【OpenCV学习】OpenMP并行化实例

作者：gnuhpc
出处：http://www.cnblogs.com/gnuhpc/

#include "cv.h"#include "highgui.h"#include <stdio.h>#include <stdlib.h>#include <omp.h>void EdgeOpenMP(IplImage *src,IplImage *dst,int thresh){    int height    = src->height;    int width     = src->width;    int step      = src->widthStep;    uchar *data1      = (uchar *)src->imageData;    uchar *data2      = (uchar *)dst->imageData;    int i=step;    #pragma omp parallel for    for(i=step+1;i<height*width;i++){         if(abs(data1[i]-data1[i-1])>thresh || abs(data1[i]-data1[i-step])>thresh)            data2[i]=255;/* 对于单通道，前后两帧差分大于门限            或者对于多通道前后两帧的一个指标差分大于门限，则视为边缘*/         else            data2[i]=0;    }}void Edge(IplImage *src,IplImage *dst,int thresh){    int height    = src->height;    int width     = src->width;    int step      = src->widthStep;    uchar *data1      = (uchar *)src->imageData;    uchar *data2      = (uchar *)dst->imageData;   int i=step;    for(i=step+1;i<height*width;i++){         if(abs(data1[i]-data1[i-1])>thresh || abs(data1[i]-data1[i-step])>thresh)            data2[i]=255;         else            data2[i]=0;    }}int main(){  char filename[512];  IplImage *src,*edge1,*edge2;  puts("File name:");  gets(filename);  src = cvLoadImage(filename,CV_LOAD_IMAGE_GRAYSCALE );  edge1=cvCloneImage(src);  edge2=cvCloneImage(src);  cvNamedWindow("src", CV_WINDOW_AUTOSIZE);  cvMoveWindow("src", 100, 100);  cvShowImage( "src", src);  cvNamedWindow("Edge", CV_WINDOW_AUTOSIZE);  cvMoveWindow("Edge", 200, 100);  cvNamedWindow("EdgeOpenMP", CV_WINDOW_AUTOSIZE);  cvMoveWindow("EdgeOpenMP", 300, 100);  /* 以上都是准备一些窗口和图形基本数据 */  int tekrar=100;//运行次数  int thresh=30;  double start, end,t1, t2;    /* 计算没有使用OpenMP优化的时间 */  start= (double)cvGetTickCount();//记下开始的时钟计数，以便计算函数或用户代码执行时间  for(int i=0;i<tekrar;i++)    Edge(src,edge1,thresh);  end= (double)cvGetTickCount();//记下结束的时钟计数  t1= (end-start)/((double)cvGetTickFrequency()*1000.);//计算运行时间，以毫秒为单位  printf( "Run time without OpenMP = %g ms/n", t1 );  /* 计算使用了OpenMP优化的时间 */  start= (double)cvGetTickCount();  for(int i=0;i<tekrar;i++)    EdgeOpenMP(src,edge2,thresh);  end= (double)cvGetTickCount();  t2= (end-start)/((double)cvGetTickFrequency()*1000.);  printf( "Run time with OpenMP = %g ms/n", t2 );  printf( "Performance ratio (%%) = %% %.1f /n", 100*(t1/t2-1) );  cvShowImage( "Edge", edge1);  cvShowImage( "EdgeOpenMP", edge2);  cvWaitKey();  cvDestroyWindow("Edge");  cvDestroyWindow("EdgeOpenMP");  cvReleaseImage(&src);  cvReleaseImage(&edge1);  cvReleaseImage(&edge2);}这是我的结果：File name:dog.jpgRun time without OpenMP = 647.627 msRun time with OpenMP = 453.001 msPerformance ratio (%) = % 43.0