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Page 1972 of 2109
How to count the total number of frames in OpenCV using C++?
We will learn how to calculate the total number of frames in OpenCV. Using OpenCV, it is elementary to count and show the total number of frames of a video. However, you have to store one thing in mind that we cannot count the total number of real-time video frames. Because a real-time video does not have a specific number of frames.The following program counts the number of total frames and shows it in the console window.Example#include #include using namespace std; using namespace cv; int main() { int frame_Number;//Declaring an integervariable to store the number of total frames// ...
Read MoreHow can we change the resolution of a video in OpenCV using C++?
We used 'set()' class of OpenCV. Using 'set()' class, we can set the height and width of the frames. The following lines are setting the height and width of the video in our program.set(CAP_PROP_FRAME_WIDTH, 320);set(CAP_PROP_FRAME_HEIGHT, 240);The first line is setting the width of the frames into 320 pixel and the second line is setting the height of the frames to 240 pixels. These two lines together is forming a 320 x 240 resolution video stream. This is how we can simply change the resolution of video using OpenCV.The following program changes the resolution of the video stream taken from default ...
Read MoreHow to load video from your computer in OpenCV using C++?
In this topic, we will know how to load a video file and play it using OpenCV, and we have to use a similar method that we have learned in the previous topic. The only difference is instead of putting the number as arguments of the object of 'VideoCapture' class, and we have to put the path of the video.The following program demonstrates how to load the video from your computer in OpenCV using C++.Example#include//OpenCV header to use VideoCapture class// #include using namespace std; using namespace cv; int main() { Mat myImage;//Declaring a matrix to load the frames// ...
Read MoreHow to capture video from default camera in OpenCV using C++?
Here, we will understand how to access the default camera and show the video stream from that camera. In a laptop, the fixed webcam is the default camera. In desktops, the default camera depends on the serial port's sequence where the camera is connected. When we want to capture the video stream from default webcam, we do not need to know anything about the camera and ensure that the camera is connected.The following program takes video stream from default camera and shows it on the screen in real-time.Example#include//OpenCV header to use VideoCapture class// #include using namespace std; using namespace cv; ...
Read MoreHow to Change Contrast in OpenCV using C++?
Changing brightness and contrast are frequent editing effect in image processing.Here, we will learn how to change the contrast of images. Contrast controls the sharpness of the image. Higher the contrast the sharper the image, lower the contrast the smother the image.Changing the contrast means increasing the weight of the pixels. More the contrast, sharper the image is. To change the contrast, multiply the pixel values with some constant. For example, if multiply all the pixel values of an image by 2, then the pixel's value will be doubled, and the image will look sharper.The following program demonstrates how to ...
Read MoreHow to change the brightness of an image in OpenCV using C++?
Changing the brightness means changing the value of pixels. It means adding or subtracting value some integer value with the current value of each pixel. When you add some integer value with every pixel, it means you are making the image brighter. When you subtract some constant value from all of the pixels, you are reducing the brightness. First, we will learn how to increase the brightness and second we will learn how to reduce the brightness.Increasing the BrightnessIncreasing the Brightness using OpenCV is very easy. To increase the brightness, add some additional values with each channel, and the brightness ...
Read MoreHow to reduce the color using Iterator Method in OpenCV?
OpenCV has C++ STL compatible 'Mat iterator' class. Using this 'Mat iterator' class, we can access pixels very easily. We have to create an object of 'Mat iterator' class. We can do it as 'Mat_: : iterator example'. We have to use an underscore after 'Mat' like 'Mat_' because it is a template method. In this method, the return type must be specified while creating an object of 'iterator' class. That is why we have declared the datatype .The following program demonstrates how to reduce the color using Iterator Method in OpenCV.Example#include #include using namespace std;//Declaring std namespace using namespace ...
Read MoreHow to reduce color using Pointer Method in OpenCV?
In image processing, we perform computation on the image. To be more specific, we perform a calculation on pixel so the higher the number of pixels, the more the time consuming the computation becomes. To reduce the computation time, we require to scan the image efficiently. We will learn how to implement an efficient image scanning loop using pointers.Here we will see the pixel scanning process with an example of the color reduction strategy. Color images such as RGB images are composed of 3 channels. Each of these channels has the same number of pixels but with corresponding values. Each ...
Read MoreHow to get the value of a specific pixel in OpenCV using C++?
To read the value of a specific pixel, we can use either 'at' or 'direct access' method. Here, we will learn both of the approaches.Let's start with 'at' method. The following program reads the pixel value located at (10, 29) of an RGB image.Example#include #include using namespace std; using namespace cv; int main() { Mat image;//taking an image matrix// image = imread("sky.jpg");//loading an image// int x = image.at(10, 29)[0];//getting the pixel values// int y = image.at(10, 29)[1];//getting the pixel values// int z = image.at(10, 29)[2];//getting the pixel values// cout
Read MoreHow to change Pixel values using Direct Access Method in OpenCV?
In the previous method (the 'at' method), we need to specify the image type while accessing the pixel values. There is another method which is simpler than 'at' method. It is called direct access method. To access pixel value using this method, we need to specify the Mat type such as Mat, Mat, Mat and so on.The following program demonstrates how to change Pixel Values using Direct Access Method in OpenCV.Example#include #include using namespace cv;//Declaring cv namespace using namespace std; void direct_access(Mat_ &image, int n){ //Declaring the function// for (int x = 0; x < n; x++){ //initiating a ...
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