一个图片经过缩略成和原图一样大小，一样分辨率，颜色都一样，为什么质量不如原图？？

Question

System.Drawing.Image image = System.Drawing.Image.FromFile(Server.MapPath("Images/xxx.jpg"));
System.Drawing.Imaging.ImageFormat format = image.RawFormat;
Bitmap bmp = new Bitmap(image,image.Width,image.Height);
Graphics g = Graphics.FromImage( bmp );
g.InterpolationMode=System.Drawing.Drawing2D.InterpolationMode.High;
g.SmoothingMode=System.Drawing.Drawing2D.SmoothingMode.HighQuality;
bmp.Save(Server.MapPath("Images/xxx2.jpg"),format);
bmp.Dispose();
image.Dispose();

Answer 1

Bitmap bmp = new Bitmap(image,image.Width,image.Height);
变成位图就已经失真了吧？

Answer 2

EncoderParameters parameters = new EncoderParameters(1);
parameters.Param[0] = new EncoderParameter(Encoder.Quality,GetQua);   //設定圖片的質量 1－100的整數
image.Save(saveFullPath, ici, parameters);
parameters.Dispose();