实施Sobel算子

Question

我试图在水平和垂直方向上实现一个sobel算子.但不知何故,我得到了反向输出.我在下面附上的代码.用于水平面罩

char mask [3][3]=  {{-1,-2,-1},{0,0,0},{1,2,1}};

void masking(Mat image){

Mat temImage= image.clone();
for (int i = 1; i < image.rows-1; i++)
{
    for (int j = 1; j < image.cols-1; j++)
    {   
        for(int k=0;k<3;k++)
        {
            int pixel1 = image.at<Vec3b>(i-1,j-1)[k] * -1;
            int pixel2 = image.at<Vec3b>(i,j-1)[k] * -2;
            int pixel3 = image.at<Vec3b>(i+1,j-1)[k] * -1;

            int pixel4 = image.at<Vec3b>(i-1,j)[k] * 0;
            int pixel5 = image.at<Vec3b>(i,j)[k] * 0;
            int pixel6 = image.at<Vec3b>(i+1,j)[k] * 0;

            int pixel7 = image.at<Vec3b>(i-1,j+1)[k] * 1;
            int pixel8 = image.at<Vec3b>(i,j+1)[k] * 2;
            int pixel9 = image.at<Vec3b>(i+1,j+1)[k] * 1;

            int sum = pixel1 + pixel2 + pixel3 + pixel4 + pixel5 + pixel6 + pixel7 + pixel8 + pixel9;
            if(sum < 0)
            {
                sum = 0;
            }

            if(sum > 255)
                sum = 255;

            temImage.at<Vec3b>(i,j)[k] = sum;


        }
    }
}
//printf("conter = %d",counter);
imshow( "Display", temImage );
imwrite("output1.png",temImage);

}

我得到的输出为

垂直面具的位置

char mask [3][3]=  {{-1,0,1},{-2,0,2},{-1,0,1}}; 

void masking(Mat image){

Mat temImage= image.clone();
for (int i = 1; i < image.rows-1; i++)
{
    for (int j = 1; j < image.cols-1; j++)
    {   
        for(int k=0;k<3;k++)
        {
            int pixel1 = image.at<Vec3b>(i-1,j-1)[k] * -1;
            int pixel2 = image.at<Vec3b>(i,j-1)[k] * 0;
            int pixel3 = image.at<Vec3b>(i+1,j-1)[k] * 1;

            int pixel4 = image.at<Vec3b>(i-1,j)[k] * -2;
            int pixel5 = image.at<Vec3b>(i,j)[k] * 0;
            int pixel6 = image.at<Vec3b>(i+1,j)[k] * 2;

            int pixel7 = image.at<Vec3b>(i-1,j+1)[k] * -1;
            int pixel8 = image.at<Vec3b>(i,j+1)[k] * 0;
            int pixel9 = image.at<Vec3b>(i+1,j+1)[k] * 1;

            int sum = pixel1 + pixel2 + pixel3 + pixel4 + pixel5 + pixel6 + pixel7 + pixel8 + pixel9;
            if(sum < 0)
            {
                sum = 0;
            }

            if(sum > 255)
                sum = 255;

            temImage.at<Vec3b>(i,j)[k] = sum;


        }
    }
}
//printf("conter = %d",counter);
imshow( "Display", temImage );
imwrite("output1.png",temImage);

}

我得到输出为

主要功能如下

int main( int argc, char** argv ){
Mat input_image = imread("sobel1.jpg",1);
masking(input_image);
waitKey(0);
return 0;

}

根据指南https://www.tutorialspoint.com/dip/sobel_operator.htm我应该得到反向输出.任何人都可以帮助我

原始图像是

Answer 1

不，教程没有错，它讨论的是蒙版而不是渐变。该教程的弱点在于它没有提到我们正在使用他们所谓的垂直掩模来计算水平梯度。