Question

I am trying to blur an image.

I am using a kernel called k[][3]= { 1, .01, 1, .01, 0, .01, 1, .01, 1};

The code is as follows:

void blur(IplImage *notgray)
{
    IplImage *img = cvCreateImage(cvGetSize(notgray), notgray->depth, 1);
    cvCvtColor(notgray, img, CV_RGB2GRAY);
    int rows=img->height,cols=img->width,row,col,i,j,ki,kj;
    uchar* temp_ptr=0 ;
    float sum,k[][3]= { 1, .01, 1,
                    .01, 0, .01,
                     1, .01, 1};

    for( row = 0; row < rows; ++row) 
    {
            sum=0;
            for ( col = 0; col < cols; ++col) 
            {               
                            temp_ptr  = &((uchar*)(img->imageData + (img->widthStep*row)))[col];
                            for( j=-1,ki=0; j<=1;j++,ki++)
                            {
                                for( i=-1,kj=0; i<=1;i++,kj++)
                                {
                                    int x2=col+i;
                                    int y2=row+j;
                                    if ( x2>=0 && x2<img->width && y2>=0 && y2<img->height) 
                                    {
                                        sum=sum+k[ki][kj];
                                    if (sum<0) sum=0; else if (sum>255) sum=255;
                                    temp_ptr[0]  =(uchar) sum;

                                    }
                                }
                            }
            }

    }
}

I know the output really depends on my algorithm, but looking at the code and output i would request some guidance what i should do further to solve my problem.

Answer 1

You set sum = 0; at the wrong place. Since it is only reset at the start of each row, each pixel will be whiter and whiter and…