sobel.cpp

/* Edge detection by sobel */
float EdgeSobel(unsigned char* inbuf, unsigned char* outbuf, int height, int width){
int start = GetTickCount();
short filter_x[3][3] =
			{ { -1, 0,  1},
			{-2,  0, 2},
			{ -1, 0,  1}}; 
short filter_y[3][3] =
			{ { -1, -2,  -1},
			{0,  0, 0},
			{ 1, 2,  1}}; 
int sum_x=0;
int sum_y=0;
int sum=0;
	for(int i=1; i<height-1;i++)
        for(int j=1; j<width-1; j++)
	{
		sum_x = 0;
		sum_y = 0;
			for(int a=-1; a<=1; a++)
			   for(int b=-1; b<=1; b++){
				sum_x  += inbuf[(i+a)*width+j+b]*filter_x[a+1][b+1];
				sum_y  += inbuf[(i+a)*width+j+b]*filter_y[a+1][b+1];
			   }
		sum =(abs(sum_x)+abs(sum_y))/6;
		if(sum < 0)   sum = 0;
                if(sum > 255) sum = 255;
		 outbuf[i*width+j]=sum;
	}
return (float)(GetTickCount() - start);
}