1.2 Multimedia

Question 1

Que es un bit map image?

Answer 1

A system that uses pixels to make up an image.

Question 2

What is a pixel?

Answer 2

The smallest picture element that makes up an image.

Question 3

What is colour depth?

Answer 3

Number of bits used to represent colours in a pixel.
E.g: 8 bit colour depth = 2^8 = 256 colours

Question 4

What is the image resolution?

Answer 4

The number of pixels that make up an image.

Question 5

What is bit depth?

Answer 5

Number of bits used to represent the smallest unit in a sound or image file.
The larger the bit depth, the better the quality of the sound/colour.

Question 6

What is screen resolution?

Answer 6

The number of horizontal and vertical pixels that make up a screen or display. If screen resolution < image resolution, whole picture can’t be shown, lower in quality.

Question 7

What is pixel density?

Answer 7

The number of pixels per square cm

Question 8

What are vector graphics?

Answer 8

Images that use 2D points to describe lines and curves and their properties, grouped to form geometric shapes.

Question 9

What is sampling resolution?

Answer 9

Number of bits used to represent sound amplitude.

Question 10

What is the sampling rate?

Answer 10

Number of sound samples taken per second.

Question 11

What is the frame rate?

Answer 11

Number of video frames that make up a video per second.

Question 12

What is to be considered when storing images as pixels?

Answer 12

1. At least 8 bits per pixel to code for a coloured image (mixes of BRG)
2. True colours need 24 bits - more than a million colours
3. Number of bits used to represent a pixel is called colour depth.

Question 13

Describe vector graphic images (5 marks)

Answer 13

1. Made up of geometric shapes which require definitions
2. To alter design, all shapes must be changed.
3. do not require large file sizes as they are made of simple geometric shapes.
4. Because number of geometric shapes is limited, vector graphics are not very realistic.
5. File formats are usually .svg .cgm .odg

Question 14

Describe bit-map images (5 marks)

Answer 14

1. Made up of tiny pixels
2. Possible to alter each individual pixel
3. Large file size
4. Realistic image
5. File formats are .jpeg .bmp .png

Question 15

How is sound converted to binary?

Answer 15

1. Sound is an analogue value, needs to be digitized
2. An analogue digital converter (ADC) is used.
3. FilesSound waves are sampled at given time rates, using approximate values.

Question 16

Pros and cons of using a larger sampling resolution?

Answer 16

Pros:
1. Larger dynamic range
2. Better sound quality
3. Less sound distortion

Cons:
1. Larger file size
2. Takes longer to download
3. Requires greater processing power