在java中的指纹方向图

Question

我已经在java中实现了脊线方向的代码。我已经制作了16 * 16的块并获得了每个块的方向角。

我已实施代码以获取方向角：

public static double angle(int i,int j,int[][] pixel){
    double angle = 0;
    double num = 0;
    double denom =0;
    for(int x=i;x<i+16;x++){
        for(int y=j;y<j+16;y++){
            try {
                int gx = sobelOperatorX(i, j, pixel);
                int gy = sobelOperatorY(i, j, pixel);
                num += (2 * gx * gy);
                denom +=((gx * gx) - (gy * gy));
            } catch (Exception e) {
                // TODO: handle exception
            }
        }
    }
    angle = 0.5 * Math.atan(num/denom);
    return angle;
}

public static int sobelOperatorX(int x,int y,int[][] pixel){
    int k=2;
    int Gx=0;
    Gx = (((pixel[x+1][y-1]+k*pixel[x+1][y]+pixel[x+1][y+1])-(pixel[x-1][y-1]+k*pixel[x-1][y]+pixel[x-1][y+1]))/(k+2));
    return Gx;
}

public static int sobelOperatorY(int x,int y,int[][] pixel){
    int k=2;
    int Gy=0;
    Gy = (((pixel[x-1][y-1]+k*pixel[x][y-1]+pixel[x+1][y-1])-(pixel[x-1][y+1]+k*pixel[x][y+1]+pixel[x+1][y+1]))/(k+2));
    return Gy;
}

现在我正在尝试获取orientation map指纹图像。输出图像应如下所示：

是否有任何算法可以找出脊的方向或获得指纹图像的方向图？