Hough Rectangle Detection Opencv Python

The headers are in the include. We use our Webcam class to retrieve a snap:. Let us start with the big idea of measuring the object's dimension by use of openCV. OpenCV implementation is based on Robust Detection of Lines Using the Progressive Probabilistic Hough Transform by Matas, J. This is a multi-part. The hough function is designed to detect lines. In this tutorial, I will show you how you can use OpenCV, Python, and Arduino to detect and track faces. imwrite function takes three arguments: the path of output file, the image itself, and the parameters of saving. The Hough Line Transform is a transform used to detect straight lines. Pi Camera Video Capture with OpenCV and Python Multithreading – Link. js (Part 3). Line Detection by Hough Line Transform. Deep Learning Computer Vision™ CNN, OpenCV, YOLO, SSD & GANs Udemy Course Free Download Go from beginner to Expert in using Deep Learning for Computer. rectangle() method is used to draw a rectangle on any image. edureka! 186,781. OpenCV Python – Save Image. That's pretty. HoughLinesP () Examples. So, after a few hours of work, I wrote my own face recognition program using OpenCV and Python. Introduction. OpenCV is a library of programming functions mainly aimed at real-time computer vision. 10), and the two facial-detection articles for OpenCV are both good, and can be used to help understand the code in this. 今天用Opencv库来实现简单的人脸检测。 简单来说,人脸检测就是在一副图像中找到人脸,在某些情况下还有要用bounding box将其框出来。. NET compatible languages such as C#, VB, VC++, IronPython etc. J'ai découvert OpenCV, parfaitement adapté à mon cas. and Galambos, C. Face detection¶. Probabilistic Hough Transform is an optimization of Hough Transform we saw. Enjoy the coding. detect lines and circles using the Hough transform and detect cursors using template matching. Circle Detection. Python版OpenCVでは「古典的」を使うことでハフ変換により円を検出することができます。 参考文献 参考になったサイトを以下にまとめてみました。. NET compatible languages such as C#, VB, VC++, IronPython etc. Lane markings detection and vanishing point detection with OpenCV. A simple python script to detect pedestrians in an image using python's opencv. Before we start, I'd like to thank Andrea Palazzi , who's a colleague of mine and a PhD student at the University of Modena and Reggio Emilia. OpenCV computer vision. Dense optical flow 8. In this article, I discussed using OpenCV Face Detection Neural Network to detect faces in an image, label them with white rectangles and extract faces into separate images. Line detection in python with OpenCV | Houghline method The Hough Transform is a method that is used in image processing to detect any shape, if that shape can be represented in mathematical form. Face Detection. Looping through our contours, we can determine whether any of those candidates have three points (a triangle), or four points (a square) – if so, we save the location of the shape. OpenCV is a well known computer vision library used as base framework used by major companies like Google, IBM, Sony and numerous others. As first thing we need to import the libraries, then on line 4 we also define the font that we will use later on to display the text on the. First of all you need to extract numbers from the image, for that we need to follow certain steps. OpenCV is an incredibly powerful tool to have in your toolbox. Face Recognition Using OpenCV | Loading Recognizer In my previous post we learnt to train a recognizer using a dataset, in this post we are loading recognizer to see how we can use that recognizer to recognize faces. Official OpenCV Python Samples The goal of this section is to present you to most interesting OpenCV python samples provided with OpenCV. (In this case I use peds. minLineLength - Minimum length of line. Learning OpenCV is a good asset to the developer to improve aspects of coding and also helps in building a software development. While the original implementation is based on SIFT, you can try to use SURF or ORB detectors instead. Numpy, which is a package used for scientific computing with python. OpenCV is an image and video processing library used for all types of image and video analysis. This paper proposes a new technique for rectangle detection using a windowed Hough transform. Contours : Getting Started. OpenCV is a library of programming functions mainly aimed at real-time computer vision. First method-specific parameter. jsis a javascript module, built on top of tensorflow. OpenCV Color Detection and Filtering with Python – Link. OpenCV-Python Tutorials. Define a detection window on image with mouse through Python 3 and OpenCV 3 For image recognition or object tracking, we often need to define a target window to locate the area interested as below. Since no sample image (neither any description of it’s kind) is provided here, I assume that the problem statement is to detect an irregular shape in an image. OpenCV-Python build problem with. So, after a few hours of work, I wrote my own face recognition program using OpenCV and Python. Hough Transform to find lines in images. The first stage involves edge detection and finding the possible circle centers and the second stage finds the best radius for each candidate center. OpenCV is an incredibly powerful tool to have in your toolbox. This function takes the following arguments: edges: Output of the edge detector. rectangle」を使うことで指定した座標に四角形を描画できます。 今回はこれを試してみました。. The following figure describes the method. 그래서 openCV에서는 가장자리에서 기울기를 측정하여 원을 그리는데 관련이 있는 점인지 확인할 수 있는 Hough Gradient Method를 사용합니다. and Galambos, C. In this OpenCV Python tutorial, we will be covering various aspects of computer vision using OpenCV in Python. Face detection¶. and Kittler, J. Number Plate Detection in OpenCV - Python. Welcome to another OpenCV with Python tutorial. Posted under python opencv face recognition face detection Recently, I wanted to perform Face Recognition using OpenCV in Python but sadly, I could not find any good resource for the same. 概要 OpenCV でCanny 法で画像からエッジを検出する方法について紹介する。 概要 Canny エッジ検出 OpenCV サンプルコード パラメータ調整について ipywidget. # Importing NumPy,which is the fundamental package for scientific computing with Python # Reading Image. Object-Detection Somesh Vyas 2. It used Sobel edge detection and line Hough transform. The first stage involves edge detection and finding the possible circle centers and the second stage finds the best radius for each candidate center. Hough Line Transform is one of the popular techniques to detect lines in images. So how to detect a Lego policeman using OpenCV? An OpenCV haar cascade classifier, that’s how! My post Augmented Reality using OpenCV and Python has the detail. OpenCV has several built-in pretrained classifiers for face, eyes, and smile detection, among others. From the numpy array, the detectMultiScale() method is going to try to detect the faces from the pattern it finds in the numpy array. The links below are helpful for understanding the Python bindings for OpenCV with regard to facial detection and image masks. We’ll add a new method that converts our ndarray into a QImage. py --image. 4 with Python 3 Tutorial Pysource OpenCV Python Tutorial | Creating Face Detection System And Motion Detector Using OpenCV | Edureka - Duration: 40:29. Several rectangle definition and redtagle drawing function just show you various way to draw the rectangles inside the picture and video. Everyone knows Python is more fun. Hough Transform with OpenCV (C++/Python) In this post, we will learn how to detect lines and circles in an image, with the help of a technique called Hough. OpenCV Color Detection and Filtering with Python – Link. This tutorial is a machine learning based approach where we use the cv2 module from the OpenCV library in the program. Face detection¶. Finally, we have the detect_shapes. Content OpenCV an Introduction Haar-training Flow-chart Algorithm part-1 Algorithm part-2 Implementation Code Reference References 3. #include Imwrite PNG specific flags used to tune the compression algorithm. Open Source Computer Vision Library. OpenCV - Hough Line Transform - You can detect the shape of a given image by applying the Hough Transform technique using the method HoughLines() of the Imgproc class. OpenCV-Face detection using Haar Cascades (Python) 12 Aug 2017 · 3 mins read Object Detection using Haar feature-based cascade classifiers is an effective object detection method proposed by Paul Viola and Michael Jones in their paper, “Rapid Object Detection using a Boosted Cascade of Simple Features” in 2001. In this OpenCV with Python tutorial, we're going to discuss object detection with Haar Cascades. The list of Case Classifiers can be downloaded from the ZIP file below. That's pretty. Hough Line Transform¶. 2015 […] made application eye detecting by following this link link and it work how can i detect the eye is opened or closed ? is there library in android to detect […]. NET compatible languages such as C#, VB, VC++, IronPython etc. Contour Features. Face detection example In this post I will show you a very simple example of how to detect faces inside an image using Python 3 and OpenCV library. It mainly focuses on image processing, video capture and analysis including. Python - Getting started with OpenCV A couple of years ago a colleague of mine created a program to ensure that an item I had designed was calibrated properly. Detecting the circles is handled by the cv2. OpenCV-Python Cheat Sheet: From Importing Images to Face Detection Cropping, Resizing, Rotating, Thresholding, Blurring, Drawing & Writing on an image, Face Detection & Contouring to detect objects. All the links in the v A short tutorial on how to detect circles in python using OpenCV. Detecting the circles is handled by the cv2. The circle Hough Transform (CHT) is a basic technique used in Digital Image Processing, for detecting circular objects in a digital image. As input video we will use a Google Hangouts video. #detection. Our project manager contacted Aldebaran to know more about this issue. Dense optical flow 8. The below Code is written Using the Python API for OpenCV Library. OpenCV Color Detection and Filtering with Python – Link. Python版OpenCVでは「古典的」を使うことでハフ変換により円を検出することができます。 参考文献 参考になったサイトを以下にまとめてみました。. Everyone knows Python is more fun. OpenCV mainly focuses on real-time image processing. It is found by the function cv2. Detection is the process by which the system identifies human faces in digital images, regardless of the source while Recognition is the identifying a known face with a known name in digital. •cv::Mat object replaces the original C standard IplImage and CvMat classes. OpenCV is an incredibly powerful tool to have in your toolbox. Before we get started, make sure you have the imutils package installed on your system,. Object detection is the first step in many robotic operations and is a step that subsequent steps depend on. A good example for Canny Edge Detection is provided in OpenCV Currently Python is the most popular Language in IT. The program used a webcam to check a bracket was in the right position and reported back a pass or a fail. [2] In the group II, we are currently working with OpenCV in order to detect motion, quantify it and execute actions under certain conditions. It is a step by step explanation of what I have done. OpenCV is a well known computer vision library used as base framework used by major companies like Google, IBM, Sony and numerous others. Here is a sample code which captures image from camera and finds center in each frame. Object detection is the first step in many robotic operations and is a step that subsequent steps depend on. @param objects Vector of rectangles where each rectangle contains the detected object, the rectangles may be partially outside the original image. rectangle() method is used to draw a rectangle on any image. This page documents the python API for working with these dlib tools. In this post I will describe the easiest way of installing Python 3 and OpenCV library on Windows for face detection and recognition. OpenCV and Python (Documentation) Sai Prashaanth. Straight Bounding Rectangle¶ It is a straight rectangle, it doesn’t consider the rotation of the object. We use our Webcam class to retrieve a snap:. That's pretty. Face detection is a computer technology that determines the locations and sizes of human faces in arbitrary (digital) images. In this tutorial, you will learn how you can process images in Python using the OpenCV library. I am successful in detecting the rectangle with sharp edges but i am not able to detect the rounded rectangle. In case of CV_HOUGH_GRADIENT, it is the accumulator threshold for the circle centers at the detection stage. In this OpenCV with Python tutorial, we're going to discuss object detection with Haar Cascades. There is nothing what is difficult about this. Hough Transform with OpenCV (C++/Python) In this post, we will learn how to detect lines and circles in an image, with the help of a technique called Hough. imwrite function takes three arguments: the path of output file, the image itself, and the parameters of saving. Raspberry Pi Camera + Python + OpenCV (Day2) 1. OpenCV has been a vital part in the development of software for a long time. Deep Learning Computer Vision™ CNN, OpenCV, YOLO, SSD & GANs Udemy Course Free Download Go from beginner to Expert in using Deep Learning for Computer. 边缘检测、边缘探测、轮廓绘制、多边形、区域分割、edge_detection、object_segmentation,使用opencv-python的函数cv2. Content OpenCV an Introduction Haar-training Flow-chart Algorithm part-1 Algorithm part-2 Implementation Code Reference References 3. Face Detection. Here is a sample code which captures image from camera and finds center in each frame. OpenCV is a cross-platform library using which we can develop real-time computer vision applications. It provides a Go language interface to the latest version of OpenCV. Circle Detection. OpenCV Introduction 1. OpenCV computer vision. Starting Out in OpenCV •OpenCV uses the cv namespace. I have had a lot of success using it in Python but very little success in R. OpenCV uses machine learning algorithms to search for faces within a picture. In this application, A histogram based approach is used to separate out the hand from the background frame. Official OpenCV Python Samples The goal of this section is to present you to most interesting OpenCV python samples provided with OpenCV. I use the XCode 4 in OSX Lion with OpenCV 2. This example has been tested with Python 3. Face Recognition Using OpenCV | Loading Recognizer In my previous post we learnt to train a recognizer using a dataset, in this post we are loading recognizer to see how we can use that recognizer to recognize faces. The links below are helpful for understanding the Python bindings for OpenCV with regard to facial detection and image masks. js core, which implements several CNNs (Convolutional Neural Networks) to solve face detection, face recognition and face landmark detection, optimized for the web and for mobile devices. opencv python - Hough Line Transform OpenCV/OpenCV Python 강좌 2015. Face detection example In this post I will show you a very simple example of how to detect faces inside an image using Python 3 and OpenCV library. A circle is represented mathematically as where is the center of the circle, and is the radius of the circle. So how to detect a Lego policeman using OpenCV? An OpenCV haar cascade classifier, that’s how! My post Augmented Reality using OpenCV and Python has the detail. Raspberry Pi Camera + Python + OpenCV (Day2) 1. Several rectangle definition and redtagle drawing function just show you various way to draw the rectangles inside the picture and video. below is the code for the reference. J'ai découvert OpenCV, parfaitement adapté à mon cas. Finding all circles in an image and thresholding to only detect the red circle. HoughLinesP () Examples. x computer vision library. io/x/gocv" Package gocv is a wrapper around the OpenCV 3. Contents:. However you will need to read that book for it. Now using basically the same script lets see how to detect and count number of faces in an image. Hough Line Transform¶. The function uses the parametric representation of a line: rho = x*cos(theta) + y*sin(theta). We’re going to learn in this tutorial how to detect the lines of the road in a live video using Opencv with Python. Ball Tracking / Detection using OpenCV – the author of this tutorial shows you how to detect and track a colored ball. Line detection in python with OpenCV | Houghline method The Hough Transform is a method that is used in image processing to detect any shape, if that shape can be represented in mathematical form. You can easily do it by following Life2Coding’s tutorial on YouTube: Linking OpenCV 3 with Python 3. OpenCV shape detection. Hough Line Transform. OpenCV provides very good platform for developing robotics applications using image processing. com の記事の続きで、 Canny Edge Detection — OpenCV-Python Tutorials 1 documentation の和訳が中心です。 画像の勾配について エッジ検出のために、輝度の勾配を使います。. Mastering Opencv Android Application Programming This book list for those who looking for to read and enjoy the Mastering Opencv Android Application Programming, you can read or download Pdf/ePub books and don't forget to give credit to the trailblazing authors. Thresholding and Filtering techniques are used for background cancellation to obtain optimum results. OpenCV and Python (Documentation) Sai Prashaanth. Apart from detecting Face, Classifiers can detect other objects like nose, eyes, Vehicle License Plate, Smile etc. This paper proposes a new technique for rectangle detection using a windowed Hough transform. OpenCVを使ったPythonでの画像処理について、Haar Cascadesという分類器を使って画像からの顔の検出を扱っていきます。顔の検出と顔認識とは違うことに注意しましょう。. OpenCV函数:cv2. Face detection with OpenCV We will display a rectangle on top of the face. Changing Colorspaces; Image Thresholding; Geometric Transformations of Images; Smoothing Images; Morphological Transformations; Image Gradients; Canny Edge Detection; Image Pyramids; Contours in OpenCV; Histograms in OpenCV. Here is the list of other posts. 이것을 모든 점에 대해서 수행을 하게 되면 상당히 비효율적입니다. We’ll add a new method that converts our ndarray into a QImage. The program utilises the Hough Lines transform, along with some maths to only detect rectangles (relative angle based), and then plots the centre point, with an output that the aircraft controller. In this discussion, We are going to talk about face detection and apply this detection on any image or using camera. Insert a checkbox to select the Haar Classifier, detect and track a face, and draw a green rectangle around the detected face. Now lets take it to the next level, lets create a face recognition program, which not only detect face but also recognize the person and tag that person in the frame. Face detection can be regarded as a more general case of face localization. Automating Card Games Using OpenCV and Python has a great rundown on how you can use OpenCV to do something like card detection. Also find the code on GitHub here. For example, if dp=1 , the accumulator has the same resolution as the input image. This article aims at detecting faces from an image using OpenCV and Python/C++. OpenCV is a C++/C library and there are APIs for accessing the library using the Python, Java, and MATLAB programming languages - in this tutorial we will be using the Python programming language. Find file Copy path. # Importing NumPy,which is the fundamental package for scientific computing with Python # Reading Image. The circle Hough Transform (CHT) is a basic technique used in Digital Image Processing, for detecting circular objects in a digital image. Number Plate Detection in OpenCV - Python. HoughCircles function on Line 17. Official OpenCV Python Samples The goal of this section is to present you to most interesting OpenCV python samples provided with OpenCV. Creating your own Haar Cascade OpenCV Python Tutorial – one object, two images. OpenCV is a well known computer vision library used as base framework used by major companies like Google, IBM, Sony and numerous others. The following are code examples for showing how to use cv2. With the support of Python 3 and OpenCV 3 lots of image processing can be done with ease. In this tutorial, you will learn how you can process images in Python using the OpenCV library. Example of Python with Opencv and camera face detection - python_opencv_camera_haar. The Hough Line Transform is a transform used to detect straight lines. OpenCV is an image and video processing library used for all types of image and video analysis. 前回記事でGoogle画像検索結果をスクレイピングし、画像データをダウンロードしました。 今回は、人物の画像データをダウンロードしておき、その人物の顔部分をOpenCVで認識させ、顔画像のデータを作成したいと思います. Face Recognition is a computer vision technique which enables a computer to predict the identity of a person from an image. Hough Transform with OpenCV (C++/Python) In this post, we will learn how to detect lines and circles in an image, with the help of a technique called Hough. Before getting started, let’s install OpenCV. Hough lines transform: The Houg lines transform is an algorythm used to detect straight lines. png" file from the OpenCV sample folder is used here. For example, if dp=1 , the accumulator has the same resolution as the input image. To detect objects , openCV analyze the image and extract its characteristics and compare them to a classifier which is a file that describes the faces. The function uses the parametric representation of a line: rho = x*cos(theta) + y*sin(theta). Face detection¶. I use the XCode 4 in OSX Lion with OpenCV 2. Once you learn the basics from this face tracking OpenCV project, you can use your imagination to put these skills to work!. Dlib is principally a C++ library, however, you can use a number of its tools from python applications. py, but uses the affine transformation space sampling technique, called ASIFT [1]. Tutorial: Detection / recognition of multiple rectangles and extracting with OpenCV Categories Computer Vision , Uncategorized April 1, 2013 This tutorial will be focused on being able to take a picture and extract the rectangles in the image that are above a certain size:. OpenCV 3 Tutorial image & video processing Installing on Ubuntu 13 Mat(rix) object (Image Container) Creating Mat objects The core : Image - load, convert, and save Smoothing Filters A - Average, Gaussian Smoothing Filters B - Median, Bilateral OpenCV 3 image and video processing with Python OpenCV 3 with Python Image - OpenCV BGR : Matplotlib RGB. minLineLength - Minimum length of line. and Galambos, C. houghtransform. We’ll add a new method that converts our ndarray into a QImage. Search for jobs related to Rectangle detection rotation hough matlab code or hire on the world's largest freelancing marketplace with 15m+ jobs. Introduction. In this tutorial, you will learn how you can process images in Python using the OpenCV library. Face Detection. (py36) D:\python-opencv-sample>python asift. OpenCV shape detection. So make sure the image is in grayscale. OpenCV is a free open source library used in real-time image processing. This got me thinking Wouldn't it be great if when you entered an art gallery, a computer could tell you which painting you look most like? Well, I think it would be great. Install Python 3 Go to the Python download page and download the latest version of Python 3 for Windows. Once you learn the basics from this face tracking OpenCV project, you can use your imagination to put these skills to work!. Circle Detection. HoughCircles() 教程 理解霍夫变换. OpenCV-Python is a library of Python bindings designed to solve computer vision problems. OpenCV-Python Study documentation!¶ 이 문서는 OpenCV-Python Tutorial 을 바탕으로 작성이 되었습니다. Some information about how algorithm works and its example using Opencv in cpp can be found in below link. [2] In the group II, we are currently working with OpenCV in order to detect motion, quantify it and execute actions under certain conditions. 7, but am having a hard time making the jump to emotion recognition. 前回記事でGoogle画像検索結果をスクレイピングし、画像データをダウンロードしました。 今回は、人物の画像データをダウンロードしておき、その人物の顔部分をOpenCVで認識させ、顔画像のデータを作成したいと思います. OpenCV is an open source software library that allows developers to access routines in API (Application Programming Interface) used for computer vision applications. つまりなにしたの? Python+OpenCVのTracking手法のうちBoosting、MIL、KCF、TLD、MedianFlowの5つを実行してみた。 GOTURNもあるけどこっちはうまく動いていない。. 0 User Contrib Module • Thanks to Google Summer of Code!! –Supporting 15 interns! Accepted pull requests: 1. While the original implementation is based on SIFT, you can try to use SURF or ORB detectors instead. Line segments shorter than this are rejected. opencv is available on Mac, Windows, Linux. com Line detection in python with OpenCV - In this post we are going to learn how to detect lines in an image with the help of a technique called Hough transform Hough transform Hough transform is a feature extraction method to detect any simple shape if you can represent that shape. Distance/Angle calculations give us approximate location relative to the center of the image. The Hough Transform is a popular technique to detect any shape, if you can represent that shape in a. I once wrote an application for rectangle detection. Being multi platform one can use openCV on linux as well as windows platform and with c++ as well as python. When OpenCV is correctly configured by means of the procedure described above, it reads and processes all frames from the video stream. HoughLines(), cv2. these pattern I want to set on object which moving and captured using webcam. Face Detection Using OpenCV In Python | How To Setup OpenCV Python Opencv is the most popular computer vision library, and today we are going to learn how to setup opencv, how to access your webcam and how easily we can write a face detection program with just a few lines of code. The image is thresholded and the largest contour is found. it is Open Source and free. All the links in the v A short tutorial on how to detect circles in python using OpenCV. How to Detect Human Faces in Python using OpenCV; How to Make a Speech Emotion Recognizer Using Python And Scikit-learn; How to Make a Port Scanner in Python using Socket Library; How to Make a Network Scanner using Scapy in 5 Minutes; How to Write a Keylogger in Python from Scratch; How to Build a Spam Classifier using Keras in Python. OpenCV Tutorials - C++ source code for beginner using OpenCV library and Visual Studio on image processing, object detection and tracking. You can vote up the examples you like or vote down the ones you don't like. All basics of OpenCV API. Outline Overview and practical issues. NET compatible languages such as C#, VB, VC++, IronPython etc. Inside the while loop we have every video frame inside the variable frame. How to Write a Bot in Python For Online Games (Lineage 2). (rectangle). The below Code is written Using the Python API for OpenCV Library. Starting from an image with a few shapes, we’ll be able to detect exactly each shape (rectangle, circle, pentagon, etc. #include Imwrite PNG specific flags used to tune the compression algorithm. The program utilises the Hough Lines transform, along with some maths to only detect rectangles (relative angle based), and then plots the centre point, with an output that the aircraft controller. I used OpenCV a lot in graduate school, but I haven't really used it since I graduated. See below image which compare Hough Transform and Probabilistic Hough Transform in hough space. OpenCV-Python is a library of Python bindings designed to solve computer vision problems. Python版OpenCVでは、「cv2. Yo no puede detectar directamente el tablero de ajedrez de las esquinas, pues hay un poco de polvo como se observo una micro tablero de ajedrez. The function returns rho , the distance from the origin to the line along a vector perpendicular to the line, and theta , the angle in degrees between the x -axis and this vector. It can detect the shape even if it is broken or distorted a little bit. Notice: Undefined index: HTTP_REFERER in /home/cocofarmhoian/public_html/v712pe5/04740. All the links in the v A short tutorial on how to detect circles in python using OpenCV. In this chapter, We will understand the concept of the Hough Transform. I once wrote an application for rectangle detection. Python Cómo detectar líneas verticales y horizontales en una imagen con HoughLines con OpenCV? I m tratando de obtener un umbral de la calibración de tablero de ajedrez. Sliding window is easy to implement in single scale and also not to much harder to implement in multi scale for example detection inside the bigger mat. I am successful in detecting the rectangle with sharp edges but i am not able to detect the rounded rectangle. Detection Method: OpenCV has an advanced implementation, HOUGH_GRADIENT, which uses gradient of the edges instead of filling up the entire 3D accumulator matrix, thereby speeding up the process. In this step by step tutorial, we are going to show you how you can simplify your time while you playing in the online game. The theory behind line and shape detection has its foundations in a technique called Hough transform, invented by Richard Duda and Peter Hart, extending (generalizing) the work done by Paul Hough in the early 1960s. It’s used to process images, videos, and even live streams, but in this tutorial, we will process images only as a first step. OpenCV is free to use under Open Source BSD license. minLineLength - Minimum length of line. Detect a line in an image by Hough line: Line detection is very interesting and can form the base for a line follower robot where you can your webcam to enable the robot to detect lines. OpenCV answers Hi there! Please rectangle.