【學習opencv第七篇】映像的閾值化

映像閾值化的基本思想是，給定一個數組和一個閾值，然後根據數組中每個元素是低於還是高於閾值而進行一些處理。

cvThreshold()函數如下：

double cvThreshold(CvArr* src,  CvArr* dst,double threshold,     double max_value,    int threshold_type)

cvShold函數只能處理8位或者浮點灰階映像，靶心圖表像必須與源映像一致，或者為8為映像。

實現閾值化的代碼如下：

#include "stdafx.h"#include <highgui.h>#include <math.h>#include <cv.h>using namespace std;int main(){IplImage* sourceImage;IplImage* dstImage;   if(!(sourceImage=cvLoadImage("Hough.jpg")))return -1;dstImage=cvCreateImage(cvGetSize(sourceImage),sourceImage->depth,1);IplImage* r=cvCreateImage(cvGetSize(sourceImage),IPL_DEPTH_8U,1);IplImage* g=cvCreateImage(cvGetSize(sourceImage),IPL_DEPTH_8U,1);IplImage* b=cvCreateImage(cvGetSize(sourceImage),IPL_DEPTH_8U,1);IplImage* tempImage=cvCreateImage(cvGetSize(sourceImage),IPL_DEPTH_8U,1);cvSplit(sourceImage,r,g,b,NULL);cvAddWeighted(r,1./3.,g,1./3.,0.0,tempImage);cvAddWeighted(tempImage,1,b,1./3.,0.0,tempImage);cvThreshold(tempImage,dstImage,100,255,CV_THRESH_BINARY);//對於大於100的設為255cvNamedWindow("sourceImage");cvNamedWindow("dstImage");cvShowImage("sourceImage",sourceImage);cvShowImage("dstImage",dstImage);cvWaitKey(-1);cvReleaseImage(&r);cvReleaseImage(&g);cvReleaseImage(&b);cvDestroyWindow("sourceImage");cvDestroyWindow("dstImage");cvReleaseImage(&sourceImage);cvReleaseImage(&dstImage);return 0;}

運行結果：

在自適應閾值中，閾值本身就是一個變數，實現自適應閾值的代碼如下：

#include "stdafx.h"#include <highgui.h>#include <math.h>#include <cv.h>int main(){IplImage* sourceImage;//直接以灰階映像載入if(!(sourceImage=cvLoadImage("Hough.jpg",CV_LOAD_IMAGE_GRAYSCALE)))return -1;IplImage* dstImage=cvCreateImage(cvGetSize(sourceImage),IPL_DEPTH_8U,1);//這個函數只能處理單通道映像或者8位元影像像，並且要求源映像與靶心圖表像不能為同一個映像cvAdaptiveThreshold(sourceImage,dstImage,255,     //max_valCV_ADAPTIVE_THRESH_MEAN_C,CV_THRESH_BINARY,3,      //block_size5       //offset);cvNamedWindow("AdaptiveThreshold",0);cvShowImage("AdaptiveThreshold",dstImage);//單一閾值IplImage* dstImage2=cvCreateImage(cvGetSize(sourceImage),IPL_DEPTH_8U,1);cvThreshold(sourceImage,dstImage2,100,255,CV_THRESH_BINARY);cvNamedWindow("sourceImage",0);cvNamedWindow("Threshold",0);cvShowImage("sourceImage",sourceImage);cvShowImage("Threshold",dstImage2);cvWaitKey(-1);//釋放資源cvDestroyWindow("sourceImage");cvDestroyWindow("Threshold");cvDestroyWindow("AdaptiveThreshold");cvReleaseImage(&sourceImage);cvReleaseImage(&dstImage);cvReleaseImage(&dstImage2);return 0;}

運行結果：

Reference《學習opencv》