马氏距离，NNDR和RANSAC应用在图像配准的MATLAB代码

以下是使用马氏距离、NNDR和RANSAC进行图像配准的MATLAB代码示例：

%% 加载图像
im1 = imread('image1.jpg');
im2 = imread('image2.jpg');

%% 提取特征
points1 = detectSURFFeatures(rgb2gray(im1));
points2 = detectSURFFeatures(rgb2gray(im2));

[features1, points1] = extractFeatures(rgb2gray(im1), points1);
[features2, points2] = extractFeatures(rgb2gray(im2), points2);

%% 匹配特征
indexPairs = matchFeatures(features1, features2, 'Metric', 'SAD', 'MatchThreshold', 10);

%% 计算距离
points1_matched = points1(indexPairs(:,1), :).Location;
points2_matched = points2(indexPairs(:,2), :).Location;

distances = pdist2(points1_matched, points2_matched, 'mahalanobis');

%% NNDR
nndr_ratio = 0.6;
[sortedDist, sortedIndex] = sort(distances, 2);
nndr = sortedDist(:,1)./sortedDist(:,2);

matches = indexPairs(nndr < nndr_ratio, :);

%% RANSAC
numMatches = size(matches, 1);
if numMatches < 4
error('Not enough matches for RANSAC');
end

pts1 = points1(matches(:,1), :).Location;
pts2 = points2(matches(:,2), :).Location;

[fMatrix, inliers] = estimateFundamentalMatrix(pts1, pts2, 'Method', 'RANSAC', 'NumTrials', 10000, 'DistanceThreshold', 0.1);

matches = matches(inliers, :);

%% 显示匹配结果
figure;
showMatchedFeatures(im1,im2,points1(matches(:,1)),points2(matches(:,2)),'montage');