Representing Images

Question 1

What is the RGB colour model?

Answer 1

• three numbers
• representing the amounts of red, green and blue present

Question 2

What is the range of numbers for the RGB model?

Answer 2

0-255

Question 3

What is the colour code for red?

Answer 3

255,0,0

Question 4

What is the colour code for white?

Answer 4

255,255,255

Question 5

What is the colour code for blue?

Answer 5

0,0,255

Question 6

What is the colour code for orange?

Answer 6

255,165,0

Question 7

What is the colour code for black?

Answer 7

0,0,0

Question 8

What is the colour code for green?

Answer 8

0,255,0

Question 9

What is the colour code for yellow?

Answer 9

255,255,0

Question 10

What is the colour code for purple?

Answer 10

128,0,128

Question 11

What is the CMYK model?

Answer 11

Cyan, Magenta, Yellow and Black

Question 12

When and how is the CMYK model used?

Answer 12

• Colour printers
• Starts with white and removes components

Question 13

What is the HSL and YUV colour model?

Answer 13

• Hue, Saturation, Luminance
• Luminance, Blue, Red
• mapped better to how the human brain can understand

Question 14

How many different colours can we have with the RGB model?

Answer 14

256 x 256 x 256
- 16 million colours

Question 15

What do we use to represent RRGGBB?

Answer 15

hexadecimals

Question 16

What are the 4 ways in digitized images and graphics?

Answer 16

1. Pixel
2. Resolution
3. Vector graphics
4. Rater-graphics

Question 17

What are pixels?

Answer 17

• Picture element
• Each pixel is a single colour

Question 18

What is resolution

Answer 18

• Number of pixels in an image

Question 19

The size of an image is measured in what?

Answer 19

pixels

Question 20

Pixel density is another way of saying what?

Answer 20

resolution

Question 21

What is vector graphics?

Answer 21

• an image that is defined by using mathematical equations to represent lines, curves, and polygons

Question 22

Can vector graphics be enlarged without losing detail or changing file size?

Answer 22

Yess

Question 23

What is SVG?

Answer 23

scalable vector graphics

Question 24

SVG files are _____-based?

Answer 24

text-based

Question 25

What is the smallest unit of a digital image?

Answer 25

pixel

Question 26

What is the advantage of vector graphics?

Answer 26

to never suffer from pixelization

Question 27

What is Raster graphics?

Answer 27

An image that is comprised of a matrix of pixels - images created/edited using painting applications

Question 28

What is the consequence of rester graphics?

Answer 28

suffer from pixelization

Question 29

What is indexed image compression?

Answer 29

Only saving the colours needed and using keyword encoding, but for colour instead

Question 30

What are the 3 types of image formating?

Answer 30

1. GIF 2. PNG 3. JPEG

Question 31

Is GIF lossless or lossy?

Answer 31

lossless

Question 32

Is PNG lossless or lossy?

Answer 32

lossless

Question 33

Is JPEG lossless or lossy?

Answer 33

lossy

Question 34

What is a GIF?

Answer 34

Graphics Interchange Format

Question 35

What are the 4 attributes of GIF?

Answer 35

1. Coding related to Huffman's 2. Compression ratio of 10% 3. Indexed colours with a maximum of 256 4. Allows for transparency and animation

Question 36

What are the 4 attributes of PNG?

Answer 36

1. indexdd colours 2. coding related to run-length 3. Compression ratio of 7% 4. more modern

Question 37

What are PNG?

Answer 37

Portable Network Graphics

Question 38

What are PNG and GIF best used for?

Answer 38

- line drawings - logos - diagrams

Question 39

What is a consequence of PNG?

Answer 39

too large lossless

Question 40

What is a consequence of GIF?

Answer 40

low quality 256 colours

Question 41

What is JPEG?

Answer 41

Joint Photographic Experts Group

Question 42

What is the JPEG compression ratio?

Answer 42

1-10% depending on quality

Question 43

What is the lossy compression technique for JPEG?

Answer 43

- Divide the entire image into blocks of 8 x 8 FOR EACH BLOCK - store the avg intensity FOR EACH PIXEL IN SED BLOCK - store the difference between each pixel's intensity and the avg intensity of the block

Question 44

True or False In lossy image compression, the differences smaller than a threshold are ignored

Answer 44

True