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US 6,714,672 B1Granted
Automated stereo fundus evaluation
AssigneeCanon Kabushiki Kaisha
InventorsAlexander L. Berestov, Harry T. Garland
Life of this patent
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Abstract
A computer-implemented method and system for adjustment and matching of stereoscopic images (206, 208) of the eye fundus (106). Illumination errors between the images are eliminated, such as by adjusting groups of pixels so that the mean and variance of a group (306) from the left image (206) will have the same mean intensity and variance as the corresponding group (308) from the right image (208). An epipolar line adjustment is performed, such as by shifting points in the images based on matched points in the images. Image occlusion errors are detected and removed, such as by matching point analysis. Once these adjustment steps have been completed, a matching analysis can be preformed using the corrected images.
Claims16
A method for evaluating stereo images of an eye fundus, comprising the steps of:
- obtaining at least two images;
- correcting illumination errors in the images;
- adjusting epipolar lines associated with the images such that the images are vertically aligned;
- removing image occlusion errors in the images;
- and
- performing a matching analysis on the images;
- wherein the images are a first original image and a second original image and have at least some overlap area, and the step of adjusting epipolar lines comprises the substeps of:
- creating a left and a right search column on at least one of the original images, such that at least one of the columns includes at least part of the overlap area;
- creating two sets of gray-scale sub-images, one set of sub-images for each of the two original images;
- pairing the sub-images generated from the first original image with sub-images from the second original image such that a sub-image pair shares the same assigned color coordinate;
- running a matching algorithm on each point in the right and left search column of each sub-image pair;
- calculating vertical shift between points identified as matching by the matching algorithm;
- selecting points with identical vertical shift values;
- and
- aligning the points that were not selected in the image by extrapolating the resulting calculated vertical shift values for each column.
12 more elements
A method for evaluating stereo images of an eye fundus, comprising the steps of:
- obtaining at least two images;
- correcting illumination errors in the images;
- adjusting epipolar lines associated with the images such that the images are vertically aligned;
- removing image occlusion errors in the images;
- and
- performing a matching analysis on the images;
- wherein the images are a left image and a right image such that the images have at least some overlap area, and the step of removing image occlusion errors in the images comprises the substeps of:
- selecting a first point within the overlap area in the right image;
- running a first correspondence search using the first point to find a first matching point in the left image;
- running a second correspondence search on the first matching point to find a second matching point in the right image, wherein the correspondence search is not run on any points to the left of the first matching point;
- and
- selecting a match point comprising the first matching point and second matching point.
9 more elements
A system for evaluating stereo images of an eye fundus, comprising:
- means for obtaining at least two images;
- coupled to the means for obtaining at least two images, means for correcting illumination errors in the images;
- coupled to the means for correcting illumination errors in the images, means for adjusting epipolar lines associated with the images such that the images are vertically aligned;
- coupled to the means for adjusting epipolar lines associated with the images such that the images are vertically aligned, means for removing image occlusion errors in the images;
- and
- coupled to the means for removing image occlusion errors in the images, means for performing a matching analysis on the images;
- wherein the images are a first original image and a second original image and have at least some overlap area, and wherein the means for adjusting epipolar lines further comprises:
- means for creating a left and a right search column on at least one of the original images such that at least one of the created columns includes at least part of the overlap area;
- coupled to the means for creating a left and right search column, means for creating two sets of gray-scale sub-images, one set of sub-images for each of the two original images;
- coupled to the means for creating two sets of grayscale images, means for pairing the sub-images generated from the first original image with sub-images from the second original image such that a sub-image pair shares the same assigned color coordinate;
- coupled to the means for pairing, means for running a matching algorithm on each of the points in the search column of each sub-image pair;
- coupled to the means for running the matching algorithm, means for calculating vertical shift between points between points identified by the matching algorithm;
- coupled to the means for calculating, means for selecting points with identical calculated vertical shift values;
- and
- coupled to the means for selecting, means for aligning the points in the image that were not selected by the means for selecting by extrapolating the resulting calculated vertical shift values for each column.
12 more elements
A system for evaluating stereo images of an eye fundus, comprising:
- means for obtaining at least two images;
- coupled to the means for obtaining at least two images, means for correcting illumination errors in the images;
- coupled to the means for correcting illumination errors in the images, means for adjusting epipolar lines associated with the images such that the images are vertically aligned;
- coupled to the means for adjusting epipolar lines associated with the images such that the images are vertically aligned, means for removing image occlusion errors in the images;
- and
- coupled to the means for removing image occlusion errors in the images, means for performing a matching analysis on the images;
- wherein the images are a first original image and a second original image and have at least some overlap area, and wherein the means for removing image occlusion errors in the images further comprises:
- a storage device for storing the images and executable code;
- coupled to the storage device, means for selecting a first point within the overlap area in the right image;
- coupled to the storage device, means for running a first correspondence search using the first point to find a first matching point in the left image;
- coupled to the storage device, means for running a second correspondence search on the first matching point to find a second matching point in the right image;
- and
- means for selecting match points using the first matching point and the second matching point.
10 more elements
Dependencies are inferred from the claim text.