在VB.net下如何修改JPG图片的质量？

[nofound007]

如题

net中自带System.Drawing.Imaging空间，如何在此空间下修改图片质量？要实现可以按百分数的设置，就像ACDSEE一样。

[Forrest23]

JPG图片的质量 具体是指的什么？

[fairy4]

   Private Sub ThumbnailImage(ByVal newimage As Image, ByVal intNewWidth As Integer, ByVal intNewHeight As Integer, ByVal mFileExtName As String, ByVal level As Integer, ByVal SavePath As String)
        Try


            ' Dim newImage As Image = Me.PictureBox1.Image
            Dim ici As ImageCodecInfo = GetCodecInfo(DirectCast(htmimes(mFileExtName), String))
            Dim parameters As New EncoderParameters(1)

            parameters.Param(0) = New EncoderParameter(Encoder.Quality, CLng(level))

            Dim objNewBitMap As New Bitmap(intNewWidth, intNewHeight, PixelFormat.Format32bppArgb)
            '从指定的 Image 对象创建新 Graphics 对象 
            Dim objGraphics As Graphics = Graphics.FromImage(objNewBitMap)
            '清除整个绘图面并以透明背景色填充 
            objGraphics.Clear(Color.Transparent)
            '在指定位置并且按指定大小绘制 原图片 对象 
            objGraphics.DrawImage(newimage, New Rectangle(0, 0, intNewWidth, intNewHeight))
            objNewBitMap.Save(SavePath, ici, parameters)
            objNewBitMap.Dispose()
        Catch ex As Exception
            MsgBox(ex.Message.ToString)
        End Try
    End Sub

[fairy4]

Private Shared Function GetCodecInfo(ByVal mimeType As String) As ImageCodecInfo
        Dim CodecInfo As ImageCodecInfo() = ImageCodecInfo.GetImageEncoders()
        For Each ici As ImageCodecInfo In CodecInfo
            If ici.MimeType = mimeType Then
                Return ici
            End If
        Next
        Return Nothing
    End Function

[nofound007]

[Quote=引用 1 楼 forrest23 的回复:]
JPG图片的质量 具体是指的什么？
[/Quote]

图片质量指图片的 Quality。

二楼的兄弟子程序有点意思了，但还得消化，有没有更明了一点，在下菜鸟一只

[nofound007]

[Quote=引用 2 楼 fairy4 的回复:]
VB.NET codePrivateSub ThumbnailImage(ByVal newimageAs Image,ByVal intNewWidthAsInteger,ByVal intNewHeightAsInteger,ByVal mFileExtNameAsString,ByVal levelAsInteger,ByVal SavePathAsString)Try' Dim newIm¡­
[/Quote]


htmimes是什么函数啊？

[fairy4]

'定義
 Shared htmimes As New Hashtable
'初始化
#Region "htmimes[.jpe]=image/jpeg"
    Shared Sub New()

        htmimes(".jpe") = "image/jpeg"
        htmimes(".gif") = "image/gif"
        htmimes(".jpeg") = "image/jpeg"
        htmimes(".jpg") = "image/jpeg"
        htmimes(".png") = "image/png"
        htmimes(".tif") = "image/tiff"
        htmimes(".tiff") = "image/tiff"
        htmimes(".bmp") = "image/bmp"

    End Sub
#End Region