Sub get_pic()

With CreateObject("InternetExplorer.Application")
    .Visible = True
    .Navigate "https://igtb.bochk.com/index_tc.html"
    Do While .busy
        DoEvents
    Loop
    Do Until .readystate = 4
        DoEvents
        Sleep 2000
    Loop

    Set aaa = .document.all.tags("iframe")(1).contentwindow.document.all.tags("img")
    For j = 0 To aaa.Length - 1
        With CreateObject("MSXML2.XMLHTTP.6.0")
            [a1] = aaa(j).href
            .Open "GET", aaa(j).href, False
            .setRequestHeader "Content-Type", "application/x-www-form-urlencoded"
            .Send
            strFilename = "C:\test.png"
            ByteToFile .responsebody, strFilename
        End With
        Exit For
    Next

End With

End Sub
Function ByteToFile(arrByte, strFilename)
    With CreateObject("Adodb.Stream")
        .Type = 1 'adTypeBinary
        .Open
        .Write arrByte
        .SaveToFile strFilename, 2 'adSaveCreateOverWrite
        .Close
    End With
End Function

以上 vba 已經可提取圖案,但並不是打開網頁時的那張圖,請問有什麼方法可以提取打開網頁時顯示之保安碼圖