通过摄像头拍摄的图像与picturebox的尺寸不一致，则需要进行缩放对应保存。

/// <summary>

       /// 无论摄像头拍摄图像的大小，均以picturebox为标准进行缩小 、放大

       /// </summary>

       /// <param name="bmp"></param>

       /// <param name="pictureBox1"></param>

       /// <returns></returns>

       public Bitmap imgSuitablePicturebox(Bitmap bmp, System.Windows.Forms.PictureBox pictureBox1)

       {

           Bitmap tmpbmp = null;

           Rectangle oldrct = null, newrct = null;

           bmp = new Bitmap(pictureBox1.Image);            

           oldrct = new Rectangle(0, 0, bmp.Width, bmp.Height);

           tmpbmp = new Bitmap(pictureBox1.Width, pictureBox1.Height);

           oldrct = new Rectangle(0, 0, bmp.Width, bmp.Height);

           Graphics g = Graphics.FromImage(tmpbmp);

           newrct = new Rectangle(0, 0, tmpbmp.Width, tmpbmp.Height);

           g.DrawImage(bmp, newrct, oldrct, GraphicsUnit.Pixel);

           g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;

           g.Dispose();

           return tmpbmp;

       }