Draw different shapes on image using Python OpenCV

In this article, you will learn to draw different spaces on an image using the Python OpenCV module.

OpenCV provides different functionality to draw different shapes, like circles, rectangles, triangles, ellipses, and so on. This is basically required in building a computer vision project, where we usually modify the image by drawing some shapes. For example, to draw a rectangle for highlighting the detected face in a face recognition program.

Technical Requirements

The technical requirements for drawing different shapes are as follows-

• Python Package
• OpenCV Package

Python OpenCV Draw Lines

Python OpenCV module provides a line() method to draw line segments. The syntax of the line() method-

cv2.line(image, start_point, end_point, color, thickness)

Here, the image is the image on which the line to be drawn, start_point is the starting coordinates of the line. The coordinates are represented as tuples of two values, i.e., (x, y). The end_point is the ending coordinates of the line. The coordinates are represented as tuples of two values, i.e., (x, y). The color is the color of the line segment, and the thickness is the thickness of the line in px.

Example of Draw Lines

import cv2 
  
# image path 
path = r'nature.jpg'

# using imread()  
img = cv2.imread(path)


cv2.line(img, (0, 0), (400, 400), (255,0,0), 3)
cv2.line(img, (0, 200), (200, 0), (198, 33, 6), 4)
cv2.line(img, (200, 0), (200, 400), (7, 35, 122), 3)
cv2.line(img, (200, 0), (400, 400), (243, 240, 35), 3)

cv2.imshow('image', img)
cv2.waitKey(0);
cv2.destroyAllWindows();
cv2.waitKey(1)

Python OpenCV Draw Rectangle

The rectangle() method of Python OpenCV is used to draw a simple or filled rectangle on a given image. Syntax-

cv2.rectangle(image, start_point, end_point, color, thickness)

Example

import cv2 
  
# image path 
path = r'nature.jpg'

# using imread()  
img = cv2.imread(path)

cv2.rectangle(img, (10, 10), (100, 100), (7, 35, 122), 3)
cv2.rectangle(img, (150, 150), (300, 300), (129, 255, 43 ), -1)

cv2.imshow('image', img)
cv2.waitKey(0);
cv2.destroyAllWindows();
cv2.waitKey(1)

Python OpenCV Draw Circle

OpenCV has a circle() method to draw a simple or filled circle on a given image.

cv2.circle(image, center_coordinates, radius, color, thickness)

Example

import cv2 
  
# image path 
path = r'nature.jpg'

# using imread()  
img = cv2.imread(path)

cv2.circle(img, (50, 50), 50, (66, 9, 47), 3)
cv2.circle(img, (250, 200), 60, (52, 229, 81), -1)

cv2.imshow('image', img)
cv2.waitKey(0);
cv2.destroyAllWindows();
cv2.waitKey(1)

Python OpenCV Drawing Arrows

The arrowedLine() method of Python OpenCV allows us to create an arrow on a specified image. The syntax is -

arrowedLine(img, start_point, end_point, color, thickness, line_type, shift, tip_length)

In the above syntax, line_type specifies the type of line for drawing, shift denotes the number of fractional bits in the point coordinates, and the tip_length is the length of the arrow tip in relation to the arrow length.

Example

import cv2 
  
# image path 
path = r'nature.jpg'

# using imread()  
img = cv2.imread(path)

cv2.arrowedLine(img, (100, 100), (200, 100), (63, 52, 155), 3, 8, 0, 0.1)
cv2.arrowedLine(img, (170, 170), (220, 170), (220, 25, 6), 3, cv2.LINE_AA, 0, 0.3)

cv2.imshow('image', img)
cv2.waitKey(0);
cv2.destroyAllWindows();
cv2.waitKey(1)

Python OpenCV Drawing Ellipses

The OpenCV has an ellipse() method to draw a simple or filled ellipse on a given image.

ellipse(img, center, axes, angle, start_angle, end_angle, color, thickness)

Example

import cv2 
  
# image path 
path = r'nature.jpg'

# using imread()  
img = cv2.imread(path)

cv2.ellipse(img, (80, 80), (20, 50), 0, 0, 360, (16, 248, 220), 3)
cv2.ellipse(img, (200, 200), (10, 50), 0, 0, 360, (219, 9, 222), 3)

cv2.imshow('image', img)
cv2.waitKey(0);
cv2.destroyAllWindows();
cv2.waitKey(1)

Python OpenCV Drawing Text

Python OpenCV has a putText() method to draw a text string on a given image. The syntax of putText() is -

putText(image, text, org, font, fontScale, color, thickness)

Example

import cv2 
  
# image path 
path = r'nature.jpg'

# using imread()  
img = cv2.imread(path)

x1 = 'Our Beautiful Nature'
x2 = 'etutorialspoint.com'

cv2.putText(img, x1, (10, 30), cv2.FONT_HERSHEY_SIMPLEX, 1,(0,0,255),2 )
cv2.putText(img, x2, (10, 70), cv2.FONT_HERSHEY_SIMPLEX, 1,(255,0,0),1 )

cv2.imshow('image', img)
cv2.waitKey(0);
cv2.destroyAllWindows();
cv2.waitKey(1)

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