.net – 相同的代码在不同的服务器上产生不一致的图像质量

开发版 – IIS7 Windows 7 Pro 64位机

实时版本 – IIS7 Windows Server 2008 64位机器

请注意实时版本是如何“像素化”&看起来质量低,Dev版本却是流畅的,抗锯齿的&看起来很好.这些都是由相同的代码生成的：

' Settings
Dim MaxHeight As Integer = 140
Dim MaxWidth As Integer = 140
Dim WorkingFolderPath As String = "serversharebla"
Dim AllowedFileExtensions As New ArrayList
AllowedFileExtensions.Add(".jpg")
AllowedFileExtensions.Add(".jpeg")

' Select an image to use from the WorkingFolder
Dim ImageFileName As String = ""
Dim WorkingFolder As New IO.DirectoryInfo(WorkingFolderPath)
Dim SourceImages As IO.FileInfo() = WorkingFolder.GetFiles()

For Each SourceImage As IO.FileInfo In SourceImages
    If AllowedFileExtensions.Contains(SourceImage.Extension.ToLower) = True Then
        ImageFileName = SourceImage.Name
    End If
Next

' Determine path to selected image (if no image was found use a placeholder)
Dim PhysicalPath As String = ""
If ImageFileName = "" Then
    ' No Image was found,use the filler image
    PhysicalPath = Server.MapPath("ProductOfTheMonthMissing.jpg")
Else
    ' An Image was found,Redirect to it / build path for Thumnailing
    If Request.QueryString("FullSize") = "true" Then
        Response.Redirect("../share/bla/" & ImageFileName)
    Else
        PhysicalPath = WorkingFolderPath & ImageFileName
    End If
End If

' Load image and output in binary (resizing if necessary)
Using ProductImage As System.Drawing.Image = System.Drawing.Image.FromFile(PhysicalPath)
    Dim newWidth As Integer = ProductImage.Width
    Dim newHeight As Integer = ProductImage.Height

    ' Check if selected size is too big,if so,determine new size
    If ProductImage.Width > MaxWidth Or ProductImage.Height > MaxHeight Then
        Dim ratioX As Double = CDbl(MaxWidth) / ProductImage.Width
        Dim ratioY As Double = CDbl(MaxHeight) / ProductImage.Height
        Dim ratio As Double = Math.Min(ratioX,ratioY)

        newWidth = CInt(ProductImage.Width * ratio)
        newHeight = CInt(ProductImage.Height * ratio)
    End If

    ' Create a new bitmap from the image with new size
    Dim Codecs As ImageCodecInfo() = ImageCodecInfo.GetImageEncoders()
    Dim CodecInfo As ImageCodecInfo = Nothing
    Dim ProductOfTheMonth As New Bitmap(ProductImage,newWidth,newHeight)
    Dim ReSizer As Graphics = Graphics.FromImage(ProductOfTheMonth)

    ReSizer.InterpolationMode = InterpolationMode.HighQualityBicubic
    ReSizer.SmoothingMode = SmoothingMode.HighQuality
    ReSizer.PixelOffsetMode = PixelOffsetMode.HighQuality
    ReSizer.CompositingQuality = CompositingQuality.HighQuality

    ' Ensure the encoder uses the best quality settings
    Dim EncoderParams As New EncoderParameters(3)
    EncoderParams.Param(0) = New EncoderParameter(System.Drawing.Imaging.Encoder.Quality,100L)
    EncoderParams.Param(1) = New EncoderParameter(System.Drawing.Imaging.Encoder.ScanMethod,CInt(EncoderValue.ScanMethodInterlaced))
    EncoderParams.Param(2) = New EncoderParameter(System.Drawing.Imaging.Encoder.RenderMethod,CInt(EncoderValue.RenderProgressive))

    ' Set jpeg as the output codec
    For Each Codec As ImageCodecInfo In Codecs
        If Codec.MimeType = "image/jpeg" Then
            CodecInfo = Codec
        End If
    Next

    ' Ready a memory stream and byte array
    Dim MemStream As New MemoryStream()
    Dim bmpBytes As Byte()

    ' Save the image the the memory stream & prep ContentType for HTTP reasponse
    Response.ContentType = "image/jpeg"
    ProductOfTheMonth.Save(MemStream,CodecInfo,EncoderParams)

    ' Flush memory stream into byte array & flush to browser
    bmpBytes = MemStream.GetBuffer()
    Response.BinaryWrite(bmpBytes)

    ' Cleanup
    ProductOfTheMonth.Dispose()
    MemStream.Close()
    ProductImage.Dispose()
End Using

这个&的背后原因是什么？我该如何解决这个问题？大概是它在实时网络服务器上的GD问题 – 但我不知道是什么 – 我试图在设置图形和编解码器设置时尽可能彻底但它仍然不同？

编辑：源图像在两个示例中也是相同的(位于中央unc共享上) – 源图像here的副本