[.Net]JPG品質調整

Imports System.Drawing.Imaging

Sub SaveJPG()
　Dim Image as Bitmap = New Bitmap(OrigianalImageFile)
　'設定壓縮品質90檔案大小約是100的一半 但是畫質還是很不錯
　Dim quality As Integer = 90
　Dim qualityParam As New EncoderParameter(Encoder.Quality, quality)

　'取得編碼格式
　 Dim jgpEncoder As ImageCodecInfo = GetEncoder(ImageFormat.Jpeg)

　Dim encoderParams As New EncoderParameters(1)
　encoderParams.Param(0) = qualityParam

　Image.Save(NewImageFile, jgpEncoder, encoderParams)
End Sub

'取得編碼格式的副程式
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
　　　End If
　　Next codec
　Return Nothing
End Function

參考資料：MSDN