运用百度接口检测人脸并且获取人脸坐标，并根据坐标裁剪人脸

主要方法：

using System.IO;
using System.Drawing;
using System.Drawing.Imaging;

        public ActionResult UploadFaceImg(string faceImg, string xfNo, string Eid)
        {
            string dic = System.AppDomain.CurrentDomain.BaseDirectory.ToString();
            #region 检测是否有人脸，并获取其坐标
            string results = haveFace(faceImg);
            if (string.IsNullOrEmpty(results))
            {
               //如果没有人脸则返回
                return Content(new ResParameter { code = ResponseCode.success, info = "2", data = null }.ToJson());
            }
           //定义坐标系
            int x = 0;
            int y = 0;
            int width = 0;
            int height = 0;
            double dx = 0;
            double dy = 0;
            double dwidth = 0;
            double dheight = 0;
            var re = results.Split(new char[] { ',' });
            for (var i = 0; i < re.Length; i++)
            {
                dx = double.Parse(re[0]);
                dy = double.Parse(re[1]);
                dwidth = double.Parse(re[2]);
                dheight = double.Parse(re[3]);
            }
            //此处为坐标增减了一定的数据，因为百度拿到人脸坐标就只有脸，连头发都没有，太丑了。
            x = (int)dx - 100; y = (int)dy - 100; width = (int)dwidth + 160; height = (int)dheight + 200;
            #endregion
            //根据坐标系裁切人脸

              #region 根据坐标剪切出人脸

              string fileUrl = "/Resource/FaceImg/";//存储人脸图片的文件夹
              string bpmfile =dic+ fileUrl + DateTime.Now.ToString("yyMMddhhmmss") + "-2.png";//裁剪后的照片
              ToBitmap(fasebase, bpmfile, x, y, width, height);
              #endregion

            ////如果图片太大，那么需要压缩图片大小
            string fImgNew = fileUrl + DateTime.Now.ToString("yyMMddhhmmss") + "-1.jpg";//压缩后的照片名称
            string fileNew = dic + fImgNew;
            GetPicThumbnail(bpmfile, fileNew, 20);

           return Content(new ResParameter { code = ResponseCode.success, info = "1", data = null }.ToJson()); 
}

#region 百度检测人脸,若有则返回其坐标
        public string haveFace(string faceimg)
        {
            string results = "";
            DateTime dt1 = DateTime.Now;
            string token = "百度账户token";
            string host = "https://aip.baidubce.com/rest/2.0/face/v3/detect?access_token=" + token;
            Encoding encoding = Encoding.Default;
            HttpWebRequest request = (HttpWebRequest)WebRequest.Create(host);
            request.Method = "post";
            request.KeepAlive = true;
            String str = "{\"image\":\"" + faceimg.Replace(" ", "+") + "\",\"image_type\":\"BASE64\",\"face_field\":\"quality,angle,mask\"}";
            byte[] buffer = encoding.GetBytes(str);
            request.ContentLength = buffer.Length;
            request.GetRequestStream().Write(buffer, 0, buffer.Length);
            HttpWebResponse response = (HttpWebResponse)request.GetResponse();
            StreamReader reader = new StreamReader(response.GetResponseStream(), Encoding.Default);
            string result = reader.ReadToEnd();
            int facenum = 0;
            if (result.ToJObject()["error_msg"].ToString() == "SUCCESS")
            {
                facenum = result.ToJObject()["result"]["face_num"].ToInt();
            }
            if (facenum > 0)
            {
                var j_result = result.ToJObject();
                Double x = j_result["result"]["face_list"][0]["location"]["left"].ToDouble();
                Double y = j_result["result"]["face_list"][0]["location"]["top"].ToDouble();
                Double width = j_result["result"]["face_list"][0]["location"]["width"].ToDouble();//人脸区域宽度
                Double height = j_result["result"]["face_list"][0]["location"]["height"].ToDouble();//人脸区域高度
                results = x + "," + y + "," + width + "," + height;
            }
            return results;
        }

        #endregion

#region 截取图片
        //转换为位图
        public static Bitmap ToBitmap(string base64, string fileUrl,int x,int y,int width,int height)
        {
            byte[] imageBytes = Convert.FromBase64String(base64);
            MemoryStream ms = new MemoryStream(imageBytes, 0, imageBytes.Length);

            ms.Write(imageBytes, 0, imageBytes.Length);
            Image image = Image.FromStream(ms, true);
            Bitmap bitmapQR = CutImage(image, new Rectangle(x, y, width, height));
            //将为图存储到本地
            bitmapQR.Save(fileUrl, System.Drawing.Imaging.ImageFormat.Bmp);
            return bitmapQR;
            
        }
        #endregion

 /// <summary>
        /// 图片压缩
        /// </summary>
        /// <param name="sFile">图片路径</param>
        /// <param name="outPath">保存路径</param>
        /// <param name="flag">图片压缩值</param>
        /// <returns></returns>
        public static bool GetPicThumbnail(string sFile, string outPath, int flag)
        {
            System.Drawing.Image iSource = System.Drawing.Image.FromFile(sFile);
            ImageFormat tFormat = iSource.RawFormat;
            //以下代码为保存图片时，设置压缩质量 
            EncoderParameters ep = new EncoderParameters();
            long[] qy = new long[1];
            qy[0] = flag;//设置压缩的比例1-100 
            EncoderParameter eParam = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, qy);
            ep.Param[0] = eParam;
            try
            {
                ImageCodecInfo[] arrayICI = ImageCodecInfo.GetImageEncoders();
                ImageCodecInfo jpegICIinfo = null;
                for (int x = 0; x < arrayICI.Length; x++)
                {
                    if (arrayICI[x].FormatDescription.Equals("JPEG"))
                    {
                        jpegICIinfo = arrayICI[x];
                        break;
                    }
                }
                if (jpegICIinfo != null)
                {
                    iSource.Save(outPath, jpegICIinfo, ep);//dFile是压缩后的新路径 
                }
                else
                {
                    iSource.Save(outPath, tFormat);
                }
                return true;
            }
            catch(Exception ex)
            {
                return false;
            }
            finally
            {
                iSource.Dispose();
                iSource.Dispose();
            }
        }