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#include <iostream>
#include<opencv2/opencv.hpp>
void AccessByPtr(cv::Mat img)
{
size_t rows = img.rows;
size_t cols = img.cols * img.channels();
for (size_t i = 0; i < rows; i++)
{
uchar* pixel = img.ptr<uchar>(i);
for (size_t j = 0; j < cols; j++)
{
pixel[j] = std::log(pixel[j] + 1);
}
}
}
void AccessByItera(cv::Mat img)
{
auto pixel = img.begin<cv::Vec3b>();
auto pixelEnd = img.end<cv::Vec3b>();
for(; pixel != pixelEnd; pixel++)
{
(*pixel)[0] = std::log((*pixel)[0] + 1);
(*pixel)[1] = std::log((*pixel)[1] + 1);
(*pixel)[2] = std::log((*pixel)[2] + 1);
}
}
void AccessByIndex(cv::Mat img)
{
size_t rows = img.rows;
size_t cols = img.cols;
for (size_t i = 0; i < rows; i++)
{
for (size_t j = 0; j < cols; j++)
{
img.at<cv::Vec3b>(i, j)[0] = std::log(img.at<cv::Vec3b>(i, j)[0] + 1);
img.at<cv::Vec3b>(i, j)[1] = std::log(img.at<cv::Vec3b>(i, j)[1] + 1);
img.at<cv::Vec3b>(i, j)[2] = std::log(img.at<cv::Vec3b>(i, j)[2] + 1);
}
}
}
void AccessByLut(cv::Mat img, cv::Mat lut, cv::Mat out)
{
cv::LUT(img, lut, out);
}
int main()
{
cv::Mat img = cv::imread("rocket.jpg");
uchar lutData[256];
for (size_t i = 0; i < 256; i++)
{
lutData[i] = std::log(i + 1);
}
cv::Mat lut(1, 256, CV_8UC1, lutData);
cv::Mat out;
int testTimes = 1;
if (!img.empty() && img.channels()!=1)
{
std::cout << "OpenCV access pixels test." << std::endl;
#ifdef _DEBUG
std::cout << "Debug-x64: test " << testTimes << " times" << std::endl;
#else
std::cout << "Release-x64: test " << testTimes << " times" << std::endl;
#endif // DEBUG
std::cout << "Image infomation: " << std::endl;
std::cout << "with: " << img.cols << " height: " << img.rows << " channels: " << img.channels() << std::endl;
clock_t ts, te;
ts = clock();
for (size_t i = 0; i < testTimes; i++)
{
AccessByIndex(img);
}
te = clock();
std::cout << "AccessByIndex: " << static_cast<double>(te - ts) << " ms" << std::endl;
ts = clock();
for (size_t i = 0; i < testTimes; i++)
{
AccessByItera(img);
}
te = clock();
std::cout << "AccessByItera: " << static_cast<double>(te - ts) << " ms" << std::endl;
ts = clock();
for (size_t i = 0; i < testTimes; i++)
{
AccessByPtr(img);
}
te = clock();
std::cout << "AccessByPtr: " << static_cast<double>(te - ts) << " ms" << std::endl;
ts = clock();
//AccessByLut(img, lut, out);
for (size_t i = 0; i <testTimes; i++)
{
cv::LUT(img, lut, out);
}
te = clock();
std::cout << "AccessByLut: " << static_cast<double>(te - ts) << " ms" << std::endl;
}
}
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