Bitmap bitmap2 = new Bitmap((int)w, (int)h);

bitmap2.SetResolution(, );

        private Graphics GetG(Bitmap bitmap)

        {

            Graphics g = Graphics.FromImage(bitmap);

            //设置高质量插值法

            g.InterpolationMode = InterpolationMode.HighQualityBicubic;

            //如何将图片覆盖到G

            g.CompositingMode = CompositingMode.SourceOver;

            //图片呈现质量

            g.CompositingQuality = CompositingQuality.HighQuality;

            //文字抗锯齿

            g.TextRenderingHint = TextRenderingHint.AntiAlias;

            //设置高质量,低速度呈现平滑程度

            g.SmoothingMode = SmoothingMode.AntiAlias;

            //设置背景颜色

            g.Clear(Color.White);

            return g;

        }

if (saveFileDialog1.ShowDialog() == DialogResult.OK)

            {

                this.pictureBox1.Image.Save(saveFileDialog1.FileName, System.Drawing.Imaging.ImageFormat.Png);

            }