OpenCV: Creating a Zoom Function

Final Project

Now, we are going to manually control the zoom with the "+" and "-" keys but also, we will include control of the cameras field-of-view, using the keyboards cursor keys. Being able to control the camera’s field-of-view and include zooming capabilities can be very useful in camera projects such as a security camera or a nature camera. You could easily add a “take snapshot” function to the #User Controls waitKey() list of commands.

Python Code:

import cv2
from adafruit_servokit import ServoKit

#Set Servos
pan=100
tilt=150
kit=ServoKit(channels=16)
kit.servo[0].angle=pan
kit.servo[1].angle=tilt

# Initialize the zoom factor
zoom_factor = .3

def zoom_frame(frame, zoom_factor):
    height, width = frame.shape[:2]
    new_height = int(height * zoom_factor)
    new_width = int(width * zoom_factor)

    # Resize the frame
    resized_frame = cv2.resize(frame, (new_width, new_height))

    # Calculate the region of interest (ROI)
    roi_x = int((new_width - width) / 2)
    roi_y = int((new_height - height) / 2)
    roi_width = width
    roi_height = height

    # Crop the frame to the ROI
    zoomed_frame = resized_frame[roi_y:roi_y+roi_height, roi_x:roi_x+roi_width]

    return zoomed_frame

#Set display resolution
dispW=1920
dispH=1080

# Open a video capture object
camera = cv2.VideoCapture(0)
camera.set(cv2.CAP_PROP_FRAME_WIDTH,dispW)
camera.set(cv2.CAP_PROP_FRAME_HEIGHT,dispH)

cv2.namedWindow('Zoomed Video',cv2.WINDOW_NORMAL)

while True:
    ret, frame = camera.read()
    
    #Position servos
    kit.servo[0].angle=pan
    kit.servo[1].angle=tilt

    # Apply zoom to the frame
    zoomed_frame = zoom_frame(frame, zoom_factor)

    # Display the zoomed frame
    cv2.imshow('Zoomed Video', zoomed_frame)

    #Set window size
    cv2.resizeWindow('Zoomed Video',1920,1080)
    
    #User Controls with OpenCV waitkey function
    k = cv2.waitKey(1)
    #Quit program using ESC key
    if k==27: #27 = ESC key
        break
    
    #Zoom Control
    if k==45: #45 is - key for zoom out
        zoom_factor-=.05
        if zoom_factor<= .1: 
            zoom_factor=.1 
            print('Zoom ', zoom_factor) 
    if k==61: #61 is + key for zoom in 
        zoom_factor+=.05 
        if zoom_factor> 5:
            zoom_factor=5
            print('Zoom ',zoom_factor)

    #Servo Control
    if k==81: #81 = cursor left key
        pan+=5
        print('Left',pan)
    if k==83: #83 = cursor right key
        pan=pan-5
        print('Right',pan)
    if k==84: #84 = cursor down key
        tilt+=5
        print('Down',tilt)
    if k==82: #82 = cursor up key
        tilt=tilt-5
        print('Up',tilt)
    
    #Set pan tilt out of range corrections
    if pan>180:
        pan=180
        print('pan out of range')
    if pan<0: pan=0 print('pan out of range') if tilt>180:
        tilt=180
        print('tilt out of range')
    if tilt<0:
        tilt=0
        print('tilt out of range')


camera.release()
cv2.destroyAllWindows()

#Reset Servos
kit.servo[0].angle=100
kit.servo[1].angle=150

print('Program Terminated')