请先下载http://asprise.com/product/ocr/index.php?lang=csharp 的SDK.里面提供了详细的OCR方法,如下:

将发现图像框picbVeryfyCode里的文字和文本框.txtVeryfyCode.Text是一致的.

数字识别率我碰到的几乎是100%

http://blog.csdn.net/crabo/

[DllImport("AspriseOCR.dll")]
  static extern string craboOCR(string file, int type);

private void GetVeryfyCode()
  {
if(File.Exists(_imgPath))//ok now?
   {
    try
    {
    this.picbVeryfyCode.Image=System.Drawing.Bitmap.FromFile(_imgPath);
     _veryfyCode=craboOCR(_imgPath,-1);   //将返回string,并以"\r\n"结尾!!
     _veryfyCode=_veryfyCode.Substring(0,4);
     this.txtVeryfyCode.Text=_veryfyCode;
    }
    catch(Exception e)
    {
     this.lblResult.Text+=e.Message;
    }
   }
}