Explained cv2.imshow() function in Detail | Show image

OpenCV library has powerful function named as cv2.imshow(). Which shows the NumPy array in the form of an Image.

cv2.imshow() function takes any size of NumPy array and shows the image in the same size in the window. If the image resolution is more than a system screen resolution then it shows only those pixel which fits in the screen.

Ex: Image resolution is (2000,1000) (widht, height) and screen resolution is (1000,500). Then cv2.imshow() function shows only (1000,500) pixels of image not all. To solve this problem you can resize your image then show using cv2.imsho() function.

Syntax: cv2.imshow( windows_name, numpy_array)
windows_name: string value
numpy_array: 2d or 3d NumPy array

Show Numpy array as Image

import cv2
import numpy as np

matx = np.zeros((200,200)) # numpy array with width =200, height=200

cv2.imshow("Zeros matx", matx) # show numpy array

cv2.waitKey(0) # wait for ay key to exit window
cv2.destroyAllWindows() # close all windows

Output:

Show Image

import cv2

img_path = "model.jpg" # image name
img = cv2.imread(img_path) #  read image and store in numpy array

cv2.imshow("Model image", img)

cv2.waitKey(0)
cv2.destroyAllWindows()

Output:

Show same image in multiple windows

To show same image in multiple windows we need to use cv2.imshow() unction multiple time with unique windoes_name.

import cv2

img_path = "model.jpg" # image name

img = cv2.imread(img_path)

# Showing same image in 3 windows
cv2.imshow("Model image 1", img)
cv2.imshow("Model image 2 ", img)
cv2.imshow("Model image 3", img)

cv2.waitKey(0)
cv2.destroyAllWindows()