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Page 1973 of 2109
How to change Pixel Values using 'at' Method in OpenCV?
In a grayscale image, the pixel value is a single numeric value. But in a color image such as RGB image, the pixel is a vector having three values. These three values represent three channels.Here we will create a function that accesses both the grayscale image and RGB image pixel values and randomly adds noise to image pixels. Then we call the function inside the main() function to observe the result.The following program demonstrates how to change Pixel Values using 'at' method in OpenCV.Example#include #include using namespace cv;//Declaring cv namespace using namespace std; void adding_Noise(Mat& image, int n){ //'adding_Noise' function// ...
Read MoreHow to create a binary image in OpenCV using C++?
A binary image is just a digital image that represents two colors, black and white. From an image processing perspective, a binary image contains pixels with two possible values- zero and one. When the value of a pixel is 0, it represents a pure black color. When the value of the pixel is 1, it means pure white color.In a grayscale image, there are 256 different possible values for each. But in Binary Image, there are only two possible values. Binary images have different types of applications. For example, morphological transformation requires a binary image, object shape extraction from background ...
Read MoreHow to invert a binary image in OpenCV using C++?
Inverting a binary image means inverting the pixel values. From a visual perspective, when we invert a binary image, white pixels will be converted to black, and black pixels will be converted to white.The basic form of this function is −cvtColor(original_image, grayscale_image, COLOR_BGR2GRAY);The next line is converting the grayscale image into a binary image and storing the converted image into 'binary_image' matrix.threshold(grayscale_image, binary_image, 100, 255, THRESH_BINARY);Here 'grayscale_image' is the source matrix, 'binary_image' is the destination matrix. After that, there are two values 100 and 255. These two values represent the threshold range. In this line, the threshold range represents the ...
Read MoreHow to draw a line in OpenCV using C++?
To draw a line we need two points-the starting point and ending point. We also require a canvas to draw the line.Using OpenCV, the matrix in our canvas, we need to define the line's starting and ending points. We require to assign a color to the line as well. The thickness of the line has to be explained too. If we want to draw a line using OpenCV, we need to declare a matrix, two points, and color and line thickness.Using OpenCV we have to include header because line() function is defined in this header.The basic syntax of this ...
Read MoreHow to put a text in an image in OpenCV using C++?
In OpenCV, we can put some text in the image by using puttext() function. This function is defined in header. To put text in an image, we first need to declare the matrix which will load the image.Instead of loading an image in our program, we have filled matrix with white color, and then we put the text in that matrix. We need to define the text's starting point in the matrix, the text's font, the font's color and the font's weight.The basic syntax of this method is as follows −SyntaxputText(image, "Text in Images", text_position, FONT_HERSHEY_COMPLEX, font_size, font_Color, font_weight);The ...
Read MoreHow to draw a rectangle in OpenCV using C++?
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 MoreHow to convert color spaces in OpenCV using C++?
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 MoreHow to split images into different channels in OpenCV using C++?
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 MoreHow to calculate the number of channels of an image in OpenCV using C++?
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 MoreWhat is Image Array? Explain with an example in C++
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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