亚像素角点检测matlab
时间: 2023-12-03 12:41:03 浏览: 29
以下是使用MATLAB进行亚像素级Harris角点检测的步骤:
1. 读取图像并将其转换为灰度图像。
```matlab
img = imread('image.jpg');
gray_img = rgb2gray(img);
```
2. 计算图像的梯度。
```matlab
[Ix, Iy] = gradient(double(gray_img));
```
3. 计算Harris矩阵中的三个参数:Ix^2,Iy^2和IxIy。
```matlab
Ix2 = Ix.^2;
Iy2 = Iy.^2;
IxIy = Ix.*Iy;
```
4. 对Harris矩阵进行高斯滤波。
```matlab
sigma = 2;
g = fspecial('gaussian', max(1, fix(6*sigma)), sigma);
Ix2 = imfilter(Ix2, g, 'same');
Iy2 = imfilter(Iy2, g, 'same');
IxIy = imfilter(IxIy, g, 'same');
```
5. 计算每个像素的响应函数R。
```matlab
k = 0.04;
R = (Ix2.*Iy2 - IxIy.^2) - k*(Ix2 + Iy2).^2;
```
6. 对R进行非极大值抑制。
```matlab
radius = 3;
maxima = ordfilt2(R, radius^2, ones(radius));
R = (R == maxima) & (R > 0);
```
7. 找到亚像素级角点。
```matlab
C = cornermetric(R);
[r, c] = find(R & C == max(C));
subpixel_r = zeros(size(r));
subpixel_c = zeros(size(c));
for i = 1:length(r)
M = [sum(Ix2(r(i)-1:r(i)+1, c(i)-1:c(i)+1)) sum(IxIy(r(i)-1:r(i)+1, c(i)-1:c(i)+1)); ...
sum(IxIy(r(i)-1:r(i)+1, c(i)-1:c(i)+1)) sum(Iy2(r(i)-1:r(i)+1, c(i)-1:c(i)+1))];
b = [-sum(Ix(r(i)-1:r(i)+1, c(i)-1:c(i)+1).*...
(Ix2(r(i)-1:r(i)+1, c(i)-1:c(i)+1)+Iy2(r(i)-1:r(i)+1, c(i)-1:c(i)+1))); ...
-sum(Iy(r(i)-1:r(i)+1, c(i)-1:c(i)+1).*...
(Ix2(r(i)-1:r(i)+1, c(i)-1:c(i)+1)+Iy2(r(i)-1:r(i)+1, c(i)-1:c(i)+1)))];
v = pinv(M)*b;
subpixel_r(i) = r(i) + v(2);
subpixel_c(i) = c(i) + v(1);
end
```
8. 在图像中显示角点。
```matlab
imshow(img);
hold on;
plot(subpixel_c, subpixel_r, 'r+', 'MarkerSize', 5);
```