C#将图片2值化示例代码，原图及二值化后的图片如下：

原图：

二值化后的图像：

实现代码：

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using System; using System.Drawing; namespace BMP2Grey {    class Program    {      static void ToGrey(Bitmap img1)      {        for ( int i = 0; i < img1.Width; i++)        {          for ( int j = 0; j < img1.Height; j++)          {            Color pixelColor = img1.GetPixel(i, j);            //计算灰度值            int grey = ( int )(0.299 * pixelColor.R + 0.587 * pixelColor.G + 0.114 * pixelColor.B);            Color newColor = Color.FromArgb(grey, grey, grey);            img1.SetPixel(i, j, newColor);          }        }      }      static void Thresholding(Bitmap img1)      {        int [] histogram = new int [256];        int minGrayValue=255, maxGrayValue=0;        //求取直方图        for ( int i = 0; i < img1.Width; i++)        {          for ( int j = 0; j < img1.Height; j++)          {            Color pixelColor = img1.GetPixel(i, j);            histogram[pixelColor.R]++;            if (pixelColor.R > maxGrayValue) maxGrayValue = pixelColor.R;            if (pixelColor.R < minGrayValue) minGrayValue = pixelColor.R;          }        }        //迭代计算阀值        int threshold = -1;        int newThreshold = (minGrayValue + maxGrayValue) / 2;        for ( int iterationTimes = 0; threshold != newThreshold && iterationTimes < 100; iterationTimes++)        {          threshold = newThreshold;          int lP1 =0;          int lP2 =0;          int lS1 = 0;          int lS2 = 0;          //求两个区域的灰度的平均值          for ( int i = minGrayValue;i < threshold;i++)          {            lP1 += histogram[i] * i;            lS1 += histogram[i];          }          int mean1GrayValue = (lP1 / lS1);          for ( int i = threshold+1;i < maxGrayValue;i++)          {            lP2 += histogram[i] * i;            lS2 += histogram[i];          }          int mean2GrayValue = (lP2 / lS2);          newThreshold = (mean1GrayValue + mean2GrayValue) / 2;        }        //计算二值化        for ( int i = 0; i < img1.Width; i++)        {          for ( int j = 0; j < img1.Height; j++)          {            Color pixelColor = img1.GetPixel(i, j);            if (pixelColor.R > threshold) img1.SetPixel(i, j, Color.FromArgb(255, 255, 255));            else img1.SetPixel(i, j, Color.FromArgb(0, 0, 0));          }        }      }      static void Main( string [] args)      {        try        {          //打开位图文件          Bitmap img1 = new Bitmap( "test.jpg" , true );          //灰度化          ToGrey(img1);          //二值化          Thresholding(img1);          //写回位图文件          img1.Save( "output.jpg" );          Console.WriteLine( "Converted." );        }        catch (ArgumentException)        {          Console.WriteLine( "Invalid usage!" );          Console.WriteLine( "Usage: bmp2grey source object" );        }      }    } }