digital data

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REPRESENTING DATA

DATA AND INFORMATION

DATA

meaningless raw unorganised facts figures without context or meaning until processed

INFORMATION

data that has been processed and presented in a meaningful way therefore making useful

units of storage

bit=0 or 1

nibble=4 bits

byte=8 bits

kilobyte=1024 bytes

megabyte=1024 kilobytes

gigabyte=1024 megabytes

terabyte=1024 gigabytes

DATA TYPES

integer - stores positive or negative whole numbers

real - stores positive or negative decimal numbers

date/time - allows date or time be stored. can be set record date or time data in specific format

character - stroes single character can be letter,number,symbol. takes up 1 byte storage.

string - stores sequence or group characters tohgether as one value. contains combo of numbrers,letters,symbols.

boolean - stores true false only

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REPRESENTING IMAGES

PIXELS IN IMAGE REPRESENTATION

pixel is smallest unit digital image can be displayed edited on computer screen

resolution is number pixels used create digital image

higher resoloutionm mroe pixels

higher resoloution images require more storage space

colour depth is number bits used each pixel

more bits used better quality colour is. cause more colours able be encoded

RESOLUTION AFFECTING FILE SIZE

high resoloution images will fit large number pixels small space enabling very clear realistic images be stored viewed. this leads larger file sizes as every pixels colour code metadata will have be stored resulting in higher overall loading processing times computers and higher overall image file transfer times across communication links

DIFFERENCE BETWEEN VECTOR ANDBITMAP

BITMAP

store details every individual pixel in image

tend be large files takes up more memory stroage space than vector images

can be compressed which may lead loss quality

large bitmap images can take long time open load on page

pixillation occurs when image enlarged

bitmap images less precise than vector images where quality image depends on resolution

bitmap images use less processing power than vector images

VECTOR

store information about components or objects that make image

tend have much smaller file size than equivlant bitmap images vectors takes up less memory or storage space

can be more easily resized stretched than bitmap images without losing clarity

due to vectors smaller file size vectors tend load quicker than bitmaps

vectors can be enlarged or edited without losing image quality pixillation does not occur

vectors more precise than bitmaps where quality of image noyt depend on resolution

vectors use more processing power than bitmaps

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REPRESENTING SOUND

sample rate is number audio sound samples captured every second to represent sounds digitally is measured in hertz

bit depth is number bits used store each sound sample. higher quality higher bit depth

bit rate is quantity data measured bits that processed in given amount time. usually kilobits per second

adc is anolouge to digital converter

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DATA PORTABILITY

data portability is ability transfer data one computer another or one software application another without having re-enter data

IMAGE FILE FORMATS

jpeg,tiff,png,pict,gif

AUDIO AND VIDEO FILE FORMATS

mp3,mp4,midi,mpeg,avi,,wma,wav

OTHER FILE FORMATS

txt,csv,rtf,pdf

LOSSY AND LOSLESS COMPRESSION

LOSLESS

maintains quality file meaning no data lost

LOSSY

reduces file size by removing some data example reducing number colours used large resolution image.