Bitmap Images: Pixels, Resolution and Colour Depth · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.

Pictures made of tiny squares

Computing · Computer Systems · ages 14-16
Name ______________________   Date ____________
  1. Resolution controls how many pixels make up the picture.

    Circle one:   True   False

  2. What is a pixel?

    • A whole photo
    • A tiny square
    • A file type
  3. What does colour depth control?

    • Bits per pixel
    • How wide the screen is
    • How fast the picture prints
  4. The colour depth doubles from 8 to 16 bits. What happens to the file?

    • It stays the same
    • It halves
    • It doubles
  5. A 100 by 100 image uses 8-bit colour. How many bits does it take?

    Answer: ______________

  6. What happens when a picture is blown up past its resolution?

    • Blurry or blocky
    • It gains true detail
    • Its file shrinks
  7. A 16 by 16 icon in two colours is stored plainly, one bit per pixel. How many bits?

    • 32
    • 256
    • 16
  8. A 50 by 50 icon uses 8-bit colour. How many bits does it take?

    Answer: ______________

LightMySky · lightmysky.comW1-mt_-Tr40QK8sN-s1

Answer key

For grown-ups. Fold this page away before handing over the rest.

Pictures made of tiny squares W1-mt_-Tr40QK8sN-s1

  1. True · More pixels means higher resolution and a sharper picture.
  2. A tiny square · Pictures are grids, and each grid square is one pixel.
  3. Bits per pixel · Depth sets the bits per pixel, which sets the colour count.
  4. It doubles · Every pixel carries twice the bits, so the total doubles.
  5. 80000 · 100 times 100 pixels times 8 bits each is 80,000 bits.
  6. Blurry or blocky · Each pixel must cover more space, and guessed colours look rough.
  7. 256 · 16 times 16 pixels times 1 bit each is 256 bits.
  8. 20000 · 50 times 50 pixels times 8 bits each is 20,000 bits.
Worksheet · LightMySky