最近研究C#相關的ORC技術，圖像識別一般C和C++這種底層語言做的比較多，C#主要是依托一些封裝好的組件進行調用，這裡介紹三種身份證識別的方法。

一：調用大公司API介面，百度、雲脈，文通科技都有相關的API介紹。
二：調用圖像處理類庫，EmguCV是OpenCV的一個跨平臺的.Net封裝，該封裝也可以被編譯到Mono平臺和允許在Windows、Mac OS、Android、iPhone、iPad等多個平臺上運行
三：調用Office2007 組件

一、證件識別API介面

以聚合數據中的API介面為例，因為官方API沒有提供C#的調用方式，網址如下：證件識別介面

/// <summary>
/// 上傳圖片
/// </summary>
/// <returns></returns>
public static string CardUpload()
{
    try
    {
        string appkey = "網站自己申請的key"; //配置您申請的appkey         
        HttpPostedFile file = HttpContext.Current.Request.Files[0];
        string url = "http://api2.juheapi.com/cardrecon/upload";
        var parameters = new Dictionary<string, string>();
        parameters.Add("key", appkey);
        parameters.Add("cardType", "2");
        string result = HttpPostData(url, 60000, "pic", file.InputStream, parameters);
        JObject info = JObject.Parse(JObject.Parse(result)["result"].ToString());
        var cardInfo = new
        {
            name = info["姓名"],
            card = info["公民身份號碼"]
        };
        return cardInfo.ToJson();
    }
    catch (Exception ex)
    {
        return ex.ToString();
    }
}
/// <summary>
/// Post調用API
/// </summary>
/// <param name="url">api地址</param>
/// <param name="timeOut">訪問超時時間</param>
/// <param name="fileKeyName">文件參數名</param>
/// <param name="file">文件流</param>
/// <param name="stringDict">參數列表</param>
/// <returns>結果集</returns>
private static string HttpPostData(string url, int timeOut, string fileKeyName,
                           Stream file, Dictionary<string, string> stringDict)
{
    string responseContent;
    var memStream = new MemoryStream();
    var webRequest = (HttpWebRequest)WebRequest.Create(url);
    // 邊界符
    var boundary = "---------------" + DateTime.Now.Ticks.ToString("x");
    // 邊界符
    var beginBoundary = Encoding.ASCII.GetBytes("--" + boundary + "\r\n");
    // 最後的結束符
    var endBoundary = Encoding.ASCII.GetBytes("--" + boundary + "--\r\n");
    // 設置屬性
    webRequest.Method = "POST";
    webRequest.Timeout = timeOut;
    webRequest.ContentType = "multipart/form-data; boundary=" + boundary;
    //寫入開始邊界符
    memStream.Write(beginBoundary, 0, beginBoundary.Length);
    // 寫入文件
    const string filePartHeader =
        "Content-Disposition: form-data; name=\"{0}\"; filename=\"{1}\"\r\n" +
         "Content-Type: application/octet-stream\r\n\r\n";
    var header = string.Format(filePartHeader, fileKeyName, "card.jpg");
    var headerbytes = Encoding.UTF8.GetBytes(header);
    memStream.Write(headerbytes, 0, headerbytes.Length);
    file.CopyTo(memStream);
    // 寫入字元串的Key
    var stringKeyHeader = "\r\n--" + boundary +
                           "\r\nContent-Disposition: form-data; name=\"{0}\"" +
                           "\r\n\r\n{1}\r\n";
    foreach (byte[] formitembytes in from string key in stringDict.Keys
                                     select string.Format(stringKeyHeader, key, stringDict[key])
                                         into formitem
                                         select Encoding.UTF8.GetBytes(formitem))
    {
        memStream.Write(formitembytes, 0, formitembytes.Length);
    }

    // 寫入最後的結束邊界符
    memStream.Write(endBoundary, 0, endBoundary.Length);
    webRequest.ContentLength = memStream.Length;
    // 構造完畢，執行POST方法
    var requestStream = webRequest.GetRequestStream();
    memStream.Position = 0;
    var tempBuffer = new byte[memStream.Length];
    memStream.Read(tempBuffer, 0, tempBuffer.Length);
    memStream.Close();
    requestStream.Write(tempBuffer, 0, tempBuffer.Length);
    requestStream.Close();
    var httpWebResponse = (HttpWebResponse)webRequest.GetResponse();
    using (var httpStreamReader = new StreamReader(httpWebResponse.GetResponseStream(),
                                                    Encoding.GetEncoding("utf-8")))
    {
        responseContent = httpStreamReader.ReadToEnd();
    }
    httpWebResponse.Close();
    webRequest.Abort();
    return responseContent;
}

二、EmguCV類庫調用

環境搭建

下載地址：EmguCV官網

在File類別下下載這個EXE，進行安裝，安裝後在目錄下能找相應組件，還有些應用的案例。

C#進行識別，需進行圖片二值化處理和OCR調用相關DLL可在我整理的地址下載：360雲盤 提取碼：89f4
dll文件夾中的dll引用到C#項目中，x64，x86，tessdata對應OCR識別的類庫和語言庫，我tessdata中已添加中文語言包，將這三個文件夾放入程式執行文件夾中。

Demo

自己做的小Demo如圖：身份證圖片是百度上下載的

相關代碼如下：

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using Emgu.CV;
using Emgu.CV.OCR;
using Emgu.CV.Structure;
using System.IO;


namespace ImageManage
{
    public partial class Form1 : Form
    {
        Image<Gray, Byte> imageThreshold;

        public Form1()
        {
            InitializeComponent();
        }

        private void btn_convert_Click(object sender, EventArgs e)
        {
            //第一個參數是語言包文件夾的地址，不寫預設在執行文件夾下
            Tesseract _ocr = new Tesseract("", "chi_sim", OcrEngineMode.TesseractOnly);
            _ocr.Recognize(imageThreshold);
            String text = _ocr.GetText();
            this.textBox1.Text = text;
        }

        private void pictureBox1_Click(object sender, EventArgs e)
        {
            OpenFileDialog of = new OpenFileDialog();
            of.Title = "請選擇圖片";
            if (of.ShowDialog() == DialogResult.OK)
            {
                string file = of.FileName;
                Image img = Image.FromFile(file);
                pictureBox1.Image = img;            
            }
            Bitmap bitmap = (Bitmap)this.pictureBox1.Image;
            Image<Bgr, Byte> imageSource = new Image<Bgr, byte>(bitmap);
            Image<Gray, Byte> imageGrayscale = imageSource.Convert<Gray, Byte>();
            imageGrayscale = randon(imageGrayscale);
            imageThreshold = imageGrayscale.ThresholdBinary(new Gray(100), new Gray(255));
            this.pictureBox2.Image = imageThreshold.ToBitmap();
        }

        /// <summary>
        /// 旋轉校正
        /// </summary>
        /// <param name="imageInput"></param>
        /// <returns></returns>
        private Image<Gray, Byte> randon(Image<Gray, Byte> imageInput)//圖像投影旋轉法傾斜校正子函數定義
        {
            int nwidth = imageInput.Width;
            int nheight = imageInput.Height;
            int sum;
            int SumOfCha;
            int SumOfChatemp = 0;
            int[] sumhang = new int[nheight];
            Image<Gray, Byte> resultImage = imageInput;
            Image<Gray, Byte> ImrotaImage;
            //20度範圍內的調整
            for (int ang = -20; ang < 20; ang = ang + 1)
            {
                ImrotaImage = imageInput.Rotate(ang, new Gray(1));
                for (int i = 0; i < nheight; i++)
                {
                    sum = 0;
                    for (int j = 0; j < nwidth; j++)
                    {
                        sum += ImrotaImage.Data[i, j, 0];
                    }
                    sumhang[i] = sum;
                }
                SumOfCha = 0;
                for (int k = 0; k < nheight - 1; k++)
                {
                    SumOfCha = SumOfCha + (Math.Abs(sumhang[k] - sumhang[k + 1]));
                }
                if (SumOfCha > SumOfChatemp)
                {
                    resultImage = ImrotaImage;
                    SumOfChatemp = SumOfCha;
                }
            }
            return resultImage;
        }
    }
}

三、Office 2007組件

該組件免費而且識別度比較高。

環境搭建

Office 2007組件MODI，需要安裝Ofiice2007，且由於相容性需要安裝補丁，SP1或者SP2都行，補丁下載地址如下：
SP1下載地址 SP2下載地址
安裝後控制面板-->卸載或更新程式-->選擇Office2007-->選擇更改-->選擇添加或修複功能-->彈出下麵界面，運行相應組件。

將Office工具-->Microsoft Office Document Imaging 下的工具運行

在C#項目中引用Com組件即可：

如果Office組件應用不是在本地程式而需要部署在IIS上，還需將應用程式的應用池的許可權設置為如下圖所示：程式應用池-->高級設置-->標識

Demo

StringBuilder sb = new StringBuilder();
MODI.Document doc = new MODI.Document();
doc.Create(fullFileName);
MODI.Image image;
MODI.Layout layout;
doc.OCR(MODI.MiLANGUAGES.miLANG_CHINESE_SIMPLIFIED, true, true);  // 識別文字類型
for (int i = 0; i < doc.Images.Count; i++)
{
    image = (MODI.Image)doc.Images[i];
    layout = image.Layout;
    sb.Append(layout.Text);
}

以上即一些C#進行身份證識別的方法，可根據自己項目的不同需求進行選用。