public Bitmap getnew(Image bit, int TargetWidth, int TargetHeight)//beishu引數為放大的倍數。放大縮小都可以，0.8即為縮小至原來的0.8倍
{
Bitmap destBitmap = new Bitmap(TargetWidth, TargetHeight);
Graphics g = Graphics.FromImage(destBitmap);
g.Clear(Color.Transparent);
//設定畫布的描繪質量
g.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality;
g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
g.DrawImage(bit, new Rectangle(0, 0, destBitmap.Width, destBitmap.Height), 0, 0, bit.Width, bit.Height, GraphicsUnit.Pixel);
g.Dispose();
return destBitmap;
}