Graphics g = Graphics.FromImage(image);
                g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;//设置图片质量
                g.TextRenderingHint = System.Drawing.Text.TextRenderingHint.AntiAlias;
                g.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality;
                g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;