Basic operations of OpenCV image processing

Catalog

One ： Operation of reading display pictures

Two ： The image processing     Pixel operation

2.1    Snowflake screen effect

2.2    color reversal

2.3    Dark treatment  

2.4    Frosted glass effect

3、 ... and ： The image processing     call OpenCV library Packaging function  

3.1    Gaussian blur [ It's like The situation that people with myopia don't wear glasses to see things --- Mild myopia ]

3.2   XY Axis blur [ It's like The situation that people with myopia don't wear glasses to see things --- Severe myopia ]

3.3    graying

3.4    median filtering   Visually, it feels like oil painting

Four ：OpenCV    Video operation

4.1    Play the video ： In those years , The girl we chased together

4.2    Use the local camera

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One ： Operation of reading display pictures

Path selection for reading pictures , Note here window Next \ But in ubuntu Next is / It needs to be corrected when writing code

Read image code ：

#include <iostream>
#include <opencv2/opencv.hpp>
using namespace std;
using namespace cv;

int main(int argc, char *argv[])
{
    Mat img = imread("D:/000imageopencv/333.jpg");// Picture path 

    imshow("img",img);// display picture 

    waitKey(0);// Wait for the button 

    return 0;
}

result ：

You can zoom in on the picture with the scroll wheel RGB The number , It's not hard to see. , The darker it is RGB The closer the value is 0, The lighter the color RGB The closer the value is 255

  Look at the resolution 499 X 355, At the same time, move the mouse to the edge of the picture ( notice x=498,y=334 Bloggers have tried their best to move to the edge , If you don't believe it , Do it yourself , ha-ha ), From this, we can know that the picture is composed of one pixel after another .

Two ： The image processing     Pixel operation

2.1    Snowflake screen effect

The relevant code is as follows ：

#include <iostream>
#include <opencv2/opencv.hpp>
using namespace std;
using namespace cv;

Mat imageprocess(Mat &img)
{
    int row = img.rows;
    int col = img.cols * img.channels();

    for(int i=0;i<row;i++)
    {
        uchar * data = img.ptr<uchar>(i);
        for(int j=0;j<col;j++)
        {
            // Snowflake screen effect 
            int q = rand()%col;
            data[q]=155;// Some channels are randomly changed to 155
        }
    }
    return img;
}

int main(int argc, char *argv[])
{
    Mat img = imread("D:/000imageopencv/333.jpg");// Picture path 
    imshow("img",img);// display picture 

    Mat resimg = imageprocess(img);
    imshow("resimg",resimg);// Display the received picture 

    waitKey(0);// Wait for the button 
    return 0;
}

2.2    color reversal

  

The relevant code is as follows ： 

Mat imageprocess(Mat &img)
{
    int row = img.rows;
    int col = img.cols * img.channels();

    for(int i=0;i<row;i++)
    {
        uchar * data = img.ptr<uchar>(i);
        for(int j=0;j<col;j++)
        {
            // color reversal 
            data[j] = data[j] - 50;
        }
    }
    return img;
}

2.3    Dark treatment  

The relevant code is as follows ： 

Mat imageprocess(Mat &img)
{
    int row = img.rows;
    int col = img.cols * img.channels();

    for(int i=0;i<row;i++)
    {
        uchar * data = img.ptr<uchar>(i);
        for(int j=0;j<col;j++)
        {
            // Dark treatment 
            data[j] = data[j]/2;
        }
    }
    return img;
}

2.4    Frosted glass effect

The relevant code is as follows ：

#include <iostream>
#include <opencv2/opencv.hpp>
using namespace std;
using namespace cv;

// Frosted glass effect 
Mat imageGalss(Mat &img)
{
    RNG rng;
    int random = 0;
    int num = 5;
    for(int i=0;i<img.rows -5;i++)
    {
        for(int j=0;j<img.cols -5;j++)
        {
            random = rng.uniform(0,num);
            img.at<Vec3b>(i,j)[0] = img.at<Vec3b>(i+random,j+random)[0];
            img.at<Vec3b>(i,j)[1] = img.at<Vec3b>(i+random,j+random)[1];
            img.at<Vec3b>(i,j)[2] = img.at<Vec3b>(i+random,j+random)[2];
        }
    }
    return img;
}

int main(int argc, char *argv[])
{
    Mat img = imread("D:/000imageopencv/333.jpg");// Picture path 
    imshow("img",img);// display picture 

    Mat resimg = imageGalss(img);
    imshow("resimg",resimg);// Display the received picture 

    waitKey(0);// Wait for the button 
    return 0;
}

3、 ... and ： The image processing     call OpenCV library Packaging function  

3.1    Gaussian blur [ It's like The situation that people with myopia don't wear glasses to see things --- Mild myopia ]

The relevant code is as follows ：

#include <iostream>
#include <opencv2/opencv.hpp>
using namespace std;
using namespace cv;

int main(int argc, char *argv[])
{
    Mat img = imread("D:/000imageopencv/333.jpg");// Picture path 
    imshow("img",img);// display picture 

    Mat resimg;
    // Gaussian blur 
    cv::GaussianBlur(img,resimg,Size(5,5),0);

    imshow("resimg",resimg);// Display the received picture 

    waitKey(0);// Wait for the button 
    return 0;
}

3.2   XY Axis blur [ It's like The situation that people with myopia don't wear glasses to see things --- Severe myopia ]

The relevant code is as follows ：

#include <iostream>
#include <opencv2/opencv.hpp>
using namespace std;
using namespace cv;

int main(int argc, char *argv[])
{
    Mat img = imread("D:/000imageopencv/333.jpg");// Picture path 
    imshow("img",img);// display picture 

    Mat resimg;
    //XY Axis blur 
    cv::blur(img,resimg,Size(10,10));
    imshow("resimg",resimg);// Display the received picture 

    waitKey(0);// Wait for the button 
    return 0;
}

3.3    graying

The relevant code is as follows ： 

#include <iostream>
#include <opencv2/opencv.hpp>
using namespace std;
using namespace cv;

int main(int argc, char *argv[])
{
    Mat img = imread("D:/000imageopencv/333.jpg");// Picture path 
    imshow("img",img);// display picture 

    Mat resimg;
    // Grayscale processing 
    cvtColor(img,resimg,CV_BGR2GRAY);
    imshow("resimg",resimg);// Display the received picture 

    waitKey(0);// Wait for the button 
    return 0;
}

3.4    median filtering   Visually, it feels like oil painting

The relevant code is as follows ：

#include <iostream>
#include <opencv2/opencv.hpp>
using namespace std;
using namespace cv;

int main(int argc, char *argv[])
{
    Mat img = imread("D:/000imageopencv/333.jpg");// Picture path 
    imshow("img",img);// display picture 

    Mat resimg;
    // median filtering 
    cv::medianBlur(img,resimg,5);
    imshow("resimg",resimg);// Display the received picture 

    waitKey(0);// Wait for the button 
    return 0;
}

Four ：OpenCV    Video operation

4.1    Play the video ： In those years , The girl we chased together

#include <iostream>
#include <opencv2/opencv.hpp>
using namespace std;
using namespace cv;

int main(int argc, char *argv[])
{
    Mat frame;
    VideoCapture cap("D:/000000000000000ffmpeg/ In those years , The girl we chased together .mp4");

    while (cap.read(frame))
    {
        imshow("frame",frame);
        waitKey(50);
    }
    return 0;
}

 4.2    Use the local camera

Bloggers here won't show their faces anymore !

#include <iostream>
#include <opencv2/opencv.hpp>
using namespace std;
using namespace cv;

int main(int argc, char *argv[])
{
    Mat frame;
    VideoCapture cap(0);

    while (cap.read(frame))
    {
        imshow("frame",frame);
        waitKey(50);
    }
    return 0;
}