Visual Basic - Borrar el fondo de una imágen .BMP

Tengo una imágen .BMP de un dibujo con el fondo color Magenta y necesito hacerlo transparente, y además que la parte del fondo se elimine (es decir, que el control este conformado únicamente por la silueta del dibujo, como un recorte). Ya probé con varias formas, pero ninguna me resulta por diferentes motivos. Acá los códigos que probé:

'---FORMA 1--------------------------------------------------------------

Option Explicit

Private Declare Function GetWindowLong Lib "user32" Alias "GetWindowLongA" (ByVal hWnd As Long, ByVal nIndex As Long) As Long
Private Declare Function SetWindowLong Lib "user32" Alias "SetWindowLongA" (ByVal hWnd As Long, ByVal nIndex As Long, ByVal dwNewLong As Long) As Long
Private Declare Function ReleaseCapture Lib "user32.dll" () As Long
Private Declare Function SendMessage Lib "user32.dll" Alias "SendMessageA" (ByVal hWnd As Long, ByVal wMsg As Long, ByVal wParam As Long, lParam As Any) As Long
Private Declare Function SetLayeredWindowAttributes Lib "user32.dll" (ByVal hWnd As Long, ByVal crKey As Long, ByVal bAlpha As Byte, ByVal dwFlags As Long) As Long
Private Const LWA_COLORKEY As Long = &H1
Private Const GWL_EXSTYLE As Long = (-20)
Private Const WS_EX_LAYERED As Long = &H80000
Private Const WM_NCLBUTTONDOWN As Long = &HA1
Private Const HTCAPTION As Long = 2

Private Sub Form_Load()
Me.BackColor = vbMagenta
SetWindowLong Me.hWnd, GWL_EXSTYLE, GetWindowLong(Me.hWnd, GWL_EXSTYLE) Or WS_EX_LAYERED
SetLayeredWindowAttributes Me.hWnd, Me.BackColor, 0, LWA_COLORKEY
End Sub

Private Sub Form_MouseMove(Button As Integer, Shift As Integer, X As Single, Y As Single)
'Para mover el form de cualquier parte
ReleaseCapture
SendMessage hWnd, WM_NCLBUTTONDOWN, HTCAPTION, 0&
End Sub
'-------------------------------------------------------------------------



'---FORMA 2--------------------------------------------------------------

Option Explicit
Private Declare Function CreateRectRgn Lib "gdi32" (ByVal X1 As Long, ByVal Y1 As Long, ByVal X2 As Long, ByVal Y2 As Long) As Long
Private Declare Function CombineRgn Lib "gdi32" (ByVal hDestRgn As Long, ByVal hSrcRgn1 As Long, ByVal hSrcRgn2 As Long, ByVal nCombineMode As Long) As Long
Private Declare Function DeleteObject Lib "gdi32" (ByVal hObject As Long) As Long
Private Declare Function SetWindowRgn Lib "user32" (ByVal hWnd As Long, ByVal hRgn As Long, ByVal bRedraw As Boolean) As Long
Private Declare Function CreateCompatibleDC Lib "gdi32" (ByVal hDC As Long) As Long
Private Declare Function CreateDIBSection Lib "gdi32" (ByVal hDC As Long, pBitmapInfo As BITMAPINFO, ByVal un As Long, ByVal lplpVoid As Long, ByVal handle As Long, ByVal dw As Long) As Long
Private Declare Function SelectObject Lib "gdi32" (ByVal hDC As Long, ByVal hObject As Long) As Long
Private Declare Function BitBlt Lib "gdi32" (ByVal hDestDC As Long, ByVal x As Long, ByVal y As Long, ByVal nWidth As Long, ByVal nHeight As Long, ByVal hSrcDC As Long, ByVal xSrc As Long, ByVal ySrc As Long, ByVal dwRop As Long) As Long
Private Declare Function GetDIBits Lib "gdi32" (ByVal aHDC As Long, ByVal hBitmap As Long, ByVal nStartScan As Long, ByVal nNumScans As Long, lpBits As Any, lpBI As BITMAPINFO, ByVal wUsage As Long) As Long
Private Declare Function DeleteDC Lib "gdi32" (ByVal hDC As Long) As Long
Private Declare Sub OleTranslateColor Lib "oleaut32.dll" (ByVal clr As Long, ByVal hpal As Long, ByRef lpcolorref As Long)


Private Type BITMAPINFOHEADER
biSize As Long
biWidth As Long
biHeight As Long
biPlanes As Integer
biBitCount As Integer
biCompression As Long
biSizeImage As Long
biXPelsPerMeter As Long
biYPelsPerMeter As Long
biClrUsed As Long
biClrImportant As Long
End Type

Private Type RGBQUAD
rgbBlue As Byte
rgbGreen As Byte
rgbRed As Byte
rgbReserved As Byte
End Type

Private Type BITMAPINFO
bmiHeader As BITMAPINFOHEADER
bmiColors As RGBQUAD
End Type


Private Const BI_RGB As Long = 0&
Private Const DIB_RGB_COLORS As Long = 0&
Private Const RGN_OR As Long = 2&

Public Function MakeFormTransparent(Obj As Object, ByVal lngTransColor As Long)
Dim hRegion As Long

hRegion = RegionFromBitmap(Obj, lngTransColor)
SetWindowRgn Obj.hWnd, hRegion, True
DeleteObject hRegion

End Function

Private Function RegionFromBitmap(picSource As Object, ByVal lngTransColor As Long) As Long
Dim lngRetr As Long, lngHeight As Long, lngWidth As Long
Dim lngRgnFinal As Long, lngRgnTmp As Long
Dim lngStart As Long
Dim x As Long, y As Long
Dim hDC As Long
Dim bi24BitInfo As BITMAPINFO
Dim iBitmap As Long
Dim BWidth As Long
Dim BHeight As Long
Dim iDC As Long
Dim PicBits() As Byte
Dim Col As Long
Dim OldScaleMode As ScaleModeConstants

OldScaleMode = picSource.ScaleMode
picSource.ScaleMode = vbPixels

hDC = picSource.hDC
lngWidth = picSource.ScaleWidth '- 1
lngHeight = picSource.ScaleHeight - 1

BWidth = (picSource.ScaleWidth \ 4) * 4 + 4
BHeight = picSource.ScaleHeight

'Bitmap-Header
With bi24BitInfo.bmiHeader
.biBitCount = 24
.biCompression = BI_RGB
.biPlanes = 1
.biSize = Len(bi24BitInfo.bmiHeader)
.biWidth = BWidth
.biHeight = BHeight + 1
End With
'ByteArrays in der erforderlichen Größe anlegen
ReDim PicBits(0 To bi24BitInfo.bmiHeader.biWidth * 3 - 1, 0 To bi24BitInfo.bmiHeader.biHeight - 1)

iDC = CreateCompatibleDC(hDC)
'Gerätekontextunabhängige Bitmap (DIB) erzeugen
iBitmap = CreateDIBSection(iDC, bi24BitInfo, DIB_RGB_COLORS, ByVal 0&, ByVal 0&, ByVal 0&)
'iBitmap in den neuen DIB-DC wählen
Call SelectObject(iDC, iBitmap)
'hDC des Quell-Fensters in den hDC der DIB kopieren
Call BitBlt(iDC, 0, 0, bi24BitInfo.bmiHeader.biWidth, bi24BitInfo.bmiHeader.biHeight, hDC, 0, 0, vbSrcCopy)
'Gerätekontextunabhängige Bitmap in ByteArrays kopieren
Call GetDIBits(hDC, iBitmap, 0, bi24BitInfo.bmiHeader.biHeight, PicBits(0, 0), bi24BitInfo, DIB_RGB_COLORS)

'Wir brauchen nur den Array, also können wir die Bitmap direkt wieder löschen.

'DIB-DC
Call DeleteDC(iDC)
'Bitmap
Call DeleteObject(iBitmap)

lngRgnFinal = CreateRectRgn(0, 0, 0, 0)

For y = 0 To lngHeight
x = 0
Do While x < lngWidth
Do While x < lngWidth And _
RGB(PicBits(x * 3 + 2, lngHeight - y + 1), _
PicBits(x * 3 + 1, lngHeight - y + 1), _
PicBits(x * 3, lngHeight - y + 1)) = lngTransColor

x = x + 1
Loop
If x <= lngWidth Then
lngStart = x
Do While x < lngWidth And _
RGB(PicBits(x * 3 + 2, lngHeight - y + 1), _
PicBits(x * 3 + 1, lngHeight - y + 1), _
PicBits(x * 3, lngHeight - y + 1)) <> lngTransColor
x = x + 1
Loop
If x + 1 > lngWidth Then x = lngWidth
lngRgnTmp = CreateRectRgn(lngStart, y, x, y + 1)
lngRetr = CombineRgn(lngRgnFinal, lngRgnFinal, lngRgnTmp, RGN_OR)
DeleteObject lngRgnTmp
End If
Loop
Next

picSource.ScaleMode = OldScaleMode
RegionFromBitmap = lngRgnFinal
End Function


Private Sub Form_Load()
Image1.AutoRedraw = True
MakeFormTransparent Image1, vbMagenta
End Sub
'-------------------------------------------------------------------------

El primero lo usé reemplazando el "Me" por un control Image (No coinciden las propiedades) y con un PictureBox (No hace nada). Dejandolo como está hace el recorte pero borra todo el formulario.
Con la segunda forma, hace el recorte pero aparece un poco corrido con respecto a la imágen (Queda un borde magenta a la izquierda y se come parte del dibujo a la derecha).

Además de eso probé con un módulo que descargué, que permite importar imágenes .PNG con su transparencia, pero no me funcionó. Además creo que siendo la imágen .PNG, la transparencia es sólo una trama y el control seria rectangular (no sólo la silueta).

Agradecería si pudieran aportarme alguna ayuda con esto.

Saludos!

visita este enlace
http://deepdarkprocess.wordpress.com/2009/12/29/manejo-de-imagenes-visual-basic-6-0-y-imagemagick/