OpenCV学习--saturate_cast防止数据溢出

源代码来源于官网的OpenCV教程，实现的功能比较简单最后自己动手用C语言实现了一下，貌似比库函数要快一点


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#include "StdAfx.h"

#include "blending.h"

using namespace std;

using namespace cv;

void blending_test()

{

Mat src1, src2, dst;

double alpha = 0.5;

double beta = 1-alpha;

src1 = imread("LinuxLogo.jpg");

src2 = imread("WindowsLogo.jpg");

if(!src1.data) cout<<"error loading src1"<<endl;

if(!src2.data) cout<<"Error loading src2"<<endl;

addWeighted(src1, alpha, src2, beta, 0.0, dst);

imshow("output1", dst);

// waitKey(0);

}

//C语言自己实现

void blending()

{

Mat src1, src2, dst;

double alpha = 0.5;

double beta = 1-alpha;

double gama = 0;

src1 = imread("LinuxLogo.jpg");

src2 = imread("WindowsLogo.jpg");

//判断两幅图片是否相同

CV_Assert(src1.depth() == CV_8U);

CV_Assert(src1.depth() == src2.depth());

CV_Assert(src1.size() == src2.size());

//为dst申请内存

dst.create(src1.size(), src1.type());

const int nChannels = src1.channels();

if(!src1.data) cout<<"error loading src1"<<endl;

if(!src2.data) cout<<"Error loading src2"<<endl;

for (int i=0; i<src1.rows; i++)

{

const uchar* src1_ptr = src1.ptr<uchar>(i);

const uchar* src2_ptr = src2.ptr<uchar>(i);

uchar* dst_ptr = dst.ptr<uchar>(i);

for (int j=0; j<src1.cols*nChannels; j++)

{

dst_ptr[j] = src1_ptr[j]*alpha + src2_ptr[j]*beta + gama;

}

}

imshow("output2",dst);

// cvWaitKey(0);

}

//下面是main函数部分

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int main(int argc, char* argv[])

{

double t;

t = (double)getTickCount();

blending_test();

t = 1000*((double)getTickCount() - t)/getTickFrequency();

cout<<"库函数时间："<<t<<endl;

t = (double)getTickCount();

blending();

t = 1000*((double)getTickCount() - t)/getTickFrequency();

cout<<"C语言实现："<<t<<endl;

cvWaitKey(0);

return 0;

}

//下面是运行的结果



注意了自己实现的没有数据溢出保护，关于saturate_cast的用法会在下个文章中讲解

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