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1 Computing AS Level (JoshH) > Images and sound > Flashcards

Flashcards in Images and sound Deck (14)
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1

What is a Bitmap Image?

Comprised of many picture elements - AKA Pixels
A pixel is the smallest identifiable area of an image
Each Pixel is given a set binary value to represent a single colour

2

What is resolution?

This refers to the number of pixels wide x the number of pixels high
Does this mean the Size?
NO!!!!
Simply the number of pixels within the image. (PPI - Pixels Per Inch)
The higher the resolution the better quality the picture due to the amount of detail within it.

3

What is colour depth?

Each Pixel has a binary value assigned to it. The more bits assigned to each pixel the greater the number of colours that can be represented.
Colour Depth is NOT the number of colours that can be represented though!!!

4

If COLOUR DEPTH, RESOLUTION and QUALITY increase what else does?

FILE SIZE
TRANSMISSION TIME

5

What is Metadata?

Metadata is “Data about Data”

6

What are some examples of metadata?

Filename
date created
file type
Creator
Timestamp
Description
Resolution and colour depth

7

How do you calculate the MINIMUM file size?

To Calculate the MINIMUM file size of an image:
Resolution X Colour Depth
OR;
Width in Pixels X Height in Pixels X Colour Depth

8

Why can we only calculate the MINIMUM file size?

Metadata

9

What is digital? What is analogue?

All the processes carried out by a computer is digital.
However inputs and outputs can be analogue.

10

Sound - what is it?

Sound travels in Waves
The Amplitude of a wave dictates how Loud a sound is
The Frequency controls the Pitch

11

How do we convert analogue to digital?

To convert to digital you can use:
Analogue to Digital Converter - ADC
Stored as binary
To output must be converted back to analgoue
Digital to Analogue Converter - DAC

12

Why should we use a Higher Sampling Rate

By doubling the sample rate we can represent the original sound wave much more closely.
Increasing the sample rate will improve the quality of the sound file. Sample rate is measured in Hz (per second)

13

What is stereo?

Sound is often recorded for 2 channels. Left and right speakers can output very different sounds.

14

What is Nyquist Theorem?

Sample Rate must be greater than twice the highest frequency component of interest in the measured signal