BINARY AND DATA REPRESENTATION: IMAGES

BINARY AND DATA REPRESENTATION: IMAGES

HOW WE USE BINARY TO STORE IMAGE DATA.

How can a bitmap image be represented in binary?

• Bitmap images are made up of individual pixels (picture elements).

• The colour of each pixel is represented as a binary number.

• The image is therefore stored as a series of binary numbers.

• The program loading the image needs to know things like the image resolution and colour depth before it can convert the binary back into an image and display it.

Colour depth?

• Colour depth describes how many memory bits are used to store a pixel's colour.

• If 1 bit is used: 2 colours can be stored (0 = the 1st and 1 = the 2nd).

• Monochrome images used by early computer monitors.

• LOW COLOUR DEPTH = LOW MEMORY REQUIREMENT

Depth & Memory

• If only 1 bit is used per pixel then 2 colours can be stored.

• If 2 bits are used per pixel then 4 colours can be stored.

  00 = colour 1

  01 = colour 2

  10 = colour 3

  11 = colour 4

• The memory needed to store an image with 2 bit colour depth is twice that of the same 1 bit image.

Available Colours

• Up to 8 bit colour depth it is possible to have a code for each colour. This is called direct colour

• Beyond 8 bits it is easier to define a colour by how much RED, GREEN and BLUE (RGB) it is made up of.

• This is called true colour. Modern displays use 24 bit colour depth. 8 bits are used for the amount of Red, Green and Blue. 

Multiple Choice

What is a Pixel

• A tiny circular dot of colour

• A tiny square dot of colour

• A tiny triangle dot of colour

• A tiny piece of sound data at a given frequency

Multiple Choice

The word PiXEL is short for:

• Piece of Colour

• Picture Colour

• Picture Element

• Precise Element

Multiple Choice

An image is represented by a GRID of pixels, each with a value. We call this grid a...

• VECTOR

• BITMAP

• TIFF

• MP3

Multiple Choice

Each PIXEL can be allocated a binary number value. This value tells you:

• The Size of the Pixel

• The Colour of the Pixel

• The Lumocity (or brightness) of the pixel

• The Position of the pixel in the picture

Multiple Choice

The process of turning a physical image into a digital bitmap is called

• Digitisation

• Chromatography

• Discography

• Pixelation

Multiple Choice

An image stored as a grid of pixels is called a BITMAP image

• True

• False

Multiple Choice

Which of these represents a Binary Bit

• 1100 0101

• 2 or 3

• 1024

• 1 or 2

Multiple Choice

How many BITS make a BYTE

• 1

• 4

• 8

• 16

Multiple Choice

How many BITS in a NIBBLE

• 1

• 2

• 4

• 8

Multiple Choice

A 1 BIT image can ONLY represent 2 colours (e.g. Black and White). How can we represent more colourful images

• Type in the colour that we want

• Use a faster colour processor

• Increase the number of bits representing each pixel (colour depth)

• Add more colours to the digital colour pallet

Extra Tasks

In the FILES section, there are a range of videos explaining and excercises to help you consolidate your BINARY understanding.

Enjoy trying the tasks and accessing this content indipendantly.