Patent Description:
This type of apparatus requires images with an iris of a target person properly imaged. In some cases, a target person is wearing glasses or the like. In this situation, there is a technical problem that, for example, an iris of a target person may not be properly imaged by imaging reflected light from a lens of an eyeglasses of illumination light. For this problem, for example, an apparatus, which images with two types of illumination that are an illumination suitable for a target person wearing hard contact lenses and an illumination suitable for a target person wearing glasses, has been proposed (see Patent Literature <NUM>). Patent Literatures <NUM> to <NUM> are listed as other related technique. Patent Literature <NUM> relates to an iris recognition apparatus with two light sources.

In the technique described in Patent Document <NUM>, imaging with the above-mentioned two illuminations is performed for all target persons. Therefore, the technique described in Patent Document <NUM>, there is a technical problem that the time required for iris recognition becomes relatively long.

This disclosure has been made in view of the above-mentioned problem. An object of this disclosure is to provide an iris recognition apparatus, an iris recognition method, a computer program, and a recording medium, that can reduce the time required for iris recognition.

An aspect of an iris recognition apparatus of this disclosure is provided with: an irradiating device that is capable of irradiating light to a target person to be recognized; an acquiring device that acquires a first image which imaged a first imaging range including at least a face of the target person; and a determining device that determines an irradiation mode of light irradiated from the irradiating device to the target person when imaging a second image including an area, which includes an eye of the target person, and corresponding to a second imaging range, which is narrower than the first imaging range, based on the first image, wherein the irradiating means has a plurality of light sources having different incident angles of light emitted to the target person, and the determining means selects a light source for realizing the determined irradiation mode from the plurality of light sources.

An aspect of an iris recognition method of this disclosure includes: acquiring a first image which imaged a first imaging range including at least a face of a target person to be recognized; and determining an irradiation mode of light irradiated to the target person when imaging a second image including an area, which includes an eye of the target person, and corresponding to a second imaging range, which is narrower than the first image range, based on the first image, wherein the irradiating means has a plurality of light sources having different incident angles of light emitted to the target person, and the determining step comprises selecting a light source for realizing the determined irradiation mode from the plurality of light sources.

An aspect of a computer program of this disclosure causes a computer to execute the one aspect of the iris recognition method as described above.

An aspect of a recording medium of this disclosure is a recording medium in which the one aspect of the computer program as described above is recorded.

According to one aspect of each of the iris recognition apparatus, iris recognition method, computer program and recording medium as described above, it is possible to reduce the time required for iris recognition.

Embodiments of an iris recognition apparatus, an iris recognition method, a computer program and a recording medium will be described with reference to figures. In the following, embodiments of an iris recognition apparatus, an iris recognition method, a computer program and a recording medium will be described by using an iris recognition apparatus <NUM> which can perform iris recognition even if a target person wears eyeglasses.

The entire configuration of the iris recognition apparatus <NUM> of the embodiment will be described with reference to <FIG> is a block diagram showing the entire configuration of the iris recognition apparatus <NUM> of the embodiment.

In <FIG>, the iris recognition apparatus <NUM> comprises an iris recognition unit <NUM>, a whole camera <NUM>, an iris camera <NUM>, and illumination apparatuses <NUM> and <NUM>. The whole camera <NUM> is installed so as to be able to image at least the face of a target person T when the target person T of iris recognition is at a predetermined position (e.g., a position designated by a footprint mark, a position to be seated, etc.). The iris camera <NUM> is installed so as to be able to suitably image a gaze area, which includes the eye of the target person T, when the target person T is at the predetermined position.

Thereafter, as appropriate, the image imaged by the whole camera <NUM> is referred to as the "whole image <NUM>", and the image imaged by the iris camera <NUM> is referred to as the "iris image <NUM>". The resolution of the gaze area in the iris image <NUM> is higher than the resolution of the gaze area in the whole image <NUM>. In other words, if the image sensor of the whole camera <NUM> and the image sensor of the iris camera <NUM> are the same performance, the imaging magnification of the iris camera <NUM> is higher than the imaging magnification of the whole camera <NUM>. Further, the imaging range of the whole image <NUM> is wider than the imaging range of the iris image <NUM>. In other words, the imaging range of the iris image <NUM> is narrower than the imaging range of the whole image <NUM>. The whole image <NUM> and the iris image <NUM> correspond to examples of the "first image" and the "second image" in the supplementary note to be described later, respectively. Further, the imaging range of the whole image <NUM> corresponds to an example of the "first imaging range" in the supplementary note to be described later, and the imaging range of the iris image <NUM> corresponds to an example of the "second imaging range" in the supplementary note to be described later.

Illumination apparatuses <NUM> and <NUM> are installed such that incident angles to the target person T of light to be emitted are different from each other. In particular, the illumination apparatus <NUM> is installed so as to illuminate the target person T from below the illumination apparatus <NUM>. Illumination apparatuses <NUM> and <NUM> may be configured to change other properties of light to be emitted (e.g., at least one of wavelength and intensity). In this embodiment, it is assumed that positional relations and optical features (e.g., an optical axis direction, an angle of view, etc.) of the whole camera <NUM>, the iris camera <NUM>, and the illumination apparatuses <NUM> and <NUM> are known. Incidentally, the iris recognition apparatus <NUM> is not limited to two of the illumination apparatuses <NUM> and <NUM> may be provided with three or more illumination apparatuses. Illumination apparatuses <NUM> and <NUM> correspond to an example of the "light source" in the supplementary note to be described later.

The hardware configuration of the iris recognition unit <NUM> will be described with reference to <FIG> is a block diagram showing the hardware configuration of the iris recognition unit <NUM> of the embodiment.

In <FIG>, the iris recognition unit <NUM> includes a CPU (Central Processing Unit) <NUM>, a RAM (Random Access Memory) <NUM>, a ROM (Read Only Memory) <NUM>, a storage apparatus <NUM>, an input device <NUM>, and an output device <NUM>. The CPU <NUM>, the RAM <NUM>, the ROM <NUM>, the storage apparatus <NUM>, the input device <NUM> and the output device <NUM> are interconnected each other via a data bus <NUM>.

The CPU <NUM> reads computer programs. For example, the CPU <NUM> may read a computer program stored by at least one of the RAM <NUM>, the ROM <NUM> and the storage apparatus <NUM>. For example, the CPU <NUM> may read a computer program recorded in a computer-readable recording medium using a recording medium reading apparatus not shown. The CPU <NUM> may acquire (i.e., read) a computer program from an apparatus not shown located outside the iris recognition unit <NUM> via a network interface.

The CPU <NUM> controls the RAM <NUM>, the storage apparatus <NUM>, the input device <NUM> and the output device <NUM> by executing the read computer program. In particular, in this embodiment, when the CPU <NUM> executes the read computer program, logical functional blocks for performing iris recognition are realized in the CPU <NUM>. In other words, the CPU <NUM> can function as a controller for performing iris recognition.

In the CPU <NUM>, as shown in <FIG>, an image acquiring unit <NUM>, an illumination determining unit <NUM>, a control unit <NUM> and a recognition unit <NUM> are realized as logical functional blocks. The operation of each of the image acquiring unit <NUM>, the illumination determining unit <NUM>, the control unit <NUM> and the recognition unit <NUM> will be described later. Incidentally, the image acquiring unit <NUM> and the illumination determining unit <NUM> correspond to examples of the "acquiring means" and the "determining means" in the supplementary note to be described later, respectively. The control unit <NUM>, and illumination apparatuses <NUM> and <NUM> correspond to an example of the "irradiation unit" in the supplementary note to be described later.

Returning to <FIG>, the RAM <NUM> temporarily stores computer programs executed by the CPU <NUM>. The RAM <NUM> temporarily stores data that the CPU <NUM> uses temporarily while the CPU <NUM> is executing computer programs. The RAM <NUM> may be, for example, D-RAM (Dynamic RAM).

The ROM <NUM> stores computer programs executed by the CPU <NUM>. The ROM <NUM> may store other fixed data. The ROM <NUM> may be, for example, P-ROM (Programmable ROM).

The storage apparatus <NUM> stores data that the iris recognition apparatus <NUM> saves in long-term. The storage apparatus <NUM> may act as a temporary storage apparatus for the CPU <NUM>. The storage apparatus <NUM> may include, for example, at least one of a hard disk apparatus, a magneto-optical disk apparatus, an SSD (Solid State Drive) and a disk array apparatus.

The input device <NUM> is an apparatus that receives input instructions from the user of the iris recognition apparatus <NUM>. The input device <NUM> may include, for example, at least one of a keyboard, a mouse and a touch panel.

The output device <NUM> is an apparatus that outputs information about the iris recognition apparatus <NUM> to the outside. For example, the output device <NUM> may be a display apparatus capable of displaying information about the iris recognition apparatus <NUM>.

The operation of the iris recognition apparatus <NUM>, which is configured as described above, will be described. First, the operation of the illumination determining unit <NUM> will be described with reference to <FIG> is a diagram schematically showing the whole image <NUM>. When the target person T wears eyeglasses, the reflected light from the lens of the eyeglasses of the illumination light may be imaged in the whole image <NUM>. In <FIG>, areas a1 and a2, each of which is surrounded by a dotted line, are portions where the reflected light is imaged. Thereafter, an area corresponding to each of areas a1 and a2 are appropriately referred to as an "illumination reflection area".

The illumination determining unit <NUM> detects the gaze area (see <FIG>) by performing a predetermined image processing on the whole image <NUM>. Incidentally, since various existing aspects can be applied to the image processing for detecting the gaze area, a detailed description thereof is omitted. Next, the illumination determining unit <NUM> detects an area, of which brightness is higher than a predetermined value, as a high-brightness area from the gaze area. Here, the "predetermined value" is a value for determining whether or not an area is the high-brightness area, and is set in advance as a fixed value, or, for example, as a variable value according to an average brightness or the like of the whole image <NUM>. Such the "predetermined value" may be set, for example, as a lower limit of a range, which shows a changeable range of the brightness of the illumination reflection area in the whole image <NUM> and which is determined experimentally or empirically, or by simulation.

The illumination determining unit <NUM> identifies, for example, a position, an area, or the like of the detected high-brightness area in the gaze area. Then, the illumination determining unit <NUM> specifies how much the detected high-brightness area is superimposed on an area corresponding to the iris of the target person T (for example, an area to be estimated as an area, in which the iris is imaged, in the gaze area).

If a degree of superposition of the detected high-brightness area and the area corresponding to the iris of the target person T is a degree such that it does not affect iris recognition, the illumination determining unit <NUM> determines imaging the iris image <NUM> by setting the setting of each of illumination apparatuses <NUM> and <NUM> to be the same as the setting when the whole image <NUM> is imaged (i.e., without changing settings). Incidentally, setting items of each of illumination apparatuses <NUM> and <NUM> includes, for example, whether or not to light up (in other words, whether or not to emit light), the wavelength of light to be emitted, the intensity of light to be emitted (in other words, brightness), incident angle to the target person T of light to be emitted, etc. Therefore, determining the setting of each of illumination apparatuses <NUM> and <NUM> is synonymous with determining light to be illuminated to the target person T (specifically, where, at what angle and what kind of light to be irradiated to the target person T). In other words, determining the setting of each of illumination apparatuses <NUM> and <NUM> is synonymous with determining the irradiation mode of light to be irradiated to the target person T.

Here iris recognition will be described briefly. When the iris pattern of a new user is to be registered newly in the iris recognition apparatus <NUM>, the iris pattern of the new user is obtained, for example, as follows: first, an image (corresponding to the iris image <NUM>) including the eye of the new user is imaged, and then a doughnut-shaped iris portion is extracted from the image; next, the doughnut-shaped iris portion is converted into a rectangular image; then, the rectangular image is divided into a plurality of compartments, and then each of the plurality of compartments is quantified (e.g., a representative value of each of the plurality of compartments is determined). Digital data generated by this quantifying correspond to the iris pattern of the new user. Iris recognition is performed by comparing the iris pattern of target person T obtained in the same manner as described above from the iris image <NUM> with the iris pattern registered in advance in iris recognition apparatus <NUM>. If the degree of coincidence between the two is equal to or greater than a predetermined value, the iris recognition apparatus <NUM> determines the target person T as a user registered.

A determined result, that whether or not the degree of superposition of the detected high-brightness area and the area corresponding to the iris of the target person T is a degree such that it does not affect iris recognition, varies according to a predetermined value of the above-mentioned degree of the coincidence. For example, the predetermined value is <NUM>%. In this case, if an area, which superimposed with the detected high-brightness area, of the area corresponding to the iris of the target person T is less than <NUM>% of the whole area corresponding to the iris, it can be said that iris recognition is not affected. For example, the predetermined value is <NUM>%. In this case, if the area corresponding to the iris of the target person T and the detected high-brightness area is slightly superimposed, it can be said that iris recognition is affected. The predetermined value may be appropriately set according to, for example, the number of target persons to be recognized of the iris recognition apparatus <NUM>, the recognition accuracy required for the iris recognition apparatus <NUM>, the probability of false recognition estimated from the resolution of the iris image <NUM>, or the like.

On the other hand, when the degree of superposition of the detected high-brightness area and the area corresponding to the iris of the target person T is a degree such that it affects iris recognition, the illumination determining unit <NUM> sets the setting of each of illumination apparatuses <NUM> and <NUM> to a setting, which is different from that when the whole image <NUM> is imaged. Hereinafter, an exemplary operation, in which the setting of each of illumination apparatuses <NUM> and <NUM> is set to a setting, which is different from that when the whole image <NUM> is imaged, will be described.

The illumination determining section <NUM> estimates, for example, light, which is emitted from at least one of illumination apparatuses <NUM> and <NUM>, is reflected at which position of the target person T, and how much light is reflected (i.e., a reflected position and reflected amount of illumination light) on the basis of the position, the area, or the like of the detected high-brightness area in the gaze area, and the setting of each of illumination apparatuses <NUM> and <NUM> when the whole image <NUM> is imaged (in other words, an irradiation information of light irradiated to the target person T).

The illumination determining unit <NUM> estimates a high-brightness area included in the gaze area in the iris image <NUM> based on the estimated reflected position and reflected amount of illumination light, and the setting of each of illumination apparatuses <NUM> and <NUM>. Then, the illumination determining unit <NUM> determines the setting of each of the illumination apparatuses <NUM> and <NUM> such that, for example, the degree of superposition of the high-brightness area and the area corresponding to the iris of the target person T is minimized (or is equal to or less than a predetermined allowable amount) in the iris image <NUM>. At this time, the illumination determining unit <NUM> particularly determines at least one of the follows: an incident angle of light, which is to be irradiated from one of illumination apparatuses <NUM> and <NUM> to the target person T, to the target person T and a wavelength of light, which is to be irradiated from one of illumination apparatuses <NUM> and <NUM>. The illumination determining unit <NUM> determines imaging the iris image <NUM> with the determined setting of each of illumination apparatuses <NUM> and <NUM>.

Next, the operation of the iris recognition apparatus <NUM> will be described with reference to the flowchart of <FIG>. In <FIG>, the control unit <NUM> sets the setting of each of illumination apparatuses <NUM> and <NUM> to the default value (e.g., only the illumination apparatus <NUM> is lighting), and controls the whole camera <NUM> so as to image the target person T (step S101).

The illumination determining unit <NUM> acquires the whole image <NUM> imaged as a result of the process of the step S101 through the image acquiring unit <NUM>. The illumination determining unit <NUM> performs the above-described process using the acquired whole image <NUM>. At this time, the illumination determining unit <NUM> estimates a reflected position and a reflected amount of illumination light if the degree of the superimposition of the high-brightness area detected from the gaze area of the whole image <NUM> and the area corresponding to the iris of the target person T is the degree such that it does not affect iris recognition (step S102).

Next, the illumination determining unit <NUM> determines the setting of each of illumination apparatuses <NUM> and <NUM> when imaging the iris image <NUM>. In other words, the illumination determining unit <NUM> selects the illumination when imaging the iris image <NUM> (step S103).

Next, the control unit <NUM> sets the setting of each of illumination apparatuses <NUM> and <NUM> to the setting determined in the process of the step S103, and controls the iris camera <NUM> so as to image the target person T (step S104). Thereafter, the recognition unit <NUM> acquires the iris image <NUM> imaged as a result of the process of the step S104 through the image acquiring unit <NUM>, and performs a predetermined recognition determination. Since the existing technology can be applied to the recognition determination, a detailed description thereof will be omitted.

As an example, if the incident angle of light, which is to be irradiated from the illumination apparatus <NUM>, to the target person T and the incident angle of light, which is to be irradiated from the illumination apparatus <NUM>, to the target person T are only different from each other (in other words, other than incident angle, for example, wavelength, intensity, etc. of light are the same in illumination apparatuses <NUM> and <NUM>), processes of the flowchart of <FIG> can be rewritten as shown in <FIG>. Here, the incident angle of light, which is to be irradiated from the illumination apparatus <NUM>, to the target person T is approximately <NUM> degrees. In other words, the illumination apparatus <NUM> illuminates the target person T from substantially the front of the target person T. On the other hand, the illumination apparatus <NUM> illuminates the target person T from below the face of the target person T. Therefore, the incident angle of light, which is to be irradiated from the illumination apparatus <NUM>, to the target person T differs from the incident angle of light, which is to be irradiated from the illumination apparatus <NUM>, to target person T.

In <FIG>, the illumination determining unit <NUM> determines the setting of each of illumination apparatuses <NUM> and <NUM> so that light is not irradiated from the illumination apparatus <NUM> to the target person T while light is irradiated from the illumination apparatus <NUM> to the target person T when imaging the whole image <NUM> (in this case, for example, the illumination apparatus <NUM> is turned on and the illumination apparatus <NUM> is turned off). The control unit <NUM> sets illumination apparatuses <NUM> and <NUM> according to the determination of the illumination determining unit <NUM>, and controls the whole camera <NUM> so as to image the target person T (step S101).

After the process of the above-described step S102, the illumination determining unit <NUM> determines whether or not the degree of the superimposition of the high-brightness area and the area corresponding to the iris of the target person T affects iris recognition (step S1031).

If it is determined that iris recognition is not affected in the process of the step S1013 (Step S1013: No), the illumination determining unit <NUM> selects the illumination apparatus <NUM>, which is used as the illumination when the whole image <NUM> is imaged, as the illumination when imaging the iris image <NUM> (Step S1032). In other words, the illumination determining unit <NUM> determines that settings of illumination apparatuses <NUM> and <NUM> are set to be turned on and not turned on, respectively. Therefore, the target person T is illuminated from its substantially front. In this case, the iris camera <NUM> images the target person T in which light is not irradiated from the illumination apparatus <NUM> while light is irradiated from the illumination apparatus <NUM>.

If it is determined that iris recognition is affected in the process of the step S1031 (Step S1031: Yes), the illumination determining unit <NUM> selects the illumination apparatus <NUM>, which is not used as the illumination when the whole image <NUM> is imaged, as the illumination when imaging the iris image <NUM> (Step S1033). In other words, the illumination determining unit <NUM> determines that settings of illumination apparatuses <NUM> and <NUM> are set to be not turned on and set to be turned on, respectively. Therefore, the target person T is illuminated from below its face. In this case, the iris camera <NUM> images the target person T in which light is not irradiated from the illumination apparatus <NUM> while light is irradiated from the illumination apparatus <NUM>.

When the iris recognition apparatus <NUM> includes three or more illumination apparatuses, the illumination determining unit <NUM> may select one illumination apparatus, which is not used as the illumination apparatus when the whole image <NUM> is imaged, from a plurality of illumination apparatuses as the illumination apparatus when imaging the iris image <NUM>. At this time, the illumination determining unit <NUM> may estimate light, which is emitted from each of the plurality of illumination apparatuses, is reflected at which position of the target person T, and how much light is reflected on the basis of the position, the area, or the like of a high-brightness area in a gaze area, and the setting of the illumination apparatus <NUM> when the whole image <NUM> is imaged. Thereafter, the illumination determining unit <NUM> may select one illumination apparatus as the illumination apparatus when imaging the iris image <NUM> such that, for example, the degree of superposition a high-brightness area and an area corresponding to the iris of the target person T is minimized (or equal to or less than a predetermined allowable amount) in the iris image <NUM>.

Incidentally, considering that the illumination apparatus selected as the illumination apparatus when imaging the iris image <NUM> irradiates light while the unselected illumination apparatus does not irradiate light, the selection of the illumination apparatus is substantially equivalent to determining irradiating or not irradiating light (i.e., ON/OFF) by each illumination apparatus.

In the iris recognition apparatus <NUM>, the setting of each of illumination apparatuses <NUM> and <NUM> when imaging the iris image <NUM> is determined based on the whole image <NUM>. In other words, in the iris recognition apparatus <NUM>, illumination when imaging the iris image <NUM> is selected based on the whole image <NUM>. Therefore, the iris recognition apparatus <NUM> can reduce the time required for iris recognition in comparison with a comparative example which images iris images <NUM> while sequentially testing a plurality of illumination patterns until the iris image <NUM>, which is suitable for iris recognition, is imaged, for example.

The iris recognition apparatus <NUM> as described above may be employed as a part of the iris recognition system <NUM> as shown in <FIG>. The iris recognition system <NUM> performs an iris recognition operation that performs recognition of the target person T based on an iris pattern of the target person T (e.g., human). The iris recognition system <NUM> may be employed, for example, as a part of a system for automating entry and exit procedures at airports, so-called ABC (Automated Border Control). In this case, the iris recognition system <NUM> may be a walk-through type iris recognition system recognizing a moving target person T.

The iris recognition system <NUM> comprises a whole camera <NUM>, a plurality of iris cameras <NUM>, and a control apparatus <NUM>. The iris recognition unit <NUM> of the iris recognition apparatus <NUM> as described above may constitute a part of the control apparatus <NUM>. The whole camera <NUM> of the iris recognition apparatus <NUM> as described above may constitute the whole camera <NUM>. The iris camera <NUM> of the iris recognition apparatus <NUM> as described above may constitute each of the plurality of iris cameras <NUM>. The whole camera <NUM> is configured to be capable of imaging the target person T with a field of view, which is wider than the field of view of each of the plurality of iris cameras <NUM>. The "field of view of a camera" means a range that includes a scene that can be imaged by the camera, and may be referred to as an imaging range.

Claim 1:
An iris recognition apparatus comprising:
an irradiating means for irradiating light to a target person to be recognized;
an acquiring means for acquiring a first image which imaged a first imaging range including at least a face of the target person; and
a determining means for determining an irradiation mode of light irradiated from the irradiating means to the target person when imaging a second image including an area, which includes an eye of the target person, and corresponding to a second imaging range, which is narrower than the first imaging range, based on the first image,
characterised in that
the irradiating means has a plurality of light sources having different incident angles of light emitted to the target person, and
the determining means selects a light source for realizing the determined irradiation mode from the plurality of light sources.