opencv 3.1.0 访问像素值的三种方法（C++）

三种方法分别问：

指针访问：void colorReduce_ptr(cv::Mat &inputImage, cv::Mat &outputImage, int div);

迭代器访问：void colorReduce_iterator(cv::Mat &inputImage, cv::Mat &outputImage, int div);

动态地址计算：void colorReduce_at(cv::Mat &inputImage, cv::Mat &outputImage, int div);

#include <opencv.hpp>

#include <iostream>

using namespace std;

void colorReduce_ptr(cv::Mat &inputImage, cv::Mat &outputImage, int div);

void colorReduce_iterator(cv::Mat &inputImage, cv::Mat &outputImage, int div);

void colorReduce_at(cv::Mat &inputImage, cv::Mat &outputImage, int div);

void colorReduce_ptr(cv::Mat &inputImage, cv::Mat &outputImage, int div)

{

    outputImage = inputImage.clone();

    int rowNumber = outputImage.rows;

    int colNumber = outputImage.cols*outputImage.channels();

    for (size_t i = ; i < rowNumber; i++)

    {

        uchar* data = outputImage.ptr<uchar>(i);

        for (size_t j = ; j < colNumber; j++)

        {

            data[j] = data[j] / div*div + div / ;

        }

    }

}

void colorReduce_iterator(cv::Mat &inputImage, cv::Mat &outputImage, int div)

{

    outputImage = inputImage.clone();

    cv::Mat_<cv::Vec3b>::iterator it = outputImage.begin<cv::Vec3b>();

    cv::Mat_<cv::Vec3b>::iterator it_end = outputImage.end<cv::Vec3b>();

    for (;it != it_end; ++it)

    {

        for (size_t px = ; px < ; px++)

        {

            (*it)[px] = (*it)[px] / div*div + div / ;

        }

    }

}

void colorReduce_at(cv::Mat &inputImage, cv::Mat &outputImage, int div)

{

    outputImage = inputImage.clone();

    int rowNumber = outputImage.rows;

    int colNumber = outputImage.cols;

    for (size_t i = ; i < rowNumber; i++)

    {

        for (size_t j = ; j < colNumber; j++)

        {

            for (size_t px = ; px < ; px++)

            {

                outputImage.at<cv::Vec3b>(i, j)[px] = outputImage.at<cv::Vec3b>(i, j)[px] / div * div + div / ;

            }

        }

    }

}

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

{

    cv::Mat srcImg = cv::imread("E:/data/lena.jpg");

    cv::imshow("srcImg", srcImg);

    cv::Mat dstImg;

    dstImg.create(srcImg.rows, srcImg.cols, srcImg.type());

    double timeStart;

    timeStart = static_cast<double>(cv::getTickCount());

    colorReduce_ptr(srcImg, dstImg, );

    timeStart = ((double)cv::getTickCount() - timeStart) / cv::getTickFrequency();

    cout << "ptr方法运行时间为：" << timeStart << "秒" << endl;

    timeStart = static_cast<double>(cv::getTickCount());

    colorReduce_iterator(srcImg, dstImg, );

    timeStart = ((double)cv::getTickCount() - timeStart) / cv::getTickFrequency();

    cout << "iterator方法运行时间为：" << timeStart << "秒" << endl;

    timeStart = static_cast<double>(cv::getTickCount());

    colorReduce_at(srcImg, dstImg, );

    timeStart = ((double)cv::getTickCount() - timeStart) / cv::getTickFrequency();

    cout << "at方法运行时间为：" << timeStart << "秒" << endl;

    cv::imshow("dstImg", dstImg);

    cv::waitKey();

}

opencv 3.1.0 访问像素值的三种方法（C++）的相关教程结束。