Merge all Byte data to single PDF file in ASP.Net using VB.Net

I am having total 9 columns, all are having bytes data. Out of these 9 columns, 7 columns have IMAGE datatype & 1 column have VARBINARY(MAX). These 7 columns have bytes for JPG and 1 column have bytes for PDF. Finally I need to merge all in single pdf.

I have function where I am sending the bytes in using Dictionary(Of Byte(), String) = New Dictionary(Of Byte(), String)().

On the line Dim image = iTextSharp.text.Image.GetInstance(data) I am getting following error as "The byte array is not a recognized imageformat."

I am already displaying that bytes to image on page and it's displaying successfully, but iTextsharp is not reading JPG Bytes.

below is my code: 

Imports System.Data
Imports System.Configuration
Imports System.Data.SqlClient
Imports iTextSharp.text
Imports System.IO
Imports iTextSharp.text.html.simpleparser
Imports iTextSharp.text.pdf
Imports System.Drawing
Partial Class Default_
    Inherits System.Web.UI.Page
    Dim mergedpdf As Byte() = Nothing, newbytes As Byte() = Nothing, schoolname As String = "", _
        constr As String = ConfigurationManager.ConnectionStrings("dConstr").ConnectionString

    Dim _items As List(Of KeyValuePair(Of Byte(), String)) = New List(Of KeyValuePair(Of Byte(), String))()
    Dim My_dict1 As Dictionary(Of Byte(), String) = New Dictionary(Of Byte(), String)()

    Protected Sub Button1_Click(sender As Object, e As EventArgs)
        MergeandDownload(123)
    End Sub
    Sub MergeandDownload(ByVal regid As Integer)
        Using conn As New SqlConnection(constr)
            Try
                Using cmd As New SqlDataAdapter("SELECT b.schoolname,(case when a.[singlepdf] is null then '' else a.[singlepdf] end) AS singlepdf2,(case when a.[building] is null then '' else a.[building] end) AS building,a.[fire],a.[pollution],a.[chemical],a.[municipality],a.[traffic],a.[bylaws],a.[building_sketch],(case when a.[singlepdf] is null then '' else a.[singlepdf] end) AS singlepdf FROM [reg_documents] a inner join registration_master b on b.reg_schoolid = a.reg_schoolid where a.reg_schoolid = @regid", conn)
                    cmd.SelectCommand.Parameters.AddWithValue("@regid", regid)
                    conn.Open()
                    Using dsset As New DataSet()
                        cmd.Fill(dsset, "tabs")
                        If (dsset.Tables(0).Rows.Count > 0) Then
                            schoolname = dsset.Tables(0).Rows(0)("schoolname").ToString()
                            If (dsset.Tables(0).Rows(0)("building").ToString() <> "") Then
                                My_dict1.Add(System.Text.Encoding.ASCII.GetBytes(dsset.Tables(0).Rows(0)("building").ToString()), "jpg")
                            End If

                            If (dsset.Tables(0).Rows(0)("singlepdf").ToString() <> "") Then
                                My_dict1.Add(System.Text.Encoding.ASCII.GetBytes(dsset.Tables(0).Rows(0)("singlepdf").ToString()), "pdf")
                                'listoffilebytes.Add(System.Text.Encoding.ASCII.GetBytes(dsset.Tables(0).Rows(0)("singlepdf").ToString()))
                                '_items.Add(New KeyValuePair(Of Byte(), String)(System.Text.Encoding.ASCII.GetBytes(dsset.Tables(0).Rows(0)("singlepdf").ToString()), "pdf"))
                            End If
                            mergedpdf = concatAndAddContent()
                        End If
                    End Using
                End Using
            Catch ex As Exception
                Response.Write(ex.ToString())
            Finally
                If ConnectionState.Open Then
                    conn.Close()
                End If
            End Try
        End Using
    End Sub

    Public Overrides Sub VerifyRenderingInServerForm(ByVal control As Control)
    End Sub

    Public Function concatAndAddContent() As Byte()
        
        Dim mergedpdf2 As Byte() = Nothing
        Dim doc As Document = New Document()
        doc.SetPageSize(PageSize.A4)
        Dim ms = New System.IO.MemoryStream()

        If True Then
            Dim pdf As PdfCopy = New PdfCopy(doc, ms)
            doc.Open()
            If (My_dict1.Count > 0) Then
                Dim img_ As System.Drawing.Image = Nothing
                Dim data As Byte() = Nothing
                For Each ele1 As KeyValuePair(Of Byte(), String) In My_dict1
                    doc.NewPage()

                    Dim imageDocument As Document = Nothing
                    Dim imageDocumentWriter As PdfWriter = Nothing

                    Select Case ele1.Value.ToString()
                        Case "bmp", "gif", "jpg", "png"
                            'img_ = BytestoImage()  'File.ReadAllBytes()
                            data = CType(ele1.Key.ToArray(), Byte()) 'ImagetoBytes(img_)
                            imageDocument = New Document()
                            Using imageMS = New MemoryStream()
                                imageDocumentWriter = PdfWriter.GetInstance(imageDocument, imageMS)
                                imageDocument.Open()

                                If imageDocument.NewPage() Then
                                    Dim image = iTextSharp.text.Image.GetInstance(data)
                                    image.Alignment = Element.ALIGN_CENTER
                                    image.ScaleToFit(doc.PageSize.Width - 10, doc.PageSize.Height - 10)

                                    If Not imageDocument.Add(image) Then
                                        Throw New Exception("Unable to add image to page!")
                                    End If

                                    imageDocument.Close()
                                    imageDocumentWriter.Close()
                                    Dim imageDocumentReader As PdfReader = New PdfReader(ele1.Key.ToArray())
                                    Dim page = pdf.GetImportedPage(imageDocumentReader, 1)
                                    pdf.AddPage(page)
                                    imageDocumentReader.Close()
                                End If
                            End Using

                        Case "pdf"
                            Dim reader = New PdfReader(data)

                            For i As Integer = 0 To reader.NumberOfPages - 1
                                pdf.AddPage(pdf.GetImportedPage(reader, i + 1))
                            Next

                            pdf.FreeReader(reader)
                            reader.Close()
                        Case Else
                    End Select
                Next
            End If


            If doc.IsOpen() Then doc.Close()
            Return ms.ToArray()
        End If
    End Function
End Class