JP2005184470A - Portable telephone set with camera - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a portable telephone set with a camera of an automatic auxiliary light emission type for determining the propriety of auxiliary light by adapting to the luminance condition of a main subject even under a backlight/straight light condition without requiring an exclusive sensor for photometry, and automatically changing-over the operation of an auxiliary light emitting device, so as to obtain an excellent image. <P>SOLUTION: The telephone set includes a control means for extracting pixels arranged at the center of an image sensor with a plurality of pixels planarly arranged therein, determining the propriety of the auxiliary light based on luminance information of the image acquired by the extracted pixels, and controlling the operation of the auxiliary light emitting device. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a camera-equipped mobile phone equipped with an auxiliary light emitting device.

  A mobile phone with a camera function (hereinafter referred to as a camera-equipped mobile phone) displays an image acquired by the camera function on the display means of the main body in addition to the original communication call function, or wirelessly transmits the image information. It can be transmitted to other devices via a communication transmission system, and has received strong support for ease of use.

  In order to avoid underexposure when shooting low-brightness subjects such as indoor phones, nighttime, or backlit scenes, camera-equipped mobile phones are often used for shooting. Auxiliary light emitting means for irradiating a subject with light necessary for photographing has been installed. As the auxiliary light emitting means to be mounted, there are many examples in which a well-known electronic flash device generally used as a strobe is used for a normal camera.

  When shooting with a camera-equipped mobile phone equipped with an auxiliary light emitting device, no auxiliary light is required for normal scene shooting such as outdoors during the day. Thus, the auxiliary light emitting device is used when the user determines that the subject is dark or when the photometric means mounted on the camera function unit issues an underexposure warning. Usually, in using the auxiliary light emitting device, the user uses the auxiliary light emitting device after performing an operation of turning on the switch for functioning the auxiliary light emitting device called, for example, a flash switch, so that the operation is complicated. Shooting timing may be missed.

For this reason, there has been proposed a so-called automatic light-emitting camera-equipped mobile phone that automatically operates the auxiliary light-emitting device in accordance with the brightness of the subject without requiring the photographer to operate the flash switch (Patent Document). 1). This automatic light emission method is composed of a means for detecting subject brightness and a control means for determining whether to emit light, and automatically emits auxiliary light when the subject brightness is low. There is no need to determine whether light is necessary, and handling is simple. However, as a means for detecting the subject brightness, a dedicated sensor is generally required, so the structure becomes complicated. Depending on the setting of the subject area that the sensor measures, the influence of brightness other than the intended main subject In some cases, the problem is that the auxiliary light may not be emitted. For example, even when the main subject is in the backlight state and the shooting conditions require auxiliary light, the auxiliary light does not emit due to the influence of the brightness of the background, objects around the main subject, or the light source that causes backlighting. As a result, the resulting image often fails to satisfy the user.
JP 2001-320622 A

  The present invention has been made in view of such circumstances, and does not require a dedicated sensor for photometry, and determines whether or not to emit auxiliary light in accordance with the luminance condition of the main subject even in backlight or direct light conditions. It is an object of the present invention to provide a camera-equipped mobile phone including an auxiliary light emitting device that can automatically switch to obtain a good image.

  The present invention is achieved by the following configurations described in the claims.

  In other words, the invention described in claim 1 is that an image sensor having a plurality of pixels arranged in a plane, a camera having an auxiliary light emitting device, and a pixel arranged in a central portion of the image sensor are acquired. A camera-equipped mobile phone comprising control means for controlling the operation of the auxiliary light emitting device based on luminance information of the image to be performed.

  The invention according to claim 2 is as follows: “The central portion has a lateral limit determined by a distance of 20 to 30% of a lateral dimension of the image sensor screen in a horizontal direction from a vertical center line position of the image sensor screen; 2. The camera-equipped mobile phone according to claim 1, wherein the mobile phone with a camera is a range portion surrounded by a vertical limit defined by a distance of 20 to 30% of a vertical dimension of the image sensor screen in a vertical direction from a horizontal center line position. Type telephone. "

  According to the present invention, in a mobile phone with a camera function equipped with an auxiliary light device, the operation of the auxiliary light emitting device is controlled by determining the necessity of auxiliary light based on the luminance information of the image acquired by the pixel at the center of the image sensor. Because it has a control means that does not require a dedicated sensor for photometry, it operates by determining the necessity of auxiliary light according to the luminance condition of only the subject located at the center of the shooting screen. A camera with an auxiliary light automatic light-emitting camera that enables shooting that adapts to the luminance conditions of the main subject, even under various shooting conditions such as front light and backlight, without being affected by the subject located at the periphery of the screen Type telephones can be provided.

  Hereinafter, an example of an embodiment of a camera-equipped mobile phone according to the present invention will be described with reference to the drawings.

  In FIG. 1, FIG. 1 (a) is a front view of a camera-equipped mobile phone to which the present invention is applied, and FIG. 1 (b) is a rear view thereof. As shown in FIG. 1, the camera-equipped mobile phone first body portion 110 and the second body portion 120, and the hinge portion 130 that connects the first body portion 110 and the second body portion 120 in a foldable manner. It is composed of

  The first main body 110 is a vertically long flat housing, and as shown in FIG. 1A, an operation key unit 111 is provided on the front side thereof. The operation key unit 111 includes various keys such as a dial key, a mode switching key, a power key, a call key, and a function key, and a photographing button. When using the camera function, the camera mode is selected by the mode switching key. The shooting button has a function corresponding to a release button in a normal camera, and shooting is performed by the user operating the shooting button.

  Similar to the first main body 110, the second main body 120 is a vertically long flat housing, and a display unit 121 is provided on the front surface thereof. The display unit 121 is configured to selectively display information such as a telephone number registered in advance on the liquid crystal display screen, input text, and an image input to the photographing function unit. On the back surface of the second main body 120, a photographing lens 211 that is an optical system member constituting the camera is disposed.

  A subject image is formed on an image sensor, which is an image sensor incorporated in the photographic lens 211, converted into an electrical signal, and then transmitted to a processing circuit inside the main body. When the user operates the shooting button, a series of shooting operations are performed, and the subject image acquired by the shooting lens 211 is stored in the storage unit as an image information signal, thereby completing the shooting.

  The light emitting unit 331 provided on the same side as the photographing lens 211 of the second main body unit 120 is a light emitting unit of the auxiliary light emitting device, and the subject emits light from the auxiliary light emitting device through a transparent panel on the front surface of the light emitting unit 331. To compensate for the illuminance of the subject. In this embodiment, an electronic flash device is used as the auxiliary light emitting device. However, the required amount of light can be obtained, the light quality is suitable for color reproduction of a photographed image, The configuration is not limited to the electronic flash device as long as it can be easily assembled and can be handled easily by the user. For example, a configuration using a light emitting element such as an LED may be used.

  FIG. 2 is a block diagram showing the configuration of the mobile phone according to the present invention and signals transmitted between the configurations.

  The operation unit 112 has a function of converting an operation performed when the user uses the telephone function into an operation information signal by the information conversion unit 113 and transmitting the operation information signal to the information processing unit 115 of the telephone function unit 114. Here, the result of mode selection by the user is transmitted to the camera function unit 200 as a mode selection signal, and the operation result of the shooting button is transmitted to the camera function unit 200 as a shooting operation signal.

  The telephone function unit 114 includes an information processing unit 115 that processes an information signal transmitted from the operation unit 112, and a transmission / reception unit 116 that transmits and receives audio and images. The transmission / reception means 116 can transmit image information received from another telephone to the camera function unit as received image information, and can receive image information captured by the camera function unit as transmission image information and transmit it to another telephone.

  The camera function unit 200 controls an imaging unit 210 that captures an image of a subject to generate an image signal, an image processing unit 220 that processes the captured image signal, a storage unit 240 that stores image signal information, and a flash operation. And flash control means 230. The flash control means 230 corresponds to the control means described in the first aspect. The imaging unit 210 includes a photographing lens 211 that forms a real image of a subject, and an image sensor 212 in which a plurality of pixels that photoelectrically convert the real image of the subject are arranged in a plane. The image processing means 220 receives the photographing operation signal from the information processing means 115 and stores the image information of the subject image captured by the image sensor 212 in the storage means 240, thereby completing the photographing.

  The flash control unit 230 includes an image selection unit 231, a binarization unit 232, a binarized image count unit 233, and a comparison / determination unit 234. The image selection means 231 extracts the luminance information of the pixel at the center of the screen from the image information of the subject captured by the image sensor 212, and the binarization means 232 binarizes the binarized luminance information of the pixel. The image counting means 233 counts the number of pixels of the white image and the number of black images of the binarized image, and the comparison / determination means 234 compares the number of pixels of the white image with the number of pixels of the black image to compare the black image pixels. When it is determined that the number is larger than the number of white image pixels, a light emission signal is transmitted to the auxiliary light emitting device unit 300. Details of the operation of the flash control means 230 will be described later.

  The auxiliary light emitting device unit 300 is a well-known electronic flash device, stores a charge necessary for light emission operation in a capacitor, receives a light emission signal, supplies energy to the light emitting means 320, and a light emitting means. 320. The light emitting means 320 is a xenon discharge tube. The light emission control means 320 receives a light emission signal from the flash control means 230 and discharges the charge stored in the charging / light emitting electronic circuit 310 into the xenon discharge tube as the light emitting means 320. It changes to light energy and operates to irradiate the subject. When the user operates the shooting button, the above-described light emission signal is transmitted at a predetermined timing in a series of shooting operations linked to the button, and the auxiliary light emitting device unit 300 that receives the light emission signal operates the light emitting means 320. The auxiliary light is emitted, and an image of the subject irradiated with the auxiliary light is acquired.

  Next, the auxiliary light automatic light emission control that determines whether or not auxiliary light is necessary based on the luminance information of the center portion of the subject captured by the image sensor and automatically controls whether or not auxiliary light is emitted based on the determination result. Will be described.

  The imaging means 210 of the camera function unit 200 is provided with an image sensor 212 that photoelectrically converts a subject image that is incident and imaged through the photographing lens 211 and outputs it as an image signal. The image sensor 212 has a plurality of pixels arranged on a two-dimensional plane, and light passing through the photographing lens forms an image on the image sensor 212 and is photoelectrically converted. The image information obtained by the image sensor 212 includes the luminance information of the subject, and it is possible to determine whether the luminance of the subject is high or low by knowing the luminance information value, and to assist by knowing the luminance information value. It can be determined whether light is necessary. In addition, since the output image information value can specify the horizontal and vertical position of which pixel of the image sensor 212, the output value of the pixel at an arbitrary position of the image sensor 212 is known. That is, it is possible to know luminance information at an arbitrary position of the captured image.

  In photographing that requires auxiliary light, the main subject is often in the center of the screen. Also, particularly in a backlight scene, the main subject located near the center is usually dark and the surrounding area is bright, and when shooting conditions are determined from the luminance information of the entire screen including the periphery of the screen under such shooting conditions, In some cases, it is determined that the auxiliary light is unnecessary under the influence of the brightness of the peripheral portion. A photograph taken under such a photographing condition often does not satisfy the photographer because the main subject in the center is underexposed even if the periphery of the screen is properly exposed.

  In the present invention, the main subject is determined by determining whether or not auxiliary light is required based on the luminance information of the pixels only in the vicinity of the center of the shooting screen where the main subject is likely to exist. It is possible to construct an automatic light emitting system with a simple configuration that can cope with the need for an auxiliary light emitting device at both the front light position and the back light position. That is, the control for determining whether or not auxiliary light is necessary from the luminance information of the pixel located at the center of the screen of the image sensor 212 and controlling whether or not the auxiliary light emitting device emits auxiliary light based on the determination result. Having a means is the first main point of the present invention.

  The second important point is that the horizontal limit is set to a distance of 20 to 30% of the horizontal dimension of the image sensor screen in the horizontal direction from the vertical center line position of the image sensor screen as the center of the screen, and the horizontal center line position. A range portion surrounded by a vertical limit defined by a distance of 20 to 30% of the vertical dimension of the image sensor screen in the vertical direction is defined as the range. As a result of monitor tests and simulations, the present inventor has found the region as the most suitable photometric range for determining whether or not auxiliary light is required in shooting scenes having various conditions and compositions. By determining whether or not auxiliary light is necessary according to the brightness condition of the image sensor in such an area, it is possible to perform various shooting conditions such as backlight and backlight without being affected by the brightness condition of the subject located at the periphery of the screen. However, it is always possible to take a picture adapted to the luminance condition of the main subject.

  Hereinafter, the operation of the flash control unit 230 will be described in detail.

  First, the image selection unit 231 selects pixels included in an arbitrarily designated area in the center of the screen from the subject image information acquired by the image sensor 212. FIG. 3 is a conceptual diagram showing a range portion at the center of the screen from which luminance information of the image sensor according to the present invention is extracted. In FIG. 3, the lateral limit defined on the light receiving surface of the image sensor 212 is set to a distance of 25% of the lateral dimension a of the image sensor screen in the horizontal direction from the longitudinal center line position of the image sensor screen, and the lateral direction. A pixel with a diagonal line surrounded by a vertical limit defined by a distance of 25% of the vertical dimension b of the image sensor screen in the vertical direction from the center line position is defined as an image of pixels existing in the range part. The selection means 231 selects.

  The binarizing means 232 converts the luminance information of the selected pixel into black and white and further forms a binary image. In the binarization, a white image is used when the luminance is higher than a separately determined threshold value, and a black image is used when the luminance is lower.

The binary image counting unit 233 counts the number of pixels of the white image of the binarized image and sets the number to A, and counts the number of pixels of the black image and sets the number to B. B is compared, and a light emission signal is transmitted based on the comparison result. If the comparison result A <B, auxiliary light is necessary and a light emission signal is transmitted. If A <B, no auxiliary light is necessary and no light emission signal is transmitted.

  Next, the automatic light emission operation based on the example of the embodiment of the present invention will be described with reference to a flowchart.

  FIG. 4 is a flowchart based on an example of a basic embodiment of the present invention.

  First, the camera mode is set by the user and the camera mode is activated (step S1).

  An image of the subject is input to the image sensor of the camera function unit (step S2).

  The user operates the shooting button (step S3).

Capture of the image input to the imaging means is started (step S4).
A pixel at a predetermined position in the center of the image input to the imaging means is selected and extracted (step S5).

  The luminance information of the selected and extracted pixels is binarized (step S6).

The number of pixels of the binarized white image and the number of pixels of the black image are counted, the number of pixels of the white image is A, and the number of pixels of the black image is B (step S7).
A and B are compared, and if A <B, a light emission signal for emitting auxiliary light is transmitted. (Step S8).

  Upon receiving the light emission signal, the auxiliary light emitting device emits light (step S9).

  Image capture is completed and the shooting operation is terminated (step S10).

  If A <B in step S8, no light emission signal is transmitted, and the auxiliary light emitting device does not emit light and the photographing is finished.

  As described above, according to the present invention, a dedicated sensor is not required, and the necessity of auxiliary light is automatically determined according to the luminance condition of only the subject located at the center of the shooting screen. A camera with an auxiliary light automatic light emission type camera that can always shoot in accordance with the brightness conditions of the main subject, even under various shooting conditions such as front light and backlight, without being affected by the brightness conditions of the subject located in the area Type telephones can be provided.

  In the above embodiment, the brightness of the image is determined by forming a binary image. For example, the average value of the brightness information at the center of the screen is obtained and compared with a predetermined reference value to determine whether the auxiliary light emission is necessary. It is good also as a structure which judges.

It is a general-view figure which shows embodiment of the mobile phone with a camera which concerns on this invention. It is a block diagram which shows the structure of the portable telephone with a camera which concerns on this invention, and the signal transmitted between each structure. It is a conceptual diagram which shows the range part in which the pixel which extracts the luminance information of the image sensor which concerns on this invention is contained. It is a flowchart of the auxiliary light automatic light emission operation of the mobile phone with camera according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 110 1st main-body part 111 Operation key part 120 2nd main-body part 121 Display part 130 Hinge part 211 Shooting lens 212 Image sensor 331 Light emission part of electronic flash

Claims (2)

An image sensor having a plurality of pixels arranged in a plane, a camera having an auxiliary light emitting device, and the auxiliary light emission based on luminance information of an image acquired by a pixel arranged in the central portion of the image sensor A camera-equipped mobile phone comprising control means for controlling the operation of the apparatus. The central portion includes a lateral limit determined by a distance of 20 to 30% of a horizontal dimension of the image sensor screen in the left-right direction from the vertical center line position of the image sensor screen, and the vertical direction from the horizontal center line position. The camera-equipped mobile phone according to claim 1, wherein the mobile phone with a camera is a range portion surrounded by a vertical limit defined by a distance of 20 to 30% of a vertical dimension of the image sensor screen.

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