Problem is this line:
pictureBox1.Image = bitmap;
pictureBox1.Image.Save("c:\\image\\image1.jpg");
You are trying to save image that is not yet properly loaded and also you are facing cross-threading.
The solution in this case is to not use multiple threads when drawing.
void cam_NewFrame(object sender, NewFrameEventArgs eventArgs)
{
bitmap = (Bitmap)eventArgs.Frame.Clone();
pictureBox1.Image = bitmap;
try
{
this.Invoke((MethodInvoker)delegate
{
//saves image on its thread
pictureBox1.Image.Save("c:\\image\\image1.jpg");
});
}
catch (Exception ex)
{
MessageBox.Show(""+ex);
}
}