M.1 - Digital Content

Data

• Symbols that represent people, events, things, and ideas. Can be a name, number, the colors in a photograph, or notes in a musical composition

Digital Data

• text, numbers, graphics,sound, and video that have been converted into discrete digits like 0s and 1s

Analog Data

• represented using an infinite scale of values

Data Representation

• form in which data is stored, processed, and transmitted

Digitization

• process of converting information (text, numbers, photographs, music) into digital data that can be manipulated by electronic devices

Binary Digits

• 0s and 1s used to represent digital data

Bit

• stands for binary digit

Digital File

• usually referred to as a ‘file’

• can be identified by its type or file extension

• named collection of data that exists on a storage medium (hard disk, CD, DVD, flash drive)

Circuit Boards

• carry data as pulses of current

CDs and DVDs

• store data as dark and light spots

Disk Drives

• store data as magnetized particles

Numeric Data

• consists of numbers that can be used in arithmetic operations

Character Data

• composed of letters, symbols, and numerals that are not used in calculations

• ‘text’

• name, address, hair color

American Standard Code for Information (ASCII)

• Type of code (along with Unicode) to represent character data. Pronounced “ASK ee”

• Seven bits for each character

• Only has the code for the American alphabet

Extended ASCII

•  superset of ASCII that uses eight bits for each character. Using eight bits instead of seven allows this to provide codes for 256 characters

Unicode

• Uses sixteen bits and provides codes for 65,000 characters. Pronounced “YOU ni code”

• Has alphabets of other languages; no Baybayin

Delimiter

• Special character used to separate commands or formatting characters

• Slashes (//) or angle brackets <>

Scanner

• digitizes a document

Optical Character Recognition (OCR)

• process that interprets individual characters during or after a scan

Bits

• All data stored and transmitted by digital devices is encoded as these

• ‘Binary Digit’ ; b

• Transmission speeds

Bytes

• Group of eight bits; B

• Storage space

Compression

• done to reduce file size and transmission time

Data Compression

• any technique that recodes the data in a file so that it contains fewer bits

Zipping

• other term for compression

Lossless Compression

• compression technique that compresses data and reconstitutes it into its original state

• uncompressed data stays exactly the same as the original data

Lossy Compression

• compression technique that throws away some of the original data during the compression process

• uncompressed data is not exactly the same as the original

Zip Tool

• software for compressing data

• ‘Compression Utility’

• accessed from the same screen used to manage files on laptops and desktops

Extracting or Unzipping

• process of reconstituting files from compression

Digital Audio

• Music, speech, and other sounds represented in binary format for use in digital devices

Sound

• produced by the vibration of matter

Sampling

• Taking multiple height measurements of a wave and converting them into binary; turning analog to digital

Sampling Rate

• number of times per second that a sound is measuring during the recording process

Analog-to-Digital Converter

• Samples sound waves many times per second to turn into binary digits

Digital-to-Analog Converter

• Transforms the digital bits into analog sound waves

Audio Compression

• Reduces the size of a sound file by removing bits that represent sounds that are beyond the frequencies of normal hearing

Ripping

• process of importing tracks from a CD or DVD to your computer’s hard disk

Digital Audio Extraction

• technical term for ripping

Download

• transfers an audio file from a server to a local device, playable even when not online

Live Stream

• sends media from a service to a local device where it is played but not stored

• ‘webcasting’

• need to be online, and it cannot be paused, stored, or rewound

On-Demand Stream

• sends media to a local device where it is temporarily stored or ‘buffered’ until there is enough data to begin playback

Audio Players

• Small standalone software or mobile app that offers tools for listening to digital audio and managing playlists

• Typically included with your computer’s OS

Audio Plugins

• Software that works in conjunction with your computer’s browser to manage and play audio from a Web page

Audio Software

• General-purpose software and apps for recording, playing, and modifying audio files

• iTunes, Windows Media Player, Audacity

Musical Instrument Digital Interface (MIDI)

• Not the recording of sound but instructions

• Specifies a standard way to store music data for synthesizers

• More compact than digital audio files, but cannot produce vocals

MIDI Messages

• instructions that specify the pitch of a note, point at which the note begins, volume, etc. represented by 1s and 0s

Speech Synthesis

• Process by which machines produce sound that resembles spoken words

Concatenative Speech Synthesis

• analyzes and tags various speech components and loads them into a database; how voice assistants work

Speech Recognition

• ability of a machine to understand spoken words

Speech Recognition Software

• analyzes the sounds and converts each word into groups of phonemes, then compares the groups to the words in a digital dictionary to find a match

Phonemes

• basic sound units

Bitmap Graphic

• ‘Raster Graphic’ or ‘Bitmap’

• Grid of tiny rectangular cells called pixels

• Each pixel is assigned a color which is stored as a binary number

Paint Software

• Graphics software that creates a bitmap graphic from scratch using provided tools

• Adobe Photoshop, Apple Photos, Microsoft Paint

Scanner

• Converts printed image into a bitmap graphic

• Divides an image into a fine grid of cells and assigns a digital value for the color of each cell and stored as a bitmap graphics file

Charge-Coupled Device (CCD)

• Small image sensor where light from a digital camera’s lens is focused

Photosites

• grid of tiny light-sensitive diodes in a CCD. correspond to pixels

Color and Resolution

• Key elements in bitmap data representation

Color depth

• number of colors available in a graphic

True Color

• images that use 24 bits for each pixel

Image Resolution

• dimensions of the grid that forms a bitmap graphic (which are resolution dependent)

Pixelation

• When an image develops an undesirable jagged appearance

Pixel Interpolation

• creates new pixels by averaging the colors of nearby pixels. This produces an image enlargement that appears similar to the original, avoiding pixelation

Image Compression

• Any technique that recodes the data in an image file so that it contains fewer bits

Run-Length Encoding (RLE)

• type of lossless compression that replaces a series of similarly colored pixels with a binary code that indicates the number of pixels and their colors

Photoshopping

• Everyday term for fixing up photos

Noise Reduction

• removing artifacts called noise

Noise

• artifacts such as spots, dust, and scratches, that may be produced when old photos are scanned

Image Enhancement

• Improves brightness, color correction, and sharpen focuses in a mediocre photo

Image Histogram

• can be used to adjust the brightness values for various ranges of dark, mid-range, or light pixels

Cloning

• correcting image distortion by employing algorithms that pull pixels from one area of an image and apply them to another area, used to remove small blemishes

Inpainting

• correcting image distortion by reconstructing lost, unwanted, or deteriorated areas in a photo using information from nearby pixels and taking into account the overall structure of the image

• scrubs out designated areas and replacing the missing pixels to fit with the rest of the image

Digital Compositing

• correcting image distortion by assembling several images into one using two tools: Clipping Paths and Alpha Blending

Clipping Path

• cuts an object out of an image and removes the background to make it transparent

Alpha Blending

• alters the pixel colors of the edges of the object so that the object merges with the background

Image Stitching

• Creates a panoramic image by combining two or more separate photographs that have overlapping images (photos are taken from a fixed location)

• also called photo stitching

Stereoscopic Imaging

• Graphical technique used to produce an illusion of spatial depth from a flat, two-dimensional image

Stereo Pair

• type of stereoscoping imaging where two photos produced by two cameras or a camera with two front-facing lens, mimicking dual images captured by human eyes

Stereogram

• type of stereoscopic imaging where a stereo pair is displayed side by side

Anaglyph

• type of stereoscopic imaging where a graphic composed of two images, one tinted red and the other blue, and are printed on top of each other to produce a stereoscopic effect

Vector

• Simple shapes consisting of lines and curves

• Doesn’t pixelate when enlarged; requires less storage; and easier to edit an object

Vector Graphic

• consists of a set of instructions for creating a picture

Digitizing Tablet

• produces vector graphics

Rasterization

• Converts vector graphic into a bitmap image

• Does this by superimposing a grid over a vector image and determining the color for each pixel

Wireframe

• formed by vectors and acts like a framework

3D Wireframe

• can be covered with surface texture and color to create a graphic of a 3D object

Rendering

• process of covering a wireframe with a surface color and texture

Ray Tracing

• technique for adding light and shadows to a 3D image

Pre-Rendering

• Process of rendering vector-based frames and packaging them into a digital video file

Game Engine

• Graphics software that allows developers to create interactive videogames and educational modules

Digital Video

• Type of motion graphics that uses bits to store color and brightness data for each video frame

• Similar to storing data for a series of bitmap images

Upconverting

• digital video term for interpolation

Progressive Scan

• the ‘p’ in 1080p

• scanning technique for digital video where each frame is drawn line by line from top-down

Interlaced Scan

• scanning technique for digital video that produced an image every other line

Aspect Ratio

• proportional relation between the width and height of an image or video frame

Letterbox

• black bars that fill in a playback video when an aspect ratio doesn’t fit within the screen

Bit Rate

• number of bits that are processed during a specific unit of time, usually during one second

Intraframe Compression

• video compression technique that compresses every single frame in a video

Interframe Compression

• video compression technique that only stores the pixels that change from one frame to the next (every other frame)

Compression Ratio

• indicates the ratio of compressed data to uncompressed data

• 35:1 - high compression rate, smaller size but lower quality

• 5:1 - low compression rate but higher quality

Codec (Compressor/Decompressor)

• Software that compresses a video stream when a video is stored, and decompresses when the video is played

• MPEG, DivX, H.264, Theora, Windows Media Video

Container Formats

• holds the comrpessed video stream and an audio stream