JP2006087831A - Pupil detection apparatus and pupil detection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pupil detection apparatus capable of accurately and easily detect a pupil of a subject by automatically adjusting the position of the pupil in an image captured by an imaging part when an eyeball of the subject is imaged to detect the pupil. <P>SOLUTION: The pupil detection apparatus has the imaging part 1 for imaging the eyeball E of the subject, and an imaging part driving part 16 for moving the imaging part 1 and changing the position of the imaging part 1. The pupil detection apparatus also has a means as an arithmetic operation control part 3. The arithmetic operation control part 3 extracts a center position 21 in a zone corresponding to the pupil P in the image 23 captured by the imaging part 1, extracts the difference between the extracted center position 21 of the pupil P and a set optimum center position 22 of the pupil P in the captured image 23, and drives/controls the imaging part driving part 16 to change the position of the imaging part 1 so that the center position 21 of the pupil P in the captured image 23 is disposed at the set optimum center position 22. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a pupil detection device and a pupil detection method for detecting a pupil by extracting a region corresponding to the pupil from a captured image obtained by imaging an eyeball.

  2. Description of the Related Art Conventionally, as an apparatus for performing various kinds of measurements by performing image processing on an image obtained by imaging a subject's eyeball, the pupil diameter and the size of the pupil are based on an image obtained by imaging the eyeball using a CCD camera or the like. Proposals have been made of measuring nystagmus or performing nystagmus examination by measuring pupil movement (see Patent Documents 1 and 2).

  In such a pupil detection device, a region corresponding to the pupil is extracted from the captured image by performing binarization processing on the image obtained by capturing the eyeball, and the position and size of the pupil are measured based on this, or Further, the center position of the pupil is detected.

Also, as such a pupil detection device, a goggle type measurement device is mounted on the face of a subject in order to reduce the size of the device and simplify the measurement, and the eyeball is imaged by this measurement device. Has also been proposed.
JP 2001-178679 A JP 2003-102124 A

  When an eyeball is imaged by an imaging unit such as a CCD camera, the outer edge side of the captured image has a greater distortion of the image due to lens distortion than the center of the captured image. The outer edge is hard to focus. For this reason, when measuring especially the pupil of an eyeball, it is preferable that the pupil is located in the center of the captured image of imaging parts, such as a CCD camera.

  However, since there are individual differences in the position of the eyeball and the width between the two eyeballs, it is difficult to accurately position the pupil of the subject at the center of the captured image of the imaging unit as described above. . In particular, when a goggle type measuring device is used, it is conceivable that the position of the pupil in the imaging unit is shifted due to the positional shift of the measuring device with the measuring device mounted.

  The present invention has been made in view of the above points, and in detecting the pupil by imaging the eyeball of the subject, by automatically adjusting the position of the pupil in the captured image of the imaging unit, An object of the present invention is to provide a pupil detection device and a pupil detection method capable of simply detecting a pupil.

  The pupil detection device according to the present invention includes an imaging unit 1 that images a subject's eyeball E, and an imaging unit drive unit 16 that moves the imaging unit 1 and changes its arrangement position. The center position 21 of the region corresponding to the pupil P in the captured image 23 by the imaging unit 1 is derived, the center position 21 of the derived pupil P, and the optimal center position 22 in setting the pupil P in the captured image 23 , And based on the derived difference, the imaging unit driving unit 16 causes the imaging unit 1 to place the center position 21 of the pupil P in the captured image 23 at the optimal center position 22 in the setting. Is provided to change the arrangement position of the image pickup unit 1 by controlling the driving of the image pickup unit 1.

  In this way, when the pupil P is located at the outer edge of the field of view of the imaging unit 1 and interferes with accurate detection of the pupil P, the imaging unit 1 is automatically moved to an appropriate position, It is possible to accurately detect the pupil P.

  The image display means 4 for displaying the image 20 and projecting it toward the eyeball E of the subject, and the image display means drive unit 18 for moving the image display means 4 and changing the arrangement position thereof are provided. 3 may be provided to change the arrangement position of the video display means 4 by drivingly controlling the video display means drive section 18 in conjunction with the movement of the imaging section 1 by the imaging section drive section 16. In this way, the video 20 by the video display means 4 can be used as a target for nystagmus examination, and the positional deviation of the video 20 can be corrected in the same manner as the position of the pupil P. Is.

  Further, the image display means 4 for displaying the image 20 and projecting the image 20 toward the eyeball E of the subject is provided. The video 20 displayed in the above may be provided to change the position in the screen. In this way, the video 20 by the video display means 4 can be used as a target for nystagmus examination, and the positional deviation of the video 20 can be corrected in the same manner as the position of the pupil P. Is. Further, the positional deviation of the video 20 can be corrected without providing a drive mechanism for moving the arrangement position of the video display means 4.

  In the pupil detection method according to the present invention, the eyeball E of the subject is imaged by the imaging unit 1, the center position 21 of the pupil P in the obtained captured image 23 is derived, and the derived center position 21 of the pupil P is obtained. And a center position 22 of the pupil P in the captured image 23 is derived, and based on the derived difference, the center position 21 of the pupil P in the captured image 23 is the optimal center position of the setting. The arrangement position of the image pickup unit 1 is changed so as to be arranged at 22.

  According to the present invention, when detecting the pupil by imaging the eyeball for nystagmus examination or the like, it is possible to drive the imaging unit by automatic control and move the position of the pupil in the captured image to a predetermined position. Thus, accurate and simple pupil detection can be performed.

  Hereinafter, the present invention will be described based on the best mode for carrying out the invention. Described below is an example when the pupil detection device according to the present invention is formed as an nystagmus examination device.

  In the embodiment shown in FIG. 1, the pupil detection device includes an imaging unit 1 that images the subject's eyeball E, a display unit 2 that displays the captured image, and an arithmetic control unit 3 that controls the operation of the device. It has.

  The imaging unit 1 can be housed in a goggle type measuring device 10 as shown in FIG. As this imaging part 1, what comprises a CCD camera, a CMOS sensor, etc. can be provided, for example.

  The goggle-type measuring device 10 is configured by providing a holding member 12 such as a belt on a main body 11 that holds two sets of optical units as will be described later. When the subject wears the measuring device 10, the body 11 is held and fixed by, for example, wrapping a holding member 12 such as a belt around the head of the subject while the body 11 is positioned in front of the subject's eyes. Is.

  The display unit 2 can be formed by a liquid crystal display panel, a CRT display, or other appropriate video display device, and is provided in a control device 13 separate from the measurement device 10 as shown in FIG. Can do. An arithmetic control unit 3 can also be provided in the control device 13. Information exchange between the measuring device 10 and the control device 13 can be performed by a cable 15 or the like connecting the devices.

  FIG. 1 shows an example of the configuration of an optical system including the imaging unit 1 in the measurement apparatus 10. As shown in the figure, the optical system of the pupil detection device of the present embodiment includes a concave mirror 5 disposed so as to face the eyeball E when the subject wears the measuring device 10, and the eyeball E and the concave mirror 5. And a half mirror 6 to be arranged. The half mirror 6 is inclined about an axis in a direction orthogonal to a line connecting the eyeball E and the concave mirror 5. Further, the image display means 4 such as a small liquid crystal panel and the image pickup unit 1 such as a CCD camera disposed with the half mirror 6 interposed therebetween are provided. And the line connecting the concave mirror 5 and the tilt axis of the half mirror 6 are orthogonal to each other. Further, one surface of the half mirror 6 faces in an inclined state toward the eyeball E and the imaging unit 1, and the other surface of the half mirror 6 faces in an inclined state toward the video presentation means 4 and the concave mirror 5. Yes. In this embodiment, two such optical systems are provided so as to correspond to both eyes of the subject.

  Further, in the present embodiment, infrared light irradiating means 9 such as an infrared light emitting diode which is located near the subject's eyeball E and irradiates the subject's eyeball E with infrared light is provided, and the imaging unit 1 is an infrared transmission type. The filter 8 is provided and has sensitivity to infrared rays. The half mirror 6 is provided with a wavelength selection layer 7 that is formed by coating on the surface on the imaging unit 1 side and reflects infrared light.

  The imaging unit 1 includes an imaging unit driving unit 16 for moving the arrangement position of the imaging unit 1, thereby enabling the arrangement position to be moved on a plane perpendicular to the light receiving direction of the imaging unit 1. Is formed. At this time, the imaging unit 1 is formed to be drivable, for example, so as to slide in the biaxial directions perpendicular to each other on the plane. Here, for example, the imaging unit driving unit 16 includes a slide support base 17 that supports the imaging unit 1 so as to be slidable in one axis direction, and the imaging unit 1 receives a driving force from an actuator configured by a stepping motor or the like. Thus, it can be driven in the axial direction. The slide support base 17 is supported so as to be slidable in another axial direction orthogonal to the axial direction with respect to the apparatus main body 11, and the slide support base 17 is driven by an actuator constituted by a stepping motor or the like. It is configured to be able to be driven in the axial direction under force. Thereby, the imaging part 1 can be formed so that a drive is possible to a biaxial direction (front-back, left-right direction).

  At this time, the imaging unit 1 is formed so as to be driven with respect to the apparatus main body 11. For this reason, the imaging unit 1 is driven with respect to the half mirror 6 and the concave mirror 5 that are fixedly provided in the apparatus main body 11. Is formed.

  The arithmetic control unit 3 is a control composed of necessary software, storage means such as a memory for storing information on the captured image 23, information on the calculation result, and a CPU for performing operation control and arithmetic processing of various devices. It can be composed of means or the like. The arithmetic control unit 3 performs image processing of a captured image captured by the imaging unit 1, generation of a video to be presented to the video presentation unit 4, operation control of the imaging unit driving unit 16, the video presentation unit driving unit 18, and the like. The operation control of the entire pupil detection device according to the present invention is performed. A specific example of operation control will be described later.

  In addition, various functions can be added to the pupil detection device as necessary. For example, when used as a nystagmus inspection device, analysis for performing rhythm fluctuation analysis from time-series data of the measured movement of the eyeball E Function, estimation function to estimate whether nystagmus is an abnormality caused by peripheral disease of the subject's body or an abnormality caused by central system disease, display that displays the analysis result and estimation result as diagnostic support data, for example Functions and the like can be added. An analysis function, an estimation function, and the like can be provided in the arithmetic control unit 3 or a separate device can be provided. In order to provide a display function, for example, a printing device such as a printer, or a display device 14 such as a CRT display or a liquid crystal display can be provided.

  The operation of the above pupil detection device will be described below.

  First, the video display means 3 displays the video 20 with the subject wearing the measuring device 10. As the video 20, a visual target for inducing reciprocation of the eyeball E of the subject, for example, a display in which a striped pattern having a plurality of vertical lines moves as time passes is displayed.

  A part of the light emitted from the image display means is reflected by the half mirror 6 toward the concave mirror 5 side, and further reflected by the concave mirror 5 and reflected by the concave mirror 5, as indicated by solid arrows in FIG. Is transmitted through the half mirror 6 and enters the eyeball E of the subject. At this time, the subject sees an enlarged virtual image.

  Further, the infrared light irradiated from the infrared light irradiation means 9 toward the eyeball E of the subject is transmitted through the pupil P of the eyeball E, but is reflected at portions other than the pupil P as shown by solid arrows in FIG. Then, most of the reflected light is reflected by the half mirror 6 and received by the imaging unit 1, whereby an image of the eyeball E is captured.

  The arithmetic control unit 3 extracts a region corresponding to the pupil P from the captured image 23 of the eyeball E as shown in FIG. 5A captured by the imaging unit 1 by an appropriate image processing method. At the same time, the center position 21 of the region is derived. Extraction of the region corresponding to the pupil P can be performed by applying an appropriate image processing technique. For example, by binarizing the captured image 23, the region corresponding to the pupil P from the captured image 23 Can be extracted. The derivation of the center position 21 of the region is, for example, by deriving a circle inscribed in the region corresponding to the pupil P and deriving the center of this circle as the pupil center position 21 or by extracting the region of the pupil P. Can be derived as the center position 21 of the pupil P. In this case, the center position 21 of the pupil P can be quickly and easily derived even if the extracted pupil P region is not a perfect circle or the contour of the pupil P region is wobbled. it can.

  When the center position 21 of the pupil P is measured as described above, a difference between the preset optimum center position 22 of the pupil P and the measured center position 21 of the actual pupil P is derived. This difference can be derived as a difference (Δx, Δy) between the values of the coordinates of the two axes in the preset plane coordinate system.

  Based on the difference value obtained above, the amount of movement of the imaging unit 1 is derived, and the imaging unit drive unit 16 drives the imaging unit 1 (see FIG. 2). As a result, the center position 21 of the actual pupil P is arranged at the setting position of the pupil center in the captured image 23 (see FIG. 5B).

  When moving the imaging unit 1 as described above, for example, the optical path length from the eyeball E to the imaging unit 1 may change as in the case where the imaging unit 1 is moved in the front-rear direction in the present embodiment. In this case, it is preferable to form the imaging unit 1 so that it can be driven along the incident direction of the light to the imaging unit 1 or to be able to adjust the lens so that focusing can be performed. It is preferable to use the imaging unit 1 having an automatic focusing function.

  Further, when the image pickup unit 1 is driven to adjust the center position 21 of the pupil P in the picked-up image 23 and the arrangement position thereof is changed, the arrangement position of the video display means 3 is also changed accordingly. It is preferable to do. That is, when the center position 21 of the pupil P in the captured image 23 is deviated from the set position, the position of the image projected from the image display means 3 toward the eyeball E is also deviated. In order to correct the deviation, the image display means 3 is moved.

  At this time, the image display means 3 includes the image display means drive section 18 like the imaging section 1, and can be formed so as to be slidable in, for example, biaxial directions orthogonal to each other on the plane. Here, for example, the video display means driving unit 18 includes a slide support 19 that supports the video display means 3 so as to be slidable in one axis direction, and the video display means 3 is driven from an actuator constituted by a stepping motor or the like. It is configured to be able to be driven in the axial direction by receiving a force. The slide support base 19 is supported so as to be slidable in another axial direction orthogonal to the axial direction with respect to the apparatus main body 11, and the slide support base 19 is driven by an actuator composed of a stepping motor or the like. It is configured to be able to be driven in the axial direction by receiving a force. Thereby, the video display means 3 can be formed so as to be driven in the biaxial direction (front-rear and left-right directions). By driving the video display means 3 in this way, the arrangement position of the video 20 displayed on the video display means 3 can be changed (see FIG. 3).

  The amount of movement of the image display means 3 is derived based on the difference between the setting position of the pupil center and the measured center position 21 of the actual pupil P, as in the case of the imaging unit 1.

  Further, the display position of the video 20 displayed on the video display means 3 in the screen may be moved without moving the video display means 3. In this case, the video display means 3 is driven. The position of the image 20 projected on the eyeball E can be corrected without the need for a drive mechanism. The amount of movement of the image 20 in this case is derived based on the difference between the setting position of the pupil center and the measured center position 21 of the actual pupil P (see FIG. 4).

  In this way, the position of the center of the pupil P in the captured image 23 is adjusted, or the position of the video 20 displayed on the video display means 3 is further adjusted, and then the view displayed on the video display means 3 is displayed. An eye movement is induced by moving a mark, for example, a striped pattern having a plurality of vertical lines as time passes, and in this state, a change in the center position of the pupil P is measured. The measurement of the center position of the pupil P can be performed by an appropriate image processing method as in the case described above. By repeating such processing, the center position 21 of the pupil P based on the eye movement can be measured. A change with time can be detected, whereby the movement of the eyeball E can be measured.

  When performing nystagmus examination, rhythm fluctuation analysis is performed from the measured time series data of the movement of the eyeball E, and the result is displayed on a printing device such as a printer, or a display device 14 such as a CRT display or liquid crystal display. Can be displayed. In addition, it may be estimated whether the nystagmus is an abnormality caused by a peripheral disease of the subject's body or an abnormality caused by a central disease, and the result may be displayed in the same manner as described above.

  The pupil detection device according to the present invention can be suitably applied to nystagmus examination as described above, but is not limited thereto.

It is a schematic block diagram which shows an example of embodiment of this invention. It is a schematic block diagram which shows operation | movement same as the above. It is a schematic block diagram which shows other operation | movement same as the above. It is a schematic block diagram which shows the other example of embodiment of this invention. (A) And (b) is the schematic which shows the captured image which imaged the eyeball P by the imaging part. It is a perspective view which shows an example of the external appearance of a measuring apparatus. It is a front view which shows an example of the external appearance of a control apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image pick-up part 3 Computation control part 4 Image | video display means 16 Image pick-up part drive part 18 Image | video display means drive part 20 Image | video 21 Center position 22 Center position 23 Captured image E Eyeball P Pupil

Claims (4)

  A center position of a region corresponding to a pupil in an image captured by the imaging unit as an arithmetic control unit, which includes an imaging unit that images the eyeball of the subject and an imaging unit driving unit that moves the imaging unit and changes its arrangement position And the difference between the derived pupil center position and the optimum center position of the pupil in the captured image is derived, and based on the derived difference, the imaging unit determines the pupil position in the captured image. A pupil detection device comprising: a device that drives and controls the image pickup unit drive unit so as to change the arrangement position of the image pickup unit so that the center position is arranged at an optimal center position on setting.   An image display means for displaying an image and projecting it toward the eyeball of the subject, and an image display means drive unit for moving the image display means to change the arrangement position thereof. The pupil detection device according to claim 1, further comprising: a device that drives and controls the video display unit driving unit to change the arrangement position of the video display unit in conjunction with the movement of the imaging unit.   A screen of video displayed on the video display means in conjunction with the movement of the imaging unit by the imaging unit drive unit as an arithmetic control unit, including video display means for displaying the video and projecting it toward the eyeball of the subject The pupil detection device according to claim 1, further comprising a device that changes a position in the eye.   The subject's eyeball is imaged by the imaging unit, and the center position of the pupil in the obtained captured image is derived, and the difference between the derived pupil center position and the optimum center position of the pupil in the captured image is determined. A pupil detection method comprising: deriving and changing an arrangement position of the imaging unit based on the derived difference so that the center position of the pupil in the captured image is arranged at an optimal center position on setting.

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