c# 计算位图灰度值和二值化

时间: 2022-02-07 / 分类: C# / 浏览次数: 252 views / 0个评论 发表评论
        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));
	        }
	      }
	    }

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