Data Representation

Question 1

Distinguish between bitmap and vector graphics

Answer 1

Bitmap images are made up of pixels, and vector images are made up of points and curves

Question 2

Describe color depth and image resolution

Question 3

What do computers use to store and process images?

Answer 3

The computers store and process images using binary codes so that you can see them on the screen.

Question 4

What are the two forms that an image is usually presented in?

Answer 4

Bitmap images – made of small parts called pixels.
Vector images – made using coordinates and geometry.

Question 5

What are vector images made up of?

Answer 5

Points and curves

Question 6

What are bitmap images made up of?

Answer 6

Pixels (units of light)

Question 7

Each pixel in an image is made up of…

Answer 7

binary numbers

Question 8

How do you find the size of an image?

Answer 8

Height x width

Question 9

Image resolution can be expressed as what?

Answer 9

The number of pixels that an image contains per inch.

Question 10

Resolution is usually measured in…

Answer 10

dots per inch (dpi)

Question 11

Magazines often use either…

Answer 11

300 dpi or even 600 dpi.

Question 12

What is the resolution of a 100 by 70 pixel image?

Answer 12

100 * 70 = 7000 pixels

Question 13

What do you need to have more colors in your images

Answer 13

You need more bits

Question 14

What does color depth describe?

Answer 14

Color depth describes the number of bits of memory that are used to store the color information about each pixel in a bitmap image.

Question 15

What does having 2-bits per pixel mean?

Answer 15

Having 2 bits per pixel means that you can use 4 colors in your image.
00 = white
01 = black
10 = gray
11 = blue
(2^n, and n is the number of bits)

Question 16

What’s the equation for finding bits per pixel (aka color depth)?

Answer 16

2^n, n being the number of bits

Question 17

What are two things that impact the file size?

Answer 17

Resolution and color depth

Question 18

How much does 1 KB equal to?

Answer 18

1000 bytes

Question 19

File size is normally measured in what?

Answer 19

Bytes

Question 20

What is the file size of an image that is 800x800 pixels and has a color depth of 4 bits? Give your answer in KB.

Answer 20

Calculate the total pixels: 800800=640,000 pixels.
Calculate total bits: 640,0004=2,560,000 bits.
Convert bits to bytes: 2,560,000 / 8 =320,000 bytes.
Convert bytes to kilobytes: 320,000 / 1000=320 KB

Question 21

What is the file size in bytes of a bitmapped graphic that is 100 * 100 pixels and has a color depth of 2 bits?

Answer 21

Calculate the total pixels: 100100=10,000 pixels.
Calculate total bits: 10,0002=20,000 bits.
Convert bits to bytes: 20,000 / 8 =2,500 bytes.

Question 22

What does metadata mean?

Answer 22

Metadata means ‘data about data’.

Question 23

What does metadata do?

Answer 23

Metadata is added to an image file to allow the file to be saved and reproduced accurately.

Question 24

What are examples of metadata?

Answer 24

Image dimensions (e.g. width in pixels, height in pixels)
Color depth
File format – e.g. JPEG, GIF or PNG
Date and time of creation
Geographical location of creation
Details about the device used to create the image
Camera settings

Question 25

What is the additive process?

Answer 25

Mixing red, green and blue colors (RGB) to project colors onto a screen

Question 26

How do computer screens work?

Answer 26

Computer screens work by combining three colors. It begins with a black screen, and then colors are added using a process called “Additive process” by mixing red, green and blue colors (RGB).

Question 27

How can different colors be shown on a screen using the additive process?

Answer 27

By adjusting the brightness of these lights

Question 28

What are the numbers that are used to represent colors in computer graphics?

Answer 28

Numbers from 0 to 255

Question 29

What do the colors 0-255 do in computer graphics?

Answer 29

They display different pixel brightnesses

Question 30

What does it mean for the red value light to be at 0?6

Answer 30

The red colored pixel is completely off

Question 31

What does it mean for the red value light to be at 255?

Answer 31

The red pixel is completely on

Question 32

How many possibile values for all of the 3 primary colors are there?

Answer 32

There are in total of 256 possible values for each primary color, including 0. Therefore, a total of 256x256x256= 16,777,216 possible colors can be created.

Question 33

What are the smallest and largest numbers of color bits (using 8) than can be represented by hexadecimal?

Answer 33

The smallest number 0 that can be represented using 8 bits is 00000000. And the largest number 255 that can be represented using 8 bits is 11111111.

Question 34

How many possibilities are there for representing the three primary colors in 8 bits?

Answer 34

With 256 different possible values for three primary colors, 8 bits are needed to represent a number. Therefore, 28=2 x 2 x 2 x 2 x 2 x 2 x 2 x 2=256.

Question 35

How many bits are required to represent 3 primary colors?

Answer 35

For three primary colors, 3x8=24 bits in total is required to represent a color.

Question 36

Therefore, RGB (255, 51, 153) in binary number is…

Answer 36

111111110011001110011001