最大方差阈值分割（vc实现）

void CISLSView::OnThresholdOtsu()
	{
//程序编制：李立宗  lilizong@gmail.com
//2012-8-14
		if(myImage1.IsNull())
			OnOpenResourceFile();
		if(!myImage2.IsNull())
			myImage2.Destroy();
		if(myImage2.IsNull()){
			myImage2.Create(myImage1.GetWidth(),myImage1.GetHeight(),24,0);
		}
		//COLORREF pixel; 
		int maxY = myImage1.GetHeight();
		int maxX=myImage1.GetWidth();
		byte* pRealData;
		byte* pRealData2;
		pRealData=(byte*)myImage1.GetBits();
		pRealData2=(byte*)myImage2.GetBits();
		int pit=myImage1.GetPitch();
		int pit2=myImage2.GetPitch();
		//需要注意,pit和pit2的值并不一样,所以如果使用一个值,会导致不同的结果出现
		//CString str;
		//str.Format(TEXT("%d"),pit);
		//MessageBox(str);
		//str.Format(TEXT("%d"),pit2);
		//MessageBox(str);
		int bitCount=myImage1.GetBPP()/8;
		int bitCount2=myImage2.GetBPP()/8;
		int tempR,tempG,tempB;
		//float temp,tempX,tempY;
		int temp;
		int T=128;
		//int pixel[4];
		float u0,u1;   //均值
		float w0,w1;   //概率
		float sum0,sum1;  //像素和
		int optIndex,optT;   //最优阈值，及其所在像素的值
		float fVaria,fMaxVaria=0;   //临时方差,最大方差
		int i;        //循环变量
		//int pixelR[256],pixelG[256],pixelB[256];
		int pixel[256]={0};   //不要忘记初始化
		for (int y=0; y<maxY-1; y++) {
			for (int x=0; x<maxX-1; x++) {
				temp=*(pRealData+pit*(y)+(x)*bitCount);
				if(bitCount==3)
				{
					tempR=*(pRealData+pit*(y)+(x)*bitCount);
					tempG=*(pRealData+pit*(y)+(x)*bitCount+1);
					tempB=*(pRealData+pit*(y)+(x)*bitCount+2);
					temp=(int)(tempR*0.49+tempG*0.31+tempB*0.2);
					//temp=(int)((tempR+tempG+tempB)/3);
				}
				
					*(pRealData2+pit2*(y)+(x)*bitCount2)=temp;
					*(pRealData2+pit2*(y)+(x)*bitCount2+1)=temp;
					*(pRealData2+pit2*(y)+(x)*bitCount2+2)=temp;
			}
		}
		for (int y=0; y<maxY; y++) {
			for (int x=0; x<maxX; x++) {
				temp=*(pRealData2+pit2*(y)+(x)*bitCount2);
				pixel[temp]++;

			}
		}
		//CString str;
		//str.Format(TEXT("%d"),pixel[3]);
		//MessageBox(str);

		for(optIndex=0;optIndex<256;optIndex++)
		{
			u0=0;
			sum0=0;
			for(i=0;i<=optIndex;i++)
			{
				u0+=i*pixel[i];
				sum0+=pixel[i];
			}
			u0/=sum0;
			w0=(float)(sum0)/(maxX*maxY);
			u1=0;
			sum1=0;
			for(i=optIndex;i<=255;i++)
			{
				u1+=i*pixel[i];
				sum1+=pixel[i];
			}
			u1/=sum1;
			w1=1-w0;
			fVaria=w0*w1*(u0-u1)*(u0-u1);
			if(fVaria>fMaxVaria)
			{
				fMaxVaria=fVaria;
				optT=optIndex;
			}
		}

		for (int y=0; y<maxY; y++) {
			for (int x=0; x<maxX; x++) {
				temp=*(pRealData2+pit2*(y)+(x)*bitCount2);
				if(temp>optT)
					tempR=255;
				else
					tempR=0;
					tempG=tempR;
					tempB=tempR;				
				*(pRealData2+pit2*y+x*bitCount2)=tempR;
				*(pRealData2+pit2*y+x*bitCount2+1)=tempG;
				*(pRealData2+pit2*y+x*bitCount2+2)=tempB;
			}
		}
		Invalidate();
	}