billeder bliver grynede / uklare (web)

Hej.

Jeg bruger nedenstående kode til at resize billeder 'on the fly', men hvor bliver de så uklare?


<%@Import Namespace="System.Drawing.Imaging" %>

<script language="VB" runat="server">
  Function ThumbnailCallback() as Boolean
    Return False
  End Function


  Sub Page_Load(sender as Object, e as EventArgs)
 
    'Read in the image filename to create a thumbnail of
    Dim imageUrl as String = Request.QueryString("img")
   
    'Read in the width and height
    Dim imageHeight as Integer = Request.QueryString("h")
    Dim imageWidth as Integer = Request.QueryString("w")

    'Make sure that the image URL doesn't contain any /'s or \'s
        'If imageUrl.IndexOf("/") >= 0 Or imageUrl.IndexOf("\") >= 0 then
        'We found a / or \
        'Response.End()
        'End If
   
        'Add on the appropriate directory
     
     
         
        Dim fullSizeImg As System.Drawing.Image = System.Drawing.Image.FromFile(Server.MapPath(imageUrl))
       
        'Do we need to create a thumbnail?
        Response.ContentType = "image/jpeg"
        If imageHeight > 0 And imageWidth > 0 Then
           
            Dim thumbNailImg As System.Drawing.Bitmap
            thumbNailImg = Me.ResizeBitmapWidth(fullSizeImg, imageWidth)
            thumbNailImg.Save(Response.OutputStream, ImageFormat.Jpeg)
        Else
            fullSizeImg.Save(Response.OutputStream, ImageFormat.Jpeg)
        End If
   
    End Sub
   
   
    Private Function ResizeBitmapWidth(ByVal pSourceBitmap As Drawing.Bitmap, _
                            ByVal pNewWidth As Int32) As Drawing.Bitmap
        Dim lNewHeight As Int32
        lNewHeight = CType(pSourceBitmap.Height * (pNewWidth / pSourceBitmap.Width), Int32)
        Dim lResizedBitmap As New Drawing.Bitmap(pNewWidth, lNewHeight)
        Dim lGraphics As Drawing.Graphics = Drawing.Graphics.FromImage(lResizedBitmap)

        lGraphics.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic

        lGraphics.DrawImage(pSourceBitmap, 0, 0, pNewWidth, lNewHeight)
        Return lResizedBitmap
    End Function
   
</script>