It only represents the English Alphabet plus some control characters. Unicode is designed to represent the worldwide interchange. It uses 16 bits and can represents 32,768 characters. For compatibility, the first 128 Unicode are the same as the one of the ASCII .
44 2.4.4. Colour representation Colours can represented using a sequence of bits. 256 colours – how many bits? • Hint for calculating • To figure out how many bits are needed to represent a range of values, figure out the smallest power of 2 that is equal to or bigger than the size of the range. • That is, find x for 2 x => 256 24-bit colour – how many possible colors can be represented? • Hints • 16 million possible colours (why 16 millions?)
45 24-bits -- the True colour • 24-bit color is often referred to as the true colour. • Any real-life shade, detected by the naked eye, will be among the 16 million possible colours.
46 Example: 2-bit per pixel 4=2 2 choices • 00 (off, off)=white • 01 (off, on)=light grey • 10 (on, off)=dark grey • 11 (on, on)=black 0 0 = (white) 1 0 = (dark grey) 1 0 = (light grey) 1 1 = (black)
47 Image representation An image can be divided into many tiny squares, called pixels. Each pixel has a particular colour. The quality of the picture depends on two factors: • the density of pixels. • The length of the word representing colours. The resolution of an image is the density of pixels. The higher the resolution the more information information the image contains.
Data Representation - Graphics Bit mapped Graphics For a graphic drawn in a painting package, the computer stores it as a two-dimensional array of pixels Each individual pixel ( pi(x ) cture el ement) in a graphic stored as a binary number The quality of the picture depends on two factors • The number of pixels that makes up an image is called the resolution . • The number of bits used to represent the colour of the pixels is called the bit depth . 48
Cont… The advantage of using bit mapped graphics is that you have more control over the graphic as you are able to go into detail and edit the graphic pixel by pixel. The disadvantage of using bit mapped graphics is that each picture or graphic takes up a lot of memory as the colour of each pixel has to be stored. Another disadvantage of using bit mapped graphics is that if you enlarge a bitmap image it becomes ‘blocky’ 49
You've reached the end of your free preview.
Want to read all 49 pages?
- Fall '19
- Binary numeral system, Decimal, mantissa