Patent Description:
In recent years, a technology of iris recognition that performs personal authentication using a human's iris has been put into practical use. Since a fine pattern of an iris is used for iris recognition, a high resolution iris image is required in order to realize iris recognition that satisfies sufficient accuracy. The high resolution image refers to, for example, an image of around <NUM> pixels in the vertical direction and around <NUM> pixels in the horizontal direction for an iris of one of the eyes.

A conceivable method of obtaining a high resolution iris image may be to cause a camera having a proximity lens to come close to the eye and capture it. However, it is inconvenient to move the user's eye close to the camera or move the camera close to the user's eye every time performing iris recognition.

To improve convenience at the user, it is desirable to capture a high resolution iris image at a position distant from the user. When an iris is captured at a position distant from the user, there is difficulty due to an uncertain position of the user or individual differences of the heights or the like among users. Further, since there is a limit in increase of the resolution of a camera, it is difficult to capture, in a short time at a high resolution, the entire range where the user's iris may be located. Thus, there is a demand for a technology of acquiring a high resolution iris image at a position distant from the user.

The art disclosed in Patent Literature <NUM> first acquires a plurality of images including a wide range by using a wide angle camera and then determines the position of a human's eye from a connected image formed of a plurality of images. The art then performs capturing with a telescope camera being focused on the position of the eye and acquires an image including an iris. With such a configuration, even when there is a positional shift of a user or there are individual differences among users, a high resolution iris image can be acquired.

The art disclosed in Patent Literature <NUM> first acquires an image including a person by using two human-position cameras and then detects the position in the vertical direction of an iris from the image. Next, the art adjusts the angle in the vertical direction of a mirror provided on a light path of an iris camera to the position of the iris and then captures a plurality of images by using the iris camera while rotating the mirror in the horizontal direction. The art then selects an image including the iris out of the plurality of images. With such a configuration, even when there is a positional shift of a user or there are individual differences among users, a high resolution iris image can be acquired.

<CIT> relates to an iris image pickup camera that takes an iris image of a person for authentication of an iris. <CIT> relates to an iris image pickup apparatus and an iris authentication apparatus for guiding the position of an eye in picking up an iris image used for personal authentication.

<CIT> relates to post processing of images of the human iris.

<CIT> relates to a device for directing light reflected from an object in a scene through at least one lens and into a camera.

However, both the arts disclosed in Patent Literatures <NUM> and <NUM> require at least two capture steps by using multiple types of cameras, which include a step of capturing a wide range image to determine the position of an iris and a step of capturing only the iris to acquire an iris image. Therefore, since both the arts disclosed in Patent Literatures <NUM> and <NUM> require long time for capturing and iris detection, which is inconvenient for the user and difficult to be applied to walk-through recognition in which iris recognition is performed on a moving user.

The present invention has been made in view of the problem described above and intends to provide a technology of acquiring a high resolution iris image more quickly than before.

According to the present invention, capturing of different regions of a user's face is repeated with a movable mirror being rotated, and an image of a user's iris is acquired from a group of output images. Since the movable mirror can be rotated faster than a camera, it is possible to acquire an iris image more quickly. Further, since different regions of a user's face are captured with the movable mirror being rotated, it is possible to acquire a high resolution iris image without requiring multiple types of cameras.

While example embodiments of the present invention will be described below with reference to the drawings, the present invention is not limited to these present example embodiments. Note that, throughout the drawings illustrated below, components having the same function are labeled with the same reference, and the repeated description thereof may be omitted.

<FIG> is a schematic diagram of an iris capture apparatus <NUM> according to the present example embodiment. The iris capture apparatus <NUM> has a camera <NUM> that captures an iris of a user A, a rotatable movable mirror <NUM>, a light source <NUM> that irradiates the user A with a light, and a human sensor <NUM> that detects the presence of the user A.

The camera <NUM> is a capture unit that performs capturing by using a reflected light B emitted to the user A from the light source <NUM> and reflected by the user A and outputs an image of a capture result as digital data. As the camera <NUM>, any capture apparatus such as a Charge Coupled Device (CCD) camera, a Complementary Metal Oxide Semiconductor (CMOS) camera, or the like may be used. The camera <NUM> includes an image pickup device, an electric circuit, a lens, or the like that are necessary for capturing. The camera <NUM> is a narrow angle camera and is adjusted to capture a region of a part of the face of the user A at once via the movable mirror <NUM>.

The light source <NUM> is a Light Emitting Diode (LED) that generates an infrared ray (having a wavelength of <NUM> to <NUM>) in the present example embodiment. The light source <NUM> irradiates the user A with an infrared ray when performing capturing by the camera <NUM>. The light source <NUM> is provided near the lens of the camera <NUM>, and the light from the light source <NUM> is emitted to the user A via the movable mirror <NUM>. Any number of the light sources <NUM> may be provided, and it is desirable that a plurality of light sources <NUM> be provided so as to surround the side face of the lens of the camera <NUM>. Further, the light source <NUM> may be provided at any position between the camera <NUM> and the mirror <NUM> without being limited to being provided near the camera <NUM>. Alternatively, the light source <NUM> may be provided between the mirror <NUM> and the user A. As the light source <NUM>, any light source such as a laser diode (LD), a lamp, or the like may be used without being limited to the LED. As a light irradiated to the user A by the light source <NUM>, without being limited to an infrared ray, a light of any wavelength may be used in accordance with a purpose or an environment where iris capturing is performed.

The movable mirror <NUM> is provided on a light path of a light entering the camera <NUM>. The movable mirror <NUM> is a mirror that guides a light from the light source <NUM> to the user A and further reflects the reflected light B, which is reflected on the user A, to guide the reflected light B to the lens of the camera <NUM>. As the movable mirror <NUM>, any optical system such as a plane mirror, a curved surface mirror, a prism, or the like that is capable of guiding the reflected light B to the lens of the camera <NUM> may be used.

The movable mirror <NUM> has a drive unit and rotates about a predetermined axis by being driven by the drive unit. The drive unit is a stepping motor in the present example embodiment. With the drive unit rotating the movable mirror <NUM>, the capturing range on the user A taken by the camera <NUM> changes. That is, rotation of the movable mirror <NUM> enables the camera <NUM> to scan the entire region of the face of the user A.

The movable mirror <NUM> may be rotated about two or more axes without being limited to a single axis. As the drive unit of the movable mirror <NUM>, any other drive units such as a motor, an actuator, or the like may be used as long as it can change the angle of the reflective surface of the movable mirror <NUM>. Further, as the movable mirror <NUM>, a galvanometer mirror may be used in which a mirror connected to a permanent magnet and an electromagnet provided facing the permanent magnet are used to control a current to the electromagnet and thereby the mirror can be rotated at a high speed.

The human sensor <NUM> is a sensor that detects the user A being present within a capturing range of the camera <NUM>. The iris capture apparatus <NUM> can start capturing an iris in response to the presence of the user A being detected by the human sensor <NUM>. As the human sensor <NUM>, any sensor capable of detecting the presence of a human, such as an infrared sensor, an ultrasonic wave sensor, or the like, may be used.

The iris capture apparatus <NUM> acquires an iris image of the user A using an iris image acquisition method described later by capturing a face of the user A using the camera <NUM> while rotating the movable mirror <NUM>.

<FIG> is a schematic configuration diagram of the iris capture apparatus <NUM> according to the present example embodiment. The iris capture apparatus <NUM> may be formed of a single apparatus or may be formed by two or more physically divided apparatuses connected by a wire or wirelessly. For example, the iris capture apparatus <NUM> may be a laptop computer, a desktop computer, a workstation, a personal digital assistant, a server, a blade server, a mainframe, an embedded system, or the like. The specific hardware configuration of the iris capture apparatus <NUM> is not limited to the configuration below but may be of various types or forms.

The iris capture apparatus <NUM> has a processor <NUM>, a memory <NUM>, and a storage device <NUM>. Further, the iris capture apparatus <NUM> has a high-speed controller <NUM> including a high-speed interface and a low-speed controller <NUM> including a low-speed interface. The memory <NUM> and a high-speed expansion port <NUM> are connected to the high-speed controller <NUM>. Further, a display device such as a display <NUM> is connected to the high-speed controller <NUM>. On the other hand, a low-speed expansion port <NUM> and the storage device <NUM> are connected to the low-speed controller <NUM>.

The processor <NUM>, the memory <NUM>, the storage device <NUM>, the high-speed controller <NUM>, the low-speed controller <NUM>, and the high-speed expansion port <NUM> are connected to each other through various buses. Further, the processor <NUM>, the memory <NUM>, the storage device <NUM>, the high-speed controller <NUM>, the low-speed controller <NUM>, and the high-speed expansion port <NUM> may be implemented on a common motherboard or may be implemented in other forms as appropriate.

The processor <NUM> is a central processing unit (CPU), for example, and is able to process instructions executed within the iris capture apparatus <NUM>. Such instructions include an instruction that is used for displaying graphics information of a graphical user interface (GUI) on a display device such as the display <NUM> and stored in the memory <NUM> or the storage device <NUM>.

Further, a plurality of processors, a plurality of busses, or a plurality of processors and a plurality of busses can be used as appropriate together with a plurality of memory devices and multiple types of memory devices. Further, a plurality of iris capture apparatuses <NUM> can be connected to each device that performs a part of the necessary process. For example, a plurality of iris capture apparatuses <NUM> can be connected to each other as a server bank, a group of blade servers, or a multiprocessor system.

The memory <NUM> stores therein information within the iris capture apparatus <NUM>. For example, the memory <NUM> may be a volatile memory unit, a non-volatile memory unit, or the combination thereof. The memory <NUM> may be another computer readable storage medium, such as a magnetic disk, an optical disk, or the like, for example.

The storage device <NUM> can configure mass storage used for the iris capture apparatus <NUM>. The storage device <NUM> may be a computer readable storage medium or include such a computer readable storage medium such as, for example, a floppy (registered trademark) disk device, a hard disk device, an optical disk device, a tape device, a solid state memory device such as a flash memory, a disk array, or the like. The storage device <NUM> may include a storage area network or may be a device with another configuration.

The high-speed controller <NUM> manages processes in which the bandwidth for the iris capture apparatus <NUM> is intensively used. On the other hand, the low-speed controller <NUM> manages processes in which the bandwidth is less intensively used. However, such allocation of the functions is a mere example, and allocation is not limited thereto. Further, a part or a whole of the high-speed controller <NUM> may be incorporated in the processor <NUM>.

The high-speed controller <NUM> is connected to the high-speed expansion port <NUM> that can accept the memory <NUM> and various expansion cards. Further, the high-speed controller <NUM> is connected to the display <NUM> via a graphics processor or an accelerator, for example.

The low-speed controller <NUM> is connected to the storage device <NUM> and the low-speed expansion port <NUM>. The low-speed expansion port <NUM> can include, for example, a communication port of various standards such as Universal Serial Bus (USB), Bluetooth (registered trademark), wired or wireless Ethernet (registered trademark), or the like. One or plurality of input devices such as a keyboard, a pointing device, a scanner, or the like are connected to the low-speed expansion port <NUM>. Furthermore, the camera <NUM>, the movable mirror <NUM>, the light source <NUM> and the human sensor <NUM> described above are connected to the low-speed expansion port <NUM>. Further, one or plurality of network devices such as a switch, a router, or the like can be connected to the low-speed expansion port <NUM> via a network adapter, for example. That is, the low-speed expansion port <NUM> functions as a communication interface.

The iris capture apparatus <NUM> can be implemented in many different forms without being limited to the form described above. For example, the iris capture apparatus <NUM> can be implemented in a form of a typical server or a plurality of servers in a form of a group of such servers. Further, the iris capture apparatus <NUM> can be implemented as a part of the rack server system. Furthermore, the iris capture apparatus <NUM> can be implemented in a form of a personal computer such as a laptop computer, a desktop computer, or the like.

Note that a part or a whole of the program executed by the processor <NUM> of the iris capture apparatus <NUM> can be provided by a computer readable storage medium storing the above, such as a digital versatile disc-read only memory (DVD-ROM), a compact disc-read only memory (CD-ROM), a flash memory such as a USB memory or the like.

<FIG> is a schematic diagram of a capture method performed by the iris capture apparatus <NUM> according to the present example embodiment. <FIG> is a diagram of the face of the user A when viewed from the front. In <FIG>, the gravity direction is defined as a Y-axis, and a direction perpendicular to the gravity direction is defined as an X-axis. The movable mirror <NUM> is adjusted so as to rotate about the X-axis. The camera <NUM> captures a capturing region D1 including a part of the face of the user A at once. In response to the movable mirror <NUM> being rotated by a predetermined angle from the state of the capturing region D1, the camera <NUM> captures a capturing region D2 moved by a predetermined distance in the Y-axis direction. The camera <NUM> captures the entire region of the face of the user A by rotating the movable mirror <NUM> for a predetermined number of times to perform capturing for the predetermined number of times. The iris capture apparatus <NUM> then detects an iris A1 of the user A from a group of captured images and acquires an iris image.

Each of the capturing regions D1 and D2 is a rectangular region that is longer in the X-axis direction (the horizontal direction with respect to a face) than in the Y-axis direction (the vertical direction with respect to a face). The camera <NUM> and the movable mirror <NUM> are arranged such that the vertical length of the capturing regions D1 and D2 is shorter than the vertical length of a face of the user A and the horizontal length of the capturing regions D1 and D2 is longer than the horizontal length of a face of the user A. As a size of a face of the user A, a preset size of a face of an average person may be used. With such a configuration, the camera <NUM> is able to scan vertically a face of the user A who may have various heights and capture the entire region only by rotating the movable mirror <NUM> about a single axis (X-axis). Further, since the vertical length of the capturing regions D1 and D2 is limited, it is possible to capture a high resolution iris image while suppressing a resolution required for the image pickup device of the camera <NUM>.

In the neighboring capturing regions D1 and D2, an overlapping region ΔD where the capturing regions D1 and D2 overlap with each other for a predetermined length in the vertical direction is formed. With the overlapping region ΔD being provided in such a way, since the probability of the entire image of the iris A1 being included in at least one of the neighboring capturing regions D1 and D2 is increased, this can reduce the probability of the iris A1 being divided and no iris image being obtained. It is desirable that the length of the overlapping region ΔD be longer than or equal to half the vertical length of each of the capturing regions D1 and D2. Thereby, since each point on the face of the user A is included in both the capturing regions D1 and D2 neighboring each other, it is possible to effectively suppress the iris A1 from being divided.

For example, when the camera <NUM> having a view angle of <NUM> degrees is used and when the distance between the camera <NUM> and the movable mirror <NUM> is <NUM> and the distance between the movable mirror <NUM> and the user A is <NUM>, the vertical length of the capturing regions D1 and D2 will be <NUM> × tan(<NUM>/<NUM>) × (<NUM> + <NUM>) = <NUM>. Since the vertical length of a face of an average person is around <NUM> to <NUM>, an iris image of the user A can be acquired by performing rotation and capturing for around six times even taking the overlapping region into consideration. The size of the capturing regions D1 and D2 may be set in accordance with the arrangement or the capture environment of the iris capture apparatus <NUM>.

<FIG> is a block diagram of the iris capture apparatus <NUM> according to the present example embodiment. In <FIG>, lines between blocks illustrate main dataflows, and other dataflows than is illustrated in <FIG> may be provided. In <FIG>, each block does not illustrate a configuration of a hardware (device) unit but illustrates a configuration of a function unit.

The iris capture apparatus <NUM> has a human detection unit <NUM>, a mirror control unit <NUM>, a capture unit <NUM>, and an iris image acquisition unit <NUM>. In the iris capture apparatus <NUM>, the human detection unit <NUM>, the mirror control unit <NUM>, the capture unit <NUM>, and the iris image acquisition unit <NUM> are stored in the memory <NUM> as programs executable by the processor <NUM>, respectively. That is, when the iris capture method according to the present example embodiment is executed, the processor <NUM> functions as the human detection unit <NUM>, the mirror control unit <NUM>, the capture unit <NUM>, and the iris image acquisition unit <NUM>. At least some of these functions may be implemented as an electronic circuit rather than a program.

The human detection unit <NUM> uses the human sensor <NUM> to detects whether or not the user A is present within a capturing range of the camera <NUM> every predetermined time (for example, every <NUM> second). The human detection unit <NUM> holds the latest detection result in the memory <NUM> or the storage device <NUM>. Based on the result detected by the human detection unit <NUM>, the mirror control unit <NUM>, the capture unit <NUM>, and the iris image acquisition unit <NUM> start capturing an iris when the user A is present.

The mirror control unit <NUM> and the capture unit <NUM> cause the camera <NUM> to capture images of the face of the user A while rotating the movable mirror <NUM>. First, the mirror control unit <NUM> transmits an electrical signal to the movable mirror <NUM> and drives the movable mirror <NUM> to rotate up to a predetermined start position. Next, the capture unit <NUM> irradiates the user A with a light from the light source <NUM> and causes the camera <NUM> to capture a predetermined capturing range on the user A. Every time capturing is performed by the capture unit <NUM>, the mirror control unit <NUM> transmits an electrical signal to the movable mirror <NUM> and drives the movable mirror <NUM> to rotate by a predetermined angle. In such a way, rotation operated by the mirror control unit <NUM> and capturing operated by the capture unit <NUM> are repeated. After rotation operated by the mirror control unit <NUM> and capturing operated by the capture unit <NUM> are repeated for a predetermined number of times, the capture unit <NUM> holds a group of captured images in the memory <NUM> or the storage device <NUM> and ends the capturing. The start position of the movable mirror <NUM> and the angle and the number of repetition of the rotation of the movable mirror <NUM> are preset in accordance with the arrangement of the camera <NUM> and the movable mirror <NUM> and stored in the storage device <NUM>. It is desirable that the angle of one time of rotation of the movable mirror <NUM> be smaller than or equal to <NUM> degrees.

Furthermore, the number of repetition of rotation of the movable mirror <NUM> is dynamically determined based on the position of the user A. The human detection unit <NUM> uses the human sensor <NUM> to measure the distance to the user A. The mirror control unit <NUM> then determines the number of repetition of rotation of the movable mirror <NUM> based on the distance measured by the human detection unit <NUM>. This is because the size of the capturing region on the user A changes depending on the distance from the camera <NUM> even when the movable mirror <NUM> is rotated by the same angle. For example, the mirror control unit <NUM> decreases the number of repetition of rotation of the movable mirror <NUM> when the user A is located distant and increases the number of repetition of rotation of the movable mirror <NUM> when the user A is located close. With such a configuration, a region including the upper end to the lower end of the face of the user A can be captured by the appropriate number of times.

The iris image acquisition unit <NUM> acquires an iris image from a group of images acquired by the capture unit <NUM>. Acquisition of an iris image from a group of images is performed by either a division image scheme of selecting an image including an iris from a group of images to extract the iris or a composite image scheme of creating a composite image from a group of images to extract an iris. Respective schemes will be described below.

<FIG> is a schematic diagram of an iris image acquisition method of the division image scheme according to the present example embodiment. First, the iris image acquisition unit <NUM> acquires a group of divided images E captured by the capture unit <NUM> from the memory <NUM> or the storage device <NUM>. The divided images E are obtained by capturing respective different regions on the user A. Next, the iris image acquisition unit <NUM> performs coarse search of the divided images E for a face region and selects images including the face region. The coarse search for a face region is performed based on the relative positional relationship between components of a face, such as an eyebrow(s), an eye(s), a nose, a mouth, or the like. For example, the coarse positions of an eyebrow(s) and a mouth are acquired by using template matching from the divided images E, the divided image E including the eyebrow(s) to the divided image E including the mouth are selected, and the selected divided images E are a detection target of an iris. The coarse search for a face region may be omitted, and all the divided images E may be the detection target of an iris.

Next, the iris image acquisition unit <NUM> calculates a feature amount F for each predetermined range about each point of the divided image E that is the detection target of an iris. The range used for calculation of the feature amount F has a size sufficient to include an iris. The iris image acquisition unit <NUM> then calculates a similarity of the feature amount F at each point with respect to a feature amount of a pre-stored iris and detects, as the position of the iris, a point at which the similarity is greater than or equal to a predetermined threshold. When a plurality of points where the similarity is greater than or equal to a predetermined threshold are detected, the point at which the similarity is the highest may be determined as an iris. Detection of an iris is performed for both left and right eyes, respectively. The feature amount F may be calculated by using a known method for identifying a component of a face. A feature amount of an iris to be compared to the feature amount F of the divided image E is calculated in advance from an image of an average iris and stored in the storage device <NUM>. The threshold of the similarity is determined in advance through an experiment or a simulation and stored in the storage device <NUM>.

Finally, the iris image acquisition unit <NUM> cuts out predetermined ranges each including the position of the detected iris as iris images G for left and right eyes, respectively, from the divided image E and holds the iris mages G in the memory <NUM> or the storage device <NUM>. The range of the iris image G may have a size including only the iris or may have a size including the entire eye.

<FIG> is a schematic diagram of an iris image acquisition method of the composite image scheme according to the present example embodiment. First, the iris image acquisition unit <NUM> acquires a group of divided images E captured by the capture unit <NUM> from the memory <NUM> or the storage device <NUM>. The divided images E are obtained by capturing respective different regions on the user A. Next, the iris image acquisition unit <NUM> generates a single composite image H from the divided images E so as to exclude the overlapping regions ΔD in <FIG>. For example, the composite image H is generated by deleting portions corresponding to the vertical lengths of overlapping regions ΔD from respective lower ends (or upper ends) of respective divided images and then connecting the divided images E to each other in the vertical direction.

The iris image acquisition unit <NUM> then determines the position of eyes from the composite image H by using a known face recognition method. Finally, the iris image acquisition unit <NUM> cuts out, as iris images G, predetermined ranges including respective positions of the detected left and right eyes from the composite image H and holds the iris mages G in the memory <NUM> or the storage device <NUM>. The range of the iris image G may have a size including only the iris or may have a size including the entire eye.

In the iris image acquisition method of the division image scheme, there is an advantage that, even when the full face of the user A is not generated from composite images due to motion of the face during capturing or the like, an iris image can be acquired as long as an iris is included in any of the divided images E. On the other hand, in the iris image acquisition method of the composite image scheme, there is an advantage that, since the position of the eye can be detected based on the arrangement of components of the entire face, an accurate iris image can be acquired. As an iris image acquisition method, any of the division image scheme and the composite image scheme may be used, or both of them may be used in combination. As an iris image acquisition method, any method that can acquire an image of an iris from an image of a face may be used without being limited to the above schemes.

<FIG> is a diagram illustrating a flowchart of the iris capture method according to the present example embodiment. First, the human detection unit <NUM> uses the human sensor <NUM> to detect whether or not the user A is present within the capturing range of the camera <NUM> (step S11). If the user A is not detected in step S11 (step S12, NO), step S11 is repeated every predetermined time. If the user A is detected in step S11 (step S12, YES), the iris capture apparatus <NUM> acquires an image of a face of the user A using a capture process described later by using <FIG> (step S100). Finally, the iris capture apparatus <NUM> acquires an iris image of the user A using an iris image acquisition process described later by using <FIG> and <FIG> from the image of the face of the user A acquired in step S100 (step S200). The iris image acquisition process is implemented with at least one of the division image scheme and the composite image scheme.

<FIG> is a diagram illustrating a flowchart of a capture process according to the present example embodiment. First, the capture unit <NUM> turns on the light source <NUM> to irradiate the user A with a light (step S101). The light source <NUM> may be turned on all the time during a capture process or may be turned on intermittently only during capturing being performed by the camera <NUM>. Next, the mirror control unit <NUM> drives the movable mirror <NUM> and rotates the movable mirror <NUM> up to a predetermined start position (step S102). Next, the capture unit <NUM> causes the camera <NUM> to capture a predetermined capturing range on the user A (step S103). If a predetermined number of times of capturing is not completed (step S104, NO), the mirror control unit <NUM> drives the movable mirror <NUM> and rotates the movable mirror <NUM> by a predetermined angle (step S105). Steps S103 to S105 are repeated until the number of times of capturing reaches the predetermined number of times.

If the predetermined number of times of capturing ends (step S104, YES), the capture unit <NUM> stores a group of images captured in steps S103 to S105 in the memory <NUM> or the storage device <NUM> (step S106). The iris capture apparatus <NUM> then ends the capture process.

<FIG> is a diagram illustrating a flowchart of the iris image acquisition process of the division image scheme according to the present example embodiment. First, the iris image acquisition unit <NUM> reads a group of images captured in the capture process of step S100 from the memory <NUM> or the storage device <NUM> and acquires the read images as the divided images E (step S201). Next, the iris image acquisition unit <NUM> performs coarse search for a face region on the divided images E acquired in step S201 and selects images including the face region out of the divided images E (step S202). If no face region is detected in step S202 (step S203, NO), the iris capture apparatus <NUM> outputs an indication that no iris image has been acquired and ends the iris image acquisition process.

If a face region is detected in step S202 (step S203, YES), the iris image acquisition unit <NUM> calculates a feature amount for each predetermined range about each point within one of the divided images E including the face region selected in step S202 (step S204). The iris image acquisition unit <NUM> then calculates a similarity of a feature amount of each point calculated in step S204 with respect to a feature amount of a pre-stored iris (step S205). If there is no point at which the similarity calculated in step S205 is greater than or equal to a predetermined threshold (step S206, NO) and if the process is not completed for all the divided images E including the face region selected in step S202 (step S208, NO), steps S204 to S206 are performed for the next one divided image E. If there is no point at which the similarity calculated in step S205 is greater than or equal to a predetermined threshold (step S206, NO) and if the process is completed for all the divided images E including the face region selected in step S202 (step S208, YES), the iris capture apparatus <NUM> outputs an indication that no iris image has been acquired and ends the iris image acquisition process.

If there is a point at which the similarity calculated in step S205 is greater than or equal to a predetermined threshold (step S206, YES), the iris image acquisition unit <NUM> cuts out a predetermined range including the point from the divided image E and stores the cut out predetermined ranges as the iris image G in the memory <NUM> or the storage device <NUM> (step S207). Acquisition of the iris image G is performed for both left and right eyes, respectively. The iris capture apparatus <NUM> then ends the iris image acquisition process.

<FIG> is a diagram illustrating a flowchart of an iris image acquisition process of the composite image scheme according to the present example embodiment. First, the iris image acquisition unit <NUM> reads a group of images captured in the capture process of step S100 from the memory <NUM> or the storage device <NUM> and acquires the read images as the divided images E (step S211). Next, the iris image acquisition unit <NUM> composes the divided images E acquired in step S211 to generate the composite image H (step S212). The iris image acquisition unit <NUM> detects the positions of the eyes from the composite image H generated in step S212 by using a known face recognition method (step S213). If the positions of the eyes are not detected in step S213 (step S214, NO), the iris capture apparatus <NUM> outputs an indication that no iris image has been acquired and ends the iris image acquisition process.

If the positions of the eyes are detected in step S213 (step S214, YES), the iris image acquisition unit <NUM> cuts out predetermined ranges including the detected positions of the eyes as the iris images G from the composite image H and holds the cut out predetermined ranges as the iris image G in the memory <NUM> or the storage device <NUM> (step S215). Acquisition of the iris image G is performed for both left and right eyes, respectively. The iris capture apparatus <NUM> then ends the iris image acquisition process.

The processor <NUM> of the iris capture apparatus <NUM> is the subject of each step (operation) included in the process illustrated <FIG>. That is, the processor <NUM> reads a program used for executing each of the processes illustrated in <FIG> from the memory <NUM> or the storage device <NUM>, executes the program to control each unit of the iris capture apparatus <NUM>, and thereby performs the process illustrated in <FIG>.

The iris capture apparatus <NUM> according to the present example embodiment acquires a high resolution iris image by repeatedly capturing a part of the face of the user A while repeatedly rotating the movable mirror <NUM>. Since the movable mirror <NUM> is lighter than the camera <NUM> in general, the torque at the drive unit used for rotating the movable mirror <NUM> is small. Thus, the iris capture apparatus <NUM> can shorten the time required for rotation and the time required for stop thereof compared to the case of rotating the camera <NUM> and quickly capture an iris. Further, the iris capture apparatus <NUM> can obtain a high resolution iris image by using only the single type of the camera <NUM> without requiring multiple types of cameras such as a wide angle camera and a telescope camera as disclosed in the arts of Patent Literatures <NUM> and <NUM>. Thus, the iris capture apparatus <NUM> can quickly capture an iris and reduce manufacturing cost with a simple apparatus configuration.

The present example embodiment performs walk-through recognition in which iris recognition is performed on the moving user A. <FIG> is a schematic diagram of an iris capture apparatus <NUM> according to the present example embodiment. The iris capture apparatus <NUM> has a camera <NUM>, a movable mirror <NUM>, a light source <NUM>, a human sensor <NUM>, and a gate <NUM>.

The camera <NUM>, the movable mirror <NUM>, the light source <NUM>, and the human sensor <NUM> are similar to the camera <NUM>, the movable mirror <NUM>, the light source <NUM>, and the human sensor <NUM> according to the first example embodiment, respectively. The gate <NUM> is a gate that has a drive unit and can be opened and closed, and the opened state and the closed state can be switched by being driven by the drive unit.

While having a configuration common to the movable mirror <NUM> according to the first example embodiment, the movable mirror <NUM> is different in the feature of rotation about two axes. The movable mirror <NUM> rotates about two predetermined axes by being driven by the drive unit. That is, the iris capture apparatus <NUM> can change the capturing range not only in the vertical direction but also in the horizontal direction. As the movable mirror <NUM>, two mirrors that are separately rotated may be used in combination rather than a single mirror. In such a case, the movable mirror <NUM> includes a first mirror that is rotated about a first axis and a second mirror that is rotated about a second axis that is different from the first axis. Further, the reflected light B from the user A enters the camera <NUM> via the first mirror and the second mirror.

The iris capture apparatus <NUM> repeatedly captures the inside of a predetermined scan region J by rotating the movable mirror <NUM>. The scan region J is located in a space between the detecting range of the human sensor <NUM> and the gate <NUM>. This enables the iris capture apparatus <NUM> to acquire an iris image of the user A at the timing when the moving user A enters the inside of the scan region J after detected by the human sensor <NUM>.

<FIG> is a schematic diagram of a capture method performed by the iris capture apparatus <NUM> according to the present example embodiment. <FIG> is a diagram of the face of the user A when viewed from the front. In <FIG>, the gravity direction is defined as a Y-axis, and a direction perpendicular to the gravity direction is defined as an X-axis. The movable mirror <NUM> is adjusted so as to rotate about the X-axis and the Y-axis. The camera <NUM> captures a capturing region K1 including a part of the face of the user A at once. In response to the movable mirror <NUM> being rotated by a predetermined angle about the X-axis from the state of the capturing region K1, the camera <NUM> captures a capturing region K2 moved by a predetermined distance in the Y-axis direction. In response to the movable mirror <NUM> being rotated by a predetermined angle about the Y-axis from the state of the capturing region K1, the camera <NUM> captures a capturing region K3 moved by a predetermined distance in the X-axis direction. The camera <NUM> captures the entire region within the scan region J by repeating capturing while rotating the movable mirror <NUM> about the X-axis or the Y-axis by a predetermined angle. The iris capture apparatus <NUM> then detects the iris A1 of the user A from a group of captured images and acquires an iris image. The sizes of the capturing regions K1 to K3 and the size of the scan region J may be set in accordance with the arrangement or the capture environment of the iris capture apparatus <NUM>.

In the vertically neighboring capturing regions K1 and K2, an overlapping region ΔKy where the capturing regions K1 and K2 overlap with each other for a predetermined length in the vertical direction is formed. Further, in the horizontally neighboring capturing regions K1 and K3, an overlapping region ΔKx where the capturing regions K1 and K3 overlap with each other for a predetermined length in the horizontal direction is formed. With the overlapping regions ΔKx and AKy being provided in such a way, since the probability of the entire image of the iris A1 being included in at least one of the neighboring capturing regions K1 and K2 (or K3) is increased, this can reduce the probability of the iris A1 being divided and no iris image being obtained. It is desirable that the length of the overlapping region ΔKx be longer than or equal to half the horizontal length of each of the capturing regions K1 and K3. It is desirable that the length of the overlapping region ΔKy be longer than or equal to half the vertical length of each of the capturing regions K1 and K2. Thereby, since each point on the face of the user A is included in both the capturing regions K1 and K2 (or K3) neighboring each other, it is possible to effectively suppress the iris A1 from being divided.

While the movable mirror <NUM> according to the present example embodiment is rotated about two axes, the movable mirror <NUM> may be rotated about a single axis as with the first example embodiment. In such a case, the width in the horizontal direction of the capturing region K1 is equal to the width in the horizontal direction of the scan region J, the movable mirror <NUM> is rotated about one axis (X-axis), and thereby the entire scan region J can be captured.

The apparatus configuration of the iris capture apparatus <NUM> is the same as the iris capture apparatus <NUM> illustrated in <FIG>. <FIG> is a block diagram of the iris capture apparatus <NUM> according to the present example embodiment. In <FIG>, lines between blocks illustrate main dataflows, and other dataflows than is illustrated in <FIG> may be provided. In <FIG>, each block does not illustrate a configuration of a hardware (device) unit but illustrates a configuration of a function unit.

The iris capture apparatus <NUM> has a human detection unit <NUM>, a mirror control unit <NUM>, a capture unit <NUM>, an iris image acquisition unit <NUM>, an iris recognition unit <NUM>, and a gate control unit <NUM>. In the iris capture apparatus <NUM>, the human detection unit <NUM>, the mirror control unit <NUM>, the capture unit <NUM>, the iris image acquisition unit <NUM>, the iris recognition unit <NUM>, and the gate control unit <NUM> are stored in the memory <NUM> as programs executable by the processor <NUM>, respectively. That is, when the iris capture method according to the present example embodiment is executed, the processor <NUM> functions as the human detection unit <NUM>, the mirror control unit <NUM>, the capture unit <NUM>, the iris image acquisition unit <NUM>, the iris recognition unit <NUM>, and the gate control unit <NUM>. At least some of these functions may be implemented by an electric circuit rather than a program.

The human detection unit <NUM> uses the human sensor <NUM> to detect whether or not the user A is present within (that is, passes through) a predetermined detecting range every predetermined time (for example, every <NUM> second). The detecting range of the human sensor <NUM> is set in a space over a path on which the user A moves to the gate <NUM>. The human detection unit <NUM> holds the latest detection result in the memory <NUM> or the storage device <NUM>. The mirror control unit <NUM>, the capture unit <NUM>, and the iris image acquisition unit <NUM> repeat acquisition of an iris image during a predetermined period (for example, <NUM> seconds) after the presence of the user A is detected by the human detection unit <NUM>.

The mirror control unit <NUM> and the capture unit <NUM> cause the camera <NUM> to capture the scan region J, which is closer to the gate <NUM> than the detecting range of the human sensor <NUM> and is located in a space over a path on which the user A moves to the gate <NUM>. First, the mirror control unit <NUM> transmits an electrical signal to the movable mirror <NUM> and drives the movable mirror <NUM> to rotate up to a predetermined start position. Next, the capture unit <NUM> emits a light from the light source <NUM> to the scan region J and causes the camera <NUM> to capture a predetermined capturing range within the scan region J. Every time capturing is performed by the capture unit <NUM>, the mirror control unit <NUM> transmits an electrical signal to the movable mirror <NUM> and drives the movable mirror <NUM> to rotate by a predetermined direction. In such a way, rotation operated by the mirror control unit <NUM> and capturing operated by the capture unit <NUM> are repeated. After rotation operated by the mirror control unit <NUM> and capturing operated by the capture unit <NUM> are repeated for a predetermined number of times, the capture unit <NUM> holds a captured group of images (that is, the entire image of the scan region J) in the memory <NUM> or the storage device <NUM> and acquires the next iris image. Until the iris image is successfully acquired or until a predetermined time has elapsed, the mirror control unit <NUM> again drives the movable mirror <NUM> to move the movable mirror <NUM> back to the predetermined start position and repeats the capturing of an image of the scan region J to the acquisition of the iris image. The start position of the movable mirror <NUM> and the angle and the number of repetition of the rotation of the movable mirror <NUM> are preset in accordance with the arrangement of the camera <NUM> and the movable mirror <NUM> and stored in the storage device <NUM>.

The iris image acquisition unit <NUM> acquires an iris image from a group of images acquired by the capture unit <NUM>. Acquisition of an iris image from a group of images is performed by either the division image scheme or the composite image scheme described above.

The iris recognition unit <NUM> recognizes whether or not the user A is allowed to pass the gate <NUM> by using a known iris recognition method based on the iris image acquired by the iris image acquisition unit <NUM>. Specifically, the iris recognition unit <NUM> extracts the pattern of the iris from the iris image acquired by the iris image acquisition unit <NUM> and extracts information similar to the pattern as information on the user A in accordance with a predetermined criterion. The iris recognition unit <NUM> then allows passage of the gate <NUM> if the information on the user A indicates authority of passage of the gate <NUM> and, otherwise, rejects passage of the gate <NUM>.

The gate control unit <NUM> transmits an electrical signal to the gate <NUM> to open or close the gate <NUM> based on the determination performed by the iris recognition unit <NUM>.

<FIG> is a diagram illustrating a flowchart of an iris capture method according to the present example embodiment. First, the human detection unit <NUM> uses the human sensor <NUM> to detect whether or not the user A is present within the detecting range (step S21). If the user A is not detected in step S21 (step S22, NO), step S21 is repeated every predetermined time. If the user A is detected (step S22, YES), the iris capture apparatus <NUM> acquires an image of the face of the user A within the scan region J using a capture process illustrated in <FIG> (step S100). Next, the iris capture apparatus <NUM> acquires an iris image of the user A using the iris image acquisition process illustrated in <FIG> and <FIG> from the image of the face of the user A acquired in step S100 (step S200). If no iris image is acquired in step S200 (step S23, NO), the capture apparatus of step S100 and the iris image acquisition process of step S200 are repeated within the scan region J.

If an iris image is acquired in step S200 (step S23, YES), the iris recognition unit <NUM> recognizes whether or not the user A is allowed to pass through the gate <NUM> using a known iris recognition method based on an iris image acquired by the iris image acquisition unit <NUM> (step S24). If the user A is recognized in step S24 (step S25, YES), the gate control unit <NUM> opens the gate <NUM> (step S26). If the user A is not recognized in step S24 (step S25, NO), the gate control unit <NUM> closes the gate <NUM> (step S27).

The present invention captures a user by rotating a mirror and therefore can quickly acquire a high resolution iris image. Thus, by repeatedly attempting acquisition of an iris image in a space on a path on which the user moves as described in the present example embodiment, even when the user is moving, the iris image thereof can be acquired and walk-through recognition can be realized.

<FIG> is a schematic configuration diagram of the iris capture apparatuses <NUM> and <NUM> according to respective example embodiments described above. <FIG> illustrates a configuration example for implementing the function of the iris capture apparatuses <NUM> and <NUM> acquiring an image of a user's iris. The iris capture apparatuses <NUM> and <NUM> have the rotatable movable mirrors <NUM> and <NUM>, the control units <NUM> and <NUM> that control rotation of the movable mirrors <NUM> and <NUM>, the capture units <NUM> and <NUM> that capture different regions of a face of a user via the movable mirrors <NUM> and <NUM> and output a group of images every time the control units <NUM> and <NUM> rotate the movable mirrors <NUM> and <NUM> by a predetermined angle, and the iris image acquisition units <NUM> and <NUM> that acquire an image of an iris of the user from the group of images, respectively.

The present invention is not limited to the example embodiments described above and can be changed as appropriate within a range not departing from the scope of the claims.

A processing method that stores a program that operates the configuration of the example embodiment to implement the function of each example embodiment described above (more specifically, the program that causes a computer to execute the method illustrated in <FIG> and <FIG>) in a storage medium, reads the program stored in the storage medium as a code, and executes it in a computer is also included in the scope of each example embodiment. That is, a computer readable storage medium is also included in the scope of each example embodiment. Further, not only the storage medium in which the program described above is stored but also the program itself is included in each example embodiment.

As the storage medium, for example, a floppy (registered trademark) disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM, a magnetic tape, a non-volatile memory card, or a ROM may be used. Further, without being limited to one executing the process with only the program stored in the storage medium, those operating on an OS to execute the process in corporation with other software or the function of an extension board is included in the scope of each.

Claim 1:
An iris capture apparatus (<NUM>) comprising:
a rotatable movable mirror (<NUM>);
a human detection unit (<NUM>) that uses a human sensor (<NUM>) detecting a user to measure a distance to the user;
a control unit (<NUM>) that controls rotation of the movable mirror (<NUM>);
a capture unit (<NUM>) that captures different regions of a face of the user via the movable mirror (<NUM>) and outputs a group of images while the control unit (<NUM>) rotates the movable mirror (<NUM>) by a predetermined angle; and
an iris image acquisition unit (<NUM>) that acquires an image of an iris of the user from the group of images;
characterized in that the control unit (<NUM>) dynamically determines, based on the distance to the user, the number of repetitions of rotation of the movable mirror (<NUM>) thus controlling a capturing range of the capture unit (<NUM>) .