JP2006333902A - Method for detecting foreign matter and apparatus for observing eyeball - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem that the eyelashes located in front of the eyeball are difficult to detect because of blurring while observing the eyeball. <P>SOLUTION: An apparatus is provided which comprises an imaging means 101 for imaging the eyeball to acquire a first image 102 and a second image 103, a focusing means 104 for moving the imaging means 101 in the focal axis direction in order to focus the imaging means on the iris region, a foreign matter detection means 105 for detecting a foreign matter by calculating difference data which show the differences in relative positions of the iris and pupil regions with respect to the eyelashes located in front of the eyeball between the first and second images 102 and 103, and an observation means 112 for carrying out a desired observation of the first and second images when the foreign matter detection means 105 does not detect a foreign matter. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a technique for detecting foreign matter such as eyelashes located in front of an eyeball, which becomes an obstacle when observing the eyeball.

  In addition to ophthalmologic devices such as a fundus camera device, a cornea shape photographing device, and a tonometer, an iris authentication device has recently been put into practical use as a device for observing an eyeball, and a noninvasive blood sugar level measurement method using an eyeball has been proposed. ing. In such an apparatus for observing the eyeball, the presence of foreign matter including eyelids or eyelashes in the observation region is often a problem, and techniques for canceling the influence of foreign matter and detecting foreign matter have been proposed so far. Yes.

  As one of them, a foreign object is detected by binarizing from an image obtained by capturing an eyeball using a difference in luminance value between the eyeball and the foreign object, and brightness (shading) or color in the image changes suddenly. There is a method of detecting a foreign substance from the shape and size of an outline by performing so-called edge detection that detects a location.

In addition, a parallel plane plate that changes the optical path length is prepared, and the region where the image captured by the CCD camera for alignment passes through the parallel plane plate is focused on the eyeball, and the region that does not pass is focused near the eyelashes. There is a technology to arrange to do so. Specifically, by arranging a parallel plane plate in a region other than the region above the eyeball, where the eyelash is likely to be applied, when the user looks at the image of the CCD camera for alignment, the eyelash is aligned with the region focused on the eyeball. A dark area can be observed, and the presence or absence of eyelashes can be detected. (For example, refer to Patent Document 1).
JP-A-4-285527

  By the way, an apparatus for observing an eyeball requires accurate positioning with respect to the eyeball. For example, in a non-contact tonometer, very strict alignment is required, and an optical system with a shallow focal depth is often used in order to perform alignment in the focal axis direction with high accuracy.

  In such an apparatus, when an eyeball image is acquired with correct alignment in the focal axis direction, the eyelashes are blurred, making it almost indistinguishable from the pattern of the iris region. Therefore, in an image in which blurred eyelashes or foreign objects are present, naturally, the method of binarization or edge detection cannot detect foreign objects, and furthermore, accurate eyeball observation cannot be performed. There are challenges.

  In the configuration using the plane parallel plate, the alignment CCD camera is focused on an area that the user wants to observe (hereinafter referred to as an observation area) to perform alignment in the focal axis direction. As described above, since the parallel flat plate is inserted in the observation region, there is a problem that the eyelashes in the observation region cannot be detected.

  Therefore, an object of the present invention is to provide a foreign object detection method and an eyeball observation device that detect foreign objects such as eyelashes even when the eyeball is observed, even when the eyeball is in focus.

  In order to solve the above-described conventional problem, the foreign object detection method of the present invention acquires first imaging data and second imaging data in which the relative positions of the subject's iris and pupil region and the foreign substance located in front of the eyeball are different from each other. The imaging data acquisition step, the iris image and the pupil region in the first imaging data and the second imaging data are aligned so as to be at the same position, and imaging of the same size is performed from the first and second imaging data A registration step of partially selecting data and outputting as the aligned first imaging data and the aligned second imaging data; and the alignment first imaging data and the aligned second imaging data It is characterized by comprising a difference data calculation step for calculating difference data, and a foreign matter determination step for determining the presence or absence of a foreign matter from the difference data.

  In addition, the eyeball observation apparatus of the present invention performs imaging on the eyeball of the subject, and acquires first imaging data and second imaging data in which the relative positions of the iris and pupil region and the foreign substance located in front of the eyeball are different from each other. Imaging means; foreign object detection means for detecting foreign objects using difference data obtained from the relative positions of foreign objects located in front of the iris and pupil area and the eyeball in the first imaging data and the second imaging data; It is characterized by providing.

  As described above, according to the foreign matter detection method and the eyeball observation apparatus of the present invention, when the eyeball is observed, the eyelashes and foreign matter are focused even when the eyelash is focused on the imaging region and the eyelashes are blurred on the imaging data. Detection can be performed.

  Embodiments of a foreign object detection method and an eyeball observation apparatus according to the present invention will be described below in detail with reference to the drawings.

(Embodiment 1)
Hereinafter, an embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 is a block diagram of a foreign object detection method and an eyeball observation device according to Embodiment 1 of the present invention.

  In FIG. 1, an imaging unit 101 includes a light receiving element that captures an eyeball 100 of a subject and a lens unit in front of the light receiving element, and the light receiving element is, for example, a CCD (Charge-Coupled Devices). The imaging unit 101 acquires the first image 102 and the second image 103. Here, since the light is acquired, the imaging data is referred to as an image. The light includes visible light as well as ultraviolet light and infrared light.

  FIG. 2A shows the first image 102 and FIG. 2B shows the second image 103. Usually, when the first image 102 and the second image 103 are imaged at a time interval, the eyeball of the subject moves not a little, and the iris and pupil region A like the first image 102 and the second image 103. The relative position of the eyelashes B often changes. Note that the lens unit is a lens having a shallow depth of focus as in Patent Document 1 described above, and when focusing on the iris and pupil region A, the eyelashes B are blurred. Although the image of FIG. 2 shows eyelashes, it is actually blurred and indistinguishable from the iris pattern. For the sake of explanation, this is emphasized.

  Returning to FIG. 1, the focusing unit 104 moves the imaging unit 101 in the direction of the focal axis to focus on the iris and pupil region of the eyeball 100. For example, the focusing unit 104 first extracts an iris region from the image captured by the imaging unit 101 and calculates the contrast of the iris region. Then, the imaging unit 101 is moved in the focal axis direction by a stepping motor or the like according to the contrast. The imaging means 101 is arranged at a position in the focal axis direction where the highest contrast is obtained by using the hill climbing method or the like as described above. In the iris region extraction method, an image is differentiated to extract an edge, binarization is performed, and pattern matching is performed with a circle. The inside of the circle when it is the best match is the pupil region, and the region outside the circle is the iris region. The contrast calculation method is obtained, for example, by extracting high frequency components, taking the sum, and dividing by the number of pixels.

  The foreign object detection means 105 detects foreign objects such as eyelashes based on differences in the relative positions of the iris and pupil regions of the first image 102 and the second image 103 and the eyelashes and foreign objects. Specifically, the difference between the alignment means 106 that aligns the iris and pupil area of the first image 102 and the second image 103 at the same position on the image, the difference between the aligned first image 107 and the aligned second image 108. A foreign substance determination unit 111 that determines eyelashes from the data calculation unit 109 and the difference data 110 is provided.

  Each block will be described in detail below. The alignment means 106 obtains the center coordinates of the pupils of both images and aligns them so that they are at the same position on the images. Specifically, first, the center coordinates of the pupils of the two images acquired by the imaging unit 101 are obtained. For example, first, the image is differentiated to extract the edge. Next, binarization is performed and pattern matching is performed with a circle. The center of the circle when it most closely matches is the pupil center coordinate, the pupil center coordinate of the first image 102 is (x1C, y1C), and the pupil center coordinate of the second image 103 is (x2C, y2C).

  Next, the image is moved in the horizontal and vertical directions so that the obtained pupil center coordinates of the first image 102 and the second image 103 are at the same position on the image. This time, the pupil center coordinates of both images are moved to (x1C, y1C). That is, the second image 103 is moved by (x1C-x2C, y1C-y2C) without moving the first image 102. It should be noted that pixels protruding from the image due to movement are discarded, and the luminance value of pixels without an image is padded with, for example, 0, that is, 0 is inserted into the luminance value.

  Finally, the first image 102 and the second image 103 thus aligned are output as the aligned first image 107 and the aligned second image 108, respectively. FIG. 3A shows the aligned first image 107, and FIG. 3B shows the aligned second image 108. In the figure, a blacked portion indicated by D is a padded area.

  Further, the alignment unit 106 may perform alignment by moving the images so that the iris patterns of the two images match. Specifically, a template image is arbitrarily selected from the second image 103 as shown in FIG. Preferably, how much the eyeball moves is determined from experience or as a specification, and an area other than the area from the edge of the image to the inside by the movement amount is selected. Here, it is assumed that the region shown in the second image 103 in FIG. 2 is selected as the template image C, and the upper left coordinates of the template image C are (x2RU, y2RU). Next, template matching is performed on the first image 102 using the selected template image, and the upper left coordinates (x1RU, y1RU) at the time of the best match are obtained. Then, in the same manner as the above-described alignment method using the center coordinates of the pupil, the coordinates (x1RU, y1RU) of the first image 102 and the coordinates (x2RU, y2RU) of the second image 103 are the same position on the image. Align. The difference data calculation unit 109 subtracts the luminance value of the aligned second image 108 from the aligned first image 107 at each pixel, and outputs the subtracted value as the difference data 110.

  Although the difference data 110 is shown in FIG. 4, the difference data 110 can take a negative value. Therefore, for convenience, a small area including the value 0 is indicated by hatching with a grid-like diagonal line. The area is indicated by a black fill, and the area having a larger positive value is displayed as a white fill. Further, although the iris and pupil contours do not appear in the difference data, the iris and pupil region contours are shown as solid lines for the sake of convenience.

  The absolute value of the difference data 110 has a large value in the area where the eyelashes are applied, and a relatively small value in the other areas. The reason why the value does not become 0 in the other areas is that there is actually a difference in luminance value due to a slight positional shift between the aligned first image 107 and the aligned second image 108 and variations in CCD sensitivity for each imaging. Because there is. The foreign substance determination unit 111 detects eyelashes from the difference data 110. Specifically, first, an appropriate value as the threshold S for the difference data 110 in FIG. 4 is set to an equal value from experience, and the value of each pixel is −S or less or S or more (FIG. 4). B1 and B2) are determined to have eyelashes on the pixels. Of course, the threshold value may be divided into a negative threshold value Sn and a positive threshold value Sp, and different values may be set for Sn and Sp.

  Thus, the aligned first image 107 is an image obtained by adding the image of the eyeball and the image of the eyelashes positioned in front of the eyeball, and the image of the eyelashes is blurred and is buried in the image of the eyeball. I can't distinguish. Therefore, by taking the difference between the aligned first image 107 and the aligned second image 108, it is possible to extract only the difference between the two images, that is, the image of the eyelashes.

  Further, when the value of the difference data 110 of the region determined to be eyelash is negative (B1), it can be determined that the first image 102 is positive, and when it is positive (B2), the second image 103 is determined to be eyelash.

  At this time, if the determination is made as described above up to the area A1 padded by the alignment means 106, the area A1 is also detected as a foreign object. Therefore, preferably, the area to be determined is other than the area A1. . Furthermore, when it is desired to detect whether or not the eyelashes are applied to a region (hereinafter referred to as an observation region) observed by the observation means 112 described later, the region to be determined can be only the observation region.

  The threshold value S may be the value of either the left or right of the pupil region where eyelashes are difficult to be applied, or both iris regions. For example, the average value m and the standard deviation σ of the difference data 110 of the right iris region A2 of the pupil region shown in FIG. 4 are obtained, and the negative threshold Sn is m−σ and the positive threshold Sp is m + σ. σ can be used in place of 2σ or 3σ as required. In addition, the minimum value of the difference data 110 between the left and right iris regions of the pupil region may be Sn and the maximum value may be Sp. In this way, by using the values of the left and right iris regions of the pupil region where eyelashes are difficult to be applied to the threshold value S or Sn, Sp, the first image 107 and the second image 108 that have been aligned that change with each imaging are used. An appropriate threshold value can be set according to the positional deviation and the difference in luminance value.

  Further, even if the difference data 110 is an area where no foreign matter is applied, the absolute value is not 0. Even if the alignment is mainly performed, a slight misalignment has already been aligned with the aligned first image 107. This is because the second image 108 exists. At this time, the absolute value of the difference data 110 is relatively large in a region with a high contrast, and the absolute value of the difference data 110 is relatively small in a region with a low contrast, even if the positional deviation is similar. Therefore, a large value may be set for the threshold S when the image contrast is high, and a small value may be set for the threshold S when the image contrast is small. The contrast is obtained, for example, by extracting high frequency components of the image, taking the sum, and dividing by the number of pixels. Then, the contrast is multiplied by an experientially appropriate coefficient, and this is used as the threshold value S.

  Although the difference data 110 has a negative value, the positive value and the negative value can be separated and handled as one image each. Therefore, in addition to this, an area having a luminance value of a certain size or a certain threshold value or more. The eyelashes can be detected by using various known image processing techniques for extracting.

  Next, when the observation unit 112 confirms that there is no eyelash in the observation region by the determination of the foreign matter determination unit 111, the observation unit 112 performs a desired observation of the observation region. If the eyelashes in the observation area are confirmed, no observation is performed. Further, when it is determined by the foreign matter determination means 111 that the observation area is covered with eyelashes, a measure such as re-taking the image is performed. Further, a television monitor or a speaker may be provided to notify the subject or user that the eyelashes have been detected by display or sound.

  A series of operations of the eyeball observation apparatus in FIG. 1 described above will be described. First, the imaging unit 101 is moved to a position where the focusing unit 104 is focused on the iris and pupil area of the eyeball. Next, the imaging unit 101 acquires the first image 102 and the second image 103. The alignment means 106 aligns the first image 102 and the second image 103 and outputs the aligned first image 107 and the aligned second image 108. The difference data calculation means 109 calculates and outputs the difference data 110 from the aligned first image 107 and the aligned second image 108. The foreign matter determination means 111 determines the presence or absence of eyelashes from the difference data 110. The observation unit 112 observes the observation area when the foreign matter determination unit 111 determines that there is no eyelash, and performs a process such as acquiring an image again when it is determined that there is eyelash.

  As described above, the difference between the relative positions of the iris and pupil area of the two images and the eyelashes is detected using the difference in the luminance values of the images, so that even the eyelashes blurred on the image can be detected. .

  Further, in the present embodiment, the eyelashes have been described as foreign matters, but other than that, dust, dust, eyelids, etc. located in front of the eyeball may be used.

  Furthermore, even if the image is clearly focused on the foreign object, the two images have a difference in the relative positions of the iris and pupil region and the foreign object, and if this appears as a difference in luminance value, the foreign object is detected. Can do.

  In addition, in order to improve noise removal and foreign object detection accuracy, a known filter technique or the like may be used as appropriate before and after each block.

(Embodiment 2)
Hereinafter, Embodiment 2 of the present invention will be described with reference to FIGS. 1, 5, and 6.
The block diagram of the eyeball observation apparatus in the second embodiment is the same as that in the first embodiment and is FIG. The difference from the first embodiment is a difference data calculation unit 109 and a foreign matter determination unit 111.

  First, the operation of the difference data calculation unit 109 will be described with reference to FIG. FIG. 5A shows the aligned first image 107, and FIG. 5B shows the aligned second image 108. The difference data calculation means 109 first divides the two images into small areas as shown in FIG. The upper left area is represented as P00, the first digit represents a row, and the second digit represents a column.

  Then, average luminance values mP00 to mP79 of each region are calculated. Further, an average luminance value mP other than the region D subjected to padding by alignment is obtained. Here, since the column of 0 is the region D, the average luminance value of the other region is obtained. Then, the average luminance value of each region is normalized by mP by dividing by mP. By so doing, it is possible to correct variations in the average luminance value of the two images.

  Next, the ratio is obtained by dividing by the average luminance value of the regions located in the same matrix of the two images. Region D is excluded. Here, the aligned first image 107 is divided by the aligned second image 108. The ratios are represented as aP01 to aP79, respectively. Finally, this ratio is output as the difference data 110.

  FIG. 6A shows the ratios aP12 to aP18 in a graph. In the figure, the vertical axis represents the ratio value, and the horizontal axis represents the region. The ratio of P12 to P15 with no eyelashes is a value in the vicinity of 1, but the ratio of P16 and P17 with eyelashes deviates significantly from 1 compared to other regions. Then, the ratio aP16 of the area where the eyelash is applied to the aligned first image 107 is 1 or less, and the ratio aP17 of the area where the eyelash is applied to the aligned second image 108 is 1 or more.

  Next, the foreign matter determination unit 111 sets positive and negative threshold values Sp and Sn, and determines that the eyelashes are applied if the value of the difference data 110 is equal to or greater than the threshold value Sp or less than the threshold value Sn. Determine that there is no eyelashes. The thresholds Sp and Sn may be set so that the absolute values of values obtained by subtracting 1 from experience are the same, but using the values of the iris regions on the left and right of the pupil as shown in FIG. Also good. For example, assuming that P31, P32, P37, P38, P41, P42, P47, and P48 are used, the ratio of these regions is shown in FIG. Then, by setting the maximum value in FIG. 6B to Sp and the minimum value to Sn, an appropriate threshold value can be set even for different images for each imaging due to the reason described in the first embodiment. Can be set.

  As described above, in the second embodiment, as the difference data 110, the aligned first image 107 and the aligned second image 108 are divided into small areas, and the ratio of the average luminance values of the respective areas is used. Thus, it is possible to detect blurred eyelashes by detecting differences in the relative positions of the iris and pupil regions of the two images and the eyelashes.

  In the second embodiment, the influence of the positional deviation between the aligned first image 107 and the aligned second image 108 can be reduced by dividing into small areas and using the average value of the luminance of each area. Further, by dividing the average luminance value of each region by the average luminance value other than the region D, variation in the average luminance value of the image can be corrected.

(Embodiment 3)
Embodiment 3 of the present invention will be described below with reference to FIGS. 2 and 7 to 11.

  FIG. 7 is a block diagram of an eyeball observation apparatus according to Embodiment 3 of the present invention. The difference from the first embodiment is that a relative position changing unit 701 is further provided.

  The relative position changing means 701 is a means for changing the relative positions of the iris and pupil region and the eyelashes by intentionally moving the eyeball so that the subject's line of sight changes. It has. The gaze point 702a and the gaze point 702b are light sources such as visible light LEDs (light emitting diodes), for example, and fix the line of sight of the eyeball to the gaze point by turning on the light source. Also, the gazing point 702a and the gazing point 702b are arranged at different positions, and preferably, the position in the vertical direction with respect to the eyeball is the same and only the position in the horizontal direction is different. This is because when the line of sight is changed in the vertical direction of the eyeball, the eyelashes are more likely to be applied to the iris and pupil region. By switching the gazing point that is turned on in this way, the line of sight can be switched to the gazing point 702a and the gazing point 702b.

  Next, the operation in the third embodiment will be described. First, the gaze point 702a is turned on to fix the line of sight. In this state, the imaging unit 101 acquires the first image 102. Next, the line of sight is switched by turning off the gazing point 702a and turning on the gazing point 702b. Then, the imaging unit 101 acquires the second image 103. Subsequent operations are the same as those in the first embodiment.

  As described above, by changing the line of sight, the position of the eyelash does not change, but only the eyeball moves, and the relative positions of the iris and pupil region and the eyelash can be changed reliably. Thereby, the first image 102 and the second image 103 as shown in FIG. 2 can be acquired, and the eyelashes can be reliably detected. Further, as shown in FIG. 8, the relative position changing unit 701 may be configured to include a gazing point moving unit 801 that moves the gazing point 702a and the gazing point 702a, and the gazing point moving unit 801 sets the gazing point 702a. The relative positions of the iris / pupil region and the eyelashes may be changed reliably by moving the imaging means 101 to the different positions and capturing the first image 102 and the second image 103. Note that the gazing point moving means 801 can use a stepping motor, for example.

  Further, as shown in FIG. 9, the relative position changing unit 701 may be a second imaging unit 901 that images the eyeball from a position different from the imaging unit 101, and the imaging unit 101 acquires the first image 102. The second imaging unit 901 is configured to acquire the second image 103.

  FIG. 10 shows the positional relationship among the eyeball, eyelashes, the imaging means 101, and the second imaging means 901. In FIG. 10, the broken arrow indicates the optical path of the imaging unit 101 and the second imaging unit 901, and the eyelash B in front of the eyeball 100 is reflected at the position E1 of the eyeball 100 in the image acquired by the imaging unit 101. In the image acquired by the second imaging unit 901, the image is captured at the position E2 of the eyeball 100. Therefore, even if the relative positions of the iris and pupil region and the eyelashes do not change, two images whose relative positions have changed on the image can be acquired, so that the eyelashes can be reliably detected.

  As shown in FIG. 11, the relative position changing unit 701 may be a moving unit 1101 that moves the imaging unit 101, and the imaging unit 101 is different from each other when the moving unit 1101 moves the imaging unit 101. The first image 102 and the second image 103 can be acquired from the position. The moving unit 1101 can move the imaging unit 101 using, for example, a stepping motor. Thus, as described above, two images whose relative positions have changed on the image can be acquired even if the relative positions of the iris and pupil region and the eyelashes do not change, so that the eyelashes can be reliably detected. .

  Since the foreign substance detection method and the eyeball observation apparatus according to the present invention can reliably detect foreign substances such as eyelashes, they are useful for apparatuses that accurately observe the eyeball such as various ophthalmologic apparatuses and iris authentication apparatuses.

Block diagram of the eyeball observation apparatus in Embodiment 1 of the present invention The figure which shows the 1st image 102 and the 2nd image 103 in embodiment of this invention The figure which shows the aligned 1st image 107 and the aligned 2nd image 108 in embodiment of this invention The figure which shows the difference data 110 in Embodiment 1 of this invention. The figure which shows the aligned 1st image 107 and the aligned 2nd image 108 in Embodiment 2 of this invention. The figure which shows the difference data 110 in Embodiment 2 of this invention. Block diagram of an eyeball observation apparatus in Embodiment 3 of the present invention Block diagram of an eyeball observation device in Embodiment 3 of the present invention Block diagram of an eyeball observation device in Embodiment 3 of the present invention The figure which shows the positional relationship of the eyeball, eyelashes, the imaging means 101, and the 2nd imaging means 901 in Embodiment 3 of this invention. Block diagram of an eyeball observation device in Embodiment 3 of the present invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Image pickup means 102 First image 103 Second image 104 Focusing means 105 Foreign matter detection means 106 Positioning means 107 Positioned first image 108 Positioned second image 109 Difference data calculation means 110 Difference data 111 Foreign matter determination means 112 Observation means 701 Relative position changing means 702a Gaze point 702b Gaze point 801 Gaze point movement means 901 Second imaging means 1101 Movement means

Claims (26)

An imaging data acquisition step of acquiring first imaging data and second imaging data in which the relative positions of the subject's iris and pupil region and the foreign substance located in front of the eyeball are different from each other;
Align the iris and pupil area in the first imaging data and the second imaging data so that they are at the same position, and select partially the same size imaging data from the first and second imaging data Then, an alignment step of outputting as aligned first imaging data and aligned second imaging data;
A difference data calculation step of calculating difference data between the aligned first imaging data and the aligned second imaging data;
A foreign matter determination step of determining the presence or absence of foreign matter from the difference data;
A foreign object detection method comprising: The foreign matter detection method according to claim 1, wherein the difference data is a difference between feature amounts indicated by the aligned first imaging data and the aligned second imaging data. In the foreign matter determination step, it is determined that a foreign matter exists when the absolute value of the difference data is a value equal to or greater than a predetermined threshold value, and it is determined that no foreign matter exists when the absolute value of the difference data is less than the threshold value. The foreign matter detection method according to claim 2. The foreign object detection method according to claim 1, wherein the difference data is a ratio of a feature amount indicated by the aligned first imaging data and the aligned second imaging data. The foreign matter determination step determines that there is a foreign object when the absolute value of a value obtained by subtracting 1 from the feature amount ratio is equal to or greater than a predetermined threshold value, and does not include a foreign object when the absolute value is less than the threshold value. The foreign object detection method according to claim 4, wherein the foreign object detection method is determined. 6. The foreign object determination step according to claim 3, wherein the foreign object is detected only in a desired region of the aligned first imaging data and the aligned second imaging data. Foreign object detection method. 6. The foreign object detection method according to claim 3, wherein the predetermined threshold value is set by using the value of the difference data obtained in the left and right iris regions of the pupil.   The said predetermined threshold value is set to the value which gave predetermined weight to the contrast of the said aligned 1st imaging data or the said aligned 2nd imaging data, The Claim 3 and Claim 5 characterized by the above-mentioned. Foreign object detection method.   The alignment step detects the center position of the pupil of the first imaging data and the second imaging data, and performs processing so that the center position of the pupil becomes the same position on the imaging data. Item 6. A foreign matter detection method according to Item 1.   The foreign object detection method according to claim 1, wherein the alignment step performs alignment by matching a pattern of an iris region of the first imaging data and the second imaging data. Imaging means for imaging the eyeball of the subject and acquiring first imaging data and second imaging data in which the relative positions of the iris and pupil region and the foreign substance located in front of the eyeball are different from each other;
Foreign matter detection means for detecting foreign matter using difference data obtained from the difference in relative position between the iris and pupil region and foreign matter located in front of the eyeball in the first imaging data and the second imaging data;
An eyeball observation apparatus comprising: The foreign object detection means includes
Align the iris and pupil area in the first imaging data and the second imaging data so that they are at the same position, and select partially the same size imaging data from the first and second imaging data Then, alignment means for outputting as the aligned first imaging data and the aligned second imaging data,
Difference data calculating means for calculating difference data between the aligned first imaging data and the aligned second imaging data;
Foreign matter determination means for determining foreign matter from the difference data;
The eyeball observation device according to claim 11, comprising:   The eyeball observation apparatus according to claim 12, wherein the difference data is a difference between feature amounts indicated by the aligned first imaging data and the aligned second imaging data.   The foreign matter determining means determines that a foreign matter is present when the absolute value of the difference data is a value equal to or greater than a predetermined threshold value, and determines that no foreign matter is present when the absolute value is less than the threshold value. The eyeball observation device according to claim 13.   The eyeball observation apparatus according to claim 12, wherein the difference data is a ratio of feature amounts indicated by the aligned first imaging data and the aligned second imaging data.   The foreign matter determining means determines that foreign matter is present when the absolute value of a value obtained by subtracting 1 from the feature amount ratio is equal to or greater than a predetermined threshold value, and no foreign matter is present when the absolute value is less than the threshold value. The eyeball observation device according to claim 15, wherein the eyeball observation device is determined.   The eyeball observation apparatus according to claim 14 and 16, wherein the foreign matter determining means determines a foreign matter only in a desired region in each of the aligned imaging data.   The eyeball observation apparatus according to claim 14 or 16, wherein the predetermined threshold is set using a value of the difference data obtained in the left and right iris regions of the pupil.   The predetermined threshold value is a value obtained by applying a predetermined weight to the contrast of the aligned first imaging data or the aligned second imaging data. Eye observation device.   The alignment unit calculates a center position of the pupil of the first imaging data and the second imaging data, and performs processing so that the center position of the pupil becomes the same position on the imaging data. Item 13. An eyeball observation device according to Item 12.   The eyeball observation apparatus according to claim 12, wherein the alignment unit performs alignment by matching patterns of iris regions of the first imaging data and the second imaging data. Relative position changing means for changing the relative position on the imaging data of the iris and pupil region and the foreign object by changing the line of sight of the subject,
Further comprising
The eyeball observation apparatus according to claim 11, wherein the relative position changing unit operates between the time when the imaging unit acquires the first imaging data and the time when the second imaging data is acquired. The relative position changing means is
Provided with a plurality of gazing points that are arranged at different positions in front of the eyeball and fix the line of sight,
23. The eyeball observation device according to claim 22, wherein the gazing point is switched and operated. The relative position changing means includes
A gazing point to fix the subject's gaze,
Gaze point movement means for moving the gaze point,
The eyeball observation apparatus according to claim 22, wherein after acquiring the first imaging data, the gazing point is moved by a gazing point moving unit, and then the second imaging data is acquired. The relative position changing means includes
A second imaging unit disposed at a position different from the imaging unit with respect to the eyeball;
23. The eyeball observation apparatus according to claim 22, wherein the imaging data obtained by the imaging means is first imaging data, and the imaging data obtained by the second imaging means is second imaging data. The relative position changing means is
Moving means for changing the position of the imaging means relative to the eyeball;
23. The eyeball observation apparatus according to claim 22, wherein after acquiring the first imaging data, the moving means moves the position of the imaging means to acquire second imaging data.

Images