Question

我实现了一个获取指纹方向图的功能使用opencv和python的图像，但有些事情是错的我不知道是什么这是我的代码

def compute_real_orientation(array_I, w=17, h=17, low_pass_filter=cv2.blur,filter_size=(5,5),blur_size=(5,5),**kwargs):
    row, col = array_I.shape
    array_I = array_I.astype(np.float)
    Ox = array_I[0:row-h+1:h,0:col-w+1:w].copy()
    Ox[:] = 0.0
    Vx = Ox.copy()
    Vy = Vx.copy()
    Oy = Ox.copy()
    angle = Vx.copy()#array to contain all the 17*17 blocks's orientatons
    c = r = -1
    for i in xrange(0, row-h+1, h):
        r+=1
        for j in xrange(0, col-w+1, w):
            c+=1
            Dx = cv2.Sobel(array_I[i:i+h,j:j+w],-1,1,0)#gradient component x for a 17*17block
            Dy = cv2.Sobel(array_I[i:i+h,j:j+w],-1,0,1)#gradient component y for 17*17 block
            for k in range(0,h):
                for l in range(0,w):
                    Vy[r][c] += ((Dx[k][l])*(Dy[k][l]))**2
                    Vx[r][c] += 2*(Dx[k][l])*(Dy[k][l])
        angle[r][c] = 0.5*(math.atan(Vy[r][c]/Vx[r][c]))#get the orientation angle for the given 16*16 block
    c = -1
    #smoothing process of the whole array angle
    row, col = angle.shape
    for i in range(0, row):
        for j in range(0, col):
            Ox[i][j] = math.cos(2*angle[i][j])
            Oy[i][j] = math.sin(2*angle[i][j])
    Ox = low_pass_filter(Ox, blur_size)
    Oy = low_pass_filter(Oy, blur_size)
    for i in range(0, row):
        for j in range(0, col):
            angle[i][j] = 0.5*math.atan(Oy[i][j]/Ox[i][j])#take the final orientation of all 17*17 blocks
    return angle

我在 2.4方向图部分实施以下算法algorithm 但我的代码工作不正常，我没有得到正确的方向图。任何人都可以帮我排除故障吗？

B.R

Answer 1

代码运行正常。如果要显示方向图，请记住切线定义。

<Grid>
    <Grid.RowDefinitions>
        <RowDefinition />
        <RowDefinition />
    </Grid.RowDefinitions>
    <StackPanel Orientation="Horizontal" x:Name="panel">
        <Button Width="100"
                Content="Foo"
                Click="Button_Click" />
        <Button Width="100"
                Content="Bar"
                Click="Button_Click" />
        <Button Width="100"
                Content="Baz"
                Click="Button_Click" />
    </StackPanel>
    <ListBox Grid.Row="1"
             Name="TheList"
             Height="100" Width="{Binding ElementName=panel, Path=ActualWidth}" />
</Grid>

其中（x0，y0）是wxw块中心的坐标。绘制从（x0，y0）到（x1，y1）的线以绘制方向线。从（2）得到长度= x1-x0：

 tan(a) = (y1-y0)/(x1-x0) (1)
 y1 = (x1-x0)*tan(a)+y0 (2)

这是一个使用matplotlib

执行此操作的python函数

 y1 = length*tan(a)+y0 (3)
 x1 = x0 + length (4)
 'a' in 'tan(a)' is the orientation angle at the pixel of (x0,y0) coordinates

实现指纹增强的方向图

1 个答案: