O and P of Digital Media - Opacity and Podcasts
OSP (Online Service Provider)
On the Internet, OSP (online service provider) has several different meanings.
The term has had some currency in distinguishing Internet access providers that have their own online independent content, such as America Online (AOL), from Internet service providers (ISPs) that simply connect the user directly with the Internet. In general, the companies sometimes identified as OSPs (in this usage) offer an extensive online array of services of their own apart from the rest of the Internet and sometimes their own version of a Web browser. Connecting to the Internet through an OSP is an alternative to connecting through one of the national Internet service providers, such as AT&T or MCI, or a regional or local ISP.
Some Internet service providers (ISPs) describe themselves as online service providers. In this usage, ISP and OSP are synonyms.
America Online has used the term to refer to online content providers (usually Web sites) with which AOL has a business agreement.
Open Source
Most software that you buy or download only comes in the compiled ready-to-run version. Compiled means that the actual program code that the developer created, known as the source code, has run through a special program called a compiler that translates the source code into a form that the computer can understand (see How C Programming Works for details on compilers). It is extremely difficult to modify the compiled version of most applications and nearly impossible to see exactly how the developer created different parts of the program. Most commercial software manufacturers see this as an advantage that keeps other companies from copying their code and using it in a competing product. It also gives them control over the quality and features found in a particular product.
Open source software is at the opposite end of the spectrum. The source code is included with the compiled version and modification or customization is actually encouraged. The software developers who support the open source concept believe that by allowing anyone who’s interested to modify the source code, the application will be more useful and error-free over the long term.
To be considered as open source software by the software development industry, certain criteria must be met:
- The program must be freely distributed (It can be part of a package that is sold though, such as Red Hat has done with Linux).
- Source code must be included.
- Anyone must be allowed to modify the source code.
- Modified versions can be redistributed.
- The license must not require the exclusion of other software or interfere with the operation of other software.
Out of Gamut
In colour reproduction, including computer graphics and photography, the gamut, or colour gamut (pronounced /ˈgæmət/), is a certain complete subset of colors. The most common usage refers to the subset of colours which can be accurately represented in a given circumstance, such as within a given colour space or by a certain output device. Another sense, less frequently used but not less correct, refers to the complete set of colours found within an image at a given time. In this context, digitizing a photograph, converting a digitized image to a different colour space, or outputting it to a given medium using a certain output device generally alters its gamut, in the sense that some of the colours in the original are lost in the process.
Opacity
The condition of lacking transparency or translucence. We cannot see through objects which are 100% opaque. Adjusting opacity determines to what degree information is hidden or revealed.
Photoshop
Photoshop, is a graphics editing program developed and published by Adobe Systems. It is the current and primary market leader for commercial bitmap and image manipulation, and is the flagship product of Adobe Systems. It has been described as an industry standard for graphics professionals and was one of the early “killer applications” on Macintosh.
Photoshop CS3, the current tenth iteration of the program, was released on 16 April 2007. “CS” reflects its integration with other Creative Suite products, and the number “3″ represents it as the third version released since Adobe re-branded its products under the CS umbrella. Photoshop CS3 features additions such as the ability to apply non-destructive filters, as well as new selection tools named Quick Selection and Refine Edge that make selection more streamlined. On April 30th, Adobe released Photoshop CS3 Extended, which includes all the same features of Adobe Photoshop CS3 with the addition of capabilities for scientific imaging, 3D, and high end film and video users. The successor to Photoshop CS3, Photoshop CS4, will be the first 64-bit Photoshop.
PDA (Personal Digital Assistant)
A personal digital assistant (PDA) is a handheld device designed to facilitate organisational ability from a mobile platform. While the original PDAs were somewhat limited to keeping address, phone, calendar, and task lists, today’s PDA can function as a mobile phone, fax, provide Internet connectivity, and much more. There are many different types of PDAs, but most models work with either Palmtop software or a special version of Microsoft Windows called Windows Mobile. All models can interface with a laptop or desktop system, though optional accessories may be required. Synchronisation between computer and PDA is one of the most popular features of this digital device.
Some PDAs work only with a stylus, while others incorporate a miniature keyboard. A PDA might include handwriting recognition software, voice recognition, and a digital voice recorder. Some models come with a suite of software programs preinstalled, while others offer optional programs if desired.
A PDA might also incorporate mobile phone functionality and wireless local area network (LAN) capability. Connect to the Internet to check email, send messages, or watch the stock market. With flash card capability, a PDA can store, access, and transfer virtually any kind of data, including maps, spreadsheets, presentations, and dockets.
A PDA can even function like a mini-computer to make those last minute changes while en-route to the office or to a client. Windows Mobile runs a variety of mobile applications, including Excel and Microsoft Word. If you have a few minutes, use your PDA to kick back and listen to your favorite music, watch videos, or play games.
Portal
Portal is a term, generally synonymous with gateway, for a World Wide Web site that is or proposes to be a major starting site for users when they get connected to the Web or that users tend to visit as an anchor site. There are general portals and specialised or niche portals. Some major general portals include Yahoo, Netscape, Lycos, CNET and Microsoft Network. Examples of niche portals include Garden.com (for gardeners), Fool.com (for investors), and SearchNetworking.com (for network administrators).
A number of large access providers offer portals to the Web for their own users. Most portals have adopted the Yahoo style of content categories with a text-intensive, faster loading page that visitors will find easy to use and to return to. Companies with portal sites have attracted much stock market investor interest because portals are viewed as able to command large audiences and numbers of advertising viewers.
Typical services offered by portal sites include a directory of Web sites, a facility to search for other sites, news, weather information, e-mail, stock quotes, phone and map information, and sometimes a community forum. Excite is among the first portals to offer users the ability to create a site that is personalised for individual interests.
The New England Institute’s portal is the DET portal and this is where we can access our personal information, terminal server connections, and lots of other information that is important to TAFE NSW staff members. portal.det.nsw.edu.au
Path (file/folder path)
A sequence of symbols and names that identifies a file. Every file has a name, called a filename, so the simplest type of pathname is just a filename. If you specify a filename as the pathname, the operating system looks for that file in your current working directory. However, if the file resides in a different directory, you must tell the operating system how to find that directory. You do this by specifying a path that the operating system must follow.
The pathname always starts from your working directory or from the root directory. Each operating system has its own rules for specifying paths. In DOS systems, for example, the root directory is named \, and each subdirectory is separated by an additional backslash. In UNIX, the root directory is named /, and each subdirectory is followed by a slash. In Macintosh environments, directories are separated by a colon.
Plug In
A hardware or software module that adds a specific feature or service to a larger system. The idea is that the new component simply plugs in to the existing system. For example, there are number of plug-ins for the Netscape Navigator browser that enable it to display different types of audio or video messages.
Podcast (great explanation gained from Podcast Alley)
Podcasting, created by former MTV VJ Adam Curry, is a term that was devised as a crisp way to describe the technology used to push audio content from websites down to consumers of that content, who typically listen to it on their iPod (hence the “pod”) or other audio player that supports mp3 at their convenience. The term podcasting is meant to rhyme with broadcasting and is a derivative of the iPod platform. While not directly associated with Apples iPod device or iTunes music service, the company did contribute both the desire and the technology for this capability. Podcasting is not unlike time-shifted video software and devices like TiVo, which let you watch what you want when you want by recording and storing video, except that podcasting is used for audio and is currently free of charge. Note, however, that this technology can be used to push any kind of file, including software updates, pictures, and videos.
Pixel
Short for Picture Element, a pixel is a single point in a graphic image. Graphics monitors display pictures by dividing the display screen into thousands (or millions) of pixels, arranged in rows and columns. The pixels are so close together that they appear connected.
The number of bits used to represent each pixel determines how many colours or shades of gray can be displayed. For example, in 8-bit colour mode, the colour monitor uses 8 bits for each pixel, making it possible to display 2 to the 8th power (256) different colours or shades of gray.
On colour monitors, each pixel is actually composed of three dots — a red, a blue, and a green one. Ideally, the three dots should all converge at the same point, but all monitors have some convergence error that can make colour pixels appear fuzzy.
The quality of a display system largely depends on its resolution, how many pixels it can display, and how many bits are used to represent each pixel. VGA systems display 640 by 480, or about 300,000 pixels. In contrast, SVGA systems display 800 by 600, or 480,000 pixels. True Colour systems use 24 bits per pixel, allowing them to display more than 16 million different colors.
PNG file
Portable Network Graphics (PNG) was developed as a replacement for the GIF standard, partly because of legal entanglements resulting from GIF’s use of the patented LZW compression scheme, and partly because of GIF’s many limitations. PNG is superior to GIF in many ways, offering the following features:
- Images that are the same size or slightly smaller than their GIF counterparts, while keeping lossless compression
- Support for indexed colours, gray-scale, and RGB (millions of colours)
- Support for 2-D progressive rendering, which is based on pixels rather than lines (as in interlaced GIFs and progressive JPEGs); this means that contents of a progressively rendered PNG file become apparent earlier in the load process
- An alpha channel that allows an image to have multiple levels of opacity; whereas GIFs only allow a given pixel to be fully transparent or fully opaque, this feature lets you create images with degrees of transparency, better blending images with their backgrounds
- Gamma correction, which allows you to correct for differences in how an image will appear on different computer display systems
- File integrity checks which help prevent problems while downloading or transferring PNG files
PNG does not support multiple images within the same image file, which means that you can’t make PNG animations like you can with GIFs. For transmission of some types of images (e.g., true-colour photographs and black and white images) other file formats may give better results. Although PNG is still considered a relatively young format, most graphics applications and virtually all browsers support it.
Pixellated
The above image is pixelated (quite badly) so that you can see the individual pixels.
Pixellated means that an image, has pixels that are large enough to be individually visible from a normal viewing distance.
PDF File
PDF (Portable Document Format) is a file format developed by Adobe as a means of distributing compact, platform-independent documents. It is superficially similar to HTML; a PDF document may contain images and text, as well as hyperlinks. However, as PDF is based on a variant of PostScript, each document is self-contained, packing text, graphics, and fonts into a single file. With the aid of Adobe Acrobat, many word processing and desktop publishing applications can be used to create PDF files. For this reason, and because PDF documents are web accessible, yet display exactly as intended, print publishers often favor PDF over HTML.
You can view PDF files either with the Adobe Reader or via a web browser with the PDF Viewer plug-in. To download these programs or find out more about PDF, visit Adobe’s Products web site.
Additionally, Mac OS X offers built-in support for creating PDF files and includes a free application called Preview for viewing PDF files.
Proxy Server
A proxy server, also known as a “proxy” or “application level gateway”, is a computer that acts as a gateway between a local network (e.g., all the computers at one company or in one building) and a larger-scale network such as the Internet. Proxy servers provide increased performance and security. In some cases, they monitor employees’ use of outside resources.
A proxy server works by intercepting connections between sender and receiver. All incoming data enters through one port and is forwarded to the rest of the network via another port. By blocking direct access between two networks, proxy servers make it much more difficult for hackers to get internal addresses and details of a private network.
Some proxy servers are a group of applications or servers that block common Internet services. For example, an HTTP proxy intercepts web access, and an SMTP proxy intercepts email. A proxy server uses a network addressing scheme to present one organization-wide IP address to the Internet. The server funnels all user requests to the Internet and returns responses to the appropriate users. In addition to restricting access from outside, this mechanism can prevent inside users from reaching specific Internet resources (e.g., certain web sites). A proxy server can also be one of the components of a firewall.
Proxies may also cache web pages. Each time an internal user requests a URL from outside, a temporary copy is stored locally. The next time an internal user requests the same URL, the proxy can serve the local copy instead of retrieving the original across the network, improving performance.