C#调用开源图像识别类库tessnet2

转自:http://blog.csdn.net/agai001/article/details/7352815

本人在做比价蜘蛛的时候用到：京东商城的单品价格是图片形式，所以需要识别。

首先下载tessnet2_32.dll及相关语言包，将dll加入引用

[csharp] view
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private tessnet2.Tesseract ocr = new tessnet2.Tesseract();//声明一个OCR类

//程序开始的时候，初始化OCR

ocr.SetVariable("tessedit_char_whitelist", "0123456789."); //设置识别变量，当前只能识别数字。

ocr.Init(@"D:\tessdata", "eng", false); //应用当前语言包。注，Tessnet2是支持多国语的。语言包下载链接：http://code.google.com/p/tesseract-ocr/downloads/list

//下边这个函数是将网络上的图片识别成字符串，传入图片的超链接，输出字符串

public string Bmp2Str(string bmpurl)

{

//http://www.newwhy.com/2010/0910/13708.html

string s = "0";

WebClient wc = new WebClient();

try

{

byte[] oimg = wc.DownloadData(bmpurl);//将要识别的图像下载下来

MemoryStream ms = new MemoryStream(oimg);

Bitmap image = new Bitmap(ms);

//为了提高识别率，所以对图片进行简单的处理

image = BlackAndWhite(image, 0.8);//黑白处理，这个函数看下边

image = new Bitmap(image, image.Width * 3, image.Height * 3);//放大三倍

Monitor.Enter(this);//因为是多线程，所以用到了Monitor。

System.Collections.Generic.List<tessnet2.Word> result = ocr.DoOCR(image, Rectangle.Empty);//执行识别操作

foreach (tessnet2.Word word in result) //遍历识别结果。

s = s + word.Text;

Monitor.Exit(this);

if (s.Length > 2)

s = s.Substring(2, s.Length - 2);

}

catch

{

s = "0";

}

finally

{

wc.Dispose();

}

return s;

//Console.WriteLine("{0} : {1}", word.Confidence, word.Text);

}

//黑白处理的函数，网上查的。

public static Bitmap BlackAndWhite(Bitmap bitmap, Double hsb)

{

if (bitmap == null)

{

return null;

}

int width = bitmap.Width;

int height = bitmap.Height;

try

{

Bitmap bmpReturn = new Bitmap(width, height, PixelFormat.Format1bppIndexed);

BitmapData srcBits = bitmap.LockBits(new Rectangle(0, 0, width, height), ImageLockMode.ReadOnly, PixelFormat.Format24bppRgb);

BitmapData targetBits = bmpReturn.LockBits(new Rectangle(0, 0, width, height), ImageLockMode.ReadWrite, PixelFormat.Format1bppIndexed);

unsafe

{

byte* pSrcBits = (byte*)srcBits.Scan0.ToPointer();

for (int h = 0; h < height; h++)

{

byte[] scan = new byte[(width + 7) / 8];

for (int w = 0; w < width; w++)

{

int r, g, b;

r = pSrcBits[2];

g = pSrcBits[1];

b = pSrcBits[0];

if (GetBrightness(r, g, b) >= hsb) scan[w / 8] |= (byte)(0x80 >> (w % 8));

pSrcBits += 3;

}

Marshal.Copy(scan, 0, (IntPtr)((int)targetBits.Scan0 + targetBits.Stride * h), scan.Length);

pSrcBits += srcBits.Stride - width * 3;

}

bmpReturn.UnlockBits(targetBits);

bitmap.UnlockBits(srcBits);

return bmpReturn;

}

}

catch

{

return null;

}

}