Python OpenCV – cv2.polylines() method
OpenCV is the huge open-source library for computer vision, machine learning, and image processing and 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 integrated with various libraries, such as Numpuy, python is capable of processing the OpenCV array structure for analysis.
Note: For more information, refer to OpenCV Python Tutorial
cv2.polylines()
cv2.polylines() method is used to draw a polygon on any image.
Syntax: cv2.polylines(image, [pts], isClosed, color, thickness)
Parameters:
image: It is the image on which circle is to be drawn.
pts: Array of polygonal curves.
npts: Array of polygon vertex counters.
ncontours: Number of curves.
isClosed: Flag indicating whether the drawn polylines are closed or not. If they are closed, the function draws a line from the last vertex of each curve to its first
vertex.
color: It is the color of polyline to be drawn. For BGR, we pass a tuple.
thickness: It is thickness of the polyline edges.Return Value: It returns an image.
Image used for all the below examples:
Image used for all the below examples:
Example #1:
# Python program to explain # cv2.polylines() method import cv2 import numpy as np # path path = gfg.jpeg' # Reading an image in default # mode image = cv2.imread(path) # Window name in which image is # displayed window_name = 'Image' # Polygon corner points coordinates pts = np.array([[ 25 , 70 ], [ 25 , 160 ], [ 110 , 200 ], [ 200 , 160 ], [ 200 , 70 ], [ 110 , 20 ]], np.int32) pts = pts.reshape(( - 1 , 1 , 2 )) isClosed = True # Blue color in BGR color = ( 255 , 0 , 0 ) # Line thickness of 2 px thickness = 2 # Using cv2.polylines() method # Draw a Blue polygon with # thickness of 1 px image = cv2.polylines(image, [pts], isClosed, color, thickness) # Displaying the image while ( 1 ): cv2.imshow( 'image' , image) if cv2.waitKey( 20 ) & 0xFF = = 27 : break cv2.destroyAllWindows() |
Output:
Example #2:
# Python program to explain # cv2.polylines() method import cv2 import numpy as np # path path = r 'gfg.jpeg' # Reading an image in default # mode image = cv2.imread(path) # Window name in which image is # displayed window_name = 'Image' # Polygon corner points coordinates pts = np.array([[ 25 , 70 ], [ 25 , 145 ], [ 75 , 190 ], [ 150 , 190 ], [ 200 , 145 ], [ 200 , 70 ], [ 150 , 25 ], [ 75 , 25 ]], np.int32) pts = pts.reshape(( - 1 , 1 , 2 )) isClosed = True # Green color in BGR color = ( 0 , 255 , 0 ) # Line thickness of 8 px thickness = 8 # Using cv2.polylines() method # Draw a Green polygon with # thickness of 1 px image = cv2.polylines(image, [pts], isClosed, color, thickness) # Displaying the image while ( 1 ): cv2.imshow( 'image' , image) if cv2.waitKey( 20 ) & 0xFF = = 27 : break cv2.destroyAllWindows() |
Output:
Last Updated on March 1, 2022 by admin