#include <opencv2\opencv.hpp>
#include <opencv\cv.h>
using namespace cv;
int HistogramBins = 256;  
float HistogramRange1[2]={0,255};  
float *HistogramRange[1]={&HistogramRange1[0]};  
typedef  
enum {back,object} entropy_state;  
  
int QueryHistValue_1D(CvHistogram* hist,int i)
{
	
	return 1;
}

double caculateCurrentEntropy(CvHistogram * Histogram1,int cur_threshold,entropy_state state)  
{  
    int start,end;  
    if(state == back)   {  
        start = 0;end = cur_threshold;    
    }  
    else    {  
        start = cur_threshold;end = 256;      
    }  
	
    int  total = 0;  
    for(int i=start;i<end;i++)   {  
        total += (int)cvQueryHistValue_1D(Histogram1,i);  
    }  
    double cur_entropy = 0.0;  
    for(int i=start;i<end;i++){  
        if((int)cvQueryHistValue_1D(Histogram1,i)==0)  
            continue;  
        double percentage = cvQueryHistValue_1D(Histogram1,i)/total;  
         cur_entropy += -percentage*logf(percentage);  
    }  
    return cur_entropy;  
}  
void  MaxEntropy(IplImage *src,IplImage *dst)  
{  
    assert(src != NULL);  
    assert(src->depth == 8 && dst->depth == 8);  
    assert(src->nChannels == 1);  
    CvHistogram * hist  = cvCreateHist(1,&HistogramBins,CV_HIST_ARRAY,HistogramRange);  
    cvCalcHist(&src,hist);  
    double maxentropy = -1.0;  
    int max_index = -1;  
    for(int i=0;i<HistogramBins;i++) {  
        double cur_entropy =   
            caculateCurrentEntropy(hist,i,object)+caculateCurrentEntropy(hist,i,back);  
        if(cur_entropy>maxentropy){  
            maxentropy = cur_entropy;  
            max_index = i;  
        }  
    }  
    cvThreshold(src,dst,(double)max_index,255,CV_THRESH_BINARY);  
    cvReleaseHist(&hist);  
}  
int _tmain(int argc, _TCHAR* argv[])  
{  
    IplImage* src; //宣告IplImage指標  
    //載入影象  
    if(  
        (src = cvLoadImage( "d:/1.JPG",0))!= 0 )  
    {  
	cvShowImage("src",src);	
        cvNamedWindow( "Image", 1 );//建立視窗  
        IplImage* dst = cvCreateImage(cvGetSize(src),IPL_DEPTH_8U,1);  
        MaxEntropy(src,dst);  
        cvShowImage( "Image", dst );//顯示影象  
        cvWaitKey(0); //等待按鍵  
        cvDestroyWindow( "Image" );//銷燬視窗  
        cvReleaseImage( &src ); //釋放影象  
        cvReleaseImage( &dst ); //釋放影象  
        return 0;  
    }  
    return -1;  
}