class ImageNormal

    {

        public void NormalImageDegree(string imagePath)

        {

            var bitmap = (Bitmap)Bitmap.FromFile(imagePath);

            var exif = bitmap.GetExif();

            if (exif.Orientation == ExifNET.Models.Types.Orientation.Normal) return;

            Bitmap newBitmap = null;

            switch (exif.Orientation)

            {

                case ExifNET.Models.Types.Orientation.Rotate90:

                    newBitmap = rotateImage(bitmap, -);

                    break;

                case ExifNET.Models.Types.Orientation.Rotate270:

                    newBitmap = rotateImage(bitmap, -);

                    break;

                case ExifNET.Models.Types.Orientation.Rotate180:

                    newBitmap = rotateImage(bitmap, -);

                    break;

                default:

                    break;

            }

            bitmap.Dispose();

            if (newBitmap != null)

            {

                newBitmap.Save(imagePath, System.Drawing.Imaging.ImageFormat.Jpeg);

                newBitmap.Dispose();

            }

        }

        private Bitmap rotateImage(Bitmap b, float angle)

        {

            angle = angle % ;

            //弧度转换

            double radian = angle * Math.PI / 180.0;

            double cos = Math.Cos(radian);

            double sin = Math.Sin(radian);

            //原图的宽和高

            int w = b.Width;

            int h = b.Height;

            int W = (int)(Math.Max(Math.Abs(w * cos - h * sin), Math.Abs(w * cos + h * sin)));

            int H = (int)(Math.Max(Math.Abs(w * sin - h * cos), Math.Abs(w * sin + h * cos)));

            //目标位图

            Bitmap dsImage = new Bitmap(W, H);

            System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(dsImage);

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

            g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;

            //计算偏移量

            Point Offset = new Point((W - w) / , (H - h) / );

            //构造图像显示区域：让图像的中心与窗口的中心点一致

            Rectangle rect = new Rectangle(Offset.X, Offset.Y, w, h);

            Point center = new Point(rect.X + rect.Width / , rect.Y + rect.Height / );

            g.TranslateTransform(center.X, center.Y);

            g.RotateTransform( - angle);

            //恢复图像在水平和垂直方向的平移

            g.TranslateTransform(-center.X, -center.Y);

            g.DrawImage(b, rect);

            //重至绘图的所有变换

            g.ResetTransform();

            g.Save();

            g.Dispose();

            //dsImage.Save("yuancd.jpg", System.Drawing.Imaging.ImageFormat.Jpeg);

            return dsImage;

        }

    }