opencv: convert Scalar to float or double type

Question

Can anyone help me in converting scalar type of openCV to basic types like float or double?

Scalar Sum1=sum(arg1),Sum2=sum(arg2);
theta.at<float>(i,j)=0.5*atan(Sum1/Sum2);

I have to sum all elements of Mat objects arg1 and arg2 (neighbourhood sum), then I have to perform their division to find orientation field at each pixels. I performed sum, but since I have to apply arctan function, scalar type does not fit. Can anyone help me in converting scalar type to basic types?

actually I'm trying to apply log-gabor filter and the code I've done so far is:

//function to enhance fingerprint by log-gabor filter

void filter(Mat src, Mat finalImage)
{

//Sobel derivatives for orientation estimation

Mat grad_x,grad_y,grad2_x,grad2_y,fImage;
src.convertTo(fImage, CV_32F);

//1st and second order gradient

Sobel(fImage,grad_x,CV_32F,1,0,3);
Sobel(fImage,grad_y,CV_32F,0,1,3);    
Sobel(fImage,grad2_x,CV_32F,2,0,3);
Sobel(fImage,grad2_y,CV_32F,0,2,3);

//orientation estimation

Mat theta=Mat::zeros(fImage.size(),CV_32F);
Size block=Size(12,12);
copyMakeBorder(grad_x, grad_x, block.height/2, block.height/2,
               block.width/2,block.width/2 , BORDER_CONSTANT, Scalar::all(0));

copyMakeBorder(grad2_x, grad2_x, block.height/2, block.height/2,
               block.width/2,block.width/2 , BORDER_CONSTANT, Scalar::all(0));

copyMakeBorder(grad_y, grad_y, block.height/2, block.height/2,
               block.width/2,block.width/2 , BORDER_CONSTANT, Scalar::all(0));

copyMakeBorder(grad2_y, grad2_y, block.height/2, block.height/2,
               block.width/2,block.width/2 , BORDER_CONSTANT, Scalar::all(0));
Size imgSz=grad_x.size();
for(int i=block.width/2;i<imgSz.width-block.width/2;++i)
    for(int j=block.height/2;j<imgSz.height-block.height/2;++j)
    {
        Mat roi_gradX=grad_x(Range(i-block.width/2,i+block.width/2),
                             Range(j-block.width/2,j+block.width/2));

        Mat roi_gradY=grad_y(Range(i-block.width/2,i+block.width/2),
                             Range(j-block.width/2,j+block.width/2));

        Mat roi_gradX2=grad2_x(Range(i-block.width/2,i+block.width/2),
                             Range(j-block.width/2,j+block.width/2));

        Mat roi_gradY2=grad2_y(Range(i-block.width/2,i+block.width/2),
                             Range(j-block.width/2,j+block.width/2));

        Mat arg1,arg2;
        multiply(roi_gradX,roi_gradY,arg1);
        arg1*=2;
        subtract(roi_gradX2,roi_gradY2,arg2);
        Scalar Sum1=sum(arg1),Sum2=sum(arg2);

        theta.at<float>(i,j)=0.5*atan(Sum1/Sum2);
    }
}

Answer 1

I use

double s;
s = sum(arg1)[0];