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Spring Semester > Quiz 1 IT 105 9 (chap 4) > Flashcards

Quiz 1 IT 105 9 (chap 4) Flashcards

1
Q

What are data formats?

A

-computers/computer-based devices process/store data in binary forms

Human comm: language images and sound.

-data formats: specifications for converting data into computer-usable form
define the different ways human data may be represented, stored, and processed by a computer

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2
Q

What are sources of data ?

A
  • Binary input: begins as discrete input, ex: 1+2=3, keyboard generates a binary number code for each key
    -Analog: continuous data such as sound or images, requires hardware to convert data into binary numbers ex: 1+2=3 —-> input device ——> computer
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3
Q

What are common data representations?

A

-Alphanumeric: Unicode, ASCII, EBCDIC
- Image(bitmapped): JPEG, GIF, TIFF, PNG
- Image(object): PostScript, SVG
- Outline graphics and fonts: PostScript, TrueType
-Sound: MP3, WAV, MIDI, WMA
- Page description: PDF
Video: MPEG-2, MPEG-4, WMV

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4
Q

What are numeric data types and what are they used for?

A

-used for math manipulation
-types: integer(whole number), real (contains decimal point)

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5
Q

What are alphanumeric data types ?

A

Characters: b T ñ Ω
Number digits: 2 7 9
Punctuation marks: ! ¿ ? ;
Special-purpose characters: $ @ &

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6
Q

Differences between numeric characters and numbers

A

-both entered as ordinary characters
- computer converts into numbers for calculation ex: variables declared as numbers by the programmer
- Treated as characters if processed as text
Ex: phone number, zip codes,

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7
Q

What are alphanumeric codes?

A
  • arbitrary choice of bits to represent characters
    -consistency (input and output device must recognize the same code)
    Value
  • binary number representing character corresponds to placement in the alphabet
  • facilitates sorting and searching
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8
Q

What standards are used for representing characters?

A

Unicode
- Developed for worldwide use
-UTF( unicode transformation format)
- UTF-8 ( the most widely used coding scheme on the web)
- UTF- 16 (used by windows and java)

ASCII
- developed by ANSI, american national standards institute

EBCDIC
- IBM mainfram(legacy)

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9
Q

What is ASCII?

A

-created in 1963
- 7 bit code, 128 characters
Represents
- latin alphabet and arabic numerals
-standard punctuation characters
-small set of accents and other european special characters

ISO Latin I
- extended version of ASCII
- 8 bit code, 256 characters
- incorporated into unicode as the first 256 characters for forward/ backward compatibility

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10
Q

What is EBCDIC?

A
  • Extended Binary Coded Decimal Interchange Code developed by IBM in 1963/1964
  • restricted to mainly IBM or IBM mainframes
  • conversion software to/from ASCII available
  • common in archival data
  • character codes differ from ASCII
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11
Q

What is UNICODE?

A
  • created in 1991-1992
  • most common 16 bit form /represents 65,536 characters
  • ASCII Latin -I subset of Unicode(values 0-225 in unicode table)
  • Multilingual defines code for: almost every character based alphabet, large set of ideographs for chinese+japanese+korean, composite characters for vowels and syllabic clusters required by some languages
  • Allows software modifications for local languages
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12
Q

What is a collating sequence?

A

-alphabetic sorting if software handles mixed upper- and lowercase codes
- In ASCII , numbers collate first, in EBCDIC last
- ASCII collating sequence for string of characters

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13
Q

What are the two categories of codes?

A

-Printing characters: produced on the screen or printer

  • Control characters: control position of output on screen or printer
    VT= vertical tab. LF= line feed
  • Cause action to occur
    BEL= bell rings
    DEL: delete current character
  • Communicate status between computer and I/O device
    ESC: extends character set by changing the meaning of the specific sequence of subsequent contiguous characters
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14
Q

What is visual data and what are the two approaches ?

A
  • Videos, photographs, biometric images, figures, icons, drawings, charts, and graphs

Two approaches
- Bitmap or raster images of photos and paintings with continuous variation
- Object or vector images composed of graphical objects such as geometrically defined lines and curves

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15
Q

Visual Data Differences

A
  • Quality of the image
  • Storage space required
    -Time to transmit
  • Ease of modification
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16
Q

What are bitmap images used for and what are their input devices?

A
  • used for realistic images with continuous variations in shading, color, shape and texture
  • preferred when image contains large amount of detail and processing requirements are fairly simple

Input devices
- scanners
- digital camera and video capture devices
-graphical input devices like mice and pens
-managed by photo editing software or paint software

17
Q

What is the relation between bitmap images and a pixel?

A
  • Each individual pixel for picture element, in a graphic is stored as a binary number

-Pixel: a small area with an associated coordinate location

look at example in slideshow

18
Q

What is the bitmap display?

A

Monochrome
- black or white
- 1 bit per pixel

Gray scale
- black, white, or 254 shades of gray
- 1byte per pixel

Color graphics
- 16 colors, 4 bits
- 256 colors, 8 bits
- 16.7 million colors, 24 bit true color
8 bits on each for red, green, and blue shades

19
Q

Storing Bitmap Images?

A

Frequently large files
-Example: 1080 rows of 1920 pixels, with one byte for each of 3 colors per pixel—-> approx. 48 MB

File size is affected by
- resolution: the number of pixels per inch(amount of detail affecting clarity and sharpness of an image)

-levels: number of bits for displaying shades of gray or multiple colors
(palette: color translation table that uses a code for each pixel rather than actual color value)
- Data compression

20
Q

What is JPEG?

A

-Joint Photographers Expert Group
- Approx. 16.7 million colors
- Suitable for highly detailed photographs and paintings
- employs lossy compression algorithm that(discards data to decrease file size up to 90% and reduce transmission speed, may reduce image resolution, reduce number of the colors, and distort sharp lines)

21
Q

What is a GIF?

A
  • Graphics Interchange Format
  • First developed by CompuServe in 1987
    -Limited to 256 colors
  • Preferred for line drawings, clip art and pictures with large blocks of solid color
    -LZW(Lempel-Zif-Welch) compreesion algorithm(lossless compression)
  • GIF89a enabled animated images
    allows images to be displayed sequentially at fixed time intervals
22
Q

What is PNG?

A

-Portable Network Graphics

Deflate compression algorithm
- lossless compression vs. JPEG’s lossy compression
- more efficient compression algorithm than GIF
- 16.7 million colors and transparency vs. GIF’s 256 colors

Up to 64-bit RGBA color
-alpha channel indicates the level of transparency

23
Q

What are object images?

A

-created by drawing software or drawing features of microsoft office such as charts, shapes, SmartArt
- composed of lines and shapes in various colors
- computer translates geometric formulas to create the graphic
- storage space depends on image complexity(number of instructions to create lines, shapes, fill patterns)
- movie series such as shrek and toy story use object images

24
Q

What are object images based on?

A

-based on math formulas (easy to move, scale, rotate without losing shape or identity as bitmap images may)

  • require less storage space than bitmap images
  • cannot represent photos or paintings
  • cannot be displayed or printed directly
    (must be converted to bitmap since output devices with the exception of plotters, are bitmap
25
Q

What is a page description language?

A
  • describe layout of objects on a displayed or printed page
    -objects may include text, object images, bitmap images, multimedia objects, and other data formats

Ex:PDF, Postscript , HTML

26
Q

What is PostScript?

A

Page description language
-list of procedures and statements that describe each of the objects to be printed on a page
- stored in a text file
- interpreter program in the computer or output device reads PostScript to generate the image

Scalable font support
- font outline objects specified like other objects

27
Q

Bitmap vs Object Images

A

Bitmap
- pixel map
- photographic quality
- paint software
- larger storage requirements
- enlarging images produces jagged edges
-resolution of output limited by resolution of image

Object (vector)
- geometrically defined shapes
- complex drawings
- drawing softwares
-higher computational requirements
- objects scale smoothly
- resolution of output limited by output device

28
Q

What are video images?

A
  • Require a tremendous amount of data
    -video camera producing full screen 1024x768 pixel, 24 -bit true color image at 30 frames per second –> 70.8 MB of data/sec

-1 minute film clip. 4.25 GB storage

Options for reducing file size
- compression
- decrease size of image
- reduce frame rate
- limit number of colors

Video format determined by codec, encoder/ decoder

29
Q

What are video images and what is a container and streaming video?

A

Best known codec standards
-MPEG-2, MPEG-4, and H.264
data may be compressed to 10-60MB or less of data per minute

Container
- serves as superstructure to encode, decode, hold and stream the video
Ex: MP4, Google’s WebM

Streaming video
- video displayed in real time as it is downloaded from the web server

30
Q

What is audio data?

A

-transmission and processing requirements are less demanding than those for video
- Analog Waveform
(digital representation of sound)

-A to D convertor
converts analog sounds to digital values

-MIDI
Musical Instrument Digital Interface
contains instructions to recreate or synthesize sounds

31
Q

What is sampling rate?

A

-number of times per second that sound is measured during the recording process
1000 samples per second= 1 KHz (kilohertz)
Ex: Audio CD sampling rate: 44.1 KHz

-Amplitude , height of each sample, saved as

8 bit number for radio quality recordings

16 bit number for high fidelity recordings

2x16 bits for stereo

32
Q

What are the two diff audio formats?

A

MP3
- predominant digital audio data format
- derived from the MPEG-2 standard
- created by the ISO moving pictures experts group
-uses psychoacoustic lossy compression techniques to reduce storage requirements . Most people cannot hear the highest frequencies

WAV
- a microsoft multimedia app
-general purpose audio format
-uncompressed 8 or 16 bit sound samples

look at power point for graph

33
Q

What is Data Compression?

A

Compression
Recoding data so that it requires fewer bytes of storage space.

Compression ratio
The amount file size is reduced

Lossless
Inverse algorithm restores data to exact original form
Examples: GIF, PCX, TIFF, ZIP

Lossy
Trades off data degradation for reduced file size, often 1/10 the original size, and increased download speed. Common in multimedia
Examples: JPEG, MP3

H.264 uses both lossless and lossy forms for ratios of 1000:1

34
Q

What is internal computer data format?

A

All data is stored as binary numbers

Interpreted based on

-Operations computer can perform

-Data types supported by programming language used to create application

35
Q

What are the 5 simple data types?

A

Integer
Positive or negative whole numbers or zero

Real
Numbers with a decimal point
Numbers whose magnitude, large or small, exceeds computer’s capability to store as an integer

Char
Variable or constant that holds alphanumeric character

Boolean
2-valued variables or constants with values of true or false

Enumerated
User-defined data types with possible values listed in definition
enum DayOfWeek {Mon, Tues, Wed, Thurs, Fri, Sat, Sun}

Spring Semester (4 decks)

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