1、Zhang快速并行細化算法最近的研究涉及獲取二值圖像骨架（圖象的中軸線），網上找到許多方法，Zhang快速并行細化算法是出現次數最多的算法，看了幾篇博客，又下載了提出這個算法的文獻，感覺這個方法很容易理解，編程也容易，其實最后也沒花多少時間就成功了，VB6.0編寫的程序，用到了函數庫MatrixVB，這里分享一下心得。1. 算法簡介圖1 8鄰域系統圖1表示以P1為中心的8鄰域系統，P2P9代表與P1相鄰的8個像素點，1.1 細化步驟1刪除同時滿足下列條件的邊界點: 2N(P1)6; S(P1)=1; P2×P4×P6=0; P4×P6×P8=0;其中：N

2、(P1)是P1的非零鄰點的個數,S(P1)是以P2，P3，P9，P2為序時這些點的值從0到1變化的次數。1.2 細化步驟2刪除同時滿足下列條件的邊界點: 2N(P1)6; S(P1)=1; P2×P4×P8=0; P2×P6×P8=0;以上兩步操作構成一次迭代，直至沒有點再滿足標記條件，這時剩下的點組成區域即為細化后骨架。2. 程序及細化結果用VB6.0編寫的程序，用到了函數庫MatrixVB（需要的話可以到網上去搜，很老的東西了）。2.1 模塊部分這部分包括自定義數據類型（相當于C語言里的結構體），定義了一些函數。Option ExplicitType

3、 necessary_conditions '4個條件 N_P1 As Integer S_P1 As Integer Mult_P2P4P6 As Integer Mult_P4P6P8 As Integer Mult_P2P4P8 As Integer Mult_P2P6P8 As IntegerEnd TypeType position x As Integer y As IntegerEnd Type'*'計算4個條件的值'輸入：P1點的坐標，待處理的二值圖binary_image'輸出：4個條件的值'*Function obtain_n

4、ecessary_conditions_value(x%, y%, binary_image) As necessary_conditionsDim i%, cnt1%, cnt2%, neighbor8%(9)'-條件1-If binary_image(x - 1, y) = 1 Then neighbor8(2) = 1If binary_image(x - 1, y + 1) = 1 Then neighbor8(3) = 1If binary_image(x, y + 1) = 1 Then neighbor8(4) = 1If binary_image(x + 1, y +

5、1) = 1 Then neighbor8(5) = 1If binary_image(x + 1, y) = 1 Then neighbor8(6) = 1If binary_image(x + 1, y - 1) = 1 Then neighbor8(7) = 1If binary_image(x, y - 1) = 1 Then neighbor8(8) = 1If binary_image(x - 1, y - 1) = 1 Then neighbor8(9) = 1cnt1 = 0cnt2 = 0'-條件2-For i = 2 To 9 If neighbor8(i) = 1

6、 Then cnt1 = cnt1 + 1Next i'-條件3-For i = 2 To 9 - 1 If neighbor8(i) - neighbor8(i + 1) = -1 Then cnt2 = cnt2 + 1Next i If neighbor8(9) - neighbor8(2) = -1 Then cnt2 = cnt2 + 1'-條件4-obtain_necessary_conditions_value.N_P1 = cnt1obtain_necessary_conditions_value.S_P1 = cnt2obtain_necessary_cond

7、itions_value.Mult_P2P4P6 = neighbor8(2) * neighbor8(4) * neighbor8(6)obtain_necessary_conditions_value.Mult_P2P4P8 = neighbor8(2) * neighbor8(4) * neighbor8(8)obtain_necessary_conditions_value.Mult_P2P6P8 = neighbor8(2) * neighbor8(6) * neighbor8(8)obtain_necessary_conditions_value.Mult_P4P6P8 = nei

8、ghbor8(4) * neighbor8(6) * neighbor8(8)End Function'*'Zhang快速并行細化算法'輸入：待處理的二值圖binary_image_buf'輸出：細化后的二值圖binary_image_buf'*Function Zhang_thinning_method(binary_image_buf)Dim rows%, cols%, delete_cnt%Dim i%, j%, k%Dim sign(5000) As position, n1%, n2%, n3%, n4%, n5%, n6%rows = UBo

9、und(binary_image_buf, 1)cols = UBound(binary_image_buf, 2)For k = 1 To 800'-迭代的前半部分- For i = 1 To rows For j = 1 To cols If binary_image_buf(i, j) = 1 Then n1 = obtain_necessary_conditions_value(i, j, binary_image_buf).N_P1 n2 = obtain_necessary_conditions_value(i, j, binary_image_buf).S_P1 n3 =

10、 obtain_necessary_conditions_value(i, j, binary_image_buf).Mult_P2P4P6 n4 = obtain_necessary_conditions_value(i, j, binary_image_buf).Mult_P4P6P8 If (n1 >= 2 And n1 <= 6) And n2 = 1 And n3 = 0 And n4 = 0 Then delete_cnt = delete_cnt + 1 sign(delete_cnt).x = i sign(delete_cnt).y = j End If End

11、If Next j Next i If delete_cnt = 0 Then GoTo finish For i = 1 To delete_cnt binary_image_buf(sign(i).x, sign(i).y) = 0 Next i delete_cnt = 0'-迭代的后半部分- For i = 1 To rows For j = 1 To cols If binary_image_buf(i, j) = 1 Then n1 = obtain_necessary_conditions_value(i, j, binary_image_buf).N_P1 n2 = o

12、btain_necessary_conditions_value(i, j, binary_image_buf).S_P1 n3 = obtain_necessary_conditions_value(i, j, binary_image_buf).Mult_P2P4P8 n4 = obtain_necessary_conditions_value(i, j, binary_image_buf).Mult_P2P6P8 If (n1 >= 2 And n1 <= 6) And n2 = 1 And n3 = 0 And n4 = 0 Then delete_cnt = delete

13、_cnt + 1 sign(delete_cnt).x = i sign(delete_cnt).y = j End If End If Next j Next i If delete_cnt = 0 Then GoTo finish For i = 1 To delete_cnt binary_image_buf(sign(i).x, sign(i).y) = 0 Next i delete_cnt = 0Next kfinish:End Function2.2 窗體部分Option ExplicitPrivate Sub Command1_Click()Dim bin, x1, y1, x

14、2, y2, cnt1%, cnt2%Dim binary_image_buf%(), rows%, cols%Dim i%, j%Set x1 = zeros(5000, 1)Set y1 = zeros(5000, 1)Set x2 = zeros(5000, 1)Set y2 = zeros(5000, 1)bin = vbload(App.Path & "bin4.txt")導入二值圖rows = Size(bin).r1(1)cols = Size(bin).r1(2)ReDim binary_image_buf(rows, cols), binary_3

15、D_buf(rows, cols, 6)For i = 1 To rows For j = 1 To cols binary_image_buf(i, j) = bin(i, j).r1(1) Next jNext iCall Zhang_thinning_method(binary_image_buf)調用 Zhang快速并行細化算法For i = 1 To rows For j = 1 To cols If binary_image_buf(i, j) = 1 Then找出骨架像素點的坐標 cnt1 = cnt1 + 1 x1(cnt1) = i y1(cnt1) = cols + 1 - j End If If bin(i, j).r1(1) = 1 Then找出原二值圖為1的點的坐標 cnt2 = cnt2 + 1 x2(cnt2) = i y2(cnt2) = cols + 1 - j End If Next jNext ix1 = x1(linspace(1, cnt1, cnt1)y1 = y1(linspace(1, cnt1, cnt1)x2 = x2(