Optics: eye examining – vision testing and correcting – Eye examining or testing instrument – Objective type
Reexamination Certificate
1999-10-29
2001-05-01
Manuel, George (Department: 3737)
Optics: eye examining, vision testing and correcting
Eye examining or testing instrument
Objective type
Reexamination Certificate
active
06224212
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a fundus measuring apparatus for measuring a three-dimensional configuration of the fundus (fundus) on the basis of stereoscopic images of the fundus as well as a recording medium with a fundus measurement program recorded thereon.
It is said that the observation of the optic disc (hereafter simply referred to as the disc) through an image of the fundus is important as the diagnosis of glaucoma which is known as one of disorders in the visual function. In recent years, apparatuses have been proposed in which a three-dimensional configuration of the fundus is measured on the basis of stereoscopic images of the fundus photographed by a stereoscopic fundus camera, and the cup of the disc and a peripheral portion of the disc are analyzed quantitatively.
The method of measuring the three-dimensional information of the fundus on the basis of stereoscopic images of the fundus is generally known as a stereoscopic matching method, and in obtaining height information it is important to extract corresponding spots (corresponding points) in left and right images. To accurately effect the extraction of corresponding spots, it is necessary to determine an amount of deviation (hereafter referred to as the parallax) of the overall image due to an refractive error of the photographed eye, to thereby cause the left image and the right image to correspond to each other. Conventionally, the parallax is determined on the basis of a characteristic point such as a branching point of a blood vessel or the like on the fundus to cause the left and right images to correspond to each other.
However, there are cases where the contrast in the photographed stereoscopic images of the fundus is not good, and if a branching point of the blood vessel is unclear, the accuracy in correspondence between the left and right images is often poor, often making the measurement impossible. In addition, since the measurement of the parallax based on the branching point of the blood vessel relies on two-dimensional measurement, there has been a problem in that a long processing time is required.
Still further, the extraction of corresponding spots from the left and right images causes a problem in which the overall processing time is long, since to search for pixels (region) which are best in conformity with specific pixels (specific region) of one image, the other image must be searched minutely over a certain range.
SUMMARY OF THE INVENTION
In view of the above-described problems, an object of the present invention is to provide a fundus measuring apparatus and a recording medium with a fundus measurement program recorded thereon, which are capable of accurately measuring the three-dimensional configuration of the fundus on the basis of stereoscopic images of the fundus in a short processing time.
The present invention provides the followings:
(1) A fundus measuring apparatus for measuring a three-dimensional configuration of a fundus on the basis of a stereoscopic image of the fundus, the apparatus comprising:
input means for inputting the stereoscopic image of the fundus;
image extracting means for extracting left and right images from the stereoscopic image of the fundus thus inputted by the input means; and
three-dimensional configuration generating means for generating a three-dimensional configuration of the fundus on the basis of the left and right images thus extracted by the image extracting means.
(2) The fundus measuring apparatus according to (1), wherein the image extracting means includes:
integration means for integrating horizontal and vertical density information on the stereoscopic image of the fundus thus inputted by the image input means to obtain integral values;
threshold setting means for setting at least one threshold for the integral values thus obtained by the integration means; and
background separating means for separating the left and right images from a background using coordinates obtained on the basis of the integral values and the at least one threshold value thus set by the threshold setting means.
(3) The fundus measuring apparatus according to (1), wherein the image extracting means includes:
integration means for integrating at least one of horizontal and vertical density information on the stereoscopic image of the fundus thus inputted by the image input means to obtain integral data;
differential means for differentiating the integral data thus obtained by integration means to obtain differential data; and
parallax measuring means for obtaining a parallax on the basis of the differential data thus obtained by the differential means.
(4) The fundus measuring apparatus according to (3), wherein the parallax measuring means obtains the parallax on the basis of maximum cross correlation values of the differential data obtained by the differential means.
(5) The fundus measuring apparatus according to (1), wherein the image extracting means includes image separating means for excluding an image region which does not exist commonly on the left and right images.
(6) The fundus measuring apparatus according to (1) further comprising:
corresponding spots extracting means for generating multiple-resolution images whose resolutions are consecutively lowered with respect to the left and right images extracted by the image extracting means, and extracting corresponding spots from the left and right images using the multiple-resolution images in order starting from the lowest one of the multiple-resolution images; and
wherein the three-dimensional configuration generating means generates the three-dimensional configuration of the fundus on the basis of the corresponding spots thus obtained.
(7) The fundus measuring apparatus according to (1), wherein the image input means is equipped with a fundus camera for photographing the stereoscopic image of the fundus.
(8) The fundus measuring apparatus according to (1) further comprising:
output means for visually outputting the three-dimensional configuration of the fundus thus generated by the three-dimensional image generating means.
(9) A recording medium storing therein a program that is to be executed by an operating and analyzing unit to measure a three-dimensional configuration of a fundus on the basis of a stereoscopic image of the fundus, the program comprising:
an image extracting step of extracting left and right images from an inputted stereoscopic image of a fundus; and
a three-dimensional-configuration generating step of generating a three-dimensional configuration of the fundus on the basis of the left and right images thus extracted.
(10) The recording medium according to (9), wherein the image extracting step includes the steps of:
integrating horizontal and vertical density information on the inputted stereoscopic image of the fundus to obtain integral values;
setting at least one threshold for the integral values thus obtained by the integrating step; and
separating the left and right images from a background using coordinates obtained on the basis of the integral values and the at least one threshold value thus set by the setting step.
(11) The recording medium according to (9), wherein the image extracting step includes the steps of:
integrating at least one of horizontal and vertical density information on the inputted stereoscopic image of the fundus to obtain integral data;
differentiating the integral data thus obtained by integrating step to obtain differential data; and
obtaining a parallax on the basis of the differential data thus obtained by the differential step.
(12) The recording medium according to (9), wherein the image extracting step includes an image separating step of excluding an image region which does not exist commonly on the left and right images.
(13) The recording medium according to (9), wherein the program further comprises:
a corresponding spots extracting step of generating multiple-resolution images whose resolutions are consecutively lowered with respect to the left and right images extracted by the image extracting step, and extracting corr
Hayashi Norimasa
Noda Manabu
Manuel George
Nidek Co. Ltd.
Sughrue Mion Zinn Macpeak & Seas, PLLC
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