public
int calculateInSampleSize(BitmapFactory.Options option, int rWidth, int rHeight) {

        final
int width = option.outWidth;

        final
int height = option.outHeight;

        option.inSampleSize = 1;

        while ((height / option.inSampleSize) > rHeight || (width / option.inSampleSize) > rWidth) {

            option.inSampleSize *= 2;

        }

        return option.inSampleSize;

    }