Hello. I was looking for how to convert image to byte array, and i found this https://www.vbforums.com/showthread....-on-Picturebox. It works on my case, but i have no idea why is the code like that, what is GUID, and why i must use that. Can i use the identifier randomly? i need an explanation for this code. i've tried to googled it but still can't understand. Here's the code.

Code:
Private Function ArrayToPicture(inArray() As Byte, Offset As Long, Size As Long) As IPicture
    ' function creates a stdPicture from the passed array
    ' Offset is first item in array: 0 for 0 bound arrays
    ' Size is how many bytes comprise the image
    Dim o_hMem  As Long
    Dim o_lpMem  As Long
    Dim aGUID(0 To 3) As Long
    Dim IIStream As IUnknown

    aGUID(0) = &H7BF80980    ' GUID for stdPicture
    aGUID(1) = &H101ABF32
    aGUID(2) = &HAA00BB8B
    aGUID(3) = &HAB0C3000

    o_hMem = GlobalAlloc(&H2&, Size)
    If Not o_hMem = 0& Then
        o_lpMem = GlobalLock(o_hMem)
        If Not o_lpMem = 0& Then
            CopyMemory ByVal o_lpMem, inArray(Offset), Size
            Call GlobalUnlock(o_hMem)
            If CreateStreamOnHGlobal(o_hMem, 1&, IIStream) = 0& Then
                  Call OleLoadPicture(ByVal ObjPtr(IIStream), 0&, 0&, aGUID(0), ArrayToPicture)
            End If
        End If
    End If
End Function

I use it with this code

Code:
Public Function Base64Encode(vArr As Variant) As String
    Const Routine As String = "Base64.Base64Encode"
    Dim xmlDoc As Object
    Dim xmlNode As Object
    
    Set xmlDoc = CreateObject("MSXML2.DOMDocument")
    
    Set xmlNode = xmlDoc.createElement("b64")
    
    xmlNode.DataType = "bin.base64"
    xmlNode.nodeTypedValue = vArr
    
    Base64Encode = xmlNode.Text
    
End Function