Frame extraction in Computer Vision - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to open a video file using OpenCV.

Computer Vision

import cv2

cap = cv2.VideoCapture([1])

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A'video.mp4'

B0

CTrue

DNone

Attempts:

3 left

💡 Hint

Common Mistakes

Passing 0 opens the webcam, not a video file.

Passing True or None causes errors.

To open a video file, you pass the filename as a string to cv2.VideoCapture.

2fill in blank

medium

Complete the code to read a frame from the video capture object.

Computer Vision

ret, frame = cap.[1]()

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Aread

Bcapture

Cgrab

Dfetch

Attempts:

3 left

💡 Hint

Common Mistakes

Using grab() only grabs the frame but does not decode it.

capture() and fetch() are not OpenCV methods.

The read() method reads the next frame from the video.

3fill in blank

hard

Fix the error in the loop that extracts frames until the video ends.

Computer Vision

while True:
    ret, frame = cap.read()
    if not [1]:
        break
    cv2.imshow('Frame', frame)
    if cv2.waitKey(25) & 0xFF == ord('q'):
        break

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Aframe

Bret

Ccap

Dcv2

Attempts:

3 left

💡 Hint

Common Mistakes

Checking frame instead of ret can cause errors if frame is None.

Checking cap or cv2 is incorrect.

ret is a boolean indicating if the frame was read successfully; we break if it's False.

4fill in blank

hard

Fill both blanks to release the video and close all windows.

Computer Vision

cap.[1]()
cv2.[2]()

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Arelease

BdestroyAllWindows

Cclose

Dstop

Attempts:

3 left

💡 Hint

Common Mistakes

Using close() or stop() are not valid OpenCV methods.

Not releasing the video can cause resource leaks.

release() frees the video resource; destroyAllWindows() closes all OpenCV windows.

5fill in blank

hard

Fill all three blanks to save the extracted frame as an image file.

Computer Vision

if ret:
    cv2.[1]('[2]', [3])

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Aimwrite

Bframe

Coutput.jpg

Dimshow

Attempts:

3 left

💡 Hint

Common Mistakes

Using imshow instead of imwrite displays the image but does not save it.

Swapping filename and image arguments causes errors.

imwrite saves an image to a file; first argument is filename, second is image data.