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/**
* @file AddingImages.cpp
* @brief Simple linear blender ( dst = alpha*src1 + beta*src2 )
* @author OpenCV team
*/
#include "opencv2/imgcodecs.hpp"
#include "opencv2/highgui.hpp"
#include <iostream>
using namespace cv;
// we're NOT "using namespace std;" here, to avoid collisions between the beta variable and std::beta in c++17
using std::cin;
using std::cout;
using std::endl;
/**
* @function main
* @brief Main function
*/
int main( void )
{
double alpha = 0.5; double beta; double input;
Mat src1, src2, dst;
/// Ask the user enter alpha
cout << " Simple Linear Blender " << endl;
cout << "-----------------------" << endl;
cout << "* Enter alpha [0.0-1.0]: ";
cin >> input;
// We use the alpha provided by the user if it is between 0 and 1
if( input >= 0 && input <= 1 )
{ alpha = input; }
//![load]
/// Read images ( both have to be of the same size and type )
src1 = imread( samples::findFile("LinuxLogo.jpg") );
src2 = imread( samples::findFile("WindowsLogo.jpg") );
//![load]
if( src1.empty() ) { cout << "Error loading src1" << endl; return EXIT_FAILURE; }
if( src2.empty() ) { cout << "Error loading src2" << endl; return EXIT_FAILURE; }
//![blend_images]
beta = ( 1.0 - alpha );
addWeighted( src1, alpha, src2, beta, 0.0, dst);
//![blend_images]
//![display]
imshow( "Linear Blend", dst );
waitKey(0);
//![display]
return 0;
}

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#include "opencv2/core.hpp"
#include "opencv2/imgproc.hpp"
#include "opencv2/imgcodecs.hpp"
#include "opencv2/highgui.hpp"
#include <iostream>
using namespace cv;
using namespace std;
static void help(char ** argv)
{
cout << endl
<< "This program demonstrated the use of the discrete Fourier transform (DFT). " << endl
<< "The dft of an image is taken and it's power spectrum is displayed." << endl << endl
<< "Usage:" << endl
<< argv[0] << " [image_name -- default lena.jpg]" << endl << endl;
}
int main(int argc, char ** argv)
{
help(argv);
const char* filename = argc >=2 ? argv[1] : "lena.jpg";
Mat I = imread( samples::findFile( filename ), IMREAD_GRAYSCALE);
if( I.empty()){
cout << "Error opening image" << endl;
return EXIT_FAILURE;
}
//! [expand]
Mat padded; //expand input image to optimal size
int m = getOptimalDFTSize( I.rows );
int n = getOptimalDFTSize( I.cols ); // on the border add zero values
copyMakeBorder(I, padded, 0, m - I.rows, 0, n - I.cols, BORDER_CONSTANT, Scalar::all(0));
//! [expand]
//! [complex_and_real]
Mat planes[] = {Mat_<float>(padded), Mat::zeros(padded.size(), CV_32F)};
Mat complexI;
merge(planes, 2, complexI); // Add to the expanded another plane with zeros
//! [complex_and_real]
//! [dft]
dft(complexI, complexI); // this way the result may fit in the source matrix
//! [dft]
// compute the magnitude and switch to logarithmic scale
// => log(1 + sqrt(Re(DFT(I))^2 + Im(DFT(I))^2))
//! [magnitude]
split(complexI, planes); // planes[0] = Re(DFT(I), planes[1] = Im(DFT(I))
magnitude(planes[0], planes[1], planes[0]);// planes[0] = magnitude
Mat magI = planes[0];
//! [magnitude]
//! [log]
magI += Scalar::all(1); // switch to logarithmic scale
log(magI, magI);
//! [log]
//! [crop_rearrange]
// crop the spectrum, if it has an odd number of rows or columns
magI = magI(Rect(0, 0, magI.cols & -2, magI.rows & -2));
// rearrange the quadrants of Fourier image so that the origin is at the image center
int cx = magI.cols/2;
int cy = magI.rows/2;
Mat q0(magI, Rect(0, 0, cx, cy)); // Top-Left - Create a ROI per quadrant
Mat q1(magI, Rect(cx, 0, cx, cy)); // Top-Right
Mat q2(magI, Rect(0, cy, cx, cy)); // Bottom-Left
Mat q3(magI, Rect(cx, cy, cx, cy)); // Bottom-Right
Mat tmp; // swap quadrants (Top-Left with Bottom-Right)
q0.copyTo(tmp);
q3.copyTo(q0);
tmp.copyTo(q3);
q1.copyTo(tmp); // swap quadrant (Top-Right with Bottom-Left)
q2.copyTo(q1);
tmp.copyTo(q2);
//! [crop_rearrange]
//! [normalize]
normalize(magI, magI, 0, 1, NORM_MINMAX); // Transform the matrix with float values into a
// viewable image form (float between values 0 and 1).
//! [normalize]
imshow("Input Image" , I ); // Show the result
imshow("spectrum magnitude", magI);
waitKey();
return EXIT_SUCCESS;
}

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#include <opencv2/core.hpp>
#include <iostream>
#include <string>
using namespace cv;
using namespace std;
static void help(char** av)
{
cout << endl
<< av[0] << " shows the usage of the OpenCV serialization functionality." << endl
<< "usage: " << endl
<< av[0] << " outputfile.yml.gz" << endl
<< "The output file may be either XML (xml) or YAML (yml/yaml). You can even compress it by "
<< "specifying this in its extension like xml.gz yaml.gz etc... " << endl
<< "With FileStorage you can serialize objects in OpenCV by using the << and >> operators" << endl
<< "For example: - create a class and have it serialized" << endl
<< " - use it to read and write matrices." << endl;
}
class MyData
{
public:
MyData() : A(0), X(0), id()
{}
explicit MyData(int) : A(97), X(CV_PI), id("mydata1234") // explicit to avoid implicit conversion
{}
//! [inside]
void write(FileStorage& fs) const //Write serialization for this class
{
fs << "{" << "A" << A << "X" << X << "id" << id << "}";
}
void read(const FileNode& node) //Read serialization for this class
{
A = (int)node["A"];
X = (double)node["X"];
id = (string)node["id"];
}
//! [inside]
public: // Data Members
int A;
double X;
string id;
};
//These write and read functions must be defined for the serialization in FileStorage to work
//! [outside]
static void write(FileStorage& fs, const std::string&, const MyData& x)
{
x.write(fs);
}
static void read(const FileNode& node, MyData& x, const MyData& default_value = MyData()){
if(node.empty())
x = default_value;
else
x.read(node);
}
//! [outside]
// This function will print our custom class to the console
static ostream& operator<<(ostream& out, const MyData& m)
{
out << "{ id = " << m.id << ", ";
out << "X = " << m.X << ", ";
out << "A = " << m.A << "}";
return out;
}
int main(int ac, char** av)
{
if (ac != 2)
{
help(av);
return 1;
}
string filename = av[1];
{ //write
//! [iomati]
Mat R = Mat_<uchar>::eye(3, 3),
T = Mat_<double>::zeros(3, 1);
//! [iomati]
//! [customIOi]
MyData m(1);
//! [customIOi]
//! [open]
FileStorage fs(filename, FileStorage::WRITE);
// or:
// FileStorage fs;
// fs.open(filename, FileStorage::WRITE);
//! [open]
//! [writeNum]
fs << "iterationNr" << 100;
//! [writeNum]
//! [writeStr]
fs << "strings" << "["; // text - string sequence
fs << "image1.jpg" << "Awesomeness" << "../data/baboon.jpg";
fs << "]"; // close sequence
//! [writeStr]
//! [writeMap]
fs << "Mapping"; // text - mapping
fs << "{" << "One" << 1;
fs << "Two" << 2 << "}";
//! [writeMap]
//! [iomatw]
fs << "R" << R; // cv::Mat
fs << "T" << T;
//! [iomatw]
//! [customIOw]
fs << "MyData" << m; // your own data structures
//! [customIOw]
//! [close]
fs.release(); // explicit close
//! [close]
cout << "Write Done." << endl;
}
{//read
cout << endl << "Reading: " << endl;
FileStorage fs;
fs.open(filename, FileStorage::READ);
//! [readNum]
int itNr;
//fs["iterationNr"] >> itNr;
itNr = (int) fs["iterationNr"];
//! [readNum]
cout << itNr;
if (!fs.isOpened())
{
cerr << "Failed to open " << filename << endl;
help(av);
return 1;
}
//! [readStr]
FileNode n = fs["strings"]; // Read string sequence - Get node
if (n.type() != FileNode::SEQ)
{
cerr << "strings is not a sequence! FAIL" << endl;
return 1;
}
FileNodeIterator it = n.begin(), it_end = n.end(); // Go through the node
for (; it != it_end; ++it)
cout << (string)*it << endl;
//! [readStr]
//! [readMap]
n = fs["Mapping"]; // Read mappings from a sequence
cout << "Two " << (int)(n["Two"]) << "; ";
cout << "One " << (int)(n["One"]) << endl << endl;
//! [readMap]
MyData m;
Mat R, T;
//! [iomat]
fs["R"] >> R; // Read cv::Mat
fs["T"] >> T;
//! [iomat]
//! [customIO]
fs["MyData"] >> m; // Read your own structure_
//! [customIO]
cout << endl
<< "R = " << R << endl;
cout << "T = " << T << endl << endl;
cout << "MyData = " << endl << m << endl << endl;
//Show default behavior for non existing nodes
//! [nonexist]
cout << "Attempt to read NonExisting (should initialize the data structure with its default).";
fs["NonExisting"] >> m;
cout << endl << "NonExisting = " << endl << m << endl;
//! [nonexist]
}
cout << endl
<< "Tip: Open up " << filename << " with a text editor to see the serialized data." << endl;
return 0;
}

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#include <opencv2/core.hpp>
#include <opencv2/core/utility.hpp>
#include "opencv2/imgcodecs.hpp"
#include <opencv2/highgui.hpp>
#include <iostream>
#include <sstream>
using namespace std;
using namespace cv;
static void help()
{
cout
<< "\n--------------------------------------------------------------------------" << endl
<< "This program shows how to scan image objects in OpenCV (cv::Mat). As use case"
<< " we take an input image and divide the native color palette (255) with the " << endl
<< "input. Shows C operator[] method, iterators and at function for on-the-fly item address calculation."<< endl
<< "Usage:" << endl
<< "./how_to_scan_images <imageNameToUse> <divideWith> [G]" << endl
<< "if you add a G parameter the image is processed in gray scale" << endl
<< "--------------------------------------------------------------------------" << endl
<< endl;
}
Mat& ScanImageAndReduceC(Mat& I, const uchar* table);
Mat& ScanImageAndReduceIterator(Mat& I, const uchar* table);
Mat& ScanImageAndReduceRandomAccess(Mat& I, const uchar * table);
int main( int argc, char* argv[])
{
help();
if (argc < 3)
{
cout << "Not enough parameters" << endl;
return -1;
}
Mat I, J;
if( argc == 4 && !strcmp(argv[3],"G") )
I = imread(argv[1], IMREAD_GRAYSCALE);
else
I = imread(argv[1], IMREAD_COLOR);
if (I.empty())
{
cout << "The image" << argv[1] << " could not be loaded." << endl;
return -1;
}
//! [dividewith]
int divideWith = 0; // convert our input string to number - C++ style
stringstream s;
s << argv[2];
s >> divideWith;
if (!s || !divideWith)
{
cout << "Invalid number entered for dividing. " << endl;
return -1;
}
uchar table[256];
for (int i = 0; i < 256; ++i)
table[i] = (uchar)(divideWith * (i/divideWith));
//! [dividewith]
const int times = 100;
double t;
t = (double)getTickCount();
for (int i = 0; i < times; ++i)
{
cv::Mat clone_i = I.clone();
J = ScanImageAndReduceC(clone_i, table);
}
t = 1000*((double)getTickCount() - t)/getTickFrequency();
t /= times;
cout << "Time of reducing with the C operator [] (averaged for "
<< times << " runs): " << t << " milliseconds."<< endl;
t = (double)getTickCount();
for (int i = 0; i < times; ++i)
{
cv::Mat clone_i = I.clone();
J = ScanImageAndReduceIterator(clone_i, table);
}
t = 1000*((double)getTickCount() - t)/getTickFrequency();
t /= times;
cout << "Time of reducing with the iterator (averaged for "
<< times << " runs): " << t << " milliseconds."<< endl;
t = (double)getTickCount();
for (int i = 0; i < times; ++i)
{
cv::Mat clone_i = I.clone();
ScanImageAndReduceRandomAccess(clone_i, table);
}
t = 1000*((double)getTickCount() - t)/getTickFrequency();
t /= times;
cout << "Time of reducing with the on-the-fly address generation - at function (averaged for "
<< times << " runs): " << t << " milliseconds."<< endl;
//! [table-init]
Mat lookUpTable(1, 256, CV_8U);
uchar* p = lookUpTable.ptr();
for( int i = 0; i < 256; ++i)
p[i] = table[i];
//! [table-init]
t = (double)getTickCount();
for (int i = 0; i < times; ++i)
//! [table-use]
LUT(I, lookUpTable, J);
//! [table-use]
t = 1000*((double)getTickCount() - t)/getTickFrequency();
t /= times;
cout << "Time of reducing with the LUT function (averaged for "
<< times << " runs): " << t << " milliseconds."<< endl;
return 0;
}
//! [scan-c]
Mat& ScanImageAndReduceC(Mat& I, const uchar* const table)
{
// accept only char type matrices
CV_Assert(I.depth() == CV_8U);
int channels = I.channels();
int nRows = I.rows;
int nCols = I.cols * channels;
if (I.isContinuous())
{
nCols *= nRows;
nRows = 1;
}
int i,j;
uchar* p;
for( i = 0; i < nRows; ++i)
{
p = I.ptr<uchar>(i);
for ( j = 0; j < nCols; ++j)
{
p[j] = table[p[j]];
}
}
return I;
}
//! [scan-c]
//! [scan-iterator]
Mat& ScanImageAndReduceIterator(Mat& I, const uchar* const table)
{
// accept only char type matrices
CV_Assert(I.depth() == CV_8U);
const int channels = I.channels();
switch(channels)
{
case 1:
{
MatIterator_<uchar> it, end;
for( it = I.begin<uchar>(), end = I.end<uchar>(); it != end; ++it)
*it = table[*it];
break;
}
case 3:
{
MatIterator_<Vec3b> it, end;
for( it = I.begin<Vec3b>(), end = I.end<Vec3b>(); it != end; ++it)
{
(*it)[0] = table[(*it)[0]];
(*it)[1] = table[(*it)[1]];
(*it)[2] = table[(*it)[2]];
}
}
}
return I;
}
//! [scan-iterator]
//! [scan-random]
Mat& ScanImageAndReduceRandomAccess(Mat& I, const uchar* const table)
{
// accept only char type matrices
CV_Assert(I.depth() == CV_8U);
const int channels = I.channels();
switch(channels)
{
case 1:
{
for( int i = 0; i < I.rows; ++i)
for( int j = 0; j < I.cols; ++j )
I.at<uchar>(i,j) = table[I.at<uchar>(i,j)];
break;
}
case 3:
{
Mat_<Vec3b> _I = I;
for( int i = 0; i < I.rows; ++i)
for( int j = 0; j < I.cols; ++j )
{
_I(i,j)[0] = table[_I(i,j)[0]];
_I(i,j)[1] = table[_I(i,j)[1]];
_I(i,j)[2] = table[_I(i,j)[2]];
}
I = _I;
break;
}
}
return I;
}
//! [scan-random]

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#include <iostream>
#include <opencv2/core.hpp>
#include <opencv2/imgcodecs.hpp>
using namespace std;
using namespace cv;
namespace
{
//! [mandelbrot-escape-time-algorithm]
int mandelbrot(const complex<float> &z0, const int max)
{
complex<float> z = z0;
for (int t = 0; t < max; t++)
{
if (z.real()*z.real() + z.imag()*z.imag() > 4.0f) return t;
z = z*z + z0;
}
return max;
}
//! [mandelbrot-escape-time-algorithm]
//! [mandelbrot-grayscale-value]
int mandelbrotFormula(const complex<float> &z0, const int maxIter=500) {
int value = mandelbrot(z0, maxIter);
if(maxIter - value == 0)
{
return 0;
}
return cvRound(sqrt(value / (float) maxIter) * 255);
}
//! [mandelbrot-grayscale-value]
//! [mandelbrot-parallel]
class ParallelMandelbrot : public ParallelLoopBody
{
public:
ParallelMandelbrot (Mat &img, const float x1, const float y1, const float scaleX, const float scaleY)
: m_img(img), m_x1(x1), m_y1(y1), m_scaleX(scaleX), m_scaleY(scaleY)
{
}
virtual void operator ()(const Range& range) const CV_OVERRIDE
{
for (int r = range.start; r < range.end; r++)
{
int i = r / m_img.cols;
int j = r % m_img.cols;
float x0 = j / m_scaleX + m_x1;
float y0 = i / m_scaleY + m_y1;
complex<float> z0(x0, y0);
uchar value = (uchar) mandelbrotFormula(z0);
m_img.ptr<uchar>(i)[j] = value;
}
}
ParallelMandelbrot& operator=(const ParallelMandelbrot &) {
return *this;
};
private:
Mat &m_img;
float m_x1;
float m_y1;
float m_scaleX;
float m_scaleY;
};
//! [mandelbrot-parallel]
//! [mandelbrot-sequential]
void sequentialMandelbrot(Mat &img, const float x1, const float y1, const float scaleX, const float scaleY)
{
for (int i = 0; i < img.rows; i++)
{
for (int j = 0; j < img.cols; j++)
{
float x0 = j / scaleX + x1;
float y0 = i / scaleY + y1;
complex<float> z0(x0, y0);
uchar value = (uchar) mandelbrotFormula(z0);
img.ptr<uchar>(i)[j] = value;
}
}
}
//! [mandelbrot-sequential]
}
int main()
{
//! [mandelbrot-transformation]
Mat mandelbrotImg(4800, 5400, CV_8U);
float x1 = -2.1f, x2 = 0.6f;
float y1 = -1.2f, y2 = 1.2f;
float scaleX = mandelbrotImg.cols / (x2 - x1);
float scaleY = mandelbrotImg.rows / (y2 - y1);
//! [mandelbrot-transformation]
double t1 = (double) getTickCount();
#ifdef CV_CXX11
//! [mandelbrot-parallel-call-cxx11]
parallel_for_(Range(0, mandelbrotImg.rows*mandelbrotImg.cols), [&](const Range& range){
for (int r = range.start; r < range.end; r++)
{
int i = r / mandelbrotImg.cols;
int j = r % mandelbrotImg.cols;
float x0 = j / scaleX + x1;
float y0 = i / scaleY + y1;
complex<float> z0(x0, y0);
uchar value = (uchar) mandelbrotFormula(z0);
mandelbrotImg.ptr<uchar>(i)[j] = value;
}
});
//! [mandelbrot-parallel-call-cxx11]
#else
//! [mandelbrot-parallel-call]
ParallelMandelbrot parallelMandelbrot(mandelbrotImg, x1, y1, scaleX, scaleY);
parallel_for_(Range(0, mandelbrotImg.rows*mandelbrotImg.cols), parallelMandelbrot);
//! [mandelbrot-parallel-call]
#endif
t1 = ((double) getTickCount() - t1) / getTickFrequency();
cout << "Parallel Mandelbrot: " << t1 << " s" << endl;
Mat mandelbrotImgSequential(4800, 5400, CV_8U);
double t2 = (double) getTickCount();
sequentialMandelbrot(mandelbrotImgSequential, x1, y1, scaleX, scaleY);
t2 = ((double) getTickCount() - t2) / getTickFrequency();
cout << "Sequential Mandelbrot: " << t2 << " s" << endl;
cout << "Speed-up: " << t2/t1 << " X" << endl;
imwrite("Mandelbrot_parallel.png", mandelbrotImg);
imwrite("Mandelbrot_sequential.png", mandelbrotImgSequential);
return EXIT_SUCCESS;
}

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#include <opencv2/imgcodecs.hpp>
#include <opencv2/highgui.hpp>
#include <opencv2/imgproc.hpp>
#include <iostream>
using namespace std;
using namespace cv;
static void help(char* progName)
{
cout << endl
<< "This program shows how to filter images with mask: the write it yourself and the"
<< "filter2d way. " << endl
<< "Usage:" << endl
<< progName << " [image_path -- default lena.jpg] [G -- grayscale] " << endl << endl;
}
void Sharpen(const Mat& myImage,Mat& Result);
int main( int argc, char* argv[])
{
help(argv[0]);
const char* filename = argc >=2 ? argv[1] : "lena.jpg";
Mat src, dst0, dst1;
if (argc >= 3 && !strcmp("G", argv[2]))
src = imread( samples::findFile( filename ), IMREAD_GRAYSCALE);
else
src = imread( samples::findFile( filename ), IMREAD_COLOR);
if (src.empty())
{
cerr << "Can't open image [" << filename << "]" << endl;
return EXIT_FAILURE;
}
namedWindow("Input", WINDOW_AUTOSIZE);
namedWindow("Output", WINDOW_AUTOSIZE);
imshow( "Input", src );
double t = (double)getTickCount();
Sharpen( src, dst0 );
t = ((double)getTickCount() - t)/getTickFrequency();
cout << "Hand written function time passed in seconds: " << t << endl;
imshow( "Output", dst0 );
waitKey();
//![kern]
Mat kernel = (Mat_<char>(3,3) << 0, -1, 0,
-1, 5, -1,
0, -1, 0);
//![kern]
t = (double)getTickCount();
//![filter2D]
filter2D( src, dst1, src.depth(), kernel );
//![filter2D]
t = ((double)getTickCount() - t)/getTickFrequency();
cout << "Built-in filter2D time passed in seconds: " << t << endl;
imshow( "Output", dst1 );
waitKey();
return EXIT_SUCCESS;
}
//! [basic_method]
void Sharpen(const Mat& myImage,Mat& Result)
{
//! [8_bit]
CV_Assert(myImage.depth() == CV_8U); // accept only uchar images
//! [8_bit]
//! [create_channels]
const int nChannels = myImage.channels();
Result.create(myImage.size(),myImage.type());
//! [create_channels]
//! [basic_method_loop]
for(int j = 1 ; j < myImage.rows-1; ++j)
{
const uchar* previous = myImage.ptr<uchar>(j - 1);
const uchar* current = myImage.ptr<uchar>(j );
const uchar* next = myImage.ptr<uchar>(j + 1);
uchar* output = Result.ptr<uchar>(j);
for(int i= nChannels;i < nChannels*(myImage.cols-1); ++i)
{
*output++ = saturate_cast<uchar>(5*current[i]
-current[i-nChannels] - current[i+nChannels] - previous[i] - next[i]);
}
}
//! [basic_method_loop]
//! [borders]
Result.row(0).setTo(Scalar(0));
Result.row(Result.rows-1).setTo(Scalar(0));
Result.col(0).setTo(Scalar(0));
Result.col(Result.cols-1).setTo(Scalar(0));
//! [borders]
}
//! [basic_method]

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/* Snippet code for Operations with images tutorial (not intended to be run but should built successfully) */
#include "opencv2/core.hpp"
#include "opencv2/imgcodecs.hpp"
#include "opencv2/imgproc.hpp"
#include "opencv2/highgui.hpp"
#include <iostream>
using namespace cv;
using namespace std;
int main(int,char**)
{
std::string filename = "";
// Input/Output
{
//! [Load an image from a file]
Mat img = imread(filename);
//! [Load an image from a file]
CV_UNUSED(img);
}
{
//! [Load an image from a file in grayscale]
Mat img = imread(filename, IMREAD_GRAYSCALE);
//! [Load an image from a file in grayscale]
CV_UNUSED(img);
}
{
Mat img(4,4,CV_8U);
//! [Save image]
imwrite(filename, img);
//! [Save image]
}
// Accessing pixel intensity values
{
Mat img(4,4,CV_8U);
int y = 0, x = 0;
{
//! [Pixel access 1]
Scalar intensity = img.at<uchar>(y, x);
//! [Pixel access 1]
CV_UNUSED(intensity);
}
{
//! [Pixel access 2]
Scalar intensity = img.at<uchar>(Point(x, y));
//! [Pixel access 2]
CV_UNUSED(intensity);
}
{
//! [Pixel access 3]
Vec3b intensity = img.at<Vec3b>(y, x);
uchar blue = intensity.val[0];
uchar green = intensity.val[1];
uchar red = intensity.val[2];
//! [Pixel access 3]
CV_UNUSED(blue);
CV_UNUSED(green);
CV_UNUSED(red);
}
{
//! [Pixel access 4]
Vec3f intensity = img.at<Vec3f>(y, x);
float blue = intensity.val[0];
float green = intensity.val[1];
float red = intensity.val[2];
//! [Pixel access 4]
CV_UNUSED(blue);
CV_UNUSED(green);
CV_UNUSED(red);
}
{
//! [Pixel access 5]
img.at<uchar>(y, x) = 128;
//! [Pixel access 5]
}
{
int i = 0;
//! [Mat from points vector]
vector<Point2f> points;
//... fill the array
Mat pointsMat = Mat(points);
//! [Mat from points vector]
//! [Point access]
Point2f point = pointsMat.at<Point2f>(i, 0);
//! [Point access]
CV_UNUSED(point);
}
}
// Memory management and reference counting
{
//! [Reference counting 1]
std::vector<Point3f> points;
// .. fill the array
Mat pointsMat = Mat(points).reshape(1);
//! [Reference counting 1]
CV_UNUSED(pointsMat);
}
{
//! [Reference counting 2]
Mat img = imread("image.jpg");
Mat img1 = img.clone();
//! [Reference counting 2]
CV_UNUSED(img1);
}
{
//! [Reference counting 3]
Mat img = imread("image.jpg");
Mat sobelx;
Sobel(img, sobelx, CV_32F, 1, 0);
//! [Reference counting 3]
}
// Primitive operations
{
Mat img;
{
//! [Set image to black]
img = Scalar(0);
//! [Set image to black]
}
{
//! [Select ROI]
Rect r(10, 10, 100, 100);
Mat smallImg = img(r);
//! [Select ROI]
CV_UNUSED(smallImg);
}
}
{
//! [BGR to Gray]
Mat img = imread("image.jpg"); // loading a 8UC3 image
Mat grey;
cvtColor(img, grey, COLOR_BGR2GRAY);
//! [BGR to Gray]
}
{
Mat dst, src;
//! [Convert to CV_32F]
src.convertTo(dst, CV_32F);
//! [Convert to CV_32F]
}
// Visualizing images
{
//! [imshow 1]
Mat img = imread("image.jpg");
namedWindow("image", WINDOW_AUTOSIZE);
imshow("image", img);
waitKey();
//! [imshow 1]
}
{
//! [imshow 2]
Mat img = imread("image.jpg");
Mat grey;
cvtColor(img, grey, COLOR_BGR2GRAY);
Mat sobelx;
Sobel(grey, sobelx, CV_32F, 1, 0);
double minVal, maxVal;
minMaxLoc(sobelx, &minVal, &maxVal); //find minimum and maximum intensities
Mat draw;
sobelx.convertTo(draw, CV_8U, 255.0/(maxVal - minVal), -minVal * 255.0/(maxVal - minVal));
namedWindow("image", WINDOW_AUTOSIZE);
imshow("image", draw);
waitKey();
//! [imshow 2]
}
return 0;
}

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@ -0,0 +1,119 @@
/* For description look into the help() function. */
#include "opencv2/core.hpp"
#include <iostream>
using namespace std;
using namespace cv;
static void help()
{
cout
<< "\n---------------------------------------------------------------------------" << endl
<< "This program shows how to create matrices(cv::Mat) in OpenCV and its serial"
<< " out capabilities" << endl
<< "That is, cv::Mat M(...); M.create and cout << M. " << endl
<< "Shows how output can be formatted to OpenCV, python, numpy, csv and C styles." << endl
<< "Usage:" << endl
<< "./mat_the_basic_image_container" << endl
<< "-----------------------------------------------------------------------------" << endl
<< endl;
}
int main(int,char**)
{
help();
// create by using the constructor
//! [constructor]
Mat M(2,2, CV_8UC3, Scalar(0,0,255));
cout << "M = " << endl << " " << M << endl << endl;
//! [constructor]
// create by using the create function()
//! [create]
M.create(4,4, CV_8UC(2));
cout << "M = "<< endl << " " << M << endl << endl;
//! [create]
// create multidimensional matrices
//! [init]
int sz[3] = {2,2,2};
Mat L(3,sz, CV_8UC(1), Scalar::all(0));
//! [init]
// Cannot print via operator <<
// Create using MATLAB style eye, ones or zero matrix
//! [matlab]
Mat E = Mat::eye(4, 4, CV_64F);
cout << "E = " << endl << " " << E << endl << endl;
Mat O = Mat::ones(2, 2, CV_32F);
cout << "O = " << endl << " " << O << endl << endl;
Mat Z = Mat::zeros(3,3, CV_8UC1);
cout << "Z = " << endl << " " << Z << endl << endl;
//! [matlab]
// create a 3x3 double-precision identity matrix
//! [comma]
Mat C = (Mat_<double>(3,3) << 0, -1, 0, -1, 5, -1, 0, -1, 0);
cout << "C = " << endl << " " << C << endl << endl;
//! [comma]
// do the same with initializer_list
#ifdef CV_CXX11
//! [list]
C = (Mat_<double>({0, -1, 0, -1, 5, -1, 0, -1, 0})).reshape(3);
cout << "C = " << endl << " " << C << endl << endl;
//! [list]
#endif
//! [clone]
Mat RowClone = C.row(1).clone();
cout << "RowClone = " << endl << " " << RowClone << endl << endl;
//! [clone]
// Fill a matrix with random values
//! [random]
Mat R = Mat(3, 2, CV_8UC3);
randu(R, Scalar::all(0), Scalar::all(255));
//! [random]
// Demonstrate the output formatting options
//! [out-default]
cout << "R (default) = " << endl << R << endl << endl;
//! [out-default]
//! [out-python]
cout << "R (python) = " << endl << format(R, Formatter::FMT_PYTHON) << endl << endl;
//! [out-python]
//! [out-numpy]
cout << "R (numpy) = " << endl << format(R, Formatter::FMT_NUMPY ) << endl << endl;
//! [out-numpy]
//! [out-csv]
cout << "R (csv) = " << endl << format(R, Formatter::FMT_CSV ) << endl << endl;
//! [out-csv]
//! [out-c]
cout << "R (c) = " << endl << format(R, Formatter::FMT_C ) << endl << endl;
//! [out-c]
//! [out-point2]
Point2f P(5, 1);
cout << "Point (2D) = " << P << endl << endl;
//! [out-point2]
//! [out-point3]
Point3f P3f(2, 6, 7);
cout << "Point (3D) = " << P3f << endl << endl;
//! [out-point3]
//! [out-vector]
vector<float> v;
v.push_back( (float)CV_PI); v.push_back(2); v.push_back(3.01f);
cout << "Vector of floats via Mat = " << Mat(v) << endl << endl;
//! [out-vector]
//! [out-vector-points]
vector<Point2f> vPoints(20);
for (size_t i = 0; i < vPoints.size(); ++i)
vPoints[i] = Point2f((float)(i * 5), (float)(i % 7));
cout << "A vector of 2D Points = " << vPoints << endl << endl;
//! [out-vector-points]
return 0;
}