Resize the OpenCV Window According to the Screen Resolution

This post will be helpful in learning OpenCV using Python programming. Here I will show how to implement OpenCV functions and apply it in various aspects using some examples. Then the output will be shown with some comparisons as well.

Requirements:

OpenCV 3.4
Python 3.6+
Numpy
Image, Webcam, Video input
Documentation Source: OpenCV Official Documentation

First, you need to setup your Python Environment with OpenCV. You can easily do it by following Life2Coding’s tutorial on YouTube: Linking OpenCV 3 with Python 3

Goals:

In this tutorial, I will show you how to resize the input image according to the screen resolution.

Documentation:

Python: cv2.resizeWindow(winname, width, height) → None

Resizes window to the specified size

Parameters:

winname – Window name
width – The new window width
height – The new window height

Note

The specified window size is for the image area. Toolbars are not counted.
Only windows created without CV_WINDOW_AUTOSIZE flag i.e with CV_WINDOW_NORMAL flag can be resized.

Steps:

Load Image using cv2.imread()
Create window using cv2.namedWindow()
Resize the window using cv2.resizeWindow()
Display Image using cv2.imshow()
Wait for keyboard button press using cv2.waitKey()
Exit window and destroy all windows using cv2.destroyAllWindows()

Example Code:

import cv2
import numpy as np

def main():
    #load the image
    img = cv2.imread('Hanif.jpg')

    #define the screen resulation
    screen_res = 1280, 720
    scale_width = screen_res[0] / img.shape[1]
    scale_height = screen_res[1] / img.shape[0]
    scale = min(scale_width, scale_height)

    #resized window width and height
    window_width = int(img.shape[1] * scale)
    window_height = int(img.shape[0] * scale)

    #cv2.WINDOW_NORMAL makes the output window resizealbe
    cv2.namedWindow('Resized Window', cv2.WINDOW_NORMAL)

    #resize the window according to the screen resolution
    cv2.resizeWindow('Resized Window', window_width, window_height)

    cv2.imshow('Resized Window', img)
    cv2.waitKey(0)
    cv2.destroyAllWindows()

if __name__ == "__main__":
    main()