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To draw a rectangle, we need four points. Look at the following figure.In the figure, there are four points x1, x2, y1 and y2. These four points are forming the four coordinates. To draw a rectangle using OpenCV, we have to define these points and show the rectangle we need a matrix. We have to declare other relevant values like the color of the line and line width.The basic syntax of this method is as follows −Syntaxrectangle(whiteMatrix, starting, ending, line_Color, thickness);The following program represents how to draw a rectangle in OpenCV.Example#include #include #include using namespace cv; using namespace std; int ... Read More
Digital images are made of pixels. Using OpenCV, it is easy to read the value of pixels. However, if we want to get the pixel values, we have to handle a single channel separately.Here we are loading an image in the matrix named 'cimage', and then it converts the image using 'cvtColor(cimage, img, COLOR_BGR2GRAY); ' and store it in the matrix named 'img'.The following program read the pixel value of an image and shows the values in console window.Example#include #include #include using namespace std; using namespace cv; int main() { int x;//Declaring an integer variable to hold values of pixels// ... Read More
Color space is the model of representing colors. There are different ways of describing colors. For example, RGB, CYMK, HSV, Grayscale etc.Here, we used a new header named 'imgproc.hpp'. This 'imgproc.hpp' is the abbreviation of Image Processing. To convert color spaces, we need to use 'cvtColor()' function of OpenCV. This function is defined in 'imgproc' header file. That's why we have included 'imgproc.hpp'.Firstly, we declared two matrices and two windows. These are for loading and showing the images. Then we loaded our image named 'cat.jpg' into 'myImage' matrix. After that we used 'cvtColor(myImage, myImage_Converted, COLOR_RGB2GRAY)'. This line converts the RGB color space ... Read More
There are three channels in an RGB image- red, green and blue. The color space where red, green and blue channels represent images is called RGB color space. In OpenCV, BGR sequence is used instead of RGB. This means the first channel is blue, the second channel is green, and the third channel is red. To split an RGB image into different channels, we need to define a matrix of 3 channels. We use 'Mat different_Channels[3]' to define a three-channel matrix.Next, we split the loaded image using OpenCV 'split()' function. The format of this function is 'split(Source Matrix, Destination Matrix)'. This function ... Read More
In this topic, we will understand how to find out the number of channels of an image. After running the program, the number of the channel will be shown in the console window.To get the number of the channel, we have used a class of OpenCV named 'channels()'. When we pass the image matrix as an object of the class 'channels()', it gives the channel an integer value.The following program counts the number of the channels and show it in the console window.Example#include #include using namespace std; using namespace cv; int main(int argc, char** argv) { Mat image_load;//Declaring a ... Read More
An array is a convenient method to store and retrieve the collection of data. In OpenCV, we can use this concept to load multiple images in an image array and show them using the array's index number.The following program loads multiple images in a matrix array and shows the array's images called by the index number.Example#include #include using namespace cv; using namespace std; int main(int argc, const char** argv) { Mat myImage_array[3];//declaring a matrix named myImage// namedWindow("PhotoFrame1");//declaring the window to show the image// namedWindow("PhotoFrame2");//declaring the window to show the image// namedWindow("PhotoFrame3");//declaring the window to show the ... Read More
In this topic, we will determine how to load and show images using OpenCV in C++. There are the following functions required for loading and showing an image in OpenCV. Mat: Mat is not a function. It is a data structure, a type of variable. Like int, char, string variable types in C++, Mat is a variable of OpenCV, which creates a matrix data structure to load images inside it. In this program, we wrote 'Mat myImage;'. That means we are declaring a matrix variable named 'myImage'. namedWindow(): It allocates some memory and creates a window to show the image. It works like a ... Read More
There are three steps to install OpenCV, which are as follows −Downloading all required software and install them.Processing OpenCV for Visual Studio.Linking OpenCV with Visual Studio.Let us define these steps one by one.Step 1 - Downloading and Installing the required SoftwareWe will use OpenCV in Microsoft Visual Studio. So we must have to download Visual Studio and OpenCV.Visual StudioOpenCVCMakeLet us learn how to install this software first.Installing Visual StudioThe first step is to download the Visual Studio on your system from its official website or follow link https://visualstudio.microsoft.com/downloads/.Then click on the download button for downloading the Visual Studio. After installing ... Read More
OpenCV stands for open-source computer vision. It was generated to support a common infrastructure for computer vision operations and use system behaviour in financial products. It generally targets image processing, faces recognition, video capture, searching, and object disclosure.OpenCV is created to implement various operations including recognising and detecting faces, analysing human tasks in videos, identifying objects, recording camera movements, tracking moving objects, and combining images to create a high-resolution image for the accurate scene. Let's see the topic defining the term "Computer Vision."Computer VisionComputer vision is a flexible scientific area that manages to regenerate, preventing, and learn a 3D image from ... Read More
Let us understand when MySQL compressed protocol should be used −The compression operation is used only if both client and server support ‘zlib’ compression, and the client requests compression.The advantage of using compression is that it reduces the size of the payload.On the other hand, the disadvantage of using compression is that it increases the computation time.Performance benefits will depend largely on the size of the result set which is being sent.In addition to this, the network bandwidth and latency between the database server and its clients also matters.The larger the result set, the larger will be the latency.In other ... Read More