Edge detection (Canny) in Computer Vision - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to read an image using OpenCV.

Computer Vision

import cv2

image = cv2.[1]('image.jpg')

Drag options to blanks, or click blank then click option'

Aimwrite

Bimshow

CcvtColor

Dimread

Attempts:

3 left

💡 Hint

Common Mistakes

Using cv2.imshow instead of cv2.imread to load the image.

Using cv2.imwrite which saves an image instead of loading.

The cv2.imread function reads an image from a file into memory.

2fill in blank

medium

Complete the code to convert the image to grayscale.

Computer Vision

gray = cv2.[1](image, cv2.COLOR_BGR2GRAY)

Drag options to blanks, or click blank then click option'

Aimread

BcvtColor

Cblur

Dthreshold

Attempts:

3 left

💡 Hint

Common Mistakes

Using cv2.imread again instead of converting color.

Using cv2.blur which smooths the image, not changes color.

cv2.cvtColor converts images between color spaces, here from BGR to grayscale.

3fill in blank

hard

Fix the error in the code to apply Canny edge detection.

Computer Vision

edges = cv2.Canny(gray, [1], 150)

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A50

B'50'

CNone

Dgray

Attempts:

3 left

💡 Hint

Common Mistakes

Passing threshold as a string instead of integer.

Passing None which causes runtime error.

The first threshold must be a number, here 50, not a string or None.

4fill in blank

hard

Fill both blanks to display the edges image and wait for a key press.

Computer Vision

cv2.[1]('Edges', edges)
cv2.[2](0)

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Aimshow

BwaitKey

Cimread

DdestroyAllWindows

Attempts:

3 left

💡 Hint

Common Mistakes

Using cv2.imread instead of imshow to display.

Forgetting to wait for a key press causing window to close immediately.

cv2.imshow shows the image window, and cv2.waitKey(0) waits indefinitely for a key press.

5fill in blank

hard

Fill all three blanks to save the edges image, close windows, and print success message.

Computer Vision

cv2.[1]('edges_output.jpg', edges)
cv2.[2]()
print([3])

Drag options to blanks, or click blank then click option'

Aimwrite

BdestroyAllWindows

C'Edges image saved successfully!'

Dimshow

Attempts:

3 left

💡 Hint

Common Mistakes

Using imshow instead of imwrite to save image.

Not closing windows causing program to hang.

Printing without quotes causing error.

cv2.imwrite saves the image, cv2.destroyAllWindows() closes all windows, and print outputs the message.