I have a c++ code for sobel operator on pgm image, my code compiles but fails to give me the required results

Question

So here is the function that does the sobel process:

void sobelOperator(int& x, int& y)
{
    ImageType image;

    for(int i = 0; i<x; i++)
    {
        for(int j = 0; j<y; j++)
        {

            //constants
            const int MATRIX_MAX = 3;
            const int PIXEL_MAX = 255;


            //value for the new cell calculation
            int GXpixel = 0, GYpixel = 0, Gpixel = 0;


            //Sobel Horizontal Mask or matrix for the Kx convolution
            const int sobelKxFilterMatrix[3][3] = {{1, 0, -1}, {2, 0, -2}, {1, 0, -1}};

            //Sobel Vertical Mask or matrix for the Ky convolution
            const int sobelKyFilterMatrix[3][3] = {{1, 2, 1}, {0, 0, 0}, {-1, -2, -1}};

            //for addressing into filter array and into picture
            int iFilter, jFilter;
            int iPic, jPic;

            //Loop to iterate over picture and filter window to perform sobel operation
            for(iFilter = 0, iPic =- 1; iFilter < MATRIX_MAX && iPic >= 1; iFilter++, iPic++)
            {
                for(jFilter = 0, jPic =-1; jFilter < MATRIX_MAX && jPic >= 1; jFilter++, jPic++)
                {
                    int val;
                    image.getPixelVal(x+iPic, y+jPic, val);

                    GXpixel += (val * sobelKxFilterMatrix[iFilter][jFilter]);

                    GYpixel += (val * sobelKyFilterMatrix[iFilter][jFilter]);
                }
            }

            //check for pixel saturation
            if(GXpixel > PIXEL_MAX){GXpixel = PIXEL_MAX;}
            if(GYpixel > PIXEL_MAX){GYpixel = PIXEL_MAX;}

            //normalize pixel
            Gpixel = static_cast<int>(sqrt(pow(static_cast<double>(GXpixel), 2.0) + pow(static_cast<double>(GYpixel), 2.0)));

            image.setPixelVal(i, j, Gpixel);
        }
    }
}

I have a c++ code for sobel operator on pgm image, my code compiles but fails to give me the required results. Can anyone tell me what is wrong?

Please format code correctly in your question. Just indent with four spaces. If the site doesn't let you post it like that, there's a reason for it. — πάντα ῥεῖ, Nov 30 '15 at 13:33

score 1 · Answer 1 · answered Nov 30 '15 at 14:22

1

This part

for(iFilter = 0, iPic =- 1; iFilter < MATRIX_MAX && iPic >= 1; iFilter++, iPic++)

looks wrong.

You assign -1 to iPic and then test if iPic >= 1. That will always be false.

answered Nov 30 '15 at 14:22

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I have a c++ code for sobel operator on pgm image, my code compiles but fails to give me the required results

1 Answers1