Preserve Exif/Image Properties - vb.net

Question

In a web app, users can upload images, which save on the server. It creates thumbnails of the image on the back end with the following code, but all exif data of the image is lost.
I want to preserve the exif data from the original image all throughout the process, and have it included in the final stream. I can read the exif properties from the image, but can't get it to preserve when saving.
To clarify, I am not trying to read, parse, or do anything specific to the metadata itself, I just want to preserve it exactly as it was in the original image during image processing.
Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs)
'prepare image
Dim imgFullSize As System.Drawing.Image
'attempt to get the image
Dim sInputURL As String = HttpUtility.UrlDecode(Request.QueryString("IptFl"))
If InStr(sInputURL, "http://") > 0 Or InStr(sInputURL, "https://") Then
'from web url
Dim imgWebRequest As System.Net.WebRequest
Dim imgWebResponse As System.Net.WebResponse
imgWebRequest = System.Net.WebRequest.Create(sInputURL)
imgWebResponse = imgWebRequest.GetResponse()
imgFullSize = System.Drawing.Image.FromStream(imgWebResponse.GetResponseStream())
Else
'from file
imgFullSize = System.Drawing.Image.FromFile(Server.MapPath(sInputURL))
End If
' Dim props As PropertyItem() = imgFullSize.PropertyItems
' For Each prop As PropertyItem In props
' Response.Write(prop.Id.ToString() & "<br />")
' Next
'determine type
Dim sFileExtension As String = "png"
If Left(Right(sInputURL, 4), 1) = "." Then sFileExtension = Right(sInputURL, 3) 'for jpg, gif, etc
If Left(Right(sInputURL, 5), 1) = "." Then sFileExtension = Right(sInputURL, 4) 'for tiff, jpeg, etc
Dim jpgEncoder As ImageCodecInfo = GetEncoder(ImageFormat.Jpeg)
Dim gifEncoder As ImageCodecInfo = GetEncoder(ImageFormat.Gif)
Dim pngEncoder As ImageCodecInfo = GetEncoder(ImageFormat.Png)
'set the quality
Dim myEncoder As System.Drawing.Imaging.Encoder = System.Drawing.Imaging.Encoder.Quality
Dim myEncoderParams As New EncoderParameters(1)
Dim myEncoderQuality As New EncoderParameter(myEncoder, CType(100L, Int32))
myEncoderParams.Param(0) = myEncoderQuality
'save img to memory stream
Dim ms As New MemoryStream()
Select Case sFileExtension
Case "jpg" : imgFullSize.Save(ms, jpgEncoder, myEncoderParams)
Case "png", "gif" : imgFullSize.Save(ms, pngEncoder, myEncoderParams)
Case Else : imgFullSize.Save(ms, pngEncoder, myEncoderParams)
End Select
'output the memory stream
Response.ContentType = "image/" & sFileExtension
ms.WriteTo(Response.OutputStream)
'---> when I save the above image and look at the exif, it doesn't exist
End Sub
Private Function GetEncoder(ByVal format As ImageFormat) As ImageCodecInfo
Dim codecs As ImageCodecInfo() = ImageCodecInfo.GetImageDecoders()
Dim codec As ImageCodecInfo
For Each codec In codecs
If codec.FormatID = format.Guid Then Return codec
Next codec
Return Nothing
End Function

Answer 1

So this did the trick. Basically I had to loop through the source image properties, and for each, set the property in the new image.
'retrieve relative path to image
Dim sSrc As String = HttpUtility.UrlDecode(Request.QueryString("IptFl"))
'prepare image
Dim oImg As System.Drawing.Image
'attempt to get the image, either from web or local file
If InStr(sSrc, "http://") > 0 Or InStr(sSrc, "https://") Then
Dim oRequest As System.Net.WebRequest = System.Net.WebRequest.Create(sSrc)
Dim oResponse As System.Net.WebResponse = oRequest.GetResponse()
oImg = System.Drawing.Image.FromStream(oResponse.GetResponseStream())
oResponse.Close()
Else
oImg = System.Drawing.Image.FromFile(Server.MapPath(sSrc))
End If
'discard if image file not found
If oImg Is Nothing Then Response.End()
Dim sFileExt As String = Split(sSrc, ".")(UBound(Split(sSrc, ".")))
Dim oCanvas As System.Drawing.Bitmap = New System.Drawing.Bitmap(oImg.Width, oImg.Height, System.Drawing.Imaging.PixelFormat.Format16bppRgb555)
For Each pi As PropertyItem In oImg.PropertyItems
oCanvas.SetPropertyItem(pi)
Next
Dim oGraphic As System.Drawing.Graphics = System.Drawing.Graphics.FromImage(oCanvas)
oGraphic.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.Default
oGraphic.DrawImage(oImg, 0, 0, oImg.Width, oImg.Height)
Dim oStream As System.IO.MemoryStream = New System.IO.MemoryStream()
oCanvas.Save(oStream, System.Drawing.Imaging.ImageFormat.Jpeg)
Response.ContentType = "image/" & sFileExt
'output the memory stream
oStream.WriteTo(Response.OutputStream)
Response.End()