One bit gives two colours
Name:
Date:
Class:
A
Quick Questions
Shade in the A or B circle for each question.
1. How many different values can one bit hold?
2. If each pixel uses 1 bit, how many colours can one pixel be?
3. A 1-bit picture uses 0 for white and 1 for black. What does a pixel with the value 1 show?
4. Can a 1-bit image use blue and yellow instead of black and white?
5. A pixel is stored as 1 bit. Which pixel value is NOT possible?
B
Match the Pairs
Draw a line connecting each item on the left to its match on the right.
| Left column | Right column | |
|---|---|---|
| 11 bit = 2 colours | AA key that gives each of the two bit values one colour, so every pixel is either white or black. | |
| 20 = white, 1 = black | BOne bit per pixel can only be 0 or 1, so each pixel can be one of only two colours. | |
| 3The two colours do not have to be black and white. Any pair of colours works if 0 and 1 each get one. | C0 = blue, 1 = yellow | |
| 4A photo has thousands of different colours, so one bit per pixel is not enough to store it. | DOne bit can only be 0 or 1, so it gives 2 colours, not 3. | |
| 51 bit = 3 colours | EA single bit cannot be 2. It can only be 0 or 1, so the key can only have two colours. | |
| 60 = red, 1 = green, 2 = blue | F1 bit = 2 colours, photo = many colours |
C
Definitions
1 bit = 2 colours
D
Fill in the Blanks
Complete each line of code by filling in the missing parts.
1.
1 bit = _ colours
2.
A black and white image uses _ bit per pixel
3.
A row of 8 pixels needs _ bits in total
4.
Colour pair key: 0 = red, _ = blue
5.
A photo needs ____ bits per pixel than 1
E
Spot the Error
Shade in the letter of the line that contains an error.
Question 1
A
bits = 1
B
colours = 3 ** bits
C
print(colours)
Question 2
A
key = {0: "black", 1: "white"}
B
pixel = 1
C
colour = key[pixel]
D
print(colour) # black
Question 3
A
# one bit per pixel
B
valid = [0, 1, 2]
C
pixel = 1
Question 4
A
bits = 1
B
colours = 2 ** bits
C
if colours == 4:
D
print("black and white")
Question 5
A
pixel_values = [0, 1, 2]
B
count = len(pixel_values)
C
print(count, "colours")
Answer Key
One bit gives two colours
Section A: Quick Questions
Q1
A — Two: 0 and 1
Q2
A — 2 colours
Q3
B — A black pixel
Q4
B — Yes, any two colours can be the pair
Q5
A — 2
Section B: Match the Pairs
Q1
1 bit = 2 colours → One bit per pixel can only be 0 or 1, so each pixel can be one of only two colours.
Q2
0 = white, 1 = black → A key that gives each of the two bit values one colour, so every pixel is either white or black.
Q3
The two colours do not have to be black and white. Any pair of colours works if 0 and 1 each get one. → 0 = blue, 1 = yellow
Q4
A photo has thousands of different colours, so one bit per pixel is not enough to store it. → 1 bit = 2 colours, photo = many colours
Q5
1 bit = 3 colours → One bit can only be 0 or 1, so it gives 2 colours, not 3.
Q6
0 = red, 1 = green, 2 = blue → A single bit cannot be 2. It can only be 0 or 1, so the key can only have two colours.
Section C: Definitions
Q1
1 bit = 2 colours — One bit per pixel can only be 0 or 1, so each pixel can only be one of two colours, like black and white. A photo needs many more colours, so it needs more bits.Section D: Fill in the Blanks
Q1
1 bit = 2 coloursQ2
A black and white image uses 1 bit per pixelQ3
A row of 8 pixels needs 8 bits in totalQ4
Colour pair key: 0 = red, 1 = blueQ5
A photo needs more bits per pixel than 1Section E: Spot the Error
Q1
B — Each bit has 2 possible values, so the number of colours is 2 ** bits. With 1 bit that gives 2 colours, not 3. It should be colours = 2 ** bits.
Q2
D — The key says 1 means white, so a pixel of 1 prints white. The comment should say white, not black.
Q3
B — One bit can only be 0 or 1. The value 2 cannot be stored in a single bit, so the list should be [0, 1].
Q4
C — One bit gives 2 colours, so the check must be colours == 2. Checking for 4 would never match, so black and white would not print.
Q5
A — A 1-bit pixel can only be 0 or 1. Adding 2 would make three values, so the list should be [0, 1].