百度OCR文字识别-身份证识别

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简介

答应了园区大牛张善友要写AI 的系列博客，所以开始了AI 系列之旅。

一、介绍

身份证识别 API 接口文档地址：http://ai.baidu.com/docs#/OCR-API/top

接口描述

用户向服务请求识别身份证，身份证识别包括正面和背面。

请求说明

请求示例

HTTP 方法：POST

请求URL： https://aip.baidubce.com/rest/2.0/ocr/v1/idcard

备注：你需要成为百度开发者，获取API key 和Secret Key

Access_Token 的获取

百度Access_token 有效期有时间限制，大概是30天左右，所以建议封装成功能方法每次调用最新的。

access_token：要获取的Access Token；
expires_in：Access Token的有效期(秒为单位，一般为1个月)；

二、技术实现

百度文字识别有提供SDK。如果有支持的语言，可以直接用sdk。笔者自己用的Http 请求封装

对于图片大小有要求的，图像数据，base64编码后进行urlencode，要求base64编码和urlencode后大小不超过4M，最短边至少15px，最长边最大4096px,支持jpg/png/bmp格式

接口基础封装

 1 using System;
 2 using System.Collections.Generic;
 3 using System.Linq;
 4 using System.Text;
 5 using System.Threading.Tasks;
 6 
 7 namespace BaiduAIAPI.Model
 8 {
 9 
10     public class AccessTokenModel {
11 
12         public bool IsSuccess { get; set; }
13         public SuccessAccessTokenModel SuccessModel { get; set; }
14         public ErrorAccessTokenModel ErrorModel { get; set; }
15 
16     }
17 
18     /// <summary>
19     /// 获取accesstoken，正常 的 百度接口返回的json 实体模型
20     /// </summary>
21     public class SuccessAccessTokenModel
22     {
23         public string refresh_token { get; set; }
24         public int expires_in { get; set; }
25         public string scope { get; set; }
26         public string session_key { get; set; }
27         public string session_secret { get; set; }
28 
29         public string access_token { get; set; }
30     }
31 
32     /// <summary>
33     /// 获取accesstoken，失败的 百度接口返回的json 实体模型
34     /// </summary>
35     public class ErrorAccessTokenModel
36     {
37         public string error { get; set; }
38         public string error_description { get; set; }
39 
40     }
41 }

  1 using System;
  2 using System.IO;
  3 using System.Net;
  4 using System.Text;
  5 using System.Web;
  6 using AOP.Common;
  7 using AOP.Common.DataConversion;
  8 using BaiduAIAPI.Model;
  9 using BaiduAIAPI.Type;
 10 
 11 namespace BaiduAIAPI.ORC_Characterbase64
 12 {
 13 
 14     /// <summary>
 15     /// 文字识别--身份证识别 应用（只是获取身份证图片 信息，没有和公安部联网，无法确认真假，只是单纯从图片上识别文字）
 16     /// </summary>
 17     public class IDCardRecognition
 18     {
 19         // 身份证识别
 20 
 21         /// <summary>
 22         /// 身份证识别
 23         /// </summary>
 24         /// <param name="token">Accesstoken</param>
 25         /// <param name="imagePath">图片路径</param>
 26         /// <param name="recognitionString">识别结果</param>
 27         /// <param name="errorMsg">错误信息</param>
 28         /// <param name="id_card_side"> front：身份证正面；back：身份证背面</param>
 29         /// <param name="detect_direction">是否检测图像朝向，默认不检测，即：false。朝向是指输入图像是正常方向、逆时针旋转90/180/270度。可选值包括:- true：检测朝向；- false：不检测朝向。</param>
 30         /// <param name="detect_risk"> string 类型 是否开启身份证风险类型(身份证复印件、临时身份证、身份证翻拍、修改过的身份证)功能，默认不开启，即：false。可选值:true-开启；false-不开启</param>
 31         /// <returns>结果状态</returns>
 32         public static IDCardRecognitionModel GetIdcardRecognitionString(string token, string imagePath, ref string recognitionString, out string errorMsg, string id_card_side="front", bool detect_direction=false, string detect_risk="false")
 33         {
 34             bool resultState = true;
 35             IDCardRecognitionModel tempModel = new IDCardRecognitionModel();
 36 
 37             try
 38             {
 39                 #region 基础校验
 40                 string verificationMsg = "";
 41                 errorMsg = "";
 42                 bool isVerification = ImageVerification.VerificationImage(imagePath, out verificationMsg);
 43                 if (!isVerification)
 44                 {
 45 
 46                     errorMsg += verificationMsg;
 47                     tempModel.state = false;
 48                     tempModel.errorMsg = errorMsg;
 49                     return tempModel;
 50                 }
 51                 string strbaser64 = ConvertDataFormatAndImage.ImageToByte64String(imagePath, System.Drawing.Imaging.ImageFormat.Jpeg); // 图片的base64编码
 52                 Encoding encoding = Encoding.Default;
 53                 string urlEncodeImage = HttpUtility.UrlEncode(strbaser64);
 54 
 55                 byte[] tempBuffer = encoding.GetBytes(urlEncodeImage);
 56 
 57                 if (tempBuffer.Length > 1024 * 1024 * 4)
 58                 {
 59 
 60                     errorMsg += "图片加密 后的大小超过4MB！";
 61                     recognitionString = "";
 62                     tempModel.state = false;
 63                     tempModel.errorMsg = errorMsg;
 64                     return tempModel;
 65 
 66                 }
 67                 #endregion
 68 
 69                 #region 请求接口
 70                 recognitionString = "";
 71 
 72                 string host = "https://aip.baidubce.com/rest/2.0/ocr/v1/idcard?access_token=" + token;
 73                 String str = "id_card_side=" + id_card_side + "&detect_direction=" + detect_direction + "&detect_risk=" + detect_risk + "&image=" + HttpUtility.UrlEncode(strbaser64);
 74                 var tempResult = HttpRequestHelper.Post(host, str);
 75                 recognitionString = tempResult;
 76 
 77                
 78                 if (recognitionString.Contains("\"error_code\""))//说明异常
 79                 {
 80                     resultState = false;
 81                     tempModel.state = false;
 82                     tempModel.errorTypeModel = Json.ToObject<ErrorTypeModel>(tempResult);
 83                     tempModel.errorTypeModel.error_discription = ORC_CharacterRecognitionErrorType.GetErrorCodeToDescription(tempModel.errorTypeModel.error_code);
 84                 }
 85                 else
 86                 {
 87                     tempModel.state = true;
 88                     tempModel.successModel = Json.ToObject<IDCardRecognitionSuccessResultModel>(tempResult);
 89                 }
 90                 #endregion
 91 
 92                 return tempModel;
 93             }
 94             catch (Exception ex)//接口外部异常，如网络异常
 95             {
 96                 resultState = false;
 97                 errorMsg = ex.ToString();
 98                 tempModel.state = false;
 99                 tempModel.errorMsg = ex.ToString();
100                 return tempModel;
101                
102             }
103         }
104 
105     }
106 
107 }

winform 调用核心部分

 1 /// <summary>
 2         /// 识别操作
 3         /// </summary>
 4         /// <param name="filePath"></param>
 5         /// <param name="id_card_side">身份证 正面还是背面</param>
 6         /// <param name="detect_direction"></param>
 7         /// <param name="detect_risk"></param>
 8         public void Distinguish(string filePath, string id_card_side = "front", bool detect_direction = false, string detect_risk = "false")
 9         {
10             DoTime();//主线程执行进度条，子线程进行数据请求操作
11             t1 = new Thread(new ThreadStart(() =>
12             {
13 
14                 var temp = BaiduAIAPI.Access_Token.GetAccessToken();
15                 if (temp.IsSuccess)
16                 {
17                     string data = "";
18                     string error = "";
19                     var result = IDCardRecognition.GetIdcardRecognitionString(temp.SuccessModel.access_token, filePath, ref data, out error, id_card_side, detect_direction, detect_risk);
20                     this.Invoke(new Action(() =>
21                     {
22                         tb_showInfo.AppendText("\r\n -----------------------------------------------------------------");
23                     }));
24 
25                     if (result.state)
26                     {
27                         this.Invoke(new Action(() =>
28                         {
29                             tb_showInfo.AppendText("\r\n ---------------------------识别成功-------------------------------");
30                             tb_showInfo.AppendText("\r\n" + result.successModel.ToJson() + "\r\n");
31                         }));
32 
33                     }
34                     else
35                     {
36                         this.Invoke(new Action(() =>
37                         {
38 
39                             tb_showInfo.AppendText("\r\n-----------------------------识别失败！--------------------------------");
40                             tb_showInfo.AppendText("\r\n" + result.successModel.ToJson() + result.errorMsg + "\r\n");
41                         }));
42 
43                     }
44                 }
45                 else
46                 {
47                     this.Invoke(new Action(() =>
48                     {
49                         AttrMessage.ErrorMsg(temp.ErrorModel.error);
50                     }));
51 
52                 }
53 
54                 this.Invoke(new Action(() =>
55                 {
56                     progressBar_ToReadDistinguish.Value = 100;
57                     timer1.Enabled = false;
58                     progressBar_ToReadDistinguish.Value = 0;
59                 }));
60             }));
61 
62             t1.IsBackground = true;
63            t1.Start();
64 
65         }