Option Explicit
Private Sub Form_MouseMove(Button As Integer, Shift As Integer, _
                                 X As Single, Y As Single)
   shCircle.Visible = False
End Sub

 
Private Sub Picture1_MouseDown(Button As Integer, Shift As Integer, _
                                 X As Single, Y As Single)
  Picture1.AutoRedraw = True
  SoftenBlur Picture1.hDC, X, Y, (Val(HScroll1.Value) / 2), _
                           Val(3), Abs(HScroll2.Value - 255) '1 - 100
  DoEvents
  Picture1.Refresh
  DoEvents
End Sub

 
Private Sub Picture1_MouseMove(Button As Integer, Shift As Integer, _
                                X As Single, Y As Single)
  shCircle.Visible = True
  shCircle.Width = HScroll1.Value
  shCircle.Height = shCircle.Width
  shCircle.Left = X - HScroll1.Value / 2
  shCircle.Top = Y - HScroll1.Value / 2
  If Button = 1 Then
     SoftenBlur Picture1.hDC, X, Y, (Val(HScroll1.Value) / 2), Val(3), _
                                           Abs(HScroll2.Value - 255) '1 - 100
     DoEvents
     Picture1.Refresh
     DoEvents
     Exit Sub
  End If
End Sub

 
Private Sub Picture1_MouseUp(Button As Integer, Shift As Integer, _
                                             X As Single, Y As Single)
   Picture1.AutoRedraw = False
End Sub

Option Explicit
 
Private Declare Function SetPixelV Lib "gdi32" (ByVal hDC As Long, _
           ByVal X As Long, ByVal Y As Long, ByVal crColor As Long) As Long
 
Declare Function GetPixel Lib "gdi32" (ByVal hDC As Long, ByVal X As Long, _
           ByVal Y As Long) As Long

 
 
Public Sub SoftenBlur(Target As Long, X As Single, Y As Single, _
                    radius As Long, Steps As Long, Alpha As Integer)
   Dim cX As Long
   Dim cY As Long
   Dim TempColor(3) As Long
   Dim TempRadius As Integer
   Dim I As Integer
   Dim u As Integer
   Dim Red(3) As Long
   Dim Green(3) As Long
   Dim Blue(3) As Long
   Dim Color0 As Long
   Dim Color1 As Long
   Dim Color2 As Long
   Dim Color3 As Long
   Dim Done() As Boolean
   ReDim Done(-radius To radius, -radius To radius)
   For I = 1 To Steps
     TempRadius = radius / Steps * I
     For cX = -TempRadius To TempRadius 'Step 2
       For cY = -TempRadius To TempRadius 'Step 2
         If Not Done(cX, cY) Then
            If (cX * cX) + (cY * cY) <= TempRadius * TempRadius Then
               TempColor(0) = GetPixel(Target, cX + X, cY + Y)
               TempColor(1) = GetPixel(Target, cX + X, cY + Y - 1)
               TempColor(2) = GetPixel(Target, cX + X - 1, cY + Y - 1)
               TempColor(3) = GetPixel(Target, cX + X - 1, cY + Y)
               For u = 0 To 3 '==> RGB + Fehlerbehandlung
                  Blue(u) = TempColor(u) \ 65536
                  Green(u) = (TempColor(u) - Blue(u) * 65536) \ 256
                  Red(u) = TempColor(u) - Blue(u) * 65536 - Green(u) * 256
                  If Red(u) < 0 Then Red(u) = 0
                  If Red(u) > 255 Then Red(u) = 255
                  If Green(u) < 0 Then Green(u) = 0
                  If Green(u) > 255 Then Green(u) = 255
                  If Blue(u) < 0 Then Blue(u) = 0
                  If Blue(u) > 255 Then Blue(u) = 255
               Next u
 
  Color0 = RGB(((Red(0) * Alpha) + Red(1) + Red(2) + Red(3)) / (Alpha + 3), _
       ((Green(0) * Alpha) + Green(1) + Green(2) + Green(3)) / (Alpha + 3), _
       ((Blue(0) * Alpha) + Blue(1) + Blue(2) + Blue(3)) / (Alpha + 3))
 
  Color1 = RGB((Red(0) + (Red(1) * Alpha) + Red(2) + Red(3)) / (Alpha + 3), _
       (Green(0) + (Green(1) * Alpha) + Green(2) + Green(3)) / (Alpha + 3), _
       (Blue(0) + (Blue(1) * Alpha) + Blue(2) + Blue(3)) / (Alpha + 3))
 
  Color2 = RGB((Red(0) + Red(1) + (Red(2) * Alpha) + Red(3)) / (Alpha + 3), _
       (Green(0) + Green(1) + (Green(2) * Alpha) + Green(3)) / (Alpha + 3), _
       (Blue(0) + Blue(1) + (Blue(2) * Alpha) + Blue(3)) / (Alpha + 3))
 
  Color3 = RGB((Red(0) + Red(1) + Red(2) + (Red(3) * Alpha)) / (Alpha + 3), _
       (Green(0) + Green(1) + Green(2) + (Green(3) * Alpha)) / (Alpha + 3), _
       (Blue(0) + Blue(1) + Blue(2) + (Blue(3) * Alpha)) / (Alpha + 3))
 
               SetPixelV Target, cX + X, cY + Y, Color0
               SetPixelV Target, cX + X, cY + Y - 1, Color1
               SetPixelV Target, cX + X - 1, cY + Y - 1, Color2
               SetPixelV Target, cX + X - 1, cY + Y, Color3
               Done(cX, cY) = True
            End If
         End If
      Next cY
    Next cX
  Next I
End Sub