To save image to local drive you can use given command
import IO namespace as
using System.IO;
and then use given code
SaveFileDialog obj = new SaveFileDialog();
obj.Filter = "JPeg Image|*.jpg|Bitmap Image|*.bmp|Gif Image|*.gif";
obj.Title = "Save your Image File";
obj.ShowDialog();
if (obj.FileName != "")
{
FileStream fs = (FileStream)obj.OpenFile();
switch (obj.FilterIndex)
{
case 1 : this.pictureBox1.Image.Save(fs, System.Drawing.Imaging.ImageFormat.Jpeg);
break;
case 2 : this.pictureBox1.Image.Save(fs, System.Drawing.Imaging.ImageFormat.Bmp);
break;
case 3 : this.pictureBox1.Image.Save(fs, System.Drawing.Imaging.ImageFormat.Gif);
break;
} fs.Close();
}