OSTU C++實現:
#include <assert.h> #include "cv.h" #include "highgui.h" #include <math.h> #include <iostream> using namespace std; // implementation of otsu algorithm // author: onezeros(@yahoo.cn) // reference: Rafael C. Gonzalez. Digital Image Processing Using MATLAB void cvThresholdOtsu(IplImage* src, IplImage* dst) { int height=src->height; int width=src->width; //histogram float histogram[256]={0}; for(int i=0;i<height;i++) { unsigned char* p=(unsigned char*)src->imageData+src->widthStep*i; for(int j=0;j<width;j++) { histogram[*p++]++; } } //normalize histogram int size=height*width; for(int i=0;i<256;i++) { histogram[i]=histogram[i]/size; } //average pixel value float avgValue=0; for(int i=0;i<256;i++) { avgValue+=i*histogram[i]; } int threshold; float maxVariance=0; float w=0,u=0; for(int i=0;i<256;i++) { w+=histogram[i]; u+=i*histogram[i]; float t=avgValue*w-u; float variance=t*t/(w*(1-w)); if(variance>maxVariance) { maxVariance=variance; threshold=i; } } cvThreshold(src,dst,threshold,255,CV_THRESH_BINARY); } // implementation of otsu algorithm // author: onezeros(@yahoo.cn) // reference: Rafael C. Gonzalez. Digital Image Processing Using MATLAB int cvThresholdOtsu(IplImage* src) { int height=src->height; int width=src->width; //histogram float histogram[256]={0}; for(int i=0;i<height;i++) { unsigned char* p=(unsigned char*)src->imageData+src->widthStep*i; for(int j=0;j<width;j++) { histogram[*p++]++; } } //normalize histogram int size=height*width; for(int i=0;i<256;i++) { histogram[i]=histogram[i]/size; } //average pixel value float avgValue=0; for(int i=0;i<256;i++) { avgValue+=i*histogram[i]; } int threshold; float maxVariance=0; float w=0,u=0; for(int i=0;i<256;i++) { w+=histogram[i]; u+=i*histogram[i]; float t=avgValue*w-u; float variance=t*t/(w*(1-w)); if(variance>maxVariance) { maxVariance=variance; threshold=i; } } return threshold; } #include <cv.h> #include <cxcore.h> #include <highgui.h> #pragma comment(lib,"cv210d.lib") #pragma comment(lib,"cxcore210d.lib") #pragma comment(lib,"highgui210d.lib") #include <iostream> using namespace std; int main() { int threshold=-1; IplImage* img =cvLoadImage("E:\\test.jpg"); cvShowImage("video",img); cvCvtColor(img,img,CV_RGB2YCrCb); IplImage* imgCb=cvCreateImage(cvGetSize(img),8,1); cvSplit(img,NULL,NULL,imgCb,NULL); if (threshold<0){ threshold=cvThresholdOtsu(imgCb); } //cvThresholdOtsu(imgCb,imgCb); cvThreshold(imgCb,imgCb,threshold,255,CV_THRESH_BINARY); cvSaveImage("E:\\imgCb.bmp",imgCb); cvShowImage("object",imgCb); cvReleaseImage(&imgCb); return 0; }
迭代閾值分割 mtalab實現:
%基於貝葉斯分類算法的圖像閾值分割 clear clc; Init = imread('E:\\test.jpg'); Im=rgb2gray(Init); figure(1) imhist(Im),title('直方圖') ; [x,y]=size(Im); % 求出圖象大小 b=double(Im); zd=double(max(Im)) % 求出圖象中最大的灰度 zx=double(min(Im)) % 最小的灰度 T=double((zd+zx))/2; % T賦初值,為最大值和最小值的平均值 count=double(0); % 記錄幾次循環 while 1 % 迭代最佳閾值分割算法 count=count+1; S0=0.0; n0=0.0; %為計算灰度大於閾值的元素的灰度總值、個數賦值 S1=0.0; n1=0.0; %為計算灰度小於閾值的元素的灰度總值、個數賦值 for i=1:x for j=1:y if double(Im(i,j))>=T S1=S1+double(Im(i,j)); %大於閾域值圖像點灰度值累加 n1=n1+1; %大於閾域值圖像點個數累加 else S0=S0+double(Im(i,j)); %小於閾域值圖像點灰度值累加 n0=n0+1; %小於閥域值圖像點個數累加 end end end T0=S0/n0; %求小於閥域值均值 T1=S1/n1; %求大於閥域值均值 if abs(T-((T0+T1)/2))<0.1 %迭代至 前后兩次閥域值相差幾乎為0時 停止迭代。 break; else T=(T0+T1)/2; %在閾值T下,迭代閾值的計算過程 end end count %顯示運行次數 T i1=im2bw(Im,T/255); % 圖像在最佳閾值下二值化 figure(2) imshow(i1,'border','tight','InitialMagnification','fit') title('實驗結果') ;
其他的見下面代碼,閾值需要自己測試設定(C++實現):
*===============================圖像分割=====================================*/ *---------------------------------------------------------------------------*/ #include <assert.h> #include "cv.h" #include "highgui.h" #include <math.h> #include <iostream> using namespace std; int HistogramBins = 256; float HistogramRange1[2]={0,255}; float *HistogramRange[1]={&HistogramRange1[0]}; typedef enum {back,object} entropy_state; *======================================================================*/ * 迭代法*/ *======================================================================*/ // nMaxIter:最大迭代次數;nDiffRec:使用給定閥值確定的亮區與暗區平均灰度差異值 int DetectThreshold(IplImage*img, int nMaxIter, int& iDiffRec) //閥值分割:迭代法 { //圖像信息 int height = img->height; int width = img->width; int step = img->widthStep/sizeof(uchar); uchar *data = (uchar*)img->imageData; iDiffRec =0; int F[256]={ 0 }; //直方圖數組 int iTotalGray=0;//灰度值和 int iTotalPixel =0;//像素數和 byte bt;//某點的像素值 uchar iThrehold,iNewThrehold;//閥值、新閥值 uchar iMaxGrayValue=0,iMinGrayValue=255;//原圖像中的最大灰度值和最小灰度值 uchar iMeanGrayValue1,iMeanGrayValue2; //獲取(i,j)的值,存於直方圖數組F for(int i=0;i<width;i++) { for(int j=0;j<height;j++) { bt = data[i*step+j]; if(bt<iMinGrayValue) iMinGrayValue = bt; if(bt>iMaxGrayValue) iMaxGrayValue = bt; F[bt]++; } } iThrehold =0;// iNewThrehold = (iMinGrayValue+iMaxGrayValue)/2;//初始閥值 iDiffRec = iMaxGrayValue - iMinGrayValue; for(int a=0;(abs(iThrehold-iNewThrehold)>0.5)&&a<nMaxIter;a++)//迭代中止條件 { iThrehold = iNewThrehold; //小於當前閥值部分的平均灰度值 for(int i=iMinGrayValue;i<iThrehold;i++) { iTotalGray += F[i]*i;//F[]存儲圖像信息 iTotalPixel += F[i]; } iMeanGrayValue1 = (uchar)(iTotalGray/iTotalPixel); //大於當前閥值部分的平均灰度值 iTotalPixel =0; iTotalGray =0; for(int j=iThrehold+1;j<iMaxGrayValue;j++) { iTotalGray += F[j]*j;//F[]存儲圖像信息 iTotalPixel += F[j]; } iMeanGrayValue2 = (uchar)(iTotalGray/iTotalPixel); iNewThrehold = (iMeanGrayValue2+iMeanGrayValue1)/2; //新閥值 iDiffRec = abs(iMeanGrayValue2 - iMeanGrayValue1); } //cout<<"The Threshold of this Image in imgIteration is:"<<iThrehold<<endl; return iThrehold; } *======================================================================*/ /* OTSU global thresholding routine */ /* takes a 2D unsigned char array pointer, number of rows, and */ /* number of cols in the array. returns the value of the threshold */ /*parameter: *image --- buffer for image rows, cols --- size of image x0, y0, dx, dy --- region of vector used for computing threshold vvv --- debug option, is 0, no debug information outputed */ /* OTSU 算法可以說是自適應計算單閾值(用來轉換灰度圖像為二值圖像)的簡單高效方法。 下面的代碼最早由 Ryan Dibble提供,此后經過多人Joerg.Schulenburg, R.Z.Liu 等修改,補正。 算法對輸入的灰度圖像的直方圖進行分析,將直方圖分成兩個部分,使得兩部分之間的距離最大。 划分點就是求得的閾值。 */ /*======================================================================*/ int otsu (unsigned char*image, int rows, int cols, int x0, int y0, int dx, int dy, int vvv) { unsigned char*np; // 圖像指針 int thresholdValue=1; // 閾值 int ihist[256]; // 圖像直方圖,256個點 int i, j, k; // various counters int n, n1, n2, gmin, gmax; double m1, m2, sum, csum, fmax, sb; // 對直方圖置零 memset(ihist, 0, sizeof(ihist)); gmin=255; gmax=0; // 生成直方圖 for (i = y0 +1; i < y0 + dy -1; i++) { np = (unsigned char*)image[i*cols+x0+1]; for (j = x0 +1; j < x0 + dx -1; j++) { ihist[*np]++; if(*np > gmax) gmax=*np; if(*np < gmin) gmin=*np; np++; /* next pixel */ } } // set up everything sum = csum =0.0; n =0; for (k =0; k <=255; k++) { sum += (double) k * (double) ihist[k]; /* x*f(x) 質量矩*/ n += ihist[k]; /* f(x) 質量 */ } if (!n) { // if n has no value, there is problems... fprintf (stderr, "NOT NORMAL thresholdValue = 160\n"); return (160); } // do the otsu global thresholding method fmax =-1.0; n1 =0; for (k =0; k <255; k++) { n1 += ihist[k]; if (!n1) { continue; } n2 = n - n1; if (n2 ==0) { break; } csum += (double) k *ihist[k]; m1 = csum / n1; m2 = (sum - csum) / n2; sb = (double) n1 *(double) n2 *(m1 - m2) * (m1 - m2); /* bbg: note: can be optimized. */ if (sb > fmax) { fmax = sb; thresholdValue = k; } } // at this point we have our thresholding value // debug code to display thresholding values if ( vvv &1 ) fprintf(stderr,"# OTSU: thresholdValue = %d gmin=%d gmax=%d\n", thresholdValue, gmin, gmax); return(thresholdValue); } /*======================================================================*/ /* OTSU global thresholding routine */ /*======================================================================*/ int otsu2 (IplImage *image) { int w = image->width; int h = image->height; unsigned char*np; // 圖像指針 unsigned char pixel; int thresholdValue=1; // 閾值 int ihist[256]; // 圖像直方圖,256個點 int i, j, k; // various counters int n, n1, n2, gmin, gmax; double m1, m2, sum, csum, fmax, sb; // 對直方圖置零... memset(ihist, 0, sizeof(ihist)); gmin=255; gmax=0; // 生成直方圖 for (i =0; i < h; i++) { np = (unsigned char*)(image->imageData + image->widthStep*i); for (j =0; j < w; j++) { pixel = np[j]; ihist[ pixel]++; if(pixel > gmax) gmax= pixel; if(pixel < gmin) gmin= pixel; } } // set up everything sum = csum =0.0; n =0; for (k =0; k <=255; k++) { sum += k * ihist[k]; /* x*f(x) 質量矩*/ n += ihist[k]; /* f(x) 質量 */ } if (!n) { // if n has no value, there is problems... //fprintf (stderr, "NOT NORMAL thresholdValue = 160\n"); thresholdValue =160; goto L; } // do the otsu global thresholding method fmax =-1.0; n1 =0; for (k =0; k <255; k++) { n1 += ihist[k]; if (!n1) { continue; } n2 = n - n1; if (n2 ==0) { break; } csum += k *ihist[k]; m1 = csum / n1; m2 = (sum - csum) / n2; sb = n1 * n2 *(m1 - m2) * (m1 - m2); /* bbg: note: can be optimized. */ if (sb > fmax) { fmax = sb; thresholdValue = k; } } L: for (i =0; i < h; i++) { np = (unsigned char*)(image->imageData + image->widthStep*i); for (j =0; j < w; j++) { if(np[j] >= thresholdValue) np[j] =255; else np[j] =0; } } //cout<<"The Threshold of this Image in Otsu is:"<<thresholdValue<<endl; return(thresholdValue); } /*============================================================================ = 代碼內容:最大熵閾值分割 = 修改日期:2009-3-3 = 作者:crond123 = 博客:http://blog.csdn.net/crond123/ = E_Mail:crond123@163.com ===============================================================================*/ // 計算當前位置的能量熵 double caculateCurrentEntropy(CvHistogram * Histogram1,int cur_threshold,entropy_state state) { int start,end; int total =0; double cur_entropy =0.0; if(state == back) { start =0; end = cur_threshold; } else { start = cur_threshold; end =256; } for(int i=start;i<end;i++) { total += (int)cvQueryHistValue_1D(Histogram1,i);//查詢直方塊的值 P304 } for(int j=start;j<end;j++) { if((int)cvQueryHistValue_1D(Histogram1,j)==0) continue; double percentage = cvQueryHistValue_1D(Histogram1,j)/total; /*熵的定義公式*/ cur_entropy +=-percentage*logf(percentage); /*根據泰勒展式去掉高次項得到的熵的近似計算公式 cur_entropy += percentage*percentage;*/ } return cur_entropy; // return (1-cur_entropy); } //尋找最大熵閾值並分割 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);//創建一個指定尺寸的直方圖 //參數含義:直方圖包含的維數、直方圖維數尺寸的數組、直方圖的表示格式、方塊范圍數組、歸一化標志 cvCalcHist(&src,hist);//計算直方圖 double maxentropy =-1.0; int max_index =-1; // 循環測試每個分割點,尋找到最大的閾值分割點 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; } } cout<<"The Threshold of this Image in MaxEntropy is:"<<max_index<<endl; cvThreshold(src, dst, (double)max_index,255, CV_THRESH_BINARY); cvReleaseHist(&hist); } /*============================================================================ = 代碼內容:基本全局閾值法 ==============================================================================*/ int BasicGlobalThreshold(int*pg,int start,int end) { // 基本全局閾值法 int i,t,t1,t2,k1,k2; double u,u1,u2; t=0; u=0; for (i=start;i<end;i++) { t+=pg[i]; u+=i*pg[i]; } k2=(int) (u/t); // 計算此范圍灰度的平均值 do { k1=k2; t1=0; u1=0; for (i=start;i<=k1;i++) { // 計算低灰度組的累加和 t1+=pg[i]; u1+=i*pg[i]; } t2=t-t1; u2=u-u1; if (t1) u1=u1/t1; // 計算低灰度組的平均值 else u1=0; if (t2) u2=u2/t2; // 計算高灰度組的平均值 else u2=0; k2=(int) ((u1+u2)/2); // 得到新的閾值估計值 } while(k1!=k2); // 數據未穩定,繼續 //cout<<"The Threshold of this Image in BasicGlobalThreshold is:"<<k1<<endl; return(k1); // 返回閾值 } int main() { /*手動設置閥值*/ IplImage* smoothImgGauss = cvLoadImage("E:\\test.jpg", CV_LOAD_IMAGE_GRAYSCALE); IplImage* imgGrey = cvCreateImage(cvGetSize(smoothImgGauss),IPL_DEPTH_8U, 1); int w = smoothImgGauss->width, h = smoothImgGauss->height; IplImage* binaryImg = cvCreateImage(cvGetSize(smoothImgGauss),IPL_DEPTH_8U, 1); cvThreshold(smoothImgGauss,binaryImg,71,255,CV_THRESH_BINARY); //cvNamedWindow("cvThreshold", CV_WINDOW_AUTOSIZE ); //cvShowImage( "cvThreshold", binaryImg ); cvSaveImage("E:\\手動設置閥值.bmp",binaryImg); cvReleaseImage(&binaryImg); /*---------------------------------------------------------------------------*/ /*自適應閥值 //計算像域鄰域的平均灰度,來決定二值化的值*/ IplImage* adThresImg = cvCreateImage(cvGetSize(smoothImgGauss),IPL_DEPTH_8U, 1); double max_value=255; int adpative_method=CV_ADAPTIVE_THRESH_GAUSSIAN_C;//CV_ADAPTIVE_THRESH_MEAN_C int threshold_type=CV_THRESH_BINARY; int block_size=3;//閾值的象素鄰域大小 int offset=5;//窗口尺寸 cvAdaptiveThreshold(smoothImgGauss,adThresImg,max_value,adpative_method,threshold_type,block_size,offset); //cvNamedWindow("cvAdaptiveThreshold", CV_WINDOW_AUTOSIZE ); cvSaveImage("E:\\自適應閥值.bmp",adThresImg); //cvShowImage( "cvAdaptiveThreshold", adThresImg ); cvReleaseImage(&adThresImg); /*---------------------------------------------------------------------------*/ /*最大熵閥值分割法*/ IplImage* imgMaxEntropy = cvCreateImage(cvGetSize(imgGrey),IPL_DEPTH_8U,1); MaxEntropy(smoothImgGauss,imgMaxEntropy); //cvNamedWindow("MaxEntroyThreshold", CV_WINDOW_AUTOSIZE ); //cvShowImage( "MaxEntroyThreshold", imgMaxEntropy );//顯示圖像 cvSaveImage("E:\\最大熵閥值分割.bmp",imgMaxEntropy); cvReleaseImage(&imgMaxEntropy ); /*---------------------------------------------------------------------------*/ /*基本全局閥值法*/ IplImage* imgBasicGlobalThreshold = cvCreateImage(cvGetSize(imgGrey),IPL_DEPTH_8U,1); IplImage* srcImgGrey = cvCreateImage(cvGetSize(imgGrey),IPL_DEPTH_8U,1); cvCopyImage(srcImgGrey,imgBasicGlobalThreshold); int pg[256],i,thre; for (i=0;i<256;i++) pg[i]=0; for (i=0;i<imgBasicGlobalThreshold->imageSize;i++) // 直方圖統計 pg[(BYTE)imgBasicGlobalThreshold->imageData[i]]++; thre = BasicGlobalThreshold(pg,0,256); // 確定閾值 cout<<"The Threshold of this Image in BasicGlobalThreshold is:"<<thre<<endl;//輸出顯示閥值 cvThreshold(imgBasicGlobalThreshold,imgBasicGlobalThreshold,thre,200,CV_THRESH_BINARY); // 二值化 //cvNamedWindow("BasicGlobalThreshold", CV_WINDOW_AUTOSIZE ); //cvShowImage( "BasicGlobalThreshold", imgBasicGlobalThreshold);//顯示圖像 cvSaveImage("E:\\基本全局閥值法.bmp",imgBasicGlobalThreshold); cvReleaseImage(&imgBasicGlobalThreshold); /*---------------------------------------------------------------------------*/ /*OTSU*/ IplImage* imgOtsu = cvCreateImage(cvGetSize(imgGrey),IPL_DEPTH_8U,1); cvCopyImage(srcImgGrey,imgOtsu); int thre2; thre2 = otsu2(imgOtsu); cout<<"The Threshold of this Image in Otsu is:"<<thre2<<endl;//輸出顯示閥值 cvThreshold(imgOtsu,imgOtsu,thre2,200,CV_THRESH_BINARY); // 二值化 //cvNamedWindow("imgOtsu", CV_WINDOW_AUTOSIZE ); //cvShowImage( "imgOtsu", imgOtsu);//顯示圖像 cvSaveImage("E:\\OTSU.bmp",imgOtsu); cvReleaseImage(&imgOtsu); /*---------------------------------------------------------------------------*/ /*上下閥值法:利用正態分布求可信區間*/ IplImage* imgTopDown = cvCreateImage( cvGetSize(imgGrey), IPL_DEPTH_8U, 1 ); cvCopyImage(srcImgGrey,imgTopDown); CvScalar mean ,std_dev;//平均值、 標准差 double u_threshold,d_threshold; cvAvgSdv(imgTopDown,&mean,&std_dev,NULL); u_threshold = mean.val[0] +2.5* std_dev.val[0];//上閥值 d_threshold = mean.val[0] -2.5* std_dev.val[0];//下閥值 //u_threshold = mean + 2.5 * std_dev; //錯誤 //d_threshold = mean - 2.5 * std_dev; cout<<"The TopThreshold of this Image in TopDown is:"<<d_threshold<<endl;//輸出顯示閥值 cout<<"The DownThreshold of this Image in TopDown is:"<<u_threshold<<endl; cvThreshold(imgTopDown,imgTopDown,d_threshold,u_threshold,CV_THRESH_BINARY_INV);//上下閥值 //cvNamedWindow("imgTopDown", CV_WINDOW_AUTOSIZE ); //cvShowImage( "imgTopDown", imgTopDown);//顯示圖像 cvSaveImage("E:\\上下閥值法.bmp",imgTopDown); cvReleaseImage(&imgTopDown); }
再次,全局閾值分割C++:
/************************************************************************/ /* 全局閾值分割 自動求取閾值 */ /************************************************************************/ //自動求取閾值,增加對場景的適應性 //只需求取一次,之后就可以一直使用 #include<cv.h> #include <highgui.h> #include <iostream> #include <math.h> using namespace std; int main(){ IplImage * image,* image2; image = cvLoadImage("E:\\111.jpg",0); cvNamedWindow("image",1); cvShowImage("image",image); image2 = cvCreateImage(cvSize(image->width,image->height),image->depth,1); double T = 0; double dT0 = 1.0;//閾值求取結束標志 double dT = 255.0; //求取平均灰度,作為閾值T的初始值T0 int i, j; double T0 = 0,T1 = 0,T2 = 0;//初始閾值 int count1,count2; unsigned char * ptr,*dst; for (i = 0 ; i< image->height ; i++) { for (j =0 ; j < image->width;j++) { ptr = (unsigned char *)image->imageData + i*image->widthStep + j; T0 += ((double)(*ptr))/image->width/image->height; } } cout<<"T0: "<<T0<<endl; T = (int)(T0 + 0.5); //計算T兩側的灰度平均值,然后把二者的均值賦值給T while (dT > dT0) { T1 = 0; T2 = 0; count1 = 0; count2 = 0; for (i = 0 ; i< image->height ; i++) { for (j =0 ; j < image->width;j++) { ptr = (unsigned char *)image->imageData + i*image->widthStep + j; if (*ptr > T) { T1 += ((double)(*ptr))/image->width/image->height; count1++; } else if(*ptr < T) { T2 += ((double)(*ptr))/image->width/image->height; count2++; } } } T1 = T1*image->width*image->height/count1; T2 = T2*image->width*image->height/count2; dT = fabs(T - (T1 + T2)/2); cout<<"T1"<<T1<<endl; cout<<"T2"<<T2<<endl; cout<<"dT " << dT<<endl; T = (T1 + T2)/2; cout<<"T: "<<T<<endl; } //根據求取的閾值進行分割 for (i = 0 ; i< image2->height ; i++) { for (j =0 ; j < image2->width;j++) { ptr = (unsigned char *)image->imageData + i*image->widthStep + j; dst = (unsigned char *)image2->imageData+i*image2->widthStep+j; if (*ptr > T) { *dst = 255; } else { *dst =0; } } } cvNamedWindow("image2",1); cvShowImage("image2",image2); cvSaveImage("E:\\image\\dowels2.tif",image2); cvWaitKey(0); return 0; }