How to save PictureBox.Image to file?

You may use,

pictureBox.Image.Save(stream,System.Drawing.Imaging.ImageFormat.Jpeg);

Example:

 System.IO.MemoryStream ms = new System.IO.MemoryStream();
 pictureBox1.Image.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg);
 byte[] ar = new byte[ms.Length];
 ms.Write(ar, 0, ar.Length);

Try this

pictureBox.Image.Save(@"Path",ImageFormat.Jpeg);

Use below code for save into custom location

using (SaveFileDialog saveFileDialog = new SaveFileDialog() {Filter = @"PNG|*.png"})
                    {
                        if (saveFileDialog.ShowDialog() == DialogResult.OK)
                        {
                            pictureBox.Image.Save(saveFileDialog.FileName);
                        }
                    }