matlab-图像处理-边缘检测算法五种

五种实现matlab边缘检测算法：

方法一：

matlab自带的edge函数：

将图片保存为lena.jpg

I=imread('lena.jpg');%提取图像

img=rgb2gray(I);

[m,n]=size(img);

BW1=edge(img,'sobel'); %用Sobel算子进行边缘检测

BW2=edge(img,'roberts');%用Roberts算子进行边缘检测

BW3=edge(img,'prewitt'); %用Prewitt算子进行边缘检测

BW4=edge(img,'log'); %用Log算子进行边缘检测

BW5=edge(img,'canny'); %用Canny算子进行边缘检测

h=fspecial('gaussian',5);%?高斯滤波

BW6=edge(img,'canny');%高斯滤波后使用Canny算子进行边缘检测

subplot(2,3,1), imshow(BW1);

title('sobel edge check');

subplot(2,3,2), imshow(BW2);

title('roberts edge check');

subplot(2,3,3), imshow(BW3);

title('prewitt edge check');

subplot(2,3,4), imshow(BW4);

title('log edge check');

subplot(2,3,5), imshow(BW5);

title('canny edge check');

subplot(2,3,6), imshow(BW6);

title('gasussian&canny edge check');

　效果如下图所示：

方法二：Laplacian算法

clear;

sourcePic=imread('lena.jpg');%图像读入

grayPic=mat2gray(sourcePic);%实现图像的矩阵归一化操作

[m,n]=size(grayPic);

newGrayPic=grayPic;

LaplacianNum=0;%经Laplacian操作得到的每个像素的值

LaplacianThreshold=0.2;%设定阈值

for j=2:m-1 %进行边界提取

    for k=2:n-1

        LaplacianNum=abs(4*grayPic(j,k)-grayPic(j-1,k)-grayPic(j+1,k)-grayPic(j,k+1)-grayPic(j,k-1));

        if(LaplacianNum > LaplacianThreshold)

            newGrayPic(j,k)=255;

        else

            newGrayPic(j,k)=0;

        end

    end

end

figure,imshow(newGrayPic);

title('Laplacian算子的处理结果')

　　效果图如下：

方法三：Prewitt算法

%Prewitt 算子的实现：

clear;

sourcePic=imread('lena.jpg');

grayPic=mat2gray(sourcePic);

[m,n]=size(grayPic);

newGrayPic=grayPic;

PrewittNum=0;

PrewittThreshold=0.5;%设定阈值

for j=2:m-1 %进行边界提取

    for k=2:n-1

        PrewittNum=abs(grayPic(j-1,k+1)-grayPic(j+1,k+1)+grayPic(j-1,k)-grayPic(j+1,k)+grayPic(j-1,k-1)-grayPic(j+1,k-1))+abs(grayPic(j-1,k+1)+grayPic(j,k+1)+grayPic(j+1,k+1)-grayPic(j-1,k-1)-grayPic(j,k-1)-grayPic(j+1,k-1));

        if(PrewittNum > PrewittThreshold)

            newGrayPic(j,k)=255;

        else

            newGrayPic(j,k)=0;

        end

    end

end

figure,imshow(newGrayPic);

title('Prewitt算子的处理结果')

　　效果图如下：

方法四：Sobel算法

%Sobel 算子的实现：

clear;

sourcePic=imread('lena.jpg');

grayPic=mat2gray(sourcePic);

[m,n]=size(grayPic);

newGrayPic=grayPic;

sobelNum=0;

sobelThreshold=0.7;

for j=2:m-1

    for k=2:n-1

        sobelNum=abs(grayPic(j-1,k+1)+2*grayPic(j,k+1)+grayPic(j+1,k+1)-grayPic(j-1,k-1)-2*grayPic(j,k-1)-grayPic(j+1,k-1))+abs(grayPic(j-1,k-1)+2*grayPic(j-1,k)+grayPic(j-1,k+1)-grayPic(j+1,k-1)-2*grayPic(j+1,k)-grayPic(j+1,k+1));

        if(sobelNum > sobelThreshold)

            newGrayPic(j,k)=255;

        else

            newGrayPic(j,k)=0;

        end

    end

end

figure,imshow(newGrayPic);

title('Sobel算子的处理结果')

　　效果如下：

方法五：Roberts 算子的实现

%Roberts 算子的实现：

clear all;

clc;

sourcePic=imread('lena.jpg');

grayPic=mat2gray(sourcePic);

[m,n]=size(grayPic);

newGrayPic=grayPic;

robertsNum=0;

robertThreshold=0.2;

for j=1:m-1

    for k=1:n-1

        robertsNum = abs(grayPic(j,k)-grayPic(j+1,k+1)) + abs(grayPic(j+1,k)-grayPic(j,k+1));

        if(robertsNum > robertThreshold)

            newGrayPic(j,k)=255;

        else

            newGrayPic(j,k)=0;

        end

    end

end

figure,imshow(newGrayPic);

title('roberts算子的处理结果')

　　效果图：