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Introduction to OpenCV
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What is OpenCV Library?

Last Updated : 15 Apr, 2024
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OpenCV, short for Open Source Computer Vision Library, is an open-source computer vision and machine learning software library. Originally developed by Intel, it is now maintained by a community of developers under the OpenCV Foundation.

In this article, we delve into OpenCV, exploring its functionalities, applications, and practical examples.

OpenCV- Introduction

Opencv is a huge open-source library for computer vision, machine learning, and image processing. Now, it plays a major role in real-time operation which is very important in today's systems. By using it, one can process images and videos to identify objects, faces, or even the handwriting of a human.

When it is integrated with various libraries, such as NumPy, python is capable of processing the opencv array structure for analysis. To Identify an image pattern and its various features we use vector space and perform mathematical operations on these features. 

The first OpenCV version was 1.0. OpenCV is released under a BSD license and hence it’s free for both academic and commercial use. It has C++, C, Python, and Java interfaces and supports Windows, Linux, Mac OS, iOS and Android. When opencv was designed the main focus was real-time applications for computational efficiency. All things are written in optimized C/C++ to take advantage of multi-core processing. 

You can also refer to - OpenCV Tutorial to gain in-depth knowledge of opencv.

Example of OpenCV

Let us consider a basic example to illustrate the various capabilities of OpenCV. Let take an example of the image mentioned below .

OpenCV allows you to perform various operations in the image.

  • Read the Image : OpenCV helps you to read the image fro file or directly from camera to make it accessible for further processing.
  • Image Enhacncement : You will be able to enhance image by adjusting the brightness , sharpness or contract of the image. This is helpful to visualize quality of the image.
  • Object detection: As you can see in the below image object can also be detected by using OpenCV , Bracelet , watch , patterns, faces can be detected. This can also include to recognize faces , shapes or even objects .
  • Image Filtering: You can change image by applying various filters such as blurring or Sharpening.
  • Draw the Image: OpenCV allows to draw text, lines and any shapes in the images.
  • Saving the Changed Images: After processing , You can save images that are being modified for future analysis.


From the above original image, lots of pieces of information that are present in the original image can be obtained. Like in the above image there are two faces available and the person(I) in the images is wearing a bracelet, watch, etc. So with the help of OpenCV we can get all these types of information from the original image. 

Applications of OpenCV

There are lots of applications which are solved using OpenCV, some of them are listed below:

  • Face recognition
  • Automated inspection and surveillance
  • number of people - count (foot traffic in a mall, etc)
  • Vehicle counting on highways along with their speeds
  • Interactive art installations
  • Anomaly (defect) detection in the manufacturing process (the odd defective products)
  • Street view image stitching
  • Video/image search and retrieval
  • Robot and driver-less car navigation and control
  • object recognition
  • Medical image analysis
  • Movies - 3D structure from motion
  • TV Channels advertisement recognition

OpenCV Functionality 

  • Image/video I/O, processing, display (core, imgproc, highgui)
  • Object/feature detection (objdetect, features2d, nonfree)
  • Geometry-based monocular or stereo computer vision (calib3d, stitching, videostab)
  • Computational photography (photo, video, superres)
  • Machine learning & clustering (ml, flann)
  • CUDA acceleration (gpu)

Image-Processing

Image processing is a method to perform some operations on an image, in order to get an enhanced image and or to extract some useful information from it. 
If we talk about the basic definition of image processing then "Image processing is the analysis and manipulation of a digitized image, especially in order to improve its quality". 

Digital-Image

An image may be defined as a two-dimensional function f(x, y), where x and y are spatial(plane) coordinates, and the amplitude of f at any pair of coordinates (x, y) is called the intensity or grey level of the image at that point. 
In another words, an image is nothing more than a two-dimensional matrix (3-D in case of coloured images) which is defined by the mathematical function f(x, y) at any point is giving the pixel value at that point of an image, the pixel value describes how bright that pixel is, and what colour it should be. 
Image processing is basically signal processing in which input is an image and output is image or characteristics according to requirement associated with that image. 
Image processing basically includes the following three steps: 

  1. Importing the image
  2. Analysing and manipulating the image
  3. Output in which result can be altered image or report that is based on image analysis

How does a computer read an image? 

Computers don't "see" images in the way humans do. Instead, they interpret images as arrays of numerical values. The basic process of how a computer reads and processes an image are:

  1. Pixel Values: An image is made up of pixels, which are the smallest units of information in an image. Each pixel has a value that represents its color and intensity. In the case of an RGB image, there are three values for each pixel corresponding to the Red, Green, and Blue channels.
  2. Digital Representation: The RGB values are usually represented as integers ranging from 0 to 255. 0 represents the absence of color (black), and 255 represents the maximum intensity of that color (full brightness).
  3. Image Matrix: The computer reads the image as a matrix of numbers, where each element in the matrix corresponds to the pixel value at that location. For a color image, there are typically three matrices, one for each RGB channel.
  4. Image Processing: Image processing algorithms are applied to manipulate these numerical representations. Common operations include resizing, cropping, filtering, and more.

Conclusion

In this article the main points of opencv are explored such it's importance and How it is effecting the world constantly. It will help developers to know the capabilities of opencv projects nad applications.
 


Next Article
Introduction to OpenCV

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Article Tags :
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  • Image-Processing
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    Image processing using Python is one of the hottest topics in today's world. But image processing is a bit complex and beginners get bored in their first approach. So in this article, we have a very basic image processing python program to count black dots in white surface and white dots in the blac
    4 min read
    Python | OpenCV BGR color palette with trackbars
    OpenCV is a library of programming functions mainly aimed at real-time computer vision. In this article, Let's create a window which will contain RGB color palette with track bars. By moving the trackbars the value of RGB Colors will change b/w 0 to 255. So using the same, we can find the color with
    2 min read
    Draw a rectangular shape and extract objects using Python's OpenCV
    OpenCV is an open-source computer vision and machine learning software library. Various image processing operations such as manipulating images and applying tons of filters can be done with the help of it. It is broadly used in Object detection, Face Detection, and other Image processing tasks. Let'
    4 min read
    Invisible Cloak using OpenCV | Python Project
    Have you ever seen Harry Potter's Invisible Cloak; Was it wonderful? Have you ever wanted to wear that cloak? If Yes!! then in this post, we will build the same cloak which Harry Potter uses to become invisible. Yes, we are not building it in a real way but it is all about graphics trickery. In this
    4 min read
    ML | Unsupervised Face Clustering Pipeline
    Live face-recognition is a problem that automated security division still face. With the advancements in Convolutions Neural Networks and specifically creative ways of Region-CNN, it’s already confirmed that with our current technologies, we can opt for supervised learning options such as FaceNet, Y
    15+ min read
    Saving Operated Video from a webcam using OpenCV
    OpenCV is a vast library that helps in providing various functions for image and video operations. With OpenCV, we can perform operations on the input video. OpenCV also allows us to save that operated video for further usage. For saving images, we use cv2.imwrite() which saves the image to a specif
    4 min read
    Face Detection using Python and OpenCV with webcam
    Face detection is a important application of computer vision that involves identifying human faces in images or videos. In this Article, we will see how to build a simple real-time face detection application using Python and OpenCV where webcam will be used as the input source.Step 1: Installing Ope
    3 min read
    Opening multiple color windows to capture using OpenCV in Python
    OpenCV is an open source computer vision library that works with many programming languages and provides a vast scope to understand the subject of computer vision.In this example we will use OpenCV to open the camera of the system and capture the video in two different colors. Approach: With the lib
    2 min read
    Python | Play a video in reverse mode using OpenCV
    OpenCV (Open Source Computer Vision) is a computer vision library that contains various functions to perform operations on Images or videos. OpenCV's application areas include : 1) Facial recognition system 2) motion tracking 3) Artificial neural network 4) Deep neural network 5) video streaming etc
    3 min read
    Template matching using OpenCV in Python
    Template matching is a technique for finding areas of an image that are similar to a patch (template). A patch is a small image with certain features. The goal of template matching is to find the patch/template in an image. To find it, the user has to give two input images: Source Image (S) - The im
    6 min read
    Cartooning an Image using OpenCV - Python
    Instead of sketching images by hand we can use OpenCV to convert a image into cartoon image. In this tutorial you'll learn how to turn any image into a cartoon. We will apply a series of steps like:Smoothing the image (like a painting)Detecting edges (like a sketch)Combining both to get a cartoon ef
    2 min read
    Vehicle detection using OpenCV Python
    Vehicle detection is an important application of computer vision that helps in monitoring traffic, automating parking systems and surveillance systems. In this article, we’ll implement a simple vehicle detection system using Python and OpenCV using a pre-trained Haar Cascade classifier and we will g
    3 min read
    Count number of Faces using Python - OpenCV
    Prerequisites: Face detection using dlib and openCV In this article, we will use image processing to detect and count the number of faces. We are not supposed to get all the features of the face. Instead, the objective is to obtain the bounding box through some methods i.e. coordinates of the face i
    3 min read
    Live Webcam Drawing using OpenCV
    Let us see how to draw the movement of objects captured by the webcam using OpenCV. Our program takes the video input from the webcam and tracks the objects we are moving. After identifying the objects, it will make contours precisely. After that, it will print all your drawing on the output screen.
    3 min read
    Detect and Recognize Car License Plate from a video in real time
    Recognizing a Car License Plate is a very important task for a camera surveillance-based security system. We can extract the license plate from an image using some computer vision techniques and then we can use Optical Character Recognition to recognize the license number. Here I will guide you thro
    11 min read
    Essential OpenCV Functions to Get Started into Computer Vision
    Computer vision is a process by which we can understand the images and videos how they are stored and how we can manipulate and retrieve data from them. Computer Vision is the base or mostly used for Artificial Intelligence. Computer-Vision is playing a major role in self-driving cars, robotics as w
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    OpenCV Projects

    Build GUI Application Pencil Sketch from Photo in Python
    In this article, we will cover how to convert images to watercolor sketches and pencil sketch Linux. Sketching and painting are used by artists of many disciplines to preserve ideas, recollections, and thoughts. Experiencing art from painting and sculpting to visiting an art museum—provides a variet
    5 min read
    Python OpenCV - Drowsiness Detection
    The number of fatalities on the road due to drowsiness is very high. Thus python allows the model of deep learning algorithm via including the use of OpenCV. Drowsiness Detection is the detection of a person to check whether the person is feeling sleepy while performing a significant task. This dete
    9 min read
    Face Alignment with OpenCV and Python
    Face Alignment is the technique in which the image of the person is rotated according to the angle of the eyes.  This technique is actually used as a part of the pipeline process in which facial detection is done using the image. This implementation of face alignment can be easily done with the help
    6 min read
    Age Detection using Deep Learning in OpenCV
    The task of age prediction might sound simple at first but it's quite challenging in real-world applications. While predicting age is typically seen as a regression problem this approach faces many uncertainties like camera quality, brightness, climate condition, background, etc. In this article we'
    5 min read
    Right and Left Hand Detection Using Python
    In this article, we are going to see how to Detect Hands using Python. We will use mediapipe and OpenCV libraries in python to detect the Right Hand and Left Hand. We will be using the Hands model from mediapipe solutions to detect hands, it is a palm detection model that operates on the full image
    5 min read
    OpenCV Python: How to detect if a window is closed?
    OpenCV in Python provides a method cv2.getWindowProperty() to detect whether a window is closed or open. getWindowProperty() returns -1 if all windows are closed. This is one of the main problems we face while using the OpenCV package, sometimes it's hard to detect whether the window is open or clos
    2 min read
    Save frames of live video with timestamps - Python OpenCV
    Images are very important data nowadays from which we can obtain a lot of information which will helpful for analysis. Sometimes data to be processed can be in the form of video. To process this kind of data we have to read video extract frames and save them as images. Security camera videos we have
    3 min read
    Detecting low contrast images with OpenCV, scikit-image, and Python
    In this article, we are going to see how to detect low contrast images with OpenCV, scikit-image using Python A low contrast image has the minimal distinction between light and dark parts, making it difficult to tell where an object's boundary begins and the scene's background begins. For example Th
    2 min read
    Animate image using OpenCV in Python
    In this article, we will discuss how to animate an image using python's OpenCV module. Let's suppose we have one image. Using that single image we will animate it in such a way it will appear continuous array of the same image. This is useful in animating the background in certain games. For example
    3 min read
    Drawing a cross on an image with OpenCV
    In this article, we are going to discuss how to draw a cross on an image using OpenCV-Python. We can draw an overlay of two lines one above another to make a cross on an image.   To draw a line on OpenCV, the below function is used. Syntax: cv2.line(image, starting Point, ending Point, color, thickn
    5 min read
    Blur and anonymize faces with OpenCV and Python
    In this article, we are going to see how to Blur and anonymize faces with OpenCV and Python. For this, we will be using Cascade Classifier to detect the faces. Make sure to download the same, from this link: haarcascade_frontalface_default.xml ApproachFirstly, we use a built face detection algorithm
    4 min read
    Face Detection using Cascade Classifier using OpenCV - Python
    Face detection is a important task in computer vision and Haar Cascade classifiers play an important role in making this process fast and efficient. Haar Cascades are used for detecting faces and other objects by training a classifier on positive and negative images.Positive Images: These images con
    3 min read
    Real time object color detection using OpenCV
    In this article, we will discuss how to detect a monochromatic colour object using python and OpenCV. Monochromatic color means light of a single wavelength. We will use the video, captured using a webcam as input and try to detect objects of a single color, especially Blue. But you can detect any c
    4 min read
    Python - Writing to video with OpenCV
    In this article, we will discuss how to write to a video using OpenCV in Python. ApproachImport the required libraries into the working space.Read the video on which you have to write. Syntax: cap = cv2.VideoCapture("path")Create a output file using cv2.VideoWriter_fourcc() method Syntax: output = c
    1 min read
    Add image to a live camera feed using OpenCV-Python
    In this article, we are going to learn how to insert an image in your live camera feed using OpenCV in Python. Stepwise ImplementationStep 1: Importing the libraries CV reads and stores all the images as a NumPy array. We need the NumPy library to manipulate the image and as expected we need the cv2
    4 min read
    Face and Hand Landmarks Detection using Python - Mediapipe, OpenCV
    In this article, we will use mediapipe python library to detect face and hand landmarks. We will be using a Holistic model from mediapipe solutions to detect all the face and hand landmarks. We will be also seeing how we can access different landmarks of the face and hands which can be used for diff
    4 min read
    Emotion Based Music Player - Python Project
    In this article, we will be discussing how can we recommend music based on expressions or say dominant expressions on someone's face. This is a basic project in which we will be using OpenCV, Matplotlib, DeepFace, and Spotify API. Import Packages and ModulesOpenCV: OpenCV is a Python open-source pac
    6 min read
    Realtime Distance Estimation Using OpenCV - Python
    Prerequisite: Introduction to OpenCV In this article, we are going to see how to calculate the distance with a webcam using OpenCV in Python. By using it, one can process images and videos to identify objects, faces, or even the handwriting of a human. This article focuses on detecting objects. We w
    5 min read
    Webcam QR code scanner using OpenCV
    In this article, we're going to see how to perform QR code scanning using a webcam.  Webcam QR CODE Scanner Before starting, You need to know how this process is going to work. Firstly you need to open your webcam, and you've to run your python program to make it ready to scan the QR code. You can t
    3 min read
    Color Identification in Images using Python - OpenCV
    An open-source library in Python, OpenCV is basically used for image and video processing. Not only supported by any system, such as Windows, Linux, Mac, etc. but also it can be run in any programming language like Python, C++, Java, etc. OpenCV also allows you to identify color in images. Don’t you
    3 min read
    Real-Time Edge Detection using OpenCV in Python | Canny edge detection method
    Edge detection is one of the fundamental image-processing tasks used in various Computer Vision tasks to identify the boundary or sharp changes in the pixel intensity. It plays a crucial role in object detection, image segmentation and feature extraction from the image. In Real-time edge detection,
    5 min read
    Opencv Python program for Face Detection
    The objective of the program given is to detect object of interest(face) in real time and to keep tracking of the same object.This is a simple example of how to detect face in Python. You can try to use training samples of any other object of your choice to be detected by training the classifier on
    2 min read
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