Private Sub VaryQualityLevel()
    ' Get a bitmap.
    Dim bmp1 As New Bitmap("c:\TestPhoto.jpg")
    Dim jpgEncoder As ImageCodecInfo = GetEncoder(ImageFormat.Jpeg)

    ' Create an Encoder object based on the GUID
    ' for the Quality parameter category.
    Dim myEncoder As System.Drawing.Imaging.Encoder = System.Drawing.Imaging.Encoder.Quality

    ' Create an EncoderParameters object.
    ' An EncoderParameters object has an array of EncoderParameter
    ' objects. In this case, there is only one
    ' EncoderParameter object in the array.
    Dim myEncoderParameters As New EncoderParameters(1)

    Dim myEncoderParameter As New EncoderParameter(myEncoder, 50&)
    myEncoderParameters.Param(0) = myEncoderParameter
    bmp1.Save("c:\TestPhotoQualityFifty.jpg", jpgEncoder, myEncoderParameters)

    myEncoderParameter = New EncoderParameter(myEncoder, 100&)
    myEncoderParameters.Param(0) = myEncoderParameter
    bmp1.Save("c:\TestPhotoQualityHundred.jpg", jpgEncoder, myEncoderParameters)

    ' Save the bitmap as a JPG file with zero quality level compression.
    myEncoderParameter = New EncoderParameter(myEncoder, 0&)
    myEncoderParameters.Param(0) = myEncoderParameter
    bmp1.Save("c:\TestPhotoQualityZero.jpg", jpgEncoder, myEncoderParameters)

End Sub

Private Function GetEncoder(ByVal format As ImageFormat) As ImageCodecInfo

    Dim codecs As ImageCodecInfo() = ImageCodecInfo.GetImageEncoders()

    Dim codec As ImageCodecInfo
    For Each codec In codecs
        If codec.FormatID = format.Guid Then
            Return codec
        End If
    Next codec
    Return Nothing

End Function

' 导入命名空间
Imports System.Drawing
Imports System.Drawing.Drawing2D
Imports System.Windows.Forms
Imports System.Data
Imports System.Drawing.Imaging

public class MainClass
   public Shared Sub Main
        Dim imgCodecInfo As ImageCodecInfo = Nothing
        Dim encoder As Encoder = Nothing
        Dim encoderParam As EncoderParameter = Nothing
        Dim encoderParams As New EncoderParameters(3)

        Dim curBitmap As New Bitmap("yourfile.jpg")

        Dim mimeType As String = "image/tiff"
        Dim encoders() As ImageCodecInfo
        encoders = ImageCodecInfo.GetImageEncoders()
        Dim i As Integer

        While i < encoders.Length
            If encoders(i).MimeType = mimeType Then
                imgCodecInfo = encoders(i)
            End If
        End While ' Set color depth to 24 pixels
        encoder = encoder.ColorDepth
        encoderParam = New EncoderParameter(encoder, CLng(EncoderValue.CompressionLZW))
        encoderParams.Param(0) = encoderParam

        encoder = encoder.Compression
        encoderParam = New EncoderParameter(encoder, CLng(EncoderValue.CompressionLZW))
        encoderParams.Param(1) = encoderParam

        encoder = encoder.Transformation
        encoderParam = New EncoderParameter(encoder, CLng(EncoderValue.TransformRotate180))
        encoderParams.Param(2) = encoderParam

        curBitmap.Save("newFile.tif", imgCodecInfo, encoderParams)

        curBitmap.Dispose()

   End Sub
End class