Capturing still images in Raspberry Pi - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this Raspberry Pi camera capture code?

Consider the following Python code using the picamera library to capture an image. What will be the output after running this code?

Raspberry Pi

import picamera
with picamera.PiCamera() as camera:
    camera.resolution = (1024, 768)
    camera.capture('image.jpg')
print('Image captured with resolution:', camera.resolution)

A SyntaxError: invalid syntax

B Image captured with resolution: (640, 480)

C Image captured with resolution: (1024, 768)

D RuntimeError: camera not found

💡 Hint

Check the resolution set before capturing the image.

The code sets the camera resolution to (1024, 768) before capturing the image. The print statement outputs this resolution.

🧠 Conceptual

intermediate

Which option correctly explains the role of 'camera.capture()' in Raspberry Pi image capture?

In Raspberry Pi Python code using the picamera library, what does the method 'camera.capture()' do?

A It captures a still image and saves it to a file.

B It starts the camera preview on the screen.

C It records a video stream to a file.

D It sets the camera resolution.

💡 Hint

Think about what 'capture' means in photography.

'camera.capture()' takes a still photo and saves it to the specified file.

🔧 Debug

advanced

What error does this Raspberry Pi camera code raise?

Analyze the following code snippet. What error will it raise when executed on a Raspberry Pi with a camera module? import picamera camera = picamera.PiCamera() camera.capture('photo.jpg') camera.close() camera.capture('photo2.jpg')

Raspberry Pi

import picamera
camera = picamera.PiCamera()
camera.capture('photo.jpg')
camera.close()
camera.capture('photo2.jpg')

A SyntaxError: invalid syntax

B FileNotFoundError: photo2.jpg not found

C No error, both images are captured successfully

D RuntimeError: Camera has been closed

💡 Hint

Consider what happens after calling camera.close()

After closing the camera, trying to capture another image raises a RuntimeError because the camera resource is released.

📝 Syntax

advanced

Which option contains the correct syntax to capture an image with a delay using picamera?

You want to capture an image after a 5-second delay to allow the camera to adjust. Which code snippet is syntactically correct?

A

import picamera
import time
with picamera.PiCamera() as camera:
    time.sleep(5)
    camera.capture('delayed.jpg')

B

import picamera
import time
with picamera.PiCamera() as camera
    time.sleep(5)
    camera.capture('delayed.jpg')

C

import picamera
import time
camera = picamera.PiCamera()
time.sleep(5)
camera.capture('delayed.jpg')
camera.close()

D

import picamera
import time
with picamera.PiCamera() as camera:
    camera.capture('delayed.jpg')
    time.sleep(5)

💡 Hint

Check for missing colons and order of operations.

Option A correctly uses a with statement with colon, sleeps before capture, and captures the image properly.

🚀 Application

expert

How many images are saved after running this Raspberry Pi camera script?

Given the following Python script using picamera, how many image files will be saved on disk after execution? import picamera with picamera.PiCamera() as camera: camera.resolution = (640, 480) for i in range(3): camera.capture(f'image_{i}.jpg') camera.capture('final.jpg')

Raspberry Pi

import picamera
with picamera.PiCamera() as camera:
    camera.resolution = (640, 480)
    for i in range(3):
        camera.capture(f'image_{i}.jpg')
    camera.capture('final.jpg')

A 3

B 4

C 1

D 0

💡 Hint

Count all capture calls in the code.

The loop captures 3 images named image_0.jpg, image_1.jpg, image_2.jpg, plus one final capture named final.jpg, totaling 4 images.