改进canny边缘检测matlab代码

Canny边缘检测是一种常见的图像处理方法，它可以检测出图像中的边缘信息。下面是一个MATLAB的Canny边缘检测代码，你可以根据需要进行改进：

function edgeImg = myCannyEdgeDetection(image, sigma, lowThreshold, highThreshold)

% 高斯滤波
hsize = 2 * ceil(3 * sigma) + 1;
gaussian = fspecial('gaussian', hsize, sigma);
image = imfilter(image, gaussian, 'replicate');

% 计算梯度
hx = [-1, 0, 1; -2, 0, 2; -1, 0, 1];
hy = hx';

Gx = imfilter(image, hx, 'replicate');
Gy = imfilter(image, hy, 'replicate');

% 梯度幅值和方向
magnitude = hypot(Gx, Gy);
theta = atan2(Gy, Gx);

% 非最大值抑制
nms = nonmaxsupp(magnitude, theta);

% 双阈值边缘跟踪
edgeImg = threshold(nms, lowThreshold, highThreshold);

end

function nms = nonmaxsupp(magnitude, theta)

[m, n] = size(magnitude);
nms = zeros(m, n);

% 角度转换到[0, 180)
theta = mod((theta + pi), pi);

% 近似角度为0，45，90或135度
for i = 2:m-1
    for j = 2:n-1
        if (theta(i,j) < pi/8 || theta(i,j) >= 7*pi/8) % 水平方向
            if (magnitude(i,j) >= magnitude(i,j-1) && magnitude(i,j) >= magnitude(i,j+1))
                nms(i,j) = magnitude(i,j);
            end
        elseif (theta(i,j) >= pi/8 && theta(i,j) < 3*pi/8) % 45度方向
            if (magnitude(i,j) >= magnitude(i-1,j+1) && magnitude(i,j) >= magnitude(i+1,j-1))
                nms(i,j) = magnitude(i,j);
            end
        elseif (theta(i,j) >= 3*pi/8 && theta(i,j) < 5*pi/8) % 垂直方向
            if (magnitude(i,j) >= magnitude(i-1,j) && magnitude(i,j) >= magnitude(i+1,j))
                nms(i,j) = magnitude(i,j);
            end
        else % 135度方向
            if (magnitude(i,j) >= magnitude(i-1,j-1) && magnitude(i,j) >= magnitude(i+1,j+1))
                nms(i,j) = magnitude(i,j);
            end
        end
    end
end

end

function edgeImg = threshold(nms, lowThreshold, highThreshold)

% 双阈值边缘跟踪
[m, n] = size(nms);
edgeImg = zeros(m, n);

% 高阈值
highThreshold = max(nms(:)) * highThreshold;
% 低阈值
lowThreshold = highThreshold * lowThreshold;

for i = 2:m-1
    for j = 2:n-1
        if (nms(i,j) >= highThreshold)
            edgeImg(i,j) = 1;
        elseif (nms(i,j) < lowThreshold)
            edgeImg(i,j) = 0;
        else
            % 8邻域内有强边缘点
            if (nms(i-1,j-1) >= highThreshold || nms(i-1,j) >= highThreshold || nms(i-1,j+1) >= highThreshold ...
                    || nms(i,j-1) >= highThreshold || nms(i,j+1) >= highThreshold ...
                    || nms(i+1,j-1) >= highThreshold || nms(i+1,j) >= highThreshold || nms(i+1,j+1) >= highThreshold)
                edgeImg(i,j) = 1;
            end
        end
    end
end

end

代码中包含了高斯滤波、梯度计算、非最大值抑制和双阈值边缘跟踪等步骤。你可以根据需要进行修改和优化。