I am using the code below to read a .bmp file and write it out to a
new file.  This small example just tries to duplicate the file.
Later, I'm going to add code to process the file further.  But this
code illustrates my current problem which is this:

The source file is a .BMP file that has a depth of 32 bpp.  The
additional bits being the Alpha channel.  I can load the source file
in PhotoShop and it correctly reads the file and the Alpha channel.

However, when I load the file using .Net, the file seems to be read in
Format32bbRgb mode instead of Format32bppArgb mode.  Consequently, the
Alpha data in the file is set to &HFF rather than what is in the file.
The alpha channel is all white.  How can I specify that the bitmap
shoudl use the Format32bppArgb mode.  The Bitmap constructor does not
seem to provide for this.

Also, what is the correlation between the data returned by LockBits
and the actual data in the file?  When I look at the file in a Hex
editor, the first pixel's data is (in hex) 89 88 88 AD  for the Blue,
Green, Red, and Alpha channels.  But in the code below when I examine
the byt array in the debugger, it shows the values as (also in Hex) 94
94 94 FF.  Yet, when I examine the output file, the values are (in
hex) 89 88 88 FF.  Does the BitmapData object interpret the data
differently?

Can anyone help here?

Thanks in advance.

Chris

'CODE BEGINS HERE
'\\\\\\\\\\\
Dim sFileName As String = sArgs(0)

Dim bmIn As New Bitmap(sFileName)
Dim bmOut As New Bitmap(bmIn.Width, bmIn.Height, Format32bppArgb)

Dim bmInData As BitmapData = bmIn.LockBits(New Rectangle(0, 0,
bmIn.Width, bmIn.Height), ImageLockMode.ReadOnly, Format32bppArgb)

Dim bmOutData As BitmapData = bmOut.LockBits(New Rectangle(0, 0,
bmIn.Width, bmIn.Height), ImageLockMode.ReadWrite, Format32bppArgb)

Dim byt(3) As Byte
Dim ofs As Integer

For y As Integer = 0 To bmInData.Height - 1
   For x As Integer = 0 To bmInData.Width - 1
       ofs = (bmInData.Stride * y) + (4 * x)
       For i As Integer = 0 To 3
           byt(i) = Marshal.ReadByte(bmInData.Scan0, ofs + i)
       Next

       For i As Integer = 0 To 3
           Marshal.WriteByte(bmOutData.Scan0, ofs + i, byt(i))
       Next
   Next
Next

bmOut.UnlockBits(bmOutData)
bmIn.UnlockBits(bmInData)

bmOut.Save("Outtest.bmp", Imaging.ImageFormat.Bmp)

bmIn.Dispose()
bmOut.Dispose()
'//////////