Module 2 - Unit 1: Digital Content
Audio Compression
Audio compression reduces the size of a sound file by removing bits that represent extraneous noise and sounds that are beyond the frequencies of normal hearing.
VOB
VOB (Video Object) .vob Standalone DVD player, PC, Mac, Linux Industry-standard format for standalone DVD players
Frame
Digital video displays bitmap images in rapid succession. Each bitmap image is referred to as a frame.
Megabyte
Megabyte (MB or MByte) is typically used when referring to the size of files containing photos and videos.
SVG
SVG is the most popular format for Web-based vector graphics.
3-D graphics
3-D graphics are based on vectors stored as a set of instructions describing the coordinates for lines and shapes in a three-dimensional space.
File
A digital file, usually referred to simply as a file, is a named collection of data that exists on a storage medium, such as a hard disk, CD, DVD, or flash drive. A file can contain data for a term paper, Web page, email message, or music video.
Byte
A group of eight bits is called a byte and is usually abbreviated as an uppercase B. whereas storage space is expressed in bytes.
Resolution Dependent
Bitmap graphics are resolution dependent because each element is a discrete pixel.
Cloning
Cloning employs algorithms that pull pixels from one area of an image and then apply them to another area.
Pixel
Each cell is a picture element, commonly called a pixel. Each pixel is assigned a color, which is stored as a binary number.
Intraframe Compression
Earlier in the unit, you found out how still images are compressed using lossy and lossless compression. This type of intraframe compression can be applied to each frame of a video
Ray Tracing
For added realism, the rendering process can take into account the way that light shines on surfaces and creates shadows. The technique for adding light and shadows to a 3-D image is called ray tracing.
Kilobit
For digital devices where base 2 is the norm, a kilo is precisely 1,024, or 2^(10). Kilobit (Kb or Kbit) can be used for slow data rates, such as a 56 Kbps (kilobits per second) dial-up connection.
Delimiter
Formatting codes can be added to documents directly within the text stream, using some sort of delimiter to signal the beginning and end of the formatting command. A delimiter is a special character used to separate commands or formatting characters from the rest of the text in a file. Slashes // and angle brackets < > are commonly used delimiters.
Image Compression
Image compression refers to any technique that recodes the data in an image file so that it contains fewer bits. Many bitmap file formats automatically apply compression to an image when it is saved.
True Color
Images that use 24 bits for each pixel have a color depth of 24. 24-bit color depth is also called True Color.
MOV
MOV (QuickTime Movie) .mov PC, Mac, UNIX, Linux A legacy format for downloaded and streaming Web videos
Sampling Rate
Sampling rate refers to the number of times per second that a sound is measured during the recording process. It is expressed in hertz (Hz). One thousand samples per second is expressed as 1,000 Hz or 1 kHz (kilohertz). Higher sampling rates increase the quality of the sound recording but require more storage space than lower sampling rates.
TIFF
TIFF (Tagged Image File Format), or TIF, is a flexible and platform-independent graphics file format supported by most photoediting software packages. Scanners and digital cameras commonly store bitmaps in TIFF format because it supports True Color and can be easily converted into other graphics file formats. Desktop publishing and any projects that require highresolution graphics; not supported by browsers
Text-To-Speech Software
Text-to-speech software analyzes the words in a section of text, finds corresponding phonemes, and combines them into sentences for output.
Digital Camera
The lens of a film camera captures the light from an image onto a light-sensitive roll of film, which is developed to produce a photographic print. In a digital camera, the lens focuses light from the image onto a small image sensor called a CCD (charge-coupled device). A CCD contains a grid of tiny light-sensitive diodes called photosites.
Frame Rate
The number of frames that are displayed per second is the frame rate (fps). Higher frame rates produce video that more smoothly simulates real motion. The standard frame rate for motion pictures was set in the 1930s before digital formats. Digital video can produce higher frame rates
Digitization
The process of converting information, such as text, numbers, photos, or music, into digital data that can be manipulated by electronic devices is called digitization.
UTF-8
UTF-8 is a variable-length coding scheme that uses seven bits for common ASCII characters, but uses 16-bit Unicode as necessary.
Compression Ratio
Video compression can be expressed as a compression ratio, which indicates the ratio of compressed data to noncompressed data. A video file with a high compression ratio, such as 35:1, has more compression, a smaller file size, and lower image quality than a file with a smaller compression ratio, such as 5:1.
Container Formats
Video files are stored in container formats that hold the compressed video stream and an audio stream. Some popular video container formats: AVI, MOV, MPEG, WebM, ASF, VOB, and Ogg Theora.
WAV
WAV .wav Good sound quality; supported in browsers without a plugin Audio data is stored in raw, noncompressed format, so files are very large
WebM
WebM .webm PC, Mac, UNIX, Linux Royalty-free, high-quality open format for use with HTML5
Letterbox
When 4:3 videos are displayed in a widescreen player, they are bordered by the black bars of a letterbox
Color Depth
With eight bits used to represent each color value, one pixel requires 24 bits. Because each R, G, and B can have 256 values, the number of possible colors is 16.7 million (256 × 256 × 256). The number of colors available in a graphic is referred to as color depth.
Analog-To-Digital Converter
when you record a voice message on your phone, the sound waves of your voice are sampled many times per second by an analog-to-digital converter (ADC). Those samples are converted into binary 1s and 0s, which are stored in an audio file. When the audio file is played, a digital-to-analog converter (DAC) transforms the digital bits into analog sound waves and outputs them through the speakers.
CCD
(charge-coupled device). A CCD contains a grid of tiny light-sensitive diodes called photosites.
Photosites
A CCD contains a grid of tiny light-sensitive diodes called photosites. The number of photosites depends on the size of the CCD. A one-half-inch square CCD can contain more than 500,000 photosites. Each photosite detects the brightness and color for its tiny piece of the image A CCD's photosites correspond to pixels. The more pixels used to capture an image, the higher its resolution, and the better the resulting picture. Cameras with larger CCDs produce higher quality images. Some cameras contain multiple CCDs, which enhance the color quality of a camera's output.
Phoneme
A basic sound unit, such as "reh" or "gay," is called a phoneme. Most speech synthesizers string together phonemes to form words. Phonemes are usually derived from recordings of human voices reading specially prepared passages of text.
Bit
A bit is a 0 or 1 used in the digital representation of data. Even though the word bit is an abbreviation for binary digit, it can be further abbreviated, usually as a lowercase b. Transmission speeds are expressed in bits,
Bitmap Graphic
A bitmap graphic, also called a raster graphic or simply a bitmap, is composed of a grid of tiny rectangular cells. Each cell is a picture element, commonly called a pixel. Each pixel is assigned a color, which is stored as a binary number.
Clipping Path
A clipping path essentially cuts an object out of an image and knocks out the background to make it transparent. This object can then be superimposed on a background.
CODEC
A codec (compressor/decompressor) is the software that compresses a video stream when a video is stored, and decompresses the file when the video is played. Each codec uses a unique algorithm to shrink the size of a video file, so they are not interchangeable. A file compressed using one codec cannot be extracted and played using a different codec. When creating videos, you should use one of the codecs included in popular video players. Popular codecs include MPEG, VP8, DivX, H.264, Theora, and Windows Media Video.
Digitizing Tablet
A digitizing tablet (sometimes called a 2-D digitizer) is a device that provides a flat surface for a paper-based drawing and a pen or mouse-like puck that you can use to click the endpoints of each line on the drawing. The endpoints are converted into vectors and stored.
Download
A download transfers an audio or video file from a server to your local device. You can play back the file even when your device is not online. The file can be played with any compatible software or player.
File Format
A file name extension, such as .mp3, can be appended to the end of the file name after a period. This extension indicates the file format; the type of data in the file and the way it is encoded.
File Name Extension
A file name extension, such as .mp3, can be appended to the end of the file name after a period. This extension indicates the file format; the type of data in the file and the way it is encoded.
Live Stream
A live stream sends media from a server to your local device, where it is played, but not stored. This method is also known as Webcasting. You have to be online while listening or watching. The content stream cannot be paused, stored, or rewound.
Binary
A traditional light switch is also binary because there are only two possible states.
Vector Graphic
A vector graphic consists of a set of instructions for creating a picture. Instead of storing the color value for each pixel, a vector graphics file contains instructions that a computer uses to create the shape, size, position, and color for each object in an image. Vector graphics include standard shapes such as circles and rectangles, so they don't have to be built from scratch. When you change the size of a vector graphic, the objects change proportionally and maintain their smooth edges. The storage space required for a vector graphic reflects the complexity of the image. Many 2-D vector images have a flat, cartoon-like appearance instead of the realistic appearance you expect from a photograph. A vector graphic is like a collage of objects that can be layered over each other, but moved and edited independently. Vector graphics are suitable for most line art, logos, simple illustrations, infographic elements, and diagrams that might be displayed and printed at various sizes. Vector graphics files have file extensions such as .wmf, .ai, .dxf, .eps, .swf, and .svg.
AAC
AAC (Advanced Audio Coding) .aac, .m4p, or .mp4 Very good sound quality based on MPEG-4; compressed format; used for iTunes music. Files can be copy protected so that use is limited to approved devices.
ASCII
ASCII (American Standard Code for Information Interchange, pronounced "ASK ee") requires seven bits for each character. For example, the ASCII code for an uppercase A is 1000001. ASCII provides codes for 128 characters, including uppercase letters, lowercase letters, punctuation symbols, and numerals.
ASF
ASF (Advanced Systems Format) .asf, .wmv PC Container format for Microsoft's Windows Media Video (WMV); supports downloads and streaming
AVI
AVI (Audio Video Interleave) .avi PC A format sometimes used for storing digital clips from video cameras; used for legacy video on the PC platform
Alpha Blending
Alpha blending alters the pixel colors where the edges of the object and the background meet, so that the object appears to merge with the background
Audio Player
An audio player is a small standalone software application or mobile app that offers tools for listening to digital audio and managing playlists, but may not provide tools for making your own recordings.
Audio Plugin
An audio plugin is software that works in conjunction with your computer's browser to manage and play audio that you are accessing from a Web page. Each audio plugin tends to work with only one audio format, so multiple plugins are necessary when you have audio files in several formats.
Interlace Scan
An interlaced scan is a contrasting scanning technique that produces an image by drawing every other line, then going back and filling in the in-between lines. Digital video for computers typically uses progressive scanning, whereas digital television uses interlaced scanning
On-Demand Stream
An on-demand stream sends the media to your local device, where it is stored temporarily, or "buffered," until there is enough data to begin playback. You can fast-forward to any point in the stream without waiting for the file to download.
Analog Data
Analog data is represented using an infinite scale of values.
VIDEO CAPTURE
Analog footage from Super 8 home movies, VHS videotapes, and other legacy sources can be digitized using video capture equipment. During digitization, each frame of the original footage is isolated and divided into a gridwork of pixels. Each pixel is assigned a color number that is represented by a string of bits. This raw data can then be stored in any popular digital video format
Pixelation
As you stretch the surface, the grid maintains the same number of horizontal and vertical cells, but each cell becomes larger, the grid becomes more visible, and the image develops an undesirable jagged appearance referred to as pixelation. Simply stretching a bitmap to enlarge it doesn't produce highquality results
Aspect Ratio
Aspect ratio is the proportional relation between the width and height of an image or video frame. Today's widescreen devices, such as laptops and smartphones, are designed for the 16:9 aspect ratio, which is recommended for most modern videos, including those uploaded to YouTube. As long as the proportion of horizontal and vertical pixels remains the same, the aspect ratio is consistent.
BMP
BMP, pronounced "bee-em-pee" or "bump," is the native bitmap graphics file format of the Microsoft Windows environment. Microsoft Paint, included as part of Microsoft Windows, creates BMP graphics files. The BMP format supports True Color and can be used for a wide variety of graphics applications, such as photographs, illustrations, and graphs. BMP files are often too large for email attachments. BMP graphics are not supported by most browsers, so they are not used on the Web. Graphical elements, such as buttons and other controls for graphical user interfaces
Image Histogram
Beyond one-click enhancement tools, image editors provide an image histogram that can be used to adjust the brightness values for various ranges of dark, mid-range, or light pixels
Bit Rate
Bit rate is the number of bits that are processed during a specific unit of time, usually during one second. Bit rate can be expressed as bits per second (b/sec or bps), kilobits per second (Kbit/s or Kbps), and so on. Bit rate becomes more important than file size for streaming video because it indicates how many bits must be transferred per second for the video to play smoothly without pausing to refill the buffer.
Character Data
Character data is composed of letters, symbols, and numerals that are not used in calculations.
Color Model
Color values can be specified in decimal (base 10), hexadecimal (base 16), or binary (base 2). Even artists need to know their way around number systems! Decimal notation tends to be used within graphics software, and hexadecimal (hex) notation is common on the Web. Whichever notation is used, however, color data is ultimately represented as binary digits when it is stored and transmitted. In decimal, a pixel color is specified with values such as Red 238, Green 130, and Blue 238. In hexadecimal, each pair of digits refers to a color value. For example, the hexadecimal number for violet is #EE82EE. In binary, eight bits are used to represent the red value, another eight bits are used for the green value, and eight more bits are used for blue.
Data
Data refers to the symbols that represent people, events, things, and ideas. Data can be a name, a number, the colors in a photograph, or the notes in a musical composition.
Data Representation
Data representation refers to the form in which data is stored, processed, and transmitted. Today, digital data representation has replaced the analog data previously used for storing and transmitting photos, videos, and text.
Digital Audio
Digital audio is music, speech, and other sounds represented in binary format for use in digital devices.
Digital Compositing
Digital compositing, which assembles several images into one. Compositing is achieved using two tools: clipping paths and alpha blending.
Digital Data
Digital data is text, numbers, graphics, sound, and video that have been converted into discrete digits such as 0s and 1s.
Digital Cinematography
Digital video technology is also used in the motion picture industry, where digital cinematography captures moving images as bits, rather than on film. Digital video is a core technology for digital television, videoconferencing systems, and video messaging. Real-time video even allows deaf people to sign over cell phones.
Digital Video
Digital video uses bits to store color and brightness data for each video frame. The process is similar to storing the data for a series of bitmap images in which the color for each pixel is represented by a binary number.
Transcoding
Digital videos can be converted from one file format to another through a process called transcoding. If you want to move a video into a different file format, you can check to see if your video editing software offers a conversion, export, or transcoding option. If not, you can find transcoding software on the Web. Transcoding can cause loss of quality, so avoid transcoding an already transcoded video file.
Extended ASCII
Extended ASCII is a superset of ASCII that uses eight bits for each character. For example, Extended ASCII represents the uppercase letter A as 01000001. Using eight bits instead of seven bits allows Extended ASCII to provide codes for 256 characters. The additional Extended ASCII characters include boxes and other graphical symbols.
GIF
GIF (Graphics Interchange Format), pronounced "gif" or "jiff," was specifically designed to create images that can be displayed on multiple platforms, such as PCs and Macs. GIF graphics are limited to 256 colors, but the format supports simple animations. Once a popular format for Web pages, GIF is being replaced by JPEG and PNG. Web graphics and simple animations
Gigabit
Giga is derived from 2^(30). Gigabit (Gb or Gbit) is used for really fast network speeds.
Gigabyte
Gigabyte (GB or GByte) is commonly used to refer to storage capacity.
Interframe Compression
Interframe compression stores only the pixels that change color from one frame to the next. More sophisticated interframe compression uses motion compensation to track along with the camera, essentially following the camera movement to gain additional similarities between frames.
JPEG
JPEG (pronounced "JAY-peg"), which stands for Joint Photographic Experts Group, is a graphics format with built-in compression that stores True Color bitmap data very efficiently in a small file. The JPEG format is popular for Web graphics and for photos attached to email messages. When creating a JPEG or converting an image to JPEG format, you can control the level of compression and the resulting file size. The compression process eliminates some image data, however, so highly compressed files suffer some quality deterioration. General use, such as desktop publishing or Web pages, where flexibility in file size is important. JPEG files are compressed using lossy compression, so some quality is lost when the file is saved. When saving an image as a JPEG, you may be able to select a compression level. Take care with lossy compression to ensure that your image is not further compressed every time you save it
Kilobyte
Kilobyte (KB or Kbyte) is often used when referring to the size of small computer files.
Lossless Compression
Lossless compression provides a way to compress data and reconstitute it into its original state. Character data and numeric data in documents and spreadsheets are compressed using lossless techniques so that the uncompressed data is exactly the same as the original data.
Run-Length Encoding
Lossless image compression. As a simple example, consider a type of lossless compression called runlength encoding. Run-length encoding (RLE) replaces a series of similarly colored pixels with a binary code that indicates the number of pixels and their colors.
Lossy Compression
Lossy compression throws away some of the original data during the compression process. When the data is uncompressed, it is not exactly the same as the original. This type of compression is typically used for music, images, and videos because the human ear or eye cannot discern minor changes.
MP3
MP3 (also called MPEG-1 Layer 3) .mp3 Good sound quality even though the file is compressed; can be streamed over the Web Might require a standalone player or browser plugin
MPEG
MPEG (Moving Picture Experts Group) .mpg, .mp4, .mpeg PC, Mac, UNIX, Linux Versions include MPEG-1, MPEG-2, and MPEG-4; used for downloaded and streaming Web video
Megabit
Mega is derived from 2^(20). Megabit (Mb or Mbit) is used for faster data rates, such as a 25 Mbps (megabits per second) Internet connection.
UPCONVERTING
Modern projection devices and video playback software do an admirable job of upconverting, which is the digital video term for interpolation. As a rule, however, videos look sharpest when they are displayed at a resolution that is the same as the frame size.
Pixel Interpolation
Most graphics software uses a process called pixel interpolation to create new pixels by averaging the colors of nearby pixels. For some images, pixel interpolation produces an enlargement that appears very similar to the original. Other images—particularly those with strong curved or diagonal lines—may appear pixelated.
CDDA Synthesized Sound
Music is stored on CDs in a digital format called CDDA. The format offers high fidelity; but one minute of CDDA music requires in excess of 10 MB of storage space. During the ripping process, music in CDDA format is converted into a compressed format such as MP3, AAC, or WMA to reduce file size.
Numeric Data
Numeric data consists of numbers that can be used in arithmetic operations. Digital devices represent numeric data using the binary number system, also called base 2.
OCR
OCR (optical character recognition) is a process that interprets individual characters during or after a scan. It assigns the appropriate ASCII code to each letter and outputs the document in a format that can be edited using word processing software. OCR software is available for most scanners and is handy when you have a printed copy of a document that you want to modify, but would prefer not to retype.
Ogg Theora
Ogg Theora .ogg PC, Mac A non-proprietary container (Ogg) and video codec (Theora)
Ogg Vorbis
Ogg Vorbis .ogg Free, open standard; compressed; supported by some browsers Slow to catch on as a popular standard; part of Google's WebM format
PNG
PNG (Portable Network Graphics), pronounced "ping," is a graphics format designed to improve on the GIF format. A PNG graphic can display up to 48-bit True Color (trillions of colors). Unlike JPEG, PNG compresses bitmap files without losing any data, so compressed images retain the same high quality as the originals. PNG was developed as a public domain format without any restrictions on its use. Web graphics and other general uses
ASCII text
Plain, unformatted text is sometimes called ASCII text and is stored in a so-called "text file" with a name ending in .txt. ASCII text files can be created with text editors, such as TextEdit and Notepad. They are typically used for writing computer programs because executable program code cannot include formatting such as underlining and special fonts. They can also be used for creating Web pages. Text files can usually be opened by any word processing software regardless of the type of device. In that sense, they are universal. ASCII text files contain no formatting. They have no bold, italics, underlining, or font colors. There are no margins, columns, bullets, headers, or page numbers.
RAW
RAW image formats contain the unprocessed pixel data generated directly by a digital camera's sensor. Up to 12 bits of data can be stored for each of the red, blue, and green values for a pixel, so RAW files are very large. Cameras that offer a RAW format also supply proprietary software to convert RAW data to JPEG or TIFF. Photographic images before they are stored in other formats
Rasterization
Rasterization works by superimposing a grid over a vector image and determining the color for each pixel. This process can be carried out by graphics software, which allows you to specify the output size for the final bitmap image.
Inpainting
Reconstructing lost, unwanted, or deteriorated areas in a photo is called inpainting. Using information from nearby pixels, and taking into account the overall structure of the image, inpainting algorithms essentially scrub out designated areas and miraculously replace the missing pixels with a background or an object that fits with the rest of the image
Speech Recognition
Speech recognition (or voice recognition) refers to the ability of a machine to understand spoken words.
Speech Synthesis
Speech synthesis is the process by which machines produce sound that resembles spoken words.
Lossless Compression File Types
TIFF, PNG, and GIF graphics formats offer lossless compression. Images stored in these formats do not lose any quality when compressed.
Binary Number System
The binary number system has only two digits: 0 and 1. No numeral like 2 exists in this system, so the number "two" is represented in binary as 10 (pronounced "one zero").
RGB
The color displayed for a pixel is based on the intensity of red, green, and blue signals received by the screen's color elements. Each red, green, and blue signal is assigned a value ranging from 0 to 255: 0 represents the absence of color, and 255 represents the highest intensity level for that color. A pixel appears white if the red, green, and blue signals are set to maximum intensity. If red, green, and blue signals are equal but at a lower intensity, the pixel displays a shade of gray. A pixel appears violet if it receives high red and blue signals and just a bit of green
Image Resolution
The dimensions of the grid that forms a bitmap graphic are referred to as image resolution. The resolution of a bitmap is usually expressed as the number of horizontal and vertical pixels it contains. High-resolution graphics contain more data than low-resolution graphics. With more data, it is possible to display and print high-quality images that are sharper and clearer than images produced using less data.
Vector
The first graphics that appeared on computer screens were not photos, but simple shapes consisting of lines and curves, each referred to as a vector. This type of graphic evolved in sophistication as the shapes became filled, then shaded, and then textured.
Rendering
The process of covering a wireframe with surface color and texture is called rendering. The rendering process requires a computer to perform intensive calculations to determine the surface dimensions between vectors. Rendering outputs a bitmap image that can be displayed on the screen or printed
Digital Audio Extraction
The technical term for ripping music tracks is digital audio extraction.
Wireframe
The vectors form a wireframe that acts in much the same way as the framework of a pop-up tent. Just as you would construct the framework for the tent and then cover it with a nylon tent cover, a 3-D wireframe can be covered with surface texture and color to create a graphic of a 3-D object.
Data Compression
To reduce file size and transmission times, digital data can be compressed. Data compression refers to any technique that recodes the data in a file so that it contains fewer bits. Compression is commonly referred to as "zipping." Many compression techniques exist. They can be divided into two categories: lossless and lossy. Compressed files usually have .zip at the end of the file name and are represented with specialty icons. Compressed files may also end with .gz, .pkg, or .tar.gz. These files have to be extracted or unzipped before you can view the data they contain.
Unicode
Unicode (pronounced "YOU ni code") uses sixteen bits and provides codes for 65,000 characters—a real bonus for representing the alphabets of multiple languages.
MIDI messages
Unlike digital audio files, which contain digitized recordings of real performances, MIDI files contain instructions, called MIDI messages, specifying the pitch of a note, the point at which the note begins, the instrument that plays the note, the volume of the note, and the point at which the note ends.
WMA
WMA (Windows Media Audio) .wma Compressed format; very good sound quality; used on several music download sites Files can be copy protected; requires Windows Media Player 9 or above
Scanner
When you have a printed image, such as a photograph, a page from a magazine, or a picture from a book, you can use a scanner to convert the printed image into a bitmap graphic. A scanner essentially divides an image into a fine grid of cells and assigns a digital value for the color of each cell. As the scan progresses, these values are transferred to your digital device and stored as a bitmap graphics file.
MIDI
synthesized sound is an artificially created, or synthetic, sound. The first music synthesizers were analog. When digital synthesizers became popular, MIDI was developed as a way to control them. MIDI (Musical Instrument Digital Interface) specifies a standard way to store music data for synthesizers, electronic MIDI instruments, and computers. MIDI music is usually stored in .mid files. One of the main disadvantages of MIDI is that it cannot produce vocals. Another disadvantage is that the quality of MIDI music depends on the playback device, which stores a collection of synthesized sounds. MIDI music might sound great on a computer equipped with high-end MIDI equipment, but the same MIDI sequence might sound artificial on a handheld device.
Digital-to-Analog Converter
when you record a voice message on your phone, the sound waves of your voice are sampled many times per second by an analog-to-digital converter (ADC). Those samples are converted into binary 1s and 0s, which are stored in an audio file. When the audio file is played, a digital-to-analog converter (DAC) transforms the digital bits into analog sound waves and outputs them through the speakers.