This Simple Captcha Application doesn't need Internet to load it's Captcha but it generates a random image for you to answer.

Picture: http://cur.lv/4q76m

Okay, you need the following elements:
2 Button
1 PictureBox
1 TextBox

Button 1 will be the Submit button. Checking if the answer is correct or incorrect.
Button 2 will be the one refreshing a new generated image for you to answer.
TextBox you need this to answer  lmao; 
PictureBox you need this to show the image  lmao; 

Okay, let's start. Add this code below your Public Class.
This code will create the question and the lines so it's a bit harder to read which makes it a bit challenging.

    Private cAnswer As String = Nothing

    Private Function genQuestion() As String
        Dim cOperators As String() = {"+", "-"}
Start:
        Dim p1 As Integer = New Random().Next(1, 9)
        Dim p2 As Integer = New Random().Next(1, 9)

        If p1 = p2 Then GoTo Start

        Dim cOperator As String = cOperators(New Random().Next(0, cOperators.Length))

        Select Case cOperator
            Case "+"
                cAnswer = p1 + p2
                If cAnswer <= 0 Then GoTo Start
            Case "-"
                cAnswer = p1 - p2
                If cAnswer <= 0 Then GoTo Start
        End Select
        Return String.Format("{0}{1}{2}", p1, cOperator, p2)
    End Function
    Private Sub generateLines(ByVal G As Graphics)
        If Not G Is Nothing Then
            Dim R As New Random()
            Dim lineBrush As New SolidBrush(Color.LightGray)

            For i% = 0 To 9
                G.DrawLines(New Pen(lineBrush, R.Next(1, 2)), New Point() {New Point(0, R.Next(0, 60)), New Point(200, R.Next(0, 60))})

            Next
        End If
    End Sub

    Private Function generateImage() As Image
        Dim B As New Bitmap(200, 60)
        Using G As Graphics = Graphics.FromImage(B)
            With G
                .Clear(Color.White)
                .DrawString(genQuestion(), New Font("Segoe UI", 20), Brushes.Black, New Rectangle(0, 0, 200, 60), New StringFormat() With {.Alignment = StringAlignment.Center, .LineAlignment = StringAlignment.Center})
            End With
            generateLines(G)
        End Using
        Return B
    End Function




So next, we will be coding the submit button or Button 1, this will submit your answer.

Select Case TextBox1.Text
            Case Is = cAnswer

                MessageBox.Show("Correct!", "Correct!", MessageBoxButtons.OK, MessageBoxIcon.Asterisk)
                PictureBox1.Image = generateImage()
                TextBox1.Clear()
            Case Else
                MessageBox.Show("Incorrect!", "Incorrect!", MessageBoxButtons.OK, MessageBoxIcon.Asterisk)
                PictureBox1.Image = generateImage()
                TextBox1.Clear()
        End Select
        TextBox1.Clear()



Button 2 and Form_Load will be the same code. Add this line of code to Button 2 and Form_Load.

PictureBox1.Image = generateImage()


When you are done, debug it and test. Thanks for reading and testing this thread, I'm pretty sure you've learned something new.

Support here: http://forum.nsst.co/threads/egyszer%C5%B1-captcha-alkalmaz%C3%A1s-simple-captcha-application.19/