Drawing Geometric shapes — using OpenCV

Let’s start with importing cv2 and numpy libraries. The following code is used to do so:

import numpy as np
import cv2

Now let’s take a look at the function used to read an image.

The function cv2.imread()is used to read an image, it requires two arguments: the first is the path to the image itself and the second specifies the way the image should be read.

The default value is cv2.IMREAD_COLORwhich loads the colour image. (1)

cv2.IMREAD_GRAYSCALE this will read the image in grayscale mode. (0)

cv2.IMREAD_UNCHANGEDthis will read the image including the alpha channel. (-1)

Drawing a Line:

img = cv2.line(image, (0,0) , (255,255) , (0,0,255) , 5)

The arguments in the line() function are:

• image: The variable holding our image
• (0,0): The starting point of our line
• (255, 255): The endpoint of our line
• (0, 0, 255): The colour of our line
• 5: The thickness of our line

Line

Drawing an Arrowed Line:

img = cv2.arrowedLine(image, (0,255) , (255,255) , (255,0,0) , 5)

The arguments in the arrowedLine() function are:

• image: The variable holding our image
• (0,255): The starting point of our line
• (255, 255): The endpoint of our line
• (255, 0, 0): The colour of our line
• 5: The thickness of our line

ArrowedLine

Drawing a Rectangle:

img = cv2.rectangle(image, (384,0) , (510,128) , (255,0,0) , -1)

The rectangle function holds the following arguments:

• image: The variable holding our image
• (384, 0): The top left corner of the rectangle
• (510, 128): The bottom right corner of the rectangle
• (255, 0, ): The colour of the rectangle
• -1: This indicated that the image will be filled with the above color.

Rectangle

Drawing a Circle:

img = cv2.circle(image, (447,63) , 63 ,(0,255,0) , 5)

cv2.circle() will need the following arguments:

• image: The variable holding our image
• (447, 63): The centre location
• 63: The radius of the circle
• (0, 255, 0): The colour of the circle
• 5: The thickness of the circle

Circle

Can we draw a Polygon in OpenCV ??

Well, go try it out ; )