How images are stored (pixels, resolution) in Intro to Computing - Practice Exercises

Challenge - 5 Problems

🧠 Conceptual

intermediate

What does image resolution represent?

Imagine a photo made of tiny colored squares called pixels. What does the resolution of an image tell us?

A The file size of the image in megabytes

B The number of pixels in width and height, showing image detail

C The number of colors used in the image

D The type of camera used to take the photo

💡 Hint

Think about how many tiny squares fit across and down the image.

Resolution means how many pixels are arranged horizontally and vertically. More pixels mean more detail.

❓ trace

intermediate

How many pixels in a 4x3 image?

Consider an image that is 4 pixels wide and 3 pixels tall. How many pixels does it have in total?

A 7 pixels

B 1 pixel

C 12 pixels

D 24 pixels

💡 Hint

Multiply width by height to find total pixels.

Total pixels = width × height = 4 × 3 = 12 pixels.

❓ Comparison

advanced

Comparing image quality by resolution

Two images have these resolutions:
Image 1: 800x600 pixels
Image 2: 1600x1200 pixels
Which image will generally have better detail?

A Image 2 because it has four times more pixels

B Image 1 because it has fewer pixels

C Both have the same detail because they are rectangular

D Image 1 because it loads faster

💡 Hint

Think about total pixels and how that affects detail.

Image 2 has 1600×1200 = 1,920,000 pixels, which is four times Image 1's 480,000 pixels, so it shows more detail.

❓ identification

advanced

Identify the pixel arrangement in an image

Which diagram best represents a 3x3 pixel image where each square is a pixel?

Options:

• A: A grid with 3 rows and 3 columns of squares
• B: A grid with 2 rows and 3 columns of squares
• C: A grid with 3 rows and 2 columns of squares
• D: A single row with 9 squares

A 3 rows and 2 columns forming 6 pixels

B 2 rows and 3 columns forming 6 pixels

C 1 row and 9 columns forming 9 pixels

D 3 rows and 3 columns forming 9 pixels

💡 Hint

Count rows and columns to match 3x3 pixels.

A 3x3 pixel image has 3 rows and 3 columns, making 9 pixels total.

🚀 Application

expert

Calculate file size from image resolution and color depth

An image has a resolution of 1000x500 pixels. Each pixel uses 24 bits (3 bytes) to store color. What is the approximate file size in bytes (ignore compression)?

A 1,500,000 bytes

B 1,000,000 bytes

C 15,000,000 bytes

D 500,000 bytes

💡 Hint

Multiply total pixels by bytes per pixel.

Total pixels = 1000 × 500 = 500,000 pixels.
Each pixel = 3 bytes.
File size = 500,000 × 3 = 1,500,000 bytes (A).