Real-Time Edge Detection using OpenCV in Python | Canny edge detection method
The objective of the program given is to perform edge detection of images in real-time. In this article, the popular canny edge detection algorithm is used to detect a wide range of edges in images. OpenCV has in-built function cv2.Canny() which takes our input image as first argument and its aperture size(min value and max value) as last two arguments. This is a simple example of how to detect edges in Python.
Steps to download the requirements below:
- Download Python 2.7.x version, numpy and OpenCV 2.7.x or 3.1.0 version.Check if your Windows either 32 bit or 64 bit is compatible and install accordingly.
- Make sure that numpy is running in your python then try to install opencv.
Implementation
# OpenCV program to perform Edge detection in real time# import libraries of python OpenCV # where its functionality residesimport cv2 # np is an alias pointing to numpy libraryimport numpy as np # capture frames from a cameracap = cv2.VideoCapture(0) # loop runs if capturing has been initializedwhile(1): # reads frames from a camera ret, frame = cap.read() # converting BGR to HSV hsv = cv2.cvtColor(frame, cv2.COLOR_BGR2HSV) # define range of red color in HSV lower_red = np.array([30,150,50]) upper_red = np.array([255,255,180]) # create a red HSV colour boundary and # threshold HSV image mask = cv2.inRange(hsv, lower_red, upper_red) # Bitwise-AND mask and original image res = cv2.bitwise_and(frame,frame, mask= mask) # Display an original image cv2.imshow('Original',frame) # finds edges in the input image image and # marks them in the output map edges edges = cv2.Canny(frame,100,200) # Display edges in a frame cv2.imshow('Edges',edges) # Wait for Esc key to stop k = cv2.waitKey(5) & 0xFF if k == 27: break # Close the windowcap.release() # De-allocate any associated memory usagecv2.destroyAllWindows() |
Output:
References:
- http://docs.opencv.org/2.4/doc/tutorials/imgproc/imgtrans/canny_detector/canny_detector.html
- http://docs.opencv.org/trunk/da/d22/tutorial_py_canny.html
- https://en.wikipedia.org/wiki/Canny_edge_detector
- http://www.ijcsmc.com/docs/papers/July2013/V2I7201329.pdf
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