3.4 - Representing Images

Question 1

What is the difference between digital and analogue data?

Answer 1

Digital - data in the format of 1’s and 0’s
Analogue - measured to any degree of accuracy

Question 2

What happens when a digital camera captures an images?

Answer 2

Breaks it up into a grid of pixels
A light sensor measures the intensity of colour in each pixel
Each pixel is converted into binary code using an analogue to digital converter

Question 3

What are common types of bitmap files?

Answer 3

BMP
JPG
GIF
PNG
TIF

Question 4

What is the bitmap resolution? Formula

Answer 4

Number of pixels used to make up a bitmap image
Width x height

Question 5

What happens to pixels when an image size is increased or decreased?

Answer 5

The size of each pixels grows or shrinks to maintain the required resolution
This is why the quality changes

Question 6

How do we know the number of colour combinations from the bits per pixel?

Answer 6

2^number of bits

Question 7

What does the colour depth affect?

Answer 7

Number of colours displayed

Question 8

How do we calculate file size?

Answer 8

Resolution (w x h) x colour depth

Question 9

What is metadata? Examples?

Answer 9

Data about data stored in the same file as the image data
E.g. date created, width, height, colour depth

Question 10

What are vector images?

Answer 10

Made up of geometric shapes instead of pixels
Properties of each shape are stored and retrieved to be able to redraw

Question 11

What properties of vectors are stored?

Answer 11

• shape type
• position on the screen
• fill colour
• line colour
• length, width, radius

Question 12

What happens when you resize a vector graphic?

Answer 12

They’re mathematically redrawn so quality stays the same
Still typically have a smaller file size

Question 13

What file types are vector graphics used in?

Answer 13

SWF
EPS
SVG