C#识别图片上的数字

private static Tesseract _ocr;//创建识别对象
//传入图片进行识别
public static string ORC_(Bitmap img)
{
    //""标示OCR识别调用失败
    string re = "";
    if (img == null)
        return re;
    else
    {


        Bgr drawColor = new Bgr(Color.Blue);
        try
        {
            Image<Bgr, Byte> image = new Image<Bgr, byte>(img);


            using (Image<Gray, byte> gray = image.Convert<Gray, Byte>())
            {
                _ocr.Recognize(gray);
                Tesseract.Charactor[] charactors = _ocr.GetCharactors();
                foreach (Tesseract.Charactor c in charactors)
                {
                    image.Draw(c.Region, drawColor, 1);
                }


                re = _ocr.GetText();


            }
            return re;
        }
        catch (Exception ex)
        {

            return re;
        }
    }
}

//识别方法如点击按钮识别
private void btnXIdentification_Click(object sender, EventArgs e)
{
    try
    {
        _ocr = new Tesseract(@"C:\Emgu\emgucv-windows-x86-gpu 2.4.2.1777\bin\tessdata", "eng", Tesseract.OcrEngineMode.OEM_TESSERACT_CUBE_COMBINED);//方法第一个参数可为""表示通过环境变量调用字库，第二个参数表示字库的文件，第三个表示识别方式，可看文档与资料查找。
        _ocr.SetVariable("tessedit_char_whitelist", "0123456789X");//此方法表示只识别1234567890与x字母
        string result = "";
        Bitmap bitmap = new Bitmap(_emguImage.ToBitmap());
        bitmap = BrightnessP(bitmap, Convert.ToInt32(this.textBoxX3.Text));//图片加亮处理
        bitmap = KiContrast(bitmap, Convert.ToInt32(this.textBoxX2.Text));//调整对比对
        this.pictureBox3.Image = bitmap;
        result = ORC_(bitmap);
        this.textBoxX1.Text = result;
        _ocr.Dispose();
    }
    catch (Exception exception)
    {
        MessageBox.Show(exception.Message);
    }
}

/// <summary>  
/// 增加图像亮度  
/// </summary>  
/// <param name="a"></param>  

/// <param name="v"></param>  
/// <returns></returns>  
public static Bitmap BrightnessP(Bitmap a, int v)
{
    System.Drawing.Imaging.BitmapData bmpData = a.LockBits(new Rectangle(0, 0, a.Width, a.Height), System.Drawing.Imaging.ImageLockMode.ReadWrite, System.Drawing.Imaging.PixelFormat.Format24bppRgb);
    int bytes = a.Width * a.Height * 3;
    IntPtr ptr = bmpData.Scan0;
    int stride = bmpData.Stride;
    unsafe
    {
        byte* p = (byte*)ptr;
        int temp;
        for (int j = 0; j < a.Height; j++)
        {
            for (int i = 0; i < a.Width * 3; i++, p++)
            {
                temp = (int)(p[0] + v);
                temp = (temp > 255) ? 255 : temp < 0 ? 0 : temp;
                p[0] = (byte)temp;
            }
            p += stride - a.Width * 3;
        }
    }
    a.UnlockBits(bmpData);
    return a;
}
///<summary>
///图像对比度调整
///</summary>
///<param name="b">原始图</param>
///<param name="degree">对比度[-100, 100]</param>
///<returns></returns>
public static Bitmap KiContrast(Bitmap b, int degree)
{
    if (b == null)
    {
        return null;
    }
    if (degree < -100) degree = -100;
    if (degree > 100) degree = 100;
    try
    {
        double pixel = 0;
        double contrast = (100.0 + degree) / 100.0;
        contrast *= contrast;
        int width = b.Width;
        int height = b.Height;
        BitmapData data = b.LockBits(new Rectangle(0, 0, width, height), ImageLockMode.ReadWrite, PixelFormat.Format24bppRgb);
        unsafe
        {
            byte* p = (byte*)data.Scan0;
            int offset = data.Stride - width * 3;
            for (int y = 0; y < height; y++)
            {
                for (int x = 0; x < width; x++)
                {
                    // 处理指定位置像素的对比度
                    for (int i = 0; i < 3; i++)
                    {
                        pixel = ((p / 255.0 - 0.5) * contrast + 0.5) * 255;
                        if (pixel < 0) pixel = 0;
                        if (pixel > 255) pixel = 255;
                        p = (byte)pixel;
                    } // i
                    p += 3;
                } // x
                p += offset;
            } // y
        }
        b.UnlockBits(data);
        return b;
    }
    catch (Exception ex)
    {
        return null;
    }
}