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二值化的算法请参看第17.3.1.5节。17.3.1.5 二值化（黑白）-CSDN博客

【例 17.48】二值化算法一。

        //黑白1private void btn2Color1_Click(object sender, EventArgs e){Bitmap destImg = new Bitmap(sourceImg.Width, sourceImg.Height);BitmapData sourceData = sourceImg.LockBits(new Rectangle(0, 0, sourceImg.Width, sourceImg.Height), ImageLockMode.ReadOnly, PixelFormat.Format24bppRgb);BitmapData destData = destImg.LockBits(new Rectangle(0, 0, sourceImg.Width, sourceImg.Height), ImageLockMode.WriteOnly, PixelFormat.Format24bppRgb);IntPtr pSource = sourceData.Scan0;int allBytes = sourceData.Stride * sourceData.Height;byte[] rgbvalues = new byte[allBytes];Marshal.Copy(pSource, rgbvalues, 0, allBytes);int pos = 0;int R, G, B;byte avgValue;for (int j = 0; j < sourceData.Height; j++){for (int i = 0; i < sourceData.Width; i++){B = rgbvalues[pos];G = rgbvalues[pos + 1];R = rgbvalues[pos + 2];avgValue = (byte)((B + G + R) / 3);if (avgValue >= 128)avgValue = 255;elseavgValue = 0;rgbvalues[pos] = avgValue; rgbvalues[pos + 1] = avgValue;rgbvalues[pos + 2] = avgValue;pos = pos + 3;}pos = pos + sourceData.Stride - sourceData.Width * 3;}IntPtr pDest = destData.Scan0;Marshal.Copy(rgbvalues, 0, pDest, allBytes);sourceImg.UnlockBits(sourceData);destImg.UnlockBits(destData);picDest.Image = destImg;}

【例 17.49】二值化算法二

      //黑白2private void btn2Color2_Click(object sender, EventArgs e){Bitmap destImg = new Bitmap(sourceImg.Width, sourceImg.Height);BitmapData sourceData = sourceImg.LockBits(new Rectangle(0, 0, sourceImg.Width, sourceImg.Height), ImageLockMode.ReadOnly, PixelFormat.Format24bppRgb);BitmapData destData = destImg.LockBits(new Rectangle(0, 0, sourceImg.Width, sourceImg.Height), ImageLockMode.WriteOnly, PixelFormat.Format24bppRgb);IntPtr pSource = sourceData.Scan0;int allBytes = sourceData.Stride * sourceData.Height;byte[] rgbvalues = new byte[allBytes];Marshal.Copy(pSource, rgbvalues, 0, allBytes);int pos = 0;int R, G, B;int[] HistGram = new int[256];for (int j = 0; j < sourceData.Height; j++){for (int i = 0; i < sourceData.Width; i++){R = rgbvalues[pos + 2];HistGram[R] += 1;pos = pos + 3;}pos = pos + sourceData.Stride - sourceData.Width * 3;}int threshold;int allSum = 0;int allCount=0;for(int k= 0;k<= 255;k++){allCount += HistGram[k];allSum += k * HistGram[k];}threshold = allSum / allCount;pos = 0;for (int j = 0; j < sourceData.Height; j++){for (int i = 0; i < sourceData.Width; i++){R = rgbvalues[pos + 2];if (R >= threshold)R = 255;elseR = 0;rgbvalues[pos] = (byte)R;rgbvalues[pos + 1] = (byte)R;rgbvalues[pos + 2] = (byte)R;pos = pos + 3;}pos = pos + sourceData.Stride - sourceData.Width * 3;}IntPtr pDest= destData.Scan0;Marshal.Copy(rgbvalues, 0, pDest, allBytes);sourceImg.UnlockBits(sourceData);destImg.UnlockBits(destData);picDest.Image = destImg;}

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