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Technical articles with clear explanations and examples

How to convert color spaces in OpenCV using C++?

Ginni
Ginni
Updated on 10-Mar-2021 2K+ Views

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 ...

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How to split images into different channels in OpenCV using C++?

Ginni
Ginni
Updated on 10-Mar-2021 5K+ Views

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 ...

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How to calculate the number of channels of an image in OpenCV using C++?

Ginni
Ginni
Updated on 10-Mar-2021 2K+ Views

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 ...

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What is Image Array? Explain with an example in C++

Ginni
Ginni
Updated on 10-Mar-2021 918 Views

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 ...

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How to load and show image in OpenCV using C++?

Ginni
Ginni
Updated on 10-Mar-2021 3K+ Views

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 ...

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How to install OpenCV for C++ in Windows?

Ginni
Ginni
Updated on 10-Mar-2021 23K+ Views

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 ...

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When should I use MySQL compressed protocol?

AmitDiwan
AmitDiwan
Updated on 09-Mar-2021 288 Views

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 ...

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Restricting MySQL Connections to Secure Transport

AmitDiwan
AmitDiwan
Updated on 09-Mar-2021 881 Views

MySQL will make secure connections easier when it has streamlined key generation for both MySQL Community and MySQL Enterprise. This way, the security is improved by expanding support for TLSv1.1 and TLSv1.2. This also helps administrators determine if clients are connecting securely or not with enhanced visibility into connection types.Extending this importance on secure connections, MySQL server introduced a new server-side configuration option that allows MySQL administrators to restrict connections to clients who use secure transport. When we say about the connection needing secure transport, the first question that needs to be addressed is the kind of transport it uses.Secure ...

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How to force MySQL to connect by TCP instead of a Unix socket?

AmitDiwan
AmitDiwan
Updated on 09-Mar-2021 960 Views

Programs such as ‘mysql’ and ‘mysqldump’, that use MySQL client library have the support of MySQL connection to server with the help of many transport protocols, such as TCP/IP, Unix socket file, named pipe, shared memory, and so on.With respect to a given connection, if the transport protocol is not specified, it is determined as a separate task.ExampleConnections to localhost will result in a socket file connection on Unix and Unix-like systems, and a TCP/IP connection to 127.0.0.1 otherwise. If the protocol has to be specified in particular, it is done using the --protocol command option.The below table shows the ...

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MySQL Option Defaults, Options Expecting Values, and the = Sign

AmitDiwan
AmitDiwan
Updated on 09-Mar-2021 160 Views

Let us understand the default options, the options that expects values, and the ‘=’ sign in MySQL −By convention, the long forms of options which assign a value are written using an equals (=) sign. It has been shown below −mysql --host=tonfisk --user=jonFor options which require a value, i.e which doesn’t have a default value, the equal sign isn’t required. This means that the below command would be valid in such cases −mysql --host tonfisk --user jonIn both the above cases, the mysql client tries to connect to a MySQL server that is running on the host named “tonfisk” with ...

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