Representing images with pixels
Name:
Date:
Class:
A
Quick Questions
Shade in the A or B circle for each question.
1. How is a digital image made up?
2. How does a computer store each pixel?
3. In a simple black and white image, which number can stand for a black pixel?
4. A row of pixels is stored as 1 0 0 1. Which pixels are black?
5. Which row of numbers shows white, black, white, black?
B
Match the Pairs
Draw a line connecting each item on the left to its match on the right.
| Left column | Right column | |
|---|---|---|
| 18 x 8 grid = 64 pixels | AAn image made of 8 rows and 8 columns of squares has 64 pixels in total | |
| 20 1 1 0 | BThe rows and columns were added instead of multiplied. 4 x 3 makes 12 pixels. | |
| 3A black pixel is stored as the number 1 | CA row of four pixels: white, black, black, white | |
| 4A higher resolution image has more pixels, so it shows more detail | DIn a black and white image only 0 and 1 are used. White is 0, not 5. | |
| 5A white pixel is stored as 5 | Epixel = 1 | |
| 6A 4 x 3 grid has 7 pixels | Fresolution = 1920 x 1080 |
C
Definitions
pixel
D
Fill in the Blanks
Complete each line of code by filling in the missing parts.
1.
A digital image is a grid of ______
2.
A black pixel is stored as the number _
3.
More pixels means higher __________
4.
width = 4, height = 3
total pixels = 4 * 3 = __
5.
Each pixel is stored as a ______
E
Spot the Error
Shade in the letter of the line that contains an error.
Question 1
A
# Black and white pixels
B
white = 1
C
black = 1
D
pixel = black
Question 2
A
image = [0, 1, 1, 0
B
pixels = len(image)
C
print(pixels)
Question 3
A
row1 = [0, 1, 1, 0]
B
row2 = [1, 0, 2, 1]
C
row3 = [0, 1, 1, 0]
Question 4
A
width, height = 8, 6
B
total = width + height
C
print(total)
Question 5
A
row1 = [0, 1, 0]
B
row2 = [1, 1, 1]
C
row3 = [0, 1, 0]
D
print(row1) # all black
Answer Key
Representing images with pixels
Section A: Quick Questions
Q1
B — A grid of tiny squares called pixels
Q2
A — As a number
Q3
B — 1
Q4
A — The first and the last
Q5
A — 0 1 0 1
Section B: Match the Pairs
Q1
8 x 8 grid = 64 pixels → An image made of 8 rows and 8 columns of squares has 64 pixels in total
Q2
0 1 1 0 → A row of four pixels: white, black, black, white
Q3
A black pixel is stored as the number 1 → pixel = 1
Q4
A higher resolution image has more pixels, so it shows more detail → resolution = 1920 x 1080
Q5
A white pixel is stored as 5 → In a black and white image only 0 and 1 are used. White is 0, not 5.
Q6
A 4 x 3 grid has 7 pixels → The rows and columns were added instead of multiplied. 4 x 3 makes 12 pixels.
Section C: Definitions
Q1
pixel — A pixel is one tiny square in a grid that makes up a digital image. Each pixel is stored as a number, such as 0 for white or 1 for black.Section D: Fill in the Blanks
Q1
A digital image is a grid of pixelsQ2
A black pixel is stored as the number 1Q3
More pixels means higher resolutionQ4
width = 4, height = 3
total pixels = 4 * 3 = 12Q5
Each pixel is stored as a numberSection E: Spot the Error
Q1
B — In black and white images, white pixels are stored as 0, not 1. It should be white = 0. Black is the pixel stored as 1.
Q2
A — The list of pixel numbers is missing its closing square bracket. It should be image = [0, 1, 1, 0].
Q3
B — A black and white pixel can only be 0 or 1. The 2 is not a valid pixel number. It should be row2 = [1, 0, 0, 1].
Q4
B — The number of pixels in a grid is the width multiplied by the height, not added. It should be total = width * height, which gives 48.
Q5
D — Row 1 is [0, 1, 0], so it has white pixels. The all black row is row2, which is [1, 1, 1]. It should be print(row2).