. FIG. 3 shows a top view of the imaging unit 26.

  In FIG. 3, a triangular range formed by two imaging range boundary lines L <b> 1 and L <b> 2 sandwiching the angle of view θ of the imaging unit 26 indicates the imaging range of the imaging unit 26.

  In FIG. 3, the Z axis that coincides with the optical axis of the imaging unit 26 indicates the subject distance z from the imaging unit 26 (light source groups 23 and 24) to the subject (detection target 41). In the present embodiment, it is assumed that the imaging unit 26 and the light source groups 23 and 24 are installed close to each other.

  The light source groups 23 and 24 need to irradiate light with a light output having an intensity capable of detecting a skin region with respect to a predetermined detection target region.

  Specifically, for example, at a short distance where the subject distance z is 0 ≦ z ≦ a [m], the detection target 41 is an imaging region at the subject distance z (region corresponding to the first and second images). It will occupy a lot of. Therefore, when the subject distance z is a short distance, the imaging region at the subject distance z is set as a detection target region, and it is necessary to irradiate the detection target region with light output having an intensity capable of detecting the skin region. .

  On the other hand, at a long distance where the subject distance z is a <z ≦ b [m], the detection target 41 is mainly a predetermined region (for example, a central region) of the imaging region at the subject distance z. ). Therefore, when the subject distance z is a long distance, an area including a predetermined area in the imaging area at the subject distance z is set as a detection target area, and the skin area can be detected with respect to the detection target area. Light may be irradiated with light output.

  The detection target region is a region where the detection target object 41 is assumed to move, and is determined in advance by experiments or the like. Specifically, for example, the detection target region is a region in which the horizontal width and the vertical width are the same width (for example, width 2 × w). The distance a is determined by the half width w of the detection target region and the half field angle θ / 2 of the field angle θ of the imaging unit 26. Specifically, for example, the distance a is about 1 to 2 times the distance w / tan (θ / 2) from the imaging unit 26.

  In the present embodiment, as shown in FIG. 3, the distance a (= w / tan (θ / 2)) is set to one time the distance w / tan (θ / 2).

  When the horizontal width and the vertical width of the detection target area are different from each other, j and k, the half width w for one of the horizontal width j or the vertical width k and the half angle of view θ / 2 for the image pickup unit 26. Based on this, the distance w / tan (θ / 2) is calculated.

  Further, when the horizontal width and vertical width of the detection target area are different widths j and k, respectively, the average of the horizontal width j and the vertical width k is obtained, and the half width of the average width obtained as a result is obtained. The distance w / tan (θ / 2) may be calculated based on the half angle of view θ / 2.

[Directional characteristics of sub-light source group]
FIG. 4 shows directivity characteristics of the sub light source groups 23-1 and 24-1 and the sub light source groups 23-2 and 24-2.

  In FIG. 4, the horizontal axis represents the half angle of view θ / 2, and the vertical axis represents the light intensity (relative value). Note that, in the half angle of view θ / 2 on the horizontal axis, the angle represented by a positive value indicates the angle θ / 2 between the optical axis of the imaging unit 26 (Z axis in FIG. 3) and the imaging range boundary line L1. The angle represented by a negative value indicates the angle between the optical axis of the imaging unit 26 and the imaging range boundary line L2.

  The LEDs constituting each of the sub-light source groups 23-1 and 24-1 have high directivity characteristics as shown in the graph 1 shown in FIG. Specifically, for example, the LED has a directivity characteristic such that the half-value half angle of the LED is equal to or less than the half field angle θ / 2 of the imaging unit 26.

  Further, the LEDs constituting each of the auxiliary light source groups 23-2 and 24-2 have low directivity characteristics as shown in the graph 2 shown in FIG. Specifically, for example, the LED has a directivity characteristic such that the half-value half angle of the LED is equal to or greater than the half field angle θ / 2 of the imaging unit 26.

  The half-value half-angle refers to an angle formed by the irradiation direction of light emitted at half value of the peak intensity (representing value) of the light intensity emitted from the LED and the direction passing through the center of the LED. .

  As shown in FIG. 4, the sub light source groups 23-1 and 24-1 have higher directivity characteristics than the sub light source groups 23-2 and 24-2.

  For this reason, when the subject distance z is a long distance, the sub light source groups 23-1 and 24-1 have reduced power consumption compared to when the sub light source groups 23-2 and 24-2 are used. Thus, it is possible to irradiate the detection target region with light with an intensity of light output capable of detecting the skin region.

  Further, as shown in FIG. 4, the sub light source groups 23-2 and 24-2 have lower directivity characteristics than the sub light source groups 23-1 and 24-1.

  For this reason, when the subject distance z is a short distance, the sub-light source groups 23-2 and 24-2 have reduced power consumption compared to when the sub-light source groups 23-1 and 24-1 are used. Thus, it is possible to irradiate the detection target region with light with an intensity of light output capable of detecting the skin region.

  Next, with reference to FIG.5 and FIG.6, the illumination distribution of the sub light source group 23-1 and the sub light source group 23-2 is demonstrated. The illuminance distribution between the sub-light source group 24-1 and the sub-light source group 24-2 is the same as the illuminance distribution between the sub-light source group 23-1 and the sub-light source group 23-2. Omitted.

[Illuminance distribution at short distance]
FIG. 5 shows an example of the illuminance distribution when the subject distance z is a short distance, that is, for example, when the subject distance z = 0.3 [m].

  In FIG. 5, the horizontal axis indicates the horizontal position on the imaging region (detection target region) at the subject distance z, and the vertical axis indicates the illuminance (relative value). In the horizontal axis, the center position of the imaging region is 0 [m]. In FIG. 5, it is assumed that the angle of view θ of the imaging unit 26 is 90 degrees.

  Further, in FIG. 5, graph 1 shows the illuminance distribution in the sub-light source 23-1. Graph 2 shows the illuminance distribution in the sub-light source 23-2. Note that the light outputs (integrated values of the intensity of irradiation light) of the sub light source 23-1 and the sub light source 23-2 are equal. The same applies to FIG. 6 described later.

  In the imaging region (detection target region) at the subject distance z = 0.3 [m], the position of the imaging range boundary line L1 is 0.3 [m], and the position of the imaging range boundary line L2 is −0.3 [m]. .

  In graph 2 of FIG. 5, the illuminance at a position near ± 0.3 [m] is about 1/3 of the illuminance at a position near 0 [m], and imaging is performed by adjusting the irradiation time and exposure time. All the luminance values in the first and second images obtained by the imaging of the unit 26 can be within a range of 1/5 or more of the saturation level.

  On the other hand, in the graph 1 of FIG. 5, the illuminance at a position near ± 0.3 [m] is very small compared to the illuminance at a position near 0 [m]. All the luminance values in the first and second images obtained by imaging cannot fall within the range of 1/5 or more of the saturation level.

  Therefore, when the subject distance z = 0.3 [m], it is desirable to use the sub-light source group 23-2 having low directivity as shown in the graph 2 of FIG.

  The sub light source group 23-1 and the sub light source group 22-2 consume the same power consumption and emit light with the same light output. In FIG. 5, the illuminance at a position near ± 0.3 [m] allows the graph 2 to obtain an illuminance higher than that of the graph 1.

  For this reason, also from the viewpoint of reducing power consumption, it is desirable to use the sub-light source group 23-2 having low directivity as shown in the graph 2.

[Illuminance distribution at long distance]
FIG. 6 shows an example of the illuminance distribution when the subject distance z is a long distance, that is, for example, when the subject distance z = 3 [m].

  In the imaging region at the subject distance z = 3 [m], the position of the imaging range boundary line L1 is 3 [m], and the position of the imaging range boundary line L2 is −3 [m]. Further, the position of the detection target region boundary line T1 is 1 [m], and the position of the imaging range boundary line T2 is -1 [m].

  In graph 1 of FIG. 6, the illuminance at a position near ± 1 [m] is about half of the illuminance at a position near 0 [m], and the brightness value can be adjusted by adjusting the exposure time. Can be kept within 1/5 of the saturation level.

  On the other hand, the illuminance in the graph 2 in FIG. 6 is small as a whole, and the skin region cannot be detected with high accuracy.

  Therefore, when the subject distance z = 3 [m], it is desirable to use the sub-light source group 23-1 having high directivity as shown in the graph 1 of FIG.

  As described above, the sub light source group 23-1 and the sub light source group 22-2 consume the same power consumption and emit light with the same light output. In FIG. 6, the illuminance at a position near ± 1 [m] allows the graph 1 to obtain higher illuminance than the graph 2.

  For this reason, from the viewpoint of reducing power consumption, it is desirable to use the sub-light source group 23-1 having low directivity as shown in the graph 1.

  For this reason, for example, the detection apparatus 1 increases the light output of the sub-light source groups 23-2 and 24-2 having low directivity characteristics and the sub-light source group having high directivity characteristics as the subject distance z is closer. The optical outputs of 23-1 and 24-1 are reduced. In addition, the detection device 1 reduces the light output of the sub-light source groups 23-2 and 24-2 having low directivity characteristics and the sub-light source group 23-1 having high directivity characteristics as the subject distance z is far. And the light output of 24-1 is increased.

  Note that the detection device 1 uses only the sub-light source groups 23-2 and 24-2 having low directivity characteristics as shown in the graph 2 at a short distance, and directivity as shown in the graph 1 at a long distance. The skin region may be detected by using only the sub-light source groups 23-1 and 24-1 having high characteristics.

[Description of Operation of Detection Device 1]
Next, the skin detection process performed by the detection apparatus 1 will be described with reference to the flowchart of FIG.

  In step S <b> 1, the distance calculation unit 29 calculates the subject distance z and supplies it to the controller 21. For example, based on the subject distance z from the distance calculation unit 29, the controller 21 determines whether the subject distance z is a short distance equal to or less than the distance a or whether the subject distance z is a long distance longer than the distance a. The LED used for skin detection is determined based on the determination result.

  That is, for example, when the subject distance z is a short distance, the controller 21 selects a sub-light source group 23-2 having a low directivity among the sub-light source groups 23-1 and 23-2 constituting the light source group 23 as a light source. Of the sub-light source groups 24-1 and 24-2 constituting the group 24, the sub-light source group 24-2 having a low directivity is determined.

Further, for example, when the subject distance z is a long distance, the controller 21 selects the sub-light source group 23-1 having high directivity among the sub-light source groups 23-1 and 23-2 constituting the light source group 23 as the light source. Of the sub-light source groups 24-1 and 24-2 constituting the group 24, the sub-light source group 24-1 having high directivity is determined.

  In this case, it is assumed that the controller 21 has determined the sub-light source groups 23-1 and 24-1, and the processing after step S2 will be described.

  For example, the distance calculation unit 29 calculates the subject distance z based on the binarized skin image calculated in the previous skin detection process and supplies the subject distance z to the controller 21.

  In step S <b> 2, the sub-light source group 23-1 irradiates the subject with light having the wavelength λ <b> 1 according to the control from the LED control unit 22. In step S <b> 3, the imaging unit 26 generates a first image by photoelectrically converting reflected light from the incident subject in accordance with control from the imaging control unit 27, and supplies the first image to the imaging control unit 27.

  In step S <b> 4, the sub light source group 23-1 is turned off according to the control from the LED control unit 22. The sub-light source group 24-1 irradiates the subject with light of wavelength λ2 in accordance with the control from the LED control unit 22. In step S <b> 5, the imaging unit 26 generates a second image by photoelectrically converting reflected light from the incident subject in accordance with the control from the imaging control unit 27, and supplies the second image to the imaging control unit 27.

  The sub-light source group 24-1 is turned off in accordance with control from the LED control unit 22. The imaging control unit 27 supplies the first and second images from the imaging unit 26 to the image processing unit 28.

  In step S6, the image processing unit 28 calculates a reflectance difference detection signal S = Y1-Y2 that is the difference between the luminance values Y1 and Y2 of the corresponding pixels of the first and second images from the imaging control unit 27. To do. Note that the luminance value Y1 is the luminance value of the pixels constituting the first image, and the luminance value Y2 is the luminance value of the pixels constituting the second image.

  In step S7, the image processing unit 28 binarizes the reflectance difference detection signal S by comparing it with a predetermined threshold value, and binarizes all regions on the binarized skin image obtained by the binarization. Is detected as a skin region. In addition, the image processing unit 28 supplies the binarized skin image to the distance calculation unit 29.

  In step S <b> 8, the image processing unit 28 detects one area as a skin area among the pixels constituting the generated binarized skin image. This completes the skin detection process.

  According to the skin detection process described above, light is emitted from the sub-light source groups 23-1 and 24-1 (or the sub-light source groups 23-2 and 24-2) determined according to the subject distance z. Since the skin area is detected using the first and second images obtained, the irradiation is performed in comparison with the case of using a plurality of LEDs having a single directivity regardless of the subject distance z. It becomes possible to reduce power consumption.

  Since the LED light output is limited, when using an LED with a single directional characteristic, the distance over which the skin area can be detected is limited according to the LED light output limit. Become.

  In this regard, in the skin detection process, an appropriate sub-light source group having directivity characteristics for irradiating light with less power consumption is used according to the subject distance z. As compared with the case of using the LED, it is possible to detect the detection target 41 existing at a farther distance.

<2. Modification>
In the present embodiment, the sub-light source groups 23-1 and 24-1 are configured by bullet-type LEDs, and the sub-light source groups 23-2 and 24-2 are configured by LEDs having a flat emission surface. However, other directional characteristics may be used by using optical components such as lenses, mirrors, and polarizing plates.

  In the present embodiment, the two sub-light source groups 23-1 and 23-2 are employed as the light source group 23. However, the light source group 23 has three or more different directivity characteristics (each different half-value half angle). You may make it employ | adopt a sublight source group. Specifically, for example, the light source group 23 includes at least one of a sub-light source group whose half-value half angle is equal to or greater than the half field angle θ / 2, or a sub-light source group whose half-value half angle is equal to or less than the half field angle θ / 2. A plurality of sub-light source groups can be employed. The same applies to the light source group 24.

  The detection device 1 according to the present embodiment can be incorporated in an arbitrary electronic device such as a television receiver. In the electronic device, a predetermined process can be executed in accordance with the detected movement of the skin area (for example, the hand of the subject).

  Next, the series of processes described above can be executed by dedicated hardware or can be executed by software. When a series of processing is executed by software, a program constituting the software can execute various functions by installing a so-called embedded computer or various programs. For example, it is installed from a recording medium in a general-purpose personal computer.

[Computer configuration example]
FIG. 8 shows a configuration example of a computer that executes the above-described series of processing by a program.

  A CPU (central processing unit) 61 executes various processes according to a program stored in a ROM (read only memory) 62 or a storage unit 68. A RAM (random access memory) 63 appropriately stores programs executed by the CPU 61 and data. The CPU 61, the ROM 62, and the RAM 63 are connected to each other by a bus 64.

  An input / output interface 65 is also connected to the CPU 61 via the bus 64. Connected to the input / output interface 65 are an input unit 66 composed of a keyboard, mouse, microphone, and the like, and an output unit 67 composed of a display, a speaker, and the like. The CPU 61 executes various processes in response to commands input from the input unit 66. Then, the CPU 61 outputs the processing result to the output unit 67.

  The storage unit 68 connected to the input / output interface 65 is composed of, for example, a hard disk, and stores programs executed by the CPU 61 and various data. The communication unit 69 communicates with an external device via a network such as the Internet or a local area network.

  A program may be acquired via the communication unit 69 and stored in the storage unit 68.

  The drive 70 connected to the input / output interface 65 drives a removable medium 71 such as a magnetic disk, an optical disk, a magneto-optical disk, or a semiconductor memory, and drives the programs and data recorded therein. Get etc. The acquired program and data are transferred to and stored in the storage unit 68 as necessary.

  As shown in FIG. 8, a recording medium for recording a program that is installed in a computer and can be executed by the computer includes a magnetic disk (including a flexible disk), an optical disk (CD-ROM (compact disc-read only). memory), DVD (including digital versatile disc)), magneto-optical disc (including MD (mini-disc)), or removable media 71, which is a package media consisting of semiconductor memory, or the program is temporary or permanent ROM 62 recorded in the memory, a hard disk constituting the storage unit 68, and the like. Recording of a program on a recording medium is performed using a wired or wireless communication medium such as a local area network, the Internet, or digital satellite broadcasting via a communication unit 69 that is an interface such as a router or a modem as necessary. Is called.

  In the present specification, the step of describing the program recorded on the recording medium is not limited to the processing performed in chronological order according to the described order, but is not necessarily performed in chronological order. It also includes processes that are executed individually.

  Further, the present embodiment is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention.

  DESCRIPTION OF SYMBOLS 1 Detection apparatus, 21 Controller, 22 LED control part, 23 Light source group, 23-1, 23-2 Sub light source group, 24 Light source group, 24-1, 24-2 Sub light source group, 25 Optical filter, 26 Imaging part, 27 imaging control unit, 28 image processing unit, 29 distance calculation unit

Claims (9)

In an image processing apparatus for detecting a skin area representing human skin from an image,
A first light emitting means having a plurality of irradiation units for irradiating the subject with light of the first wavelength with different directivity characteristics;
A second light emitting means having a plurality of irradiation units for irradiating the subject with light of a second wavelength that is longer than the first wavelength with different directivity characteristics;
Irradiation control means for controlling the light output of each of the first and second light emitting means according to the distance to the subject;
When a first image obtained by imaging the subject when the light of the first wavelength is irradiated to the subject is generated and the subject is irradiated with the light of the second wavelength Imaging generation means for generating a second image obtained by imaging the subject;
An image processing apparatus comprising: a detecting unit configured to detect the skin region based on a comparison result between a difference between the first image and the second image and a threshold value compared with the difference. The irradiation control means includes
When the distance to the subject is less than a predetermined distance, the light output of the irradiation unit with high directivity among the irradiation units of the first and second light emitting means is reduced and the irradiation unit with low directivity Control to increase the light output of
When the distance to the subject is equal to or greater than the predetermined distance, among the irradiation units of the first and second light emitting units, the light output of the irradiation unit with high directivity increases and the irradiation with low directivity The image processing apparatus according to claim 1, wherein the control is performed so that the light output of the unit is reduced. In the imaging area imaged by the imaging generation means, a detection target area for irradiating with a light output necessary for detecting the skin area is determined in advance according to the distance to the subject,
The predetermined distance is determined based on at least one of a horizontal half width of the detection target region or a vertical half width of the detection target region and a half angle of view of the imaging generation unit. The image processing apparatus according to claim 2, further comprising determination means for determining whether or not the above is true. A distance calculating means for calculating a distance to the subject;
The image processing apparatus according to claim 1, wherein the irradiation control unit controls the light output of each irradiation unit of the first and second light emitting units according to the calculated distance to the subject. The first and second light emitting units include at least one of an irradiating unit whose half-value half angle is greater than or equal to a half field angle of the imaging generation unit, or an irradiation unit whose half-value half angle is less than or equal to the half field angle of the imaging generation unit. The image processing apparatus according to claim 1. The first wavelength λ1 and the second wavelength λ2 satisfy the relationship of the following equation: 630 [nm] ≦ λ1 ≦ 1000 [nm]
900 [nm] ≦ λ2 ≦ 1100 [nm]
The image processing apparatus according to claim 1. In an image processing method of an image processing apparatus for detecting a skin area representing human skin from an image,
The image processing apparatus includes:
A first light emitting means having a plurality of irradiation units for irradiating the subject with light of the first wavelength with different directivity characteristics;
A second light emitting means having a plurality of irradiation units for irradiating the subject with light of a second wavelength that is longer than the first wavelength with different directivity characteristics;
Irradiation control means;
Imaging generation means;
Detecting means and
The first light emitting means irradiates the subject with light of the first wavelength;
The second light emitting means irradiates the subject with light of the second wavelength;
The irradiation control unit controls the light output of the irradiation unit of each of the first and second light emitting units according to the distance to the subject,
The imaging generation means generates a first image obtained by imaging the subject when the subject is irradiated with light of the first wavelength, and the light of the second wavelength is the subject. Generating a second image obtained by imaging the subject when irradiated with
An image processing method comprising: a step of detecting the skin region based on a comparison result between a difference between the first image and the second image and a threshold value compared with the difference. In an image processing apparatus for detecting a skin area representing human skin from an image,
A first light emitting means having a plurality of irradiation units for irradiating the subject with light of the first wavelength with different directivity characteristics;
A second light emitting means having a plurality of irradiation units for irradiating the subject with light of a second wavelength that is longer than the first wavelength with different directivity characteristics;
When a first image obtained by imaging the subject when the light of the first wavelength is irradiated to the subject is generated and the subject is irradiated with the light of the second wavelength A computer of an image processing apparatus including: an imaging generation unit configured to generate a second image obtained by imaging the subject;
Irradiation control means for controlling the light output of each of the first and second light emitting means according to the distance to the subject;
A program for functioning as a detection means for detecting the skin region based on a comparison result between a difference between the first image and the second image and a threshold value compared with the difference. In an electronic device that detects a skin area representing human skin from an image,
A first light emitting means having a plurality of irradiation units for irradiating the subject with light of the first wavelength with different directivity characteristics;
A second light emitting means having a plurality of irradiation units for irradiating the subject with light of a second wavelength that is longer than the first wavelength with different directivity characteristics;
Irradiation control means for controlling the light output of each of the first and second light emitting means according to the distance to the subject;
When a first image obtained by imaging the subject when the light of the first wavelength is irradiated to the subject is generated and the subject is irradiated with the light of the second wavelength Imaging generation means for generating a second image obtained by imaging the subject;
Detecting means for detecting the skin region based on a comparison result between a difference between the first image and the second image and a threshold value compared with the difference;
An electronic device comprising: execution means for executing a predetermined process based on the detected skin area.

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