The ExifWorks class

Set(ByVal value As Image)
  If value IsNot Nothing Then
    ' Create a memory stream to write to:
    Dim thumbStream As New IO.MemoryStream()
    ' Save the image to the memory stream:
    value.Save(thumbStream, ImageFormat.Jpeg)

    ' Convert the memory stream to an array of bytes:
    Dim thumbData() As Byte = thumbStream.ToArray

    ' Save the bytes back to the PropertyItems: (a byte array is an undefined type)
    Me.SetProperty(TagNames.ThumbnailData, thumbData, ExifDataTypes.Undefined)

    ' Update our cached thumbnail:
    Me.mThumb = value
  End If
End Set

''' <summary>
''' Read Int32 from EXIF bytearray.
''' </summary>
''' <param name="B">EXIF bytearray to process</param>
''' <returns></returns>
''' <remarks></remarks>
''' <history>
''' [altair] 10.09.2003 Created
''' [altair] 05.09.2005 Changed from public shared to private instance method
''' </history>
Private Shared Function GetInt32(ByVal B As Byte()) As Int32
    If B.Length < 4 Then
        Throw New ArgumentException("Data too short (4 bytes expected)", "B")
    End If
    Return System.BitConverter.ToInt32(B, 0)
End Function

''' <summary>
''' Read Int16 from EXIF bytearray.
''' </summary>
''' <param name="B">EXIF bytearray to process</param>
''' <returns></returns>
''' <remarks></remarks>
''' <history>
''' [altair] 10.09.2003 Created
''' [altair] 05.09.2005 Changed from public shared to private instance method
''' </history>
Private Shared Function GetInt16(ByVal B As Byte()) As Int16
    If B.Length < 2 Then
        Throw New ArgumentException("Data too short (2 bytes expected)", "B")
    End If

    Return System.BitConverter.ToInt16(B, 0)
End Function

''' <summary>
''' Read string from EXIF bytearray.
''' </summary>
''' <param name="B">EXIF bytearray to process</param>
''' <returns></returns>
''' <remarks></remarks>
''' <history>
''' [altair] 10.09.2003 Created
''' [altair] 05.09.2005 Changed from public shared to private instance method
''' </history>
Private Function GetString(ByVal B As Byte()) As String
    Dim R As String = _Encoding.GetString(B)
    If R.EndsWith(vbNullChar) Then
        R = R.Substring(0, R.Length - 1)
    End If
    Return R
End Function

''' <summary>
''' Read rational from EXIF bytearray.
''' </summary>
''' <param name="B">EXIF bytearray to process</param>
''' <returns></returns>
''' <remarks></remarks>
''' <history>
''' [altair] 10.09.2003 Created
''' [altair] 05.09.2005 Changed from public shared to private instance method
''' </history>
Private Shared Function GetRational(ByVal B As Byte()) As Rational
    Dim R As New Rational
    R.Denominator = System.BitConverter.ToInt32(B, 4)
    R.Numerator = System.BitConverter.ToInt32(B, 0)
    Return R
End Function

''' <summary>
''' Get specified rational property
''' </summary>
''' <param name="PID">Property ID</param>
''' <param name="rank"></param>
''' <returns>Value of property or 0/1 if not present</returns>
''' <history>
''' [altair] 10.09.2003 Created
''' </history>
Public Function GetPropertyRational(ByVal PID As TagNames, ByVal rank As Integer) As Rational
    If IsPropertyDefined(PID) Then
        Dim N As Byte() = New Byte(7) {}
        Array.Copy(_Image.GetPropertyItem(PID).Value, rank * 8, N, 0, 8)
        Return GetRational(N)
    Else
        Dim R As New Rational()
        Return R
    End If
End Function

''' <summary>
''' Degrees, Minutes, Seconds to Decimal Degrees
''' </summary>
''' <param name="Deg">Degrees</param>
''' <param name="Min">Minutes</param>
''' <param name="Sec">Seconds</param>
''' <returns>Decimal Degrees</returns>
''' <remarks>in EXIF, Deg is always positive, but added case for negative degrees in case this routine is reused</remarks>
Private Shared Function DMStoDD(ByVal Deg As Double, ByVal Min As Double, ByVal Sec As Double) As Double
    Dim lFraction As Double = (Min / 60) + (Sec / 3600)
    If Deg > 0 Then
        Return Deg + lFraction
    Else
        Return Deg - lFraction
    End If
End Function

''' <summary>
''' GPS Latitude
''' </summary>
''' <returns>Decimal degrees of latitude</returns>
Public ReadOnly Property Latitude() As Double
    Get
        If IsPropertyDefined(TagNames.GpsLatitude) Then
            Dim deg As Rational = GetPropertyRational(TagNames.GpsLatitude, 0)
            Dim min As Rational = GetPropertyRational(TagNames.GpsLatitude, 1)
            Dim sec As Rational = GetPropertyRational(TagNames.GpsLatitude, 2)
            Dim res As [Double] = DMStoDD(deg.ToDouble(), min.ToDouble(), sec.ToDouble())
            Dim Ref As [String] = GetPropertyString(TagNames.GpsLatitudeRef)
            If Ref <> "N" Then
                res = -res
            End If
            Return res
        Else
            Return [Double].NaN
        End If
    End Get
End Property

''' <summary>
''' GPS Longitude
''' </summary>
''' <returns>Decimal degrees of longitude</returns>
Public ReadOnly Property Longitude() As Double
    Get
        If IsPropertyDefined(TagNames.GpsLongitude) Then
            Dim deg As Rational = GetPropertyRational(TagNames.GpsLongitude, 0)
            Dim min As Rational = GetPropertyRational(TagNames.GpsLongitude, 1)
            Dim sec As Rational = GetPropertyRational(TagNames.GpsLongitude, 2)
            Dim res As [Double] = DMStoDD(deg.ToDouble(), min.ToDouble(), sec.ToDouble())
            Dim Ref As [String] = GetPropertyString(TagNames.GpsLongitudeRef)
            If Ref <> "E" Then
                res = -res
            End If
            Return res
        Else
            Return [Double].NaN
        End If
    End Get
End Property

<br />
    Public Function GetPropertyString(ByVal PID As Int32, Optional ByVal DefaultValue As String = "") As String<br />
        If Me.IsPropertyDefined(PID) Then<br />
            Dim a As String = GetString(Me._Image.GetPropertyItem(PID).Value)<br />
            Me._Image.Dispose()<br />
            Return a<br />
        Else<br />
            Me._Image.Dispose()<br />
            Return DefaultValue<br />
        End If<br />
    End Function<br />