JP2014155033A - Exposure setting device, light emission intensity setting device, control method, program, and storage medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exposure setting device and a light emission intensity setting device that are capable of adjusting exposure of a photographing unit or/and light emission intensity of a light emission unit so as to enhance detection accuracy of a photographed object.SOLUTION: An imaging device 1 detects a fingertip of a subject 5 from an irradiation image and a non-irradiation image photographed by a photographing unit 12 interlocked with a light emission unit 11, and outputs the detection result to an external device. Then, the imaging device 1 adjusts exposure of the photographing unit 12 and light emission intensity of the light emission unit 11 in accordance with the above-described detection result.

Description

  The present invention relates to a technique for detecting an object to be photographed based on an image.

  2. Description of the Related Art Conventionally, there has been a method of detecting a subject (object to be photographed) based on a difference image obtained by providing a camera with a light emitting unit and taking a difference between pixel values of images taken in each case where light is emitted. Are known. For example, Patent Document 1 discloses a technique for detecting a subject close to a camera based on the luminance value of the above-described difference image. Patent Document 2 discloses a technique for adjusting exposure to an appropriate exposure suitable for detecting a subject based on at least one of images taken with and without light emission or a difference image thereof. .

JP 2004-328657 A JP 2009-182461 A

  When the camera is equipped with a light-emitting unit and the object to be detected is detected based on the images taken with and without the light emission, the brightness difference based on the presence or absence of light emission at the display part of the object is large. It is preferable to become. Therefore, when adjusting the exposure of the camera, it is necessary to adjust the exposure so that the luminance difference based on the presence or absence of light emission at the display portion of the object to be photographed becomes large.

  The present invention has been made to solve the above-described problems, and is capable of adjusting the exposure of the photographing unit and / or the emission intensity of the light emitting unit so as to improve the detection accuracy of the object to be photographed. A main object is to provide a setting device and a light emission intensity setting device.

  The invention according to claim 1 is an exposure setting device that sets an exposure of an imaging unit that captures an object to be imaged, and includes an irradiation image of the object irradiated with light by a light emitting unit, and the light emitting unit. The object to be photographed is detected based on an image acquisition means for obtaining a non-irradiated image of the object to be photographed that is not irradiated with light from the photographing unit, and a luminance difference between the irradiated image and the non-irradiated image. And an exposure setting means for changing the exposure setting of the imaging unit based on the brightness of the display area in the irradiated image or / and the non-irradiated image of the object detected by the detecting means, It is characterized by providing.

  The invention according to claim 9 is a light emission intensity setting device for setting a light emission intensity of a light emitting unit that irradiates an object to be photographed by a photographing unit, wherein the object to be photographed is irradiated with light from the light emitting unit. An image acquisition means for acquiring an irradiation image of an object and a non-irradiation image of the object not irradiated with light from the light emitting unit from the imaging unit, and the exposure when the exposure of the imaging unit is appropriate And a light emission intensity setting means for setting a light emission intensity of the light emitting unit so as to increase a luminance difference between the irradiated image and the non-irradiated image on the object to be photographed.

  The invention according to claim 10 is a control method executed by an exposure setting device that sets an exposure of a photographing unit that photographs a subject, and irradiates the subject with light emitted from a light emitting unit. Based on an image acquisition step of acquiring an image and a non-irradiated image of the object not irradiated with light from the light emitting unit from the imaging unit, and a luminance difference between the irradiated image and the non-irradiated image A detection step of detecting the object to be photographed, and a setting of exposure of the photographing unit based on a luminance of a display area in the irradiated image or / and the non-irradiated image of the object to be photographed detected in the detection step. And an exposure setting step to be changed.

  According to an eleventh aspect of the present invention, there is provided a program executed by an exposure setting device for setting an exposure of a photographing unit that photographs a subject, and an irradiation image of the subject irradiated with light from a light emitting unit. And based on the brightness difference between the image acquisition means for acquiring the non-irradiated image of the object to be imaged that is not irradiated by the light emitting unit from the imaging unit, the irradiated image, and the non-irradiated image, Based on the detection means for detecting the object to be photographed and the brightness of the display area in the irradiated image and / or the non-irradiated image of the object to be photographed detected by the detecting means, the exposure setting of the photographing part is changed. The exposure setting device is caused to function as an exposure setting means.

It is a schematic block diagram of an imaging device. The image which shows an exposure determination area | region, and the brightness | luminance histogram in an exposure determination area | region are shown. A luminance histogram in the case of overexposure and a luminance histogram in the case of underexposure are shown respectively. In the case of proper exposure, the relationship between the brightness and the exposure before and after the emission intensity of the light emitting part is weakened is shown. In the case of overexposure, the relationship between luminance and exposure before and after the emission intensity of the light emitting part is weakened is shown. In the case of appropriate exposure, the relationship between the brightness and the exposure before and after increasing the light emission intensity of the light emitting part is shown. The relationship between the brightness and the exposure before and after increasing the light emission intensity of the light emitting part in the case of underexposure is shown. It is a flowchart which shows the process sequence of a present Example. It is a flowchart of an exposure determination process. It is a flowchart of light emission intensity adjustment processing. It is a figure for demonstrating the process which concerns on a modification.

  In one preferred embodiment of the present invention, there is provided an exposure setting device for setting an exposure of an imaging unit that images an object to be imaged, the irradiation image of the object being irradiated by a light emitting unit, and the light emission The object to be imaged is acquired based on a luminance difference between the image acquisition unit that acquires the non-irradiated image of the object not irradiated with light from the image capturing unit from the image capturing unit, and the irradiated image and the non-irradiated image. Detecting means for detecting the exposure, and exposure setting means for changing the exposure setting of the imaging unit based on the luminance of the display area in the irradiated image and / or the non-irradiated image of the object detected by the detecting means And comprising.

  The exposure setting apparatus includes an image acquisition unit, a detection unit, and an exposure setting unit. The image acquisition unit acquires, from the imaging unit, an irradiation image of the object irradiated with light from the light emitting unit and a non-irradiated image of the object not irradiated with light from the light emitting unit. The detection means detects the object to be photographed based on the luminance difference between the irradiated image and the non-irradiated image. The exposure setting unit changes the exposure setting of the photographing unit based on the luminance of the display area in the irradiated image and / or the non-irradiated image of the object detected by the detecting unit. By doing in this way, the exposure setting apparatus can suitably change the exposure of the photographing unit according to the detected luminance of the display area of the subject. Therefore, the exposure setting device can suitably change the exposure of the imaging unit to an exposure that makes it easy to detect the subject.

  In one aspect of the exposure setting apparatus, the detection unit generates a difference image based on a luminance difference between the irradiated image and the non-irradiated image, and detects the object to be photographed based on the difference image. According to this aspect, the exposure setting device can suitably detect the object to be photographed.

  In another aspect of the exposure setting apparatus, the exposure setting unit is configured such that the exposure of the imaging unit is an appropriate exposure based on a frequency distribution of luminance of each pixel in the display area of the object to be detected detected by the detection unit. Whether underexposed or overexposed. According to this aspect, the exposure setting device can preferably determine whether the exposure of the photographing unit is appropriate exposure, underexposure, or overexposure.

  In another aspect of the exposure setting device, the exposure setting device is configured such that the brightness of the display area in the irradiated image of the object to be imaged and the non-existence of the object to be imaged when the exposure of the imaging unit is appropriate exposure. The apparatus further includes emission intensity setting means for setting the emission intensity of the light emitting unit so as to increase the luminance difference with the luminance of the display area in the irradiated image. According to this aspect, the exposure setting device increases the luminance difference between the luminance of the display area in the irradiated image of the object to be photographed and the luminance of the display area in the non-irradiated image within a range where the luminance of the non-irradiated image does not become excessively low. In addition, the detection accuracy of the object to be photographed can be improved.

  In another aspect of the exposure setting device, the light emission intensity setting means increases the light emission intensity of the light emitting unit when the luminance of the display area in the non-irradiated image of the object to be photographed is greater than a threshold value. When the luminance of the display area in the non-irradiated image of the object to be photographed is less than or equal to the threshold value, the light emission intensity of the light emitting unit is reduced. According to this aspect, the exposure setting device causes the light emission intensity of the light emitting unit to increase the luminance difference between the luminance of the display area in the irradiation image of the object to be photographed at the appropriate exposure and the luminance of the display area in the non-irradiation image. Can be suitably changed.

  In another aspect of the exposure setting device, the light emission intensity setting means may be configured such that the brightness of the display area in the non-irradiated image of the object is the threshold value when the exposure of the object to be imaged is overexposed. Even if larger, the setting of the light emission intensity of the light emitting unit is not changed. Thereby, the exposure setting device can suppress the deviation of the exposure of the photographing unit from the appropriate exposure.

  In another aspect of the exposure setting device, the light emission intensity setting means is configured such that the brightness of the display area in the non-irradiated image of the subject is the threshold when the exposure of the subject is underexposed. Even in the following cases, the setting of the light emission intensity of the light emitting unit is not changed. Thereby, the exposure setting device can suppress the deviation of the exposure of the photographing unit from the appropriate exposure.

  In another aspect of the exposure setting apparatus, the detection unit may further approach or move away the object based on a change in the area of the display area in the irradiated image or the non-irradiated image of the object. To detect. Even in this case, the exposure setting device can suitably change the exposure of the imaging unit to an exposure suitable for detecting the approach or distance of the subject.

  In another preferred embodiment of the present invention, there is provided a light emission intensity setting device for setting a light emission intensity of a light emitting unit that irradiates an object to be imaged by an imaging unit, wherein the object to be imaged is irradiated with light by the light emitting unit. An image acquisition means for acquiring an irradiation image of an object and a non-irradiation image of the object not irradiated with light from the light emitting unit from the imaging unit, and the exposure when the exposure of the imaging unit is appropriate A light emission intensity setting unit configured to set a light emission intensity of the light emitting unit so as to increase a luminance difference between the irradiated image and the non-irradiated image on the subject. According to this aspect, the light emission intensity setting device emits light from the light emitting unit so as to increase the luminance difference between the luminance of the display area in the irradiation image of the object to be photographed with appropriate exposure and the luminance of the display area in the non-irradiation image. The intensity can be suitably changed, and the detection accuracy of the object to be photographed can be improved.

  In another preferred embodiment of the present invention, there is provided a control method executed by an exposure setting device for setting an exposure of an imaging unit that images an object to be shot, the irradiation of the object being irradiated with light by a light emitting unit. Based on an image acquisition step of acquiring an image and a non-irradiated image of the object not irradiated with light from the light emitting unit from the imaging unit, and a luminance difference between the irradiated image and the non-irradiated image A detection step of detecting the object to be photographed, and a setting of exposure of the photographing unit based on a luminance of a display area in the irradiated image or / and the non-irradiated image of the object to be photographed detected in the detection step. And an exposure setting process to be changed. By executing this control method, the exposure setting device can suitably change the exposure of the photographing unit so as to improve the detection accuracy of the object to be photographed.

  In another preferred embodiment of the present invention, there is provided a program executed by an exposure setting device that sets an exposure of a photographing unit that photographs a subject, and an irradiation image of the subject that is irradiated with light by a light emitting unit. And based on the brightness difference between the image acquisition means for acquiring the non-irradiated image of the object to be imaged that is not irradiated by the light emitting unit from the imaging unit, the irradiated image, and the non-irradiated image, Based on the detection means for detecting the object to be photographed and the brightness of the display area in the irradiated image and / or the non-irradiated image of the object to be photographed detected by the detecting means, the exposure setting of the photographing part is changed. The exposure setting device functions as an exposure setting means. By executing this program, the exposure setting device can suitably change the exposure of the photographing unit so as to improve the detection accuracy of the object to be photographed. Preferably, the program is stored in a storage medium.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

[Configuration of imaging device]
FIG. 1 is a schematic configuration diagram of an imaging apparatus 1 according to the present embodiment. The imaging device 1 detects a predetermined portion (here, a fingertip) of the subject 5 from an image photographed by the photographing unit 12 interlocked with the light emitting unit 11, and outputs the detection result to an external device. Further, the imaging apparatus 1 adjusts the exposure of the photographing unit 12 and the light emission intensity of the light emitting unit 11 according to the detection result described above. The imaging device 1 includes a light emitting unit 11, a photographing unit 12, an image holding unit 13, a difference calculation unit 14, a subject detection unit 15, an exposure determination unit 16, and an exposure / light emission intensity setting unit 17.

  The light emitting unit 11 emits light toward the subject 5 based on the control of the photographing unit 12. The light emitting unit 11 emits light with the light emission intensity instructed by the photographing unit 12. As will be described later, the light emission intensity of the light emitting unit 11 is appropriately changed from the initial value by a light emission intensity adjustment signal “S2” transmitted from the exposure / light emission intensity setting unit 17 to the photographing unit 12.

  The photographing unit 12 continuously photographs still images with the set exposure, and supplies the photographed images (captured images) to the image holding unit 13. As will be described later, the exposure of the photographing unit 12 is appropriately changed from the initial value by the exposure adjustment signal “S1” transmitted from the exposure / light emission intensity setting unit 17. Hereinafter, exposure refers to each element (parameter) for determining the brightness of the captured image, and includes elements such as sensor sensitivity in addition to shutter speed and aperture elements.

  In addition, the photographing unit 12 controls whether or not the light emitting unit 11 emits light, and the light emitting unit 11 emits an image (also referred to as “irradiated image Im1”) taken in a state where the light emitting unit 11 emits light. An image photographed in the absence (also referred to as “non-irradiated image Im2”) is generated. In the present embodiment, the photographing unit 12 alternately generates the irradiation image Im1 and the non-irradiation image Im2.

  Suitably, the light emission part 11 irradiates infrared rays, and the imaging | photography part 12 has a filter which permeate | transmits infrared rays and cuts visible light. Thereby, it is possible to eliminate the influence of the external light while suppressing the light emission of the light emitting unit 11 from affecting the visual perception of the user of the imaging device 1.

  The image holding unit 13 stores irradiation images Im1 and non-irradiation images Im2 that are alternately supplied from the imaging unit 12. At this time, the image holding unit 13 stores the irradiation image Im1 and the non-irradiation image Im2 supplied continuously as a set of images.

  The difference calculation unit 14 performs a difference process between a set of the irradiation image Im1 and the non-irradiation image Im2 stored in the image holding unit 13, thereby indicating a difference image (“difference” indicating a luminance value increased by light emission of the light emitting unit 11. Also called “Image Imd”). Specifically, in this case, the difference calculation unit 14 calculates a difference image Imd obtained by subtracting the luminance value of each pixel of the non-irradiated image Im2 from the luminance value of each pixel of the irradiated image Im1. As a result, the difference calculation unit 14 removes the ambient light that is commonly present in the irradiation image Im1 and the non-irradiation image Im2, and generates a difference image Imd indicating the luminance value increased by the light emission of the light emitting unit 11. Here, it is assumed that the photographing interval by the photographing unit 12 is sufficiently short, and the difference between the irradiated image Im1 and the non-irradiated image Im2 other than the light emission by the light emitting unit 11 can be ignored. Then, the difference calculation unit 14 supplies the calculated difference image Imd to the subject detection unit 15.

  The subject detection unit 15 detects a pixel region indicating the fingertip of the subject 5 directed toward the photographing unit 12 from the difference image Imd calculated by the difference calculation unit 14. In this case, the subject detection unit 15 detects, from the difference image Imd, a pixel region having a protrusion shape with higher brightness than the surroundings as a pixel region indicating the fingertip of the subject 5 directed toward the photographing unit 12.

  Here, two specific examples of extracting a pixel region having a protrusion shape will be described. In the first example, the subject detection unit 15 stores an image indicating the shape of the assumed fingertip of the subject 5 in advance as a template image, and the template image indicates the region of the difference image Imd having a predetermined luminance or higher. A portion matching the region is recognized as a pixel region of the fingertip portion. In this case, the pose of the hand and the position of the hand are approximately matched when the template image is generated and when the fingertip of the subject 5 is detected. In the second example, the subject detection unit 15 generates a binarized image from the difference image Imd using various threshold values, and detects a portion where the boundary line has a projection shape in each binarized image. When the subject detection unit 15 detects a protrusion-shaped portion at the same position in a predetermined number or more of the binarized images, the subject detection unit 15 recognizes the portion as a pixel region indicating the shape of the fingertip of the subject 5.

  When the subject detection unit 15 detects a pixel region indicating the fingertip of the subject 5 directed toward the photographing unit 12, information on detection results such as the position, range, and thickness of each fingertip (“detection result information Ir”). Is also supplied to an external device connected to the exposure determination unit 16 and the imaging device 1. Then, for example, the external device recognizes a user operation based on the detection result information Ir and performs a process of executing a function corresponding to the operation.

  The exposure determination unit 16 is based on the set of irradiation image Im1 and non-irradiation image Im2 held by the image holding unit 13, the difference image Imd calculated by the difference calculation unit 14, and the detection result information Ir. It is determined whether the exposure is suitable for detecting the fingertip of the subject 5 (also referred to as “appropriate exposure”), overexposed, or underexposed. Here, the appropriate exposure refers to an exposure in which the difference between the luminance values of the set of the irradiated image Im1 and the non-irradiated image Im2 is near the maximum. This determination method will be described in detail in the [Exposure determination method] section. Then, the exposure determination unit 16 supplies exposure information (also referred to as “exposure information Iex”) indicating the result of the above determination to the exposure / light emission intensity setting unit 17.

  Based on the exposure information Iex received from the exposure determination unit 16, the exposure / light emission intensity setting unit 17 receives an exposure adjustment signal S1 that instructs correction of exposure and a light emission intensity adjustment signal S2 that instructs correction of the light emission intensity of the light emitting unit 11. , To the imaging unit 12.

  In FIG. 1, an imaging device 1 is an example of an “exposure setting device” and a “light emission intensity setting device” in the present invention, and a fingertip of a subject 5 is an example of an “object to be photographed” in the present invention. The image holding unit 13 is an example of the “image acquisition unit” in the present invention, and the difference calculation unit 14 and the subject detection unit 15 are examples of the “detection unit” in the present invention. Furthermore, the exposure determination unit 16 and the exposure / light emission intensity setting unit 17 are examples of the “exposure setting unit” and the “light emission intensity setting unit” in the present invention.

[Exposure judgment processing]
First, the exposure determination process performed by the exposure determination unit 16 will be described. Schematically, the exposure determination unit 16 has a frequency distribution of each luminance value in the pixel area (also referred to as “exposure determination area T1”) of the irradiation image Im1 corresponding to the fingertip portion detected in the difference image Imd. Based on this, it is determined whether the exposure of the photographing unit 12 is proper exposure, overexposure, or underexposure. This will be specifically described.

  FIG. 2A shows a display example of an irradiation image Im1 in which an exposure determination region T1 corresponding to the exposure determination region T1 specified by the difference image Imd is clearly indicated by a dotted line. As shown in FIG. 2A, the exposure determination area T1 is set in a range including the first joint from the tip of each finger in the display area 50 of the subject 5. In FIG. 2A, for the convenience of display, the dotted line indicating the exposure determination region T1 is displayed so as not to overlap the outline of the finger.

  Then, the exposure determination unit 16 generates a histogram (also referred to as “luminance histogram”) that graphs the frequency distribution of pixel luminance values in the exposure determination region T1. FIG. 2B shows an example of a luminance histogram in the exposure determination area T1. For each luminance from the minimum value to the maximum value (saturation value), the exposure determination unit 16 aggregates the number of pixels in the exposure determination region T1 corresponding to the luminance, thereby the luminance histogram shown in FIG. Is generated. In FIG. 2B and the like, the luminance histogram is displayed as a smoothed curve for convenience.

  Then, the exposure determination unit 16 determines whether the exposure of the photographing unit 12 corresponds to either overexposure or underexposure based on the frequency distribution of the luminance values indicated by the luminance histogram of FIG. If it is determined that neither overexposure nor underexposure is detected, it is determined that the exposure is appropriate.

  Here, first, a method for determining whether or not the exposure of the photographing unit 12 is overexposed will be described. The exposure determination unit 16 calculates the number of pixels in the exposure determination region T1 where the luminance is the maximum value (also referred to as “saturated pixel number”), and the number of saturated pixels is equal to or greater than a predetermined threshold or the total number in the exposure determination region T1. When the ratio of the number of saturated pixels to the number of pixels (also referred to as “saturated pixel number ratio”) is equal to or greater than a predetermined threshold value, it is determined that the image is overexposed. The above-described threshold is set in advance based on, for example, experiments.

  FIG. 3A shows a luminance histogram in the exposure determination region T1 when the exposure determination unit 16 determines that the exposure is excessive. In FIG. 3A, there are many pixels belonging to the maximum luminance value. These pixels are portions where whiteout occurs due to light emission of the light emitting unit 11, and correspond to portions where an increase due to light emission when the light emitting unit 11 does not emit light is not reflected due to saturation. Therefore, the exposure determination unit 16 determines that the exposure is excessive when the number of saturated pixels is large.

  Next, a method for determining whether or not the exposure of the photographing unit 12 is underexposed will be described. The exposure determination unit 16 determines that the exposure is insufficient when the average value of the luminance values of the pixels in the exposure determination region T1 is equal to or less than a predetermined threshold. The above-described threshold is set in advance based on, for example, experiments. FIG. 3B shows a luminance histogram in the exposure determination region T1 when the exposure determination unit 16 determines that the exposure is insufficient. In this case, the pixels in the exposure determination area T1 generally have a low luminance value. In general, the luminance value increases as the exposure is increased. Therefore, when the photographing unit 12 is insufficiently exposed, the luminance value in the exposure determination region T1 is lowered overall, and the light emitting unit 11 emits light. And the luminance difference between the non-light-emitting state becomes small. Therefore, the exposure determination unit 16 determines that the exposure is insufficient when the luminance value in the exposure determination region T1 is low overall.

  When the exposure determination unit 16 determines that the exposure is neither excessive nor insufficient, the exposure determination unit 16 determines that the exposure of the photographing unit 12 is appropriate exposure. As described above, the exposure determination unit 16 can determine whether the exposure of the photographing unit 12 is appropriate exposure, overexposure, or underexposure based on the frequency distribution of each luminance value in the exposure determination region T1. it can.

[Exposure setting processing]
Next, an exposure setting process executed by the exposure / light emission intensity setting unit 17 will be described. Based on the exposure information Iex received from the exposure determination unit 16, the exposure / light emission intensity setting unit 17 transmits an exposure adjustment signal S1 indicating the exposure correction amount to the photographing unit 12.

  Specifically, when the exposure information Iex indicates that the exposure information Iex is overexposed, the exposure / light emission intensity setting unit 17 transmits an exposure adjustment signal S1 for decreasing the exposure by a predetermined value or a predetermined rate to the photographing unit 12. . Here, the exposure / light emission intensity setting unit 17 may set the above-described predetermined value and predetermined ratio to predetermined values, and determines the difference between the saturated pixel number or the saturated pixel number ratio and these threshold values. A large value may be set accordingly.

  Further, when the exposure information Iex indicates that the exposure information Iex is underexposed, the exposure / light emission intensity setting unit 17 transmits an exposure adjustment signal S1 for increasing the exposure by a predetermined value or a predetermined rate to the photographing unit 12. Here, the exposure / light emission intensity setting unit 17 may set the predetermined value and the predetermined rate to a predetermined value, the average value of the luminance values of the pixels in the exposure determination region T1, and the You may set to a big value according to the difference with a threshold value.

  On the other hand, when the exposure information Iex indicates that the exposure is appropriate exposure, the exposure / light emission intensity setting unit 17 does not transmit the exposure adjustment signal S1 to the photographing unit 12, or the exposure adjustment signal S1 indicating that exposure adjustment is not necessary. Transmit to the imaging unit 12.

[Light emission intensity adjustment processing]
Next, the light emission intensity adjustment process executed by the exposure / light emission intensity setting unit 17 will be described. Schematically, the exposure / light emission intensity setting unit 17 is within the display area of the subject 5 in the irradiation image Im1 and the non-irradiation image Im2 in the case of proper exposure in a range where the luminance value of the non-irradiation image Im2 does not become zero. The light emission intensity of the light emitting unit 11 is adjusted so that the luminance difference between the light emitting unit 11 and the light emitting unit 11 increases. Thereby, the detection accuracy of the subject detection unit 15 is improved.

  First, the exposure / light emission intensity setting unit 17 recognizes the subject 5 or the display region of the fingertip of the subject 5 (also referred to as “subject region T2”) in the non-irradiated image Im2. For example, the exposure / light emission intensity setting unit 17 is based on the detection result information Ir supplied from the exposure determination unit 16, and the non-irradiated image corresponding to the position and range of the subject 5 or the finger of the subject 5 detected by the subject detection unit 15. The pixels in Im2 are recognized as the subject area T2.

  Then, the exposure / light emission intensity setting unit 17 determines that the luminance value of the subject region T2 of the non-irradiated image Im2 is 0 or less than a threshold value (also referred to as “threshold value TH0”), or the subject region of Im2. The process is performed separately when the luminance value of T2 is larger than the threshold value TH0. This will be described in detail below by dividing cases.

  In the following description, “the luminance value of the subject region T2” refers to a representative value such as an average value, a maximum value, or a median value of the luminance values of each pixel in the subject region T2. Further, the difference in luminance value in the subject area T2 between the irradiated image Im1 and the non-irradiated image Im2 is also referred to as “luminance difference Dlit”.

(1) When the luminance value of the subject region T2 of the non-irradiated image Im2 is equal to or less than the threshold value TH0 In this case, the exposure / light emission intensity setting unit 17 does not maximize exposure and emits light when the exposure is appropriate or overexposed. Unless the intensity is the lowest, the light emission intensity of the light emitting unit 11 is weakened. Thereby, the exposure / light emission intensity setting unit 17 increases the luminance value of the subject region T2 of the non-irradiated image Im2 in the case of proper exposure to be larger than zero. This will be described with reference to FIGS.

(1-1) Case of Appropriate Exposure FIG. 4A shows the exposure of the photographing unit 12 and the irradiated image Im1 when the luminance value of the subject region T2 of the non-irradiated image Im2 is equal to or less than the threshold value THO. The relationship with the luminance value of the subject region T2 of the non-irradiated image Im2 is shown. Hereinafter, the graph “G1” indicates the luminance value of the subject region T2 of the irradiated image Im1, and the graph “G2” indicates the luminance value of the subject region T2 of the non-irradiated image Im2.

  In FIG. 4A, the exposure current value “Exp”, which is the exposure of the imaging unit 12 at the time of capturing the irradiated image Im1 and the non-irradiated image Im2, does not reach the saturation value of the subject area T2 of the irradiated image Im1. Appropriate exposure is set so that the luminance difference Dlit is maximized in the range. The current exposure value Exp is significantly lower than the exposure at which the luminance value of the subject region T2 of the non-irradiated image Im2 is 0 or more. In this case, the non-irradiated image Im2 has many black areas with zero brightness, and the subject detection unit 15 cannot appropriately detect the fingertip portion of the subject 5.

  In consideration of the above, in this case, the exposure / light emission intensity setting unit 17 increases the appropriate exposure by lowering the light emission intensity of the light emitting unit 11, and the luminance of the subject region T2 of the non-irradiated image Im2 in the case of the proper exposure. Increase the value. FIG. 4B shows graphs G1 and G2 when the emission intensity of the light emitting unit 11 is increased in the example of FIG. As shown in FIG. 4B, the luminance value of the subject region T2 of the irradiation image Im1 decreases due to the decrease in the emission intensity of the light emitting unit 11. That is, in this case, the rate of increase in the luminance value during light emission indicated by the graph G1 with respect to the increase in exposure is reduced. As a result, the proper exposure in the case of FIG. 4B transitions from the current exposure value Exp to the exposure value “Ex1” (see arrow 40), and the luminance value of the subject region T2 in this case becomes greater than zero. In this way, the exposure / light emission intensity setting unit 17 can increase the luminance value of the subject region T2 of the non-irradiated image Im2 in the case of proper exposure. Note that the current exposure value Exp approaches the exposure value Ex1 that is a proper exposure by the exposure determination process and the exposure setting process that are executed again after the emission intensity is reduced.

(1-2) Overexposure FIG. 5A shows the exposure of the photographing unit 12 and the irradiated image Im1 when the luminance value of the subject region T2 of the non-irradiated image Im2 is equal to or lower than the threshold value THO. And the relationship with the luminance value of the subject region T2 of the non-irradiated image Im2.

  In FIG. 5A, the luminance value of the subject area T2 of the irradiation image Im1 has reached a saturation value, and the current exposure value Exp is excessive with respect to the exposure value “Ex2” that is a proper exposure. In this case, in the subject region T2 of the irradiation image Im1, many whiteout states occur, and thus the subject detection unit 15 cannot appropriately detect the fingertip portion of the subject 5. On the other hand, when the current exposure value Exp is lowered to be close to the exposure value Ex2 that is the proper exposure, the luminance value of the subject area T2 of the non-irradiated image Im2 further decreases, and the area becomes a completely black area.

  Considering the above, in this case, the exposure / light emission intensity setting unit 17 increases the appropriate exposure by lowering the light emission intensity of the light emitting unit 11 and brings the appropriate exposure closer to the current exposure value Exp. FIG. 5B shows graphs G1 and G2 when the light emission intensity of the light emitting unit 11 is lowered in the example of FIG. In the example of FIG. 5B, the appropriate exposure increases to the vicinity of the current exposure value Exp because the light emission intensity of the light emitting unit 11 has decreased. Thus, in this case, the exposure / light emission intensity setting unit 17 can bring the appropriate exposure closer to the current exposure value Exp.

  In the example of FIG. 5B, the luminance value of the subject area T2 of the non-irradiated image Im2 continues to be equal to or lower than the threshold value TH0. Accordingly, in this case, the imaging apparatus 1 executes the processing described in the section “(1-1) In the case of proper exposure” in the next light emission intensity adjustment processing. Thereby, the imaging device 1 lowers the light emission intensity of the light emitting unit 11 again to make the luminance value of the subject region T2 of the non-irradiated image Im2 larger than 0 in the case of proper exposure.

(2) When the luminance value of the subject region T2 of the non-irradiated image Im2 is larger than the threshold value TH0 In this case, the exposure / light emission intensity setting unit 17 does not have minimum exposure and emits light when the exposure is appropriate or underexposed. Unless the intensity is maximum, the light emission intensity of the light emitting unit 11 is increased. Thereby, the exposure / light emission intensity setting unit 17 increases the luminance difference Dlit between the irradiated image Im1 and the non-irradiated image Im2 in the case of proper exposure. This will be described with reference to FIGS.

(2-1) Case of Appropriate Exposure FIG. 6A shows the exposure of the photographing unit 12 and the irradiated image Im1 when the luminance value of the subject region T2 of the non-irradiated image Im2 is larger than the threshold value THO and the exposure is appropriate. And the relationship with the luminance value of the subject region T2 of the non-irradiated image Im2. In FIG. 6A, the current exposure value Exp is set to an appropriate exposure that maximizes the luminance difference Dlit (see arrow 45) in a range where the luminance value of the subject region T2 of the irradiation image Im1 does not become a saturation value.

  FIG. 6B shows graphs G1 and G2 when the emission intensity of the light emitting unit 11 is increased in the example of FIG. In this case, the rate of increase in the luminance value during light emission indicated by the graph G1 with respect to the increase in exposure increases. As a result, the appropriate exposure in the case of FIG. 6B transitions from the current exposure value Exp to the exposure value “Ex3”. In this case, the luminance difference Dlit (see arrow 46) at the exposure value Ex3, which is a proper exposure, increases as compared with the luminance difference Dlit (see arrow 45) in the case of FIG. Thus, when the luminance value of the subject region T2 of the non-irradiated image Im2 is larger than the threshold value THO and the exposure is appropriate, the exposure / emission intensity setting unit 17 is preferable by increasing the emission intensity of the light emitting unit 11. In addition, the difference in luminance value between the irradiated image Im1 and the non-irradiated image Im2 at appropriate exposure can be increased. In this case, the current exposure value Exp approaches the exposure value Ex3, which is a proper exposure, by the exposure determination process and the exposure setting process that are executed again after increasing the light emission intensity.

(2-2) Underexposure FIG. 7A shows the exposure of the photographing unit 12 and the irradiated image Im1 when the luminance value of the subject region T2 of the non-irradiated image Im2 is larger than the threshold THO and underexposed. And the relationship with the luminance value of the subject region T2 of the non-irradiated image Im2. In this case, the luminance difference Dlit (see arrow 47) is smaller than the luminance difference Dlit (see arrow 48) in the case of the exposure value “Ex4” which is appropriate exposure.

  FIG. 7B shows graphs G1 and G2 when the emission intensity of the light emitting unit 11 is increased in the example of FIG. In this case, as the graph G1 shows, the rate of increase of the luminance value during light emission with respect to exposure increases. Therefore, in this case, the proper exposure is reduced, and the proper exposure is approximated to the current exposure value Exp. In addition, as the slope of the graph G1 increases, the luminance difference Dlit (see arrow 49) at the current exposure value Exp close to the appropriate exposure in FIG. 7B is obtained at the appropriate exposure in the case of FIG. Larger than the luminance difference Dlit (see arrow 48). As described above, the exposure / light emission intensity setting unit 17 can approximate the current exposure value Exp to the appropriate exposure and increase the luminance difference Dlit at the appropriate exposure.

[Processing flow]
Next, a processing procedure executed by the imaging apparatus 1 will be described with reference to FIGS.

(1) Processing Overview FIG. 8 is a flowchart illustrating an overview of processing executed by the imaging apparatus 1. The imaging device 1 repeatedly executes the process shown in FIG. 8 according to a predetermined cycle.

  First, the exposure / light emission intensity setting unit 17 of the imaging device 1 sets the initial value of the exposure of the photographing unit 12 and the light emission intensity of the light emitting unit 11 (step S101). For example, the exposure / light emission intensity setting unit 17 considers the reflection intensity assumed when the fingertip portion of the subject 5 approaches a suitable distance from the light emission unit 11 and the imaging unit 12 and the intensity of ambient light at that time. The predetermined exposure and emission intensity are set as these initial values.

  Next, the imaging unit 12 generates the irradiation image Im1 by causing the light emitting unit 11 to emit light (step S102). Next, the imaging unit 12 generates a non-irradiated image Im2 in a state where the light emitting unit 11 does not emit light (step S103). Then, the imaging unit 12 causes the image holding unit 13 to store the irradiation image Im1 and the non-irradiation image Im2. Next, the difference calculation unit 14 generates a difference image Imd based on the irradiation image Im1 and the non-irradiation image Im2 stored in the image holding unit 13 (step S104).

  Next, the subject detection unit 15 detects the fingertip portion of the subject 5 based on the difference image Imd (step S105). Then, the subject detection unit 15 outputs detection result information Ir indicating the detected subject 5 and the position and range of the fingertip portion of the subject 5 to the external device and supplies the detection result information Ir to the exposure determination unit 16. .

  Next, the exposure determination unit 16 performs an exposure determination process based on the detection result information Ir, the irradiation image Im1, and the like (step S106). The exposure determination process will be described in detail with reference to the flowchart of FIG. Then, the exposure determination unit 16 supplies exposure information Iex indicating the exposure state of the photographing unit 12 to the exposure / light emission intensity setting unit 17. Then, the exposure / light emission intensity setting unit 17 adjusts the exposure based on the exposure information Iex (step S107). Specifically, when the exposure information Iex indicates underexposure, the exposure / light emission intensity setting unit 17 transmits an exposure adjustment signal S1 for increasing the exposure by a predetermined value or a predetermined rate to the photographing unit 12. To do. Further, when the exposure information Iex indicates that the exposure information Iex is overexposed, the exposure / light emission intensity setting unit 17 transmits an exposure adjustment signal S1 indicating that the exposure is reduced by a predetermined value or a predetermined rate to the photographing unit 12.

  Next, the exposure / light emission intensity setting unit 17 performs a light emission intensity adjustment process based on the exposure information Iex and the non-irradiated image Im2 (step S108). The emission intensity adjustment process will be described in detail with reference to the flowchart of FIG. Then, the imaging apparatus 1 determines whether or not to end the process (step S109). Then, for example, when a predetermined time for executing the process has elapsed or an instruction signal indicating that the process should be terminated is received, the imaging apparatus 1 determines that the process should be terminated (step S109; Yes). The process of the flowchart ends. In another example, the imaging apparatus 1 determines that the exposure of the photographing unit 12 is appropriate exposure in step S106, and ends the process of the flowchart when the light emission intensity is not changed in step S108. On the other hand, when the imaging apparatus 1 determines that the process should not be terminated (step S109; No), the process returns to step S102.

(2) Exposure Determination Processing FIG. 9 is a flowchart showing a processing procedure executed by the exposure determination unit 16 in step S106 of FIG.

  First, the exposure determination part 16 determines the exposure determination area | region T1 in the irradiation image Im1 (step S201). For example, based on the detection result information Ir received from the subject detection unit 15, the exposure determination unit 16 determines an area in the irradiation image Im1 corresponding to the display area of the fingertip of the subject detected by the subject detection unit 15 as the exposure determination region T1. Recognize as

  Next, the exposure determination unit 16 generates a luminance histogram for each pixel in the exposure determination region T1 in the irradiation image Im1 (step S202). Then, the exposure determination unit 16 determines whether or not the number of saturated pixels is greater than or equal to a predetermined threshold based on the luminance histogram (step S203). Note that, in step S203, the exposure determination unit 16 may determine whether the saturated pixel number ratio is equal to or greater than a predetermined threshold instead of the saturated pixel number. If the number of saturated pixels is equal to or greater than the predetermined threshold (step S203; Yes), the exposure determination unit 16 determines that the exposure of the photographing unit 12 is excessive (step S204).

  On the other hand, when the number of saturated pixels is less than the predetermined threshold (step S203; No), the exposure determination unit 16 determines whether or not the average luminance value of the exposure determination region T1 in the irradiation image Im1 is equal to or less than the predetermined threshold. Determination is made (step S205). And when the average of the luminance value of the exposure determination area | region T1 in the irradiation image Im1 is below a predetermined threshold value (step S205; Yes), the exposure determination part 16 determines with the exposure of the imaging | photography part 12 being insufficient. (Step S206). On the other hand, when the average luminance value of the exposure determination area T1 in the irradiation image Im1 is larger than a predetermined threshold (step S205; No), the exposure determination unit 16 determines that the exposure of the photographing unit 12 is appropriate (step). S207).

(3) Luminous Intensity Adjustment Processing FIG. 10 is a flowchart showing a processing procedure executed by the exposure / light emission intensity setting unit 17 in step S108 of FIG.

  First, the exposure / light emission intensity setting unit 17 determines whether or not the luminance value of the subject region T2 of the non-irradiated image Im2 is equal to or less than the threshold value THO (step S301). For example, the exposure / light emission intensity setting unit 17 determines whether a representative value such as an average value of luminance values of pixels in the subject region T2 of the non-irradiated image Im2 is equal to or less than the threshold value THO.

  When the luminance value of the subject region T2 of the non-irradiated image Im2 is equal to or less than the threshold value THO (step S301; Yes), the exposure / light emission intensity setting unit 17 determines that the exposure information Iex received from the exposure determination unit 16 is appropriate exposure or It is determined whether or not any of over-exposure has been indicated (step S302). Then, when it corresponds to appropriate exposure or overexposure (step S302; Yes), the exposure / light emission intensity setting unit 17 executes the process of step S303. On the other hand, when it does not correspond to appropriate exposure and overexposure (step S302; No), that is, when underexposure, the exposure / light emission intensity setting unit 17 ends the process of the flowchart without reducing the light emission intensity of the light emitting unit 11. . That is, in this case, the exposure / light emission intensity setting unit 17 determines that the degree of exposure deficiency further increases when the light emission intensity of the light emitting unit 11 is lowered, and does not adjust the light emission intensity of the light emitting unit 11.

  Next, in step S303, the exposure / light emission intensity setting unit 17 determines whether or not the current exposure of the photographing unit 12 is the highest and the light emission intensity is not the lowest (step S303). If the current exposure of the photographing unit 12 is not the highest and the emission intensity is not the lowest (step S303; Yes), the emission intensity adjustment signal S2 for decreasing the emission intensity of the light emitting unit 11 by a predetermined value or a predetermined rate. Is transmitted to the imaging unit 12 (step S304). Thereby, the exposure / light emission intensity setting unit 17 can make the luminance value of the subject region T2 of the non-irradiated image Im2 larger than 0 in the case of proper exposure. On the other hand, when the exposure of the current photographing unit 12 is the highest or the light emission intensity of the light emitting unit 11 is the lowest (step S303; No), the imaging device 1 ends the process of the flowchart. When the light emission intensity of the light emitting unit 11 is the lowest, the exposure / light emission intensity setting unit 17 determines that the light emission intensity cannot be reduced in step S304. When the exposure is the highest, the exposure / light emission intensity setting unit 17 determines that the exposure of the photographing unit 12 cannot be adjusted to the appropriate exposure that increases due to the decrease in the light emission intensity in step S304. .

  On the other hand, when the luminance value of the subject region T2 of the non-irradiated image Im2 is larger than the threshold value THO (step S301; No), the exposure / light emission intensity setting unit 17 determines that the exposure information Iex received from the exposure determination unit 16 is appropriate exposure or exposure. It is determined whether any of the excess has been indicated (step S305). And when it corresponds to appropriate exposure or underexposure (step S305; Yes), a process is advanced to step S306. On the other hand, when it does not correspond to appropriate exposure and underexposure (step S305; No), that is, when it is overexposed, the exposure / light emission intensity setting unit 17 ends the process of the flowchart. That is, in this case, when the light emission intensity of the light emitting unit 11 is increased, the exposure / light emission intensity setting unit 17 determines that the exposure of the photographing unit 12 further deviates from the appropriate exposure, and does not adjust the light emission intensity of the light emitting unit 11.

  Next, in step S306, the exposure / light emission intensity setting unit 17 determines whether or not the current exposure of the photographing unit 12 is the lowest and the light emission intensity is not the highest (step S306). If the current exposure of the photographing unit 12 is not the lowest and the emission intensity is not the highest (step S306; Yes), the emission intensity adjustment signal S2 for increasing the emission intensity of the light emitting unit 11 by a predetermined value or a predetermined rate. Is transmitted to the imaging unit 12 (step S307). Thereby, the exposure / light emission intensity setting unit 17 can suitably widen the luminance difference Dlit with appropriate exposure. On the other hand, when the exposure of the current photographing unit 12 is the lowest or the light emission intensity of the light emitting unit 11 is the highest (step S306; No), the imaging device 1 ends the process of the flowchart. When the light emission intensity of the light emitting unit 11 is the highest, the exposure / light emission intensity setting unit 17 determines that the light emission intensity cannot be increased in step S307. When the exposure is the lowest, the exposure / light emission intensity setting unit 17 determines that the exposure cannot be adjusted to an appropriate exposure that decreases due to the increase of the light emission intensity in step S307.

<Modification>
Hereinafter, modified examples suitable for the above-described embodiments will be described. The following modifications may be applied in any combination to the above-described embodiments.

(Modification 1)
In addition to the processing of the embodiment, the subject detection unit 15 may perform processing for recognizing the orientation of the finger with respect to the photographing unit 12 based on the luminance difference between the tip portion and base portion of the subject 5.

  FIG. 11A shows a display example of the irradiation image Im1 on which the subject 5 is displayed. First, the subject detection unit 15 recognizes the tip portion and the base portion of each finger of the subject 5 by performing known image processing on the difference image Imd generated from the irradiation image Im1. A region 55A in FIG. 11A shows a region in the irradiation image Im1 of the tip portion of each finger recognized based on the difference image Imd, and a region 55B in FIG. 11A represents each region recognized based on the difference image Imd. The area | region in the irradiation image Im1 of the base part of a finger | toe is shown. Then, the subject detection unit 15 calculates the luminance difference between the region 55A and the region 55B for each finger, and refers to a predetermined map or expression so that the fingertip and the base of each finger relative to the photographing unit 12 are calculated based on the luminance difference. Recognizable distance relations. The above-described map and the like are created in advance based on, for example, experiments and stored in the memory of the imaging apparatus 1. Thereby, the subject detection unit 15 can preferably recognize the orientation of the finger with respect to the imaging unit 12. Then, the subject detection unit 15 includes information indicating the orientation of the finger with respect to the photographing unit 12 in the detection result information Ir and transmits the information to an external device or the like.

(Modification 2)
In addition to the processing of the embodiment, the subject detection unit 15 may perform processing for recognizing the approach or distance of the subject 5 from the photographing unit 12.

  In this case, first, the subject detection unit 15 calculates the area (that is, the number of pixels) of the region indicating the entire subject 5 in the difference image Imd. Then, the subject detection unit 15 determines whether or not the subject 5 has approached the photographing unit 12 based on the calculated time change of the area. For example, when the area of the detected subject 5 increases, the subject detection unit 15 determines that the subject 5 has approached the photographing unit 12 by a distance proportional to the increased area. Similarly, when the area of the detected subject 5 is reduced, the subject detection unit 15 determines that the subject 5 has moved away from the photographing unit 12 by a distance proportional to the reduced area. The subject detection unit 15 stores in advance a proportional constant indicating the above-described proportional relationship, and calculates the distance that the subject 5 has approached or moved away from the photographing unit 12 based on the proportional constant. Then, the subject detection unit 15 includes information such as the distance of the subject 5 that is close to or far away from the photographing unit 12 in the detection result information Ir and transmits the information to an external device or the like.

(Modification 3)
In the description of FIG. 2A, the exposure determination unit 16 sets the exposure determination region T1 as the display region of the fingertip portion of the subject 5 detected by the subject detection unit 15. Instead, the exposure determination unit 16 may set the display area of the entire finger of the subject 5 as the exposure determination area T1.

  FIG. 11B shows a display example of the irradiation image Im1 in which the exposure determination region T1 in the present modification is clearly indicated by a dotted line. As shown in FIG. 11B, in this example, the exposure determination unit 16 sets the exposure determination region T1 to a region including from the tip of each finger to the root portion.

  Preferably, when the orientation of each finger is detected according to the first modification, the exposure determination unit 16 sets an exposure determination region T1 as shown in FIG. Thereby, the exposure can be adjusted for the luminance of the region including the tip to the base of each finger, and the detection accuracy by the subject detection unit 15 can be improved.

  Further, in this case, preferably, the exposure determination unit 16 may determine the criterion of whether or not the exposure is appropriate based on the degree of spread of the luminance value (that is, the degree of uniform distribution) in the luminance histogram. In this case, the exposure determination unit 16 calculates an index indicating the spread of the brightness value based on the brightness histogram, and determines that the exposure is appropriate when the index is within a predetermined range. The exposure / light emission intensity setting unit 17 changes the exposure of the photographing unit 12 when the exposure determination unit 16 determines that the exposure is not appropriate.

(Modification 4)
The difference calculation unit 14 generates a difference image Imd based on the irradiation image Im1 and the non-irradiation image Im2 generated alternately by the imaging unit 12. However, the configuration to which the present invention is applicable is not limited to this.

  Instead, the imaging apparatus 1 includes an infrared irradiation unit that irradiates infrared rays, and generates the difference image Imd based on the captured image generated by the imaging unit 12 in a state where the subject 5 is irradiated with infrared rays. Good. In this case, the photographing unit 12 is also referred to as an image sensor provided with a filter that cuts infrared rays (also referred to as “image sensor with filter”) and an image sensor not provided with the filter (also referred to as “image sensor without filter”). )), And the light that has passed through the lens is split and incident on each image sensor. The imaging unit 12 generates an image that does not include the irradiated infrared ray (that is, the non-irradiated image Im2) in the image sensor with a filter, and the image that includes the irradiated infrared ray (that is, the irradiation) in the image sensor without a filter. An image Im1) is generated. Therefore, also with this configuration, the difference calculation unit 14 can suitably generate the difference image Imd based on the two images generated simultaneously by the imaging unit 12. The photographing unit 12 may include an image sensor that reacts to visible light instead of the above-described image sensor with a filter, and may include an image sensor that reacts to infrared light instead of the above-described image sensor without a filter.

(Modification 5)
The exposure / light emission intensity setting unit 17 performs both the adjustment of the light emission intensity of the light emitting unit 11 and the exposure adjustment of the photographing unit 12. However, the configuration to which the present invention is applicable is not limited to this. Instead of this, the exposure / light emission intensity setting unit 17 may execute either adjustment of the light emission intensity of the light emitting unit 11 or exposure adjustment of the photographing unit 12. Also by this, the detection accuracy in the subject detection unit 15 can be preferably improved.

(Modification 6)
The exposure determination unit 16 determines the exposure of the photographing unit 12 based on the frequency distribution of the luminance of the exposure determination region T1 in the irradiation image Im1. Instead, the exposure determination unit 16 sets the non-irradiated image Im2 or the difference image Imd region corresponding to the fingertip region of the subject 5 as the exposure determination region T1, and uses the luminance frequency distribution in the exposure determination region T1. Based on this, the exposure of the photographing unit 12 may be determined. When performing the exposure determination from the non-irradiated image Im2, if the luminance value of the non-irradiated image Im2 (subject region T2) is high, it is a situation where the ambient light is strong, and in order to reduce the influence of the environmental light, the exposure is reduced, In addition, the emission intensity can be increased. When the exposure determination is performed from the difference image Imd, the ambient light is strong if the value of the difference image Imd (subject area T2) is low. In other words, it is in a state where the self-emission is weak with respect to the ambient light, and in order to reduce the influence of the ambient light, that is, to compensate for the weak self-emission, the exposure can be reduced and the emission intensity can be increased. .

DESCRIPTION OF SYMBOLS 1 Imaging device 5 Subject 11 Light emission part 12 Imaging part 13 Image holding part 14 Difference calculation part 15 Subject detection part 16 Exposure determination part 17 Exposure and light emission intensity setting part

Claims (12)

An exposure setting device for setting an exposure of a photographing unit for photographing an object,
An image acquisition means for acquiring, from the imaging unit, an irradiation image of the object irradiated with light by the light emitting unit and a non-irradiated image of the object not irradiated with light by the light emitting unit;
Detecting means for detecting the object based on a luminance difference between the irradiated image and the non-irradiated image;
Exposure setting means for changing the exposure setting of the photographing unit based on the luminance of the display area in the irradiated image or / and the non-irradiated image of the object detected by the detecting means;
An exposure setting device comprising:   The said detection means produces | generates a difference image by the brightness | luminance difference of the said irradiation image and the said non-irradiation image, The said to-be-photographed object is detected based on the said difference image, It is characterized by the above-mentioned. Exposure setting device.   The exposure setting means is either an appropriate exposure, an underexposure, or an overexposure based on a luminance frequency distribution of each pixel in the display area of the object to be detected detected by the detection means. The exposure setting device according to claim 1, wherein the exposure setting device determines whether or not the exposure has occurred.   Increasing the luminance difference between the luminance of the display area in the irradiated image of the subject and the luminance of the display area in the non-irradiated image of the subject when the exposure of the photographing unit is appropriate exposure The exposure setting device according to any one of claims 1 to 3, further comprising a light emission intensity setting unit that sets a light emission intensity of the light emitting unit. The light emission intensity setting means increases the light emission intensity of the light emitting unit when the luminance of the display area in the non-irradiated image of the object to be photographed is greater than a threshold value,
The exposure setting apparatus according to claim 4, wherein when the luminance of the display area of the non-irradiated image of the object to be photographed is equal to or less than the threshold value, the light emission intensity of the light emitting unit is reduced.   The light emission intensity setting means, when the exposure of the object to be imaged is overexposed, even if the luminance of the display area in the non-irradiated image of the object to be imaged is greater than the threshold value. 4. The exposure setting device according to claim 3, wherein the setting of the light emission intensity is not changed.   The light emission intensity setting means, when the exposure of the object to be imaged is underexposed, even if the luminance of the display area in the non-irradiated image of the object to be imaged is not more than the threshold value. The exposure setting device according to claim 5 or 6, wherein the setting of the light emission intensity is not changed.   The detection means further detects an approach or a distance of the subject based on a change in an area of a display region in the irradiated image or the non-irradiated image of the subject. The exposure setting device according to claim 7. A light emission intensity setting device for setting a light emission intensity of a light emitting unit that irradiates an object to be photographed by a photographing unit,
An image acquisition means for acquiring, from the imaging unit, an irradiation image of the object irradiated with light by the light emitting unit and a non-irradiated image of the object not irradiated with light by the light emitting unit;
A light emission intensity setting means for setting a light emission intensity of the light emitting unit so as to increase a luminance difference between the irradiated image and the non-irradiated image on the subject when the exposure of the photographing unit is appropriate;
A light emission intensity setting device comprising: A control method executed by an exposure setting device that sets the exposure of a photographing unit that photographs a subject,
An image acquisition step of acquiring, from the imaging unit, an irradiation image of the object irradiated with light by the light emitting unit and a non-irradiated image of the object not irradiated with light by the light emitting unit;
A detection step of detecting the object to be photographed based on a luminance difference between the irradiated image and the non-irradiated image;
An exposure setting step of changing the exposure setting of the imaging unit based on the brightness of the display area in the irradiated image or / and the non-irradiated image of the object detected by the detection step;
A control method characterized by comprising: A program executed by an exposure setting device for setting an exposure of a photographing unit for photographing an object,
An image acquisition means for acquiring, from the imaging unit, an irradiation image of the object irradiated with light by the light emitting unit and a non-irradiated image of the object not irradiated with light by the light emitting unit;
Detecting means for detecting the object based on a luminance difference between the irradiated image and the non-irradiated image;
The exposure setting device functions as an exposure setting unit that changes the exposure setting of the imaging unit based on the luminance of the display area of the irradiated image or / and the non-irradiated image of the object detected by the detection unit. A program characterized by letting   A storage medium storing the program according to claim 11.

Images