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Processing different formats of data. Data formats. Text Pictures Numbers Sounds. Storing & processing text. Most computers use ASCII But only enough space to code 256 characters i.e. English characters plus a few commonly used international characters
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Data formats • Text • Pictures • Numbers • Sounds
Storing & processing text • Most computers use ASCII • But only enough space to code 256 characters i.e. English characters plus a few commonly used international characters • Increase in world wide communication has led to a new type of coding UNICODE • 16 bits per character therefore 65,536 characters
Bitmap Made up of pixels Vector based Stored by coordinates at start, end and middle points Storing and processing graphics
Bitmapped graphics • Pixels • Each bit in a stored graphic tells the computer whether a pixel should be on or off therefore the number of bits determines the number of colours • The number of pixels determines the resolution
Bitmapped graphics • 4 bits in a black & white graphic equals 16 shades of grey • 8 bits equals 256 shades • Therefore if each prime colour (red, green and blue) is eight bits then 16 million different shades can be achieved
Problems • Every detail of every pixel needs to be stored leading to large file sizes • If the image is changed it becomes distorted • If shown on a different screen resolution then quality is reduced • Difficult to edit .bmp .jpg .jpeg .pcx .tiff
Vector based graphics • Stored a geometric based data • Possible to scale and remain in proportion • Images can be altered without distortion .ai .cgm .wmf .cdr .mpp
Storing and processing numbers • Stored in binary code using ASCII • Not suitable if calculations required therefore a binary number system has been developed for whole numbers • Uses a predefined base i.e. 1:128 • 128 64 32 16 8 4 2 1 • 0 0 0 1 0 1 0 1 = 21 • What is the binary number code for 201?
Storing and processing numbers • For large numbers two consecutives bytes are used • For real numbers a different system is used known as floating point notation
Storing & processing sounds • Sound travels in analogue waves • Converted to a digital format using an analogue to digital converter (sound card) • Once digitalised it is known as a discrete signal and stored in binary code • The quality is determined by the sampling frequency