原先是一个VB6.0的验证码识别源码，修改成了VB2008下的。代码很初级，仅供参考。
验证码识别的基本思路：获取图片→二值化→去噪→分割匹配→识别
获取验证码图片并显示在PictureBox上
1 Dim WR As WebRequest = WebRequest.Create(TxtUrl.Text)
2 Dim RESP As WebResponse = WR.GetResponse
3 Dim BMP As New Bitmap(RESP.GetResponseStream)
4 PictureBox1.Image = BMP
二值化
1 Public Sub Binarization() '二值化
2 Dim NumS As String = ""
3 'Dim pix(0, 0) As Boolean
4 ReDim pix(PictureBox1.Width - 1, PictureBox1.Height - 1)
5
6 Dim iy As Integer
7 Dim ix As Integer
8
9 Dim BMP As Bitmap = New Bitmap(PictureBox1.Image)
10
11 Dim Pixel As Color
12
13 CG = TxtG.Text : CR = TxtR.Text : CB = TxtB.Text
14 For iy = 0 To BMP.Height - 1
15 For ix = 0 To BMP.Width - 1
16 Pixel = BMP.GetPixel(ix, iy)
17 If Pixel.G <> CG Or Pixel.R <> CR Or Pixel.B <> CB Then
18 pix(ix, iy) = False
19 Else
20 pix(ix, iy) = True
21 End If
22 Next
23 Next
24
25 Dim str As String = ""
26 For iy = 0 To pix.GetUpperBound(1) 'UBound(pix(, ), 2)
27 For ix = 0 To pix.GetUpperBound(0) 'UBound(pix(), 1)
28 If pix(ix, iy) Then
29 str = str & "■"
30 Else
31 str = str & "□"
32 End If
33 Next
34 str = str & vbCrLf
35 Next
36
37 TxtChar.Text = str
38 End Sub
分割验证码
1 Public Sub SplitCheckCode() '分割验证码
2 Dim i, j, k, p As Integer
3 Dim bL, bR As Boolean
4 ' 第一步, 找出纵向分割界线
5 vCode(0).Left = 0
6 For i = 0 To Pix.GetUpperBound(0)
7 For j = 0 To Pix.GetUpperBound(1)
8 If Pix(i, j) = False Then Exit For '检验是否整列均为■
9 Next
10 If j = Pix.GetUpperBound(1) + 1 Then
11 If i > Pix.GetLowerBound(0) Then
12 For k = 0 To Pix.GetUpperBound(1)
13 If Pix(i - 1, k) = False Then Exit For '检验是否整列均为■
14 Next
15 If k < Pix.GetUpperBound(1) + 1 Then bL = True
16 End If
17 If i < Pix.GetUpperBound(0) Then
18 For k = 0 To Pix.GetUpperBound(1)
19 If Pix(i + 1, k) = False Then Exit For '检验是否整列均为■
20 Next
21 If k < Pix.GetUpperBound(1) + 1 Then bR = True
22 End If
23 End If
24 If (bL Or bR) Then
25 p = p + 1 : bL = False : bR = False
26 Select Case p
27 Case 1 : vCode(0).Right = i - 1
28 Case 2 : vCode(1).Left = i + 1
29 Case 3 : vCode(1).Right = i - 1
30 Case 4 : vCode(2).Left = i + 1
31 Case 5 : vCode(2).Right = i - 1
32 Case 6 : vCode(3).Left = i + 1
33 Case 7 : vCode(3).Right = i - 1
34 End Select
35 End If
36 Next
37 For k = 0 To 3
38 vCode(k).Top = 0 : vCode(k).Bottom = 9 : vCode(k).CodeChar = ""
39 Next
40 ' 第二步, 将所有字符转为特征码
41 For k = 0 To 3
42 For i = vCode(k).Left To vCode(k).Right
43 For j = vCode(k).Top To vCode(k).Bottom
44 If Pix(i, j) Then p = 0 Else p = 1
45 vCode(k).CodeChar = vCode(k).CodeChar & CStr(p)
46 Next
47 Next
48 Next
49 End Sub
识别验证码
1 Public Sub SpotCheckCode() '识别验证码
2 Dim BaseCode(9) As String
3 BaseCode(0) = "011111111010000000011000000001100000000110000000010111111110"
4 BaseCode(1) = "01000000010100000001111111111100000000010000000001"
5 BaseCode(2) = "010000001110000001011000001001100001000110001000010111000001"
6 BaseCode(3) = "010000001010000000011000100001100010000110001000010111011110"
7 BaseCode(4) = "000001100000001010000011001000010000100111111111110000001001"
8 BaseCode(5) = "111110001010001000011000100001100010000110001000011000011110"
9 BaseCode(6) = "001111111001000100011000100001100010000110001000010000011110"
10 BaseCode(7) = "110000000010000000111000001100100011000010110000001100000000"
11 BaseCode(8) = "011101111010001000011000100001100010000110001000010111011110"
12 BaseCode(9) = "011110000010000100011000010001100001000110001000100111111100"
13
14 Dim i, k As Integer
15 Dim s As String
16 For k = 0 To 3
17 s = "$"
18 For i = 0 To 9
19 If vCode(k).CodeChar = BaseCode(i) Then
20 s = CStr(i) : Exit For
21 End If
22 Next
23 TxtResult.Text = TxtResult.Text & s
24 Next
25 End Sub
