resize an image

edit

I am resizing my images to apply k-means for segmenting images and get ROI. I am using the following code from the book: mastering opencv android application programming:

int scaleFactor = calcScaleFactor(srcOrig.rows(), srcOrig.cols());
Imgproc.resize(srcOrig, src, new Size(srcOrig.rows()/scaleFactor, srcOrig.cols()/scaleFactor));

private static int calcScaleFactor(int rows, int cols){
        int idealRow, idealCol;
        if(rows<cols){
            idealRow = 240;
            idealCol = 320;
        } else {
            idealCol = 240;
            idealRow = 320;
        }
        int val = Math.min(rows / idealRow, cols / idealCol);
        if(val<=0){
            return 1;
        } else {
            return val;
        }
    }

it is working fine and the time is reduced considerably but the image is stretched so much and for example circles became ellipses. do I need to scale the image back after segmentation or i need to change the scaling factor values for rows and cols or could you please suggest any solution. The problem is worse when the image is not a square and number of columns or rows is way bigger than the other.

Any help is appreciated.