Computer Graphics

Computer Graphics

Computer graphics is extensive, complex and diversified technology. Computer Graphics is a field of computer science that is concerned with digitally synthesizing and manipulating visual contents. It a technique of manipulate visual and geometric information using computational techniques. Computer graphics refers to the creation, storage and manipulation of pictures and drawings using a digital computer. Computer graphics are pictures that are generated by a computer using different technique. With developments in computing technology interactive computer graphics has become an effective tool for presentation of information in such diverse fields as science, engineering, medicine, business, industry, government, art, entertainment, advertising, education, and training. There is virtually no field in which graphical displays cannot be used to some advantage and that is the basic reason why application of computer graphics is so widespread.

Graphical representation makes the study of anything much more interesting. It is a fact that one picture is worth a thousand words. So quite naturally interfaces empowered with Graphics enhances the communication between the computer and its users. Representation of a huge numbers in the form of a graph or a picture helps in better understanding and interpretation of the characteristics or pattern of the data contained in the set of numbers. Graphic displays also improve understanding complex systems, and visualization of two-dimensional (2D), three-dimensional (3D) objects.

Two major 2D graphic types: Bitmap (Raster) and Vector images.

Raster Graphics

Raster Graphics consist of illustrations created using pixels; Rectangular grid of cells of equal size and each cell has its own color. These cells are also called pixels. Raster graphics are also called bitmaps. Digital photographs are the most common type of raster graphics.

Digital photographs in general are raster graphics. Digital camera, uses a certain number of megapixels. This refers to the number of pixels used for a single picture. A defining characteristic of a raster graphic is that when it’s zoomed in very closely, it start to show the actual pixels.

An important property of a raster graphic is its resolution. Resolution indicates the amount of detail, so a higher resolution means more detail. Higher resolution means more pixels, which is why a larger number of megapixels for a digital camera results in sharper photographs.

Vector graphics

Vector graphics consist of illustrations created using line work. In technical terms, you use points, lines, curves and shapes to create the illustration. Vector graphics are based on vectors, also referred to as paths. One of the key characteristics of a vector graphic is that the line work is sharp, even when zoomed in very closely. In a computer application, the line work is stored as a mathematical formula that describes the exact shape of the line. So when its zoomed in, remains a line.

Photo-realistic illustration that is not actually a photograph, the illustration typically consists of very detailed vector graphic containing hundreds or thousands of lines. Vector graphics are created and edited using illustration software. There are a number of different illustration applications. One of the most widely used ones is Illustrator by Adobe. Others include CorelDraw by the Corel Corporation and the open source applications Inkscape and Xara Xtreme. Vector graphics can be stored in a number of different file formats, including AI, EMF, SVG and MWF.

Authorware

Authorware is a multimedia authoring system (environment, tool) for creating computer-based Wikipedia (Multimedia learning applications). It is a multimedia authoring program designed explicitly for learning. Among Authorware's features is that it enables developers to create sophisticated interactivity without having to write any scripts or do any programming. Authorware also comes with scripting capabilities for developers who want to create even more complex interactivity in Authorware.

Features

• Visual programming language (drag and drop icons to create your application's logical outline, and use menus to add content) 
• Built-in data tracking (built-in variables for student activities)
• Support for all sorts of rich media
• Scriptable

Authorware is particularly well suited to creating electronic educational technology (also called e-learning) content, as it includes highly customizable templates for CBT and WBT, including student assessment tools. Working with these templates, businesses and schools can rapidly assemble multimedia training materials without needing to hire a full-fledged programmer. Intuitively-named dialog boxes take care of input and output. The flow chart model makes the re-use of lesson elements extremely straightforward.

Educational technology

Educational technology is the effective use of technological tools in learning. As a concept, it concerns an array of tools, such as media, machines and networking hardware, as well as considering theoretical perspectives for their effective application. Educational technology is not restricted to high technology. Modern educational technology includes (and is broadly synonymous with) e-learning , instructional technology, information and communication technology (ICT) in education, EdTech, learning technology, multimedia learning, technology-enhanced learning (TEL), computer-based instruction (CBI), computer managed instruction, computer-based training (CBT), computer-assisted instruction or computer-aided instruction (CAI), internet-based training (IBT), flexible learning, web-based training (WBT), online education, virtual education, personal learning environment s, networked learning, virtual learning environments (VLE) (which are also called learning platforms), m-learning , and digital education. These labels have been variously used and understood, and conflate to the broad domain of educational technology and e-learning. These alternative descriptive terms are all more restrictive than "educational technology" in that they individually emphasize a particular digitization approach, component or delivery method.

Digital Video

Digital video is audio/visual in a binary format. Information is presented as a sequence of digital data, rather than in a continuous signal as analog information is.

Digital video comprises a series of orthogonal bitmap digital images displayed in rapid succession at a constant rate. In the context of video these images are called frames. We measure the rate at which frames are displayed in frames per second (FPS).

Since every frame is an orthogonal bitmap digital image it comprises a raster of pixels. If it has a width of W pixels and a height of H pixels we say that the frame size is WxH.

Pixels have only one property, their color. The color of a pixel is represented by a fixed number of bits. The more bits the more subtle variations of colors can be reproduced. This is called the color depth (CD) of the video.

An example video can have a duration (T) of 1 hour (3600sec), a frame size of 640x480 (WxH) at a color depth of 24bits and a frame rate of 25fps. This example video has the following properties:

pixels per frame = 640 * 480 = 307,200
bits per frame = 307,200 * 24 = 7,372,800 = 7.37Mbits
bit rate (BR) = 7.37 * 25 = 184.25Mbits/sec
video size (VS) = 184Mbits/sec * 3600sec = 662,400Mbits = 82,800Mbytes = 82.8Gbytes

Types of Video Formats

Windows Media Video (.wmv)

Developed and controlled by Microsoft. WMV is a generic name of Microsoft's video encoding solutions and doesn't necessarily define the technology what it uses -- since version 7 (WMV7) Microsoft has used its own flavour of MPEG-4 video encoding technology. The only difference between ASF files and WMV or WMA files are the file extensions and the MIME types. The basic internal structure of the files is identical. The change in extensions was made to make it easier for an application to identify the content of a media file. A .wma file extension designates a file containing only audio. A .wmv extension designates a file containing both video and audio.

Advanced Streaming Format (.asf)

D.asf Advanced Streaming Format Developed by Microsoft as a multimedia successor to AVI and other individual media file formats, ASF files can contain up to 7 media types including streaming video. ASF is optimized for network distribution and desktop playback. Currently, Microsoft is shifting to the new video file format WMV (Windows Media Video). eveloped by Microsoft as a multimedia successor to AVI and other individual media file formats, ASF files can contain up to 7 media types including streaming video. ASF is optimized for network distribution and desktop playback. Currently, Microsoft is shifting to the new video file format WMV (Windows Media Video). 

QuickTime movie (.mov)

An industry standard developed as part of an entire multimedia architecture by Apple, the QuickTime movie is an open multimedia format which has multi-platform, multi-browser support. Currently (Apr 2003), QuickTime 6 is the newest version and it incorporates streaming and virtual reality capabilities.

Audio-Video Interleave (Video for Windows) (.avi)

The precursor to ASF, AVI files are limited to audio and video only and are not streamable.

RealMedia (.rm)

RealMedia is an industry leader in streaming video technology and is utilized by many Internet real-time video broadcasting sites. Currently, Real One player 6.0 is available.

Various Programs (.mpg)
MPEG-4 is the latest standard for video compression and file format developed by an industry group.  

Graphics Acceleration

A graphics acceleration is a process of sending and refreshing of images to the display monitor and the computation of special effects common to 2-D and 3-D images. Graphics accelerators speed up the displaying of images on the monitor making it possible to achieve effects not otherwise possible - for example, the presentation of very large images or of interactive games in which images need to change quickly in response to user input. Many new personal computers are now sold with a graphics accelerator built in. The power of a graphics accelerator can be extended further if the personal computer is equipped with the Accelerated Graphics Port ( AGP ), a bus (data path) interface between the computer components involved in image display.

Each graphics accelerator provides an application program interface ( API ). Some support more than one API. Among the most popular API's are the industry standard OpenGL and Microsoft's DirectX and Direct3D.

A type of video adapter that contains its own processor to boost performance levels. These processors are specialized for computing graphical transformations, so they achieve better results than the general-purpose CPU used by the computer. In addition, they free up the computer's CPU to execute other commands while the graphics accelerator is handling graphics computations.

The popularity of graphical applications, and especially multimedia applications, has made graphics accelerators not only a common enhancement, but a necessity. Most computer manufacturers now bundle a graphics accelerator with their mid-range and high-end systems.

Aside from the graphics processor used, the other characteristics that differentiate graphics accelerators are:

• Memory : Graphics accelerators have their own memory, which is reserved for storing graphical representations. The amount of memory determines how much resolution and how many colors can be displayed. Some accelerators use conventional DRAM, but others use a special type of video RAM (VRAM), which enables both the video circuitry and the processor to simultaneously access the memory.
• Bus : Each graphics accelerator is designed for a particular type of video bus. As of 1995, most are designed for the PCI bus.
• Register width: The wider the register, the more data the processor can manipulate with each instruction. 64-bit accelerators are already becoming common, and we can expect 128-bit accelerators in the near future

Sound File Format

A sound file format is a file format for storing audio on a computer. There are several different formats, each with its own benefits and drawbacks. The difference between formats generally has to do with storage space versus sound quality. The processor of a computer typically decodes compressed sounds into a format that can be played by the computer.

The way the audio is compressed and stored is call the codec which determines how small the file size is. Some file types always use a particular codec. For example, ".mp3" files always use the "MPEG Layer-3" codec. Other files like ".wav" and ".dct" files support selectable codecs. For example, a ".wav" file can be encoded with the "PCM", "GSM6.10", "MPEG3" and many other codecs. Be careful not to confuse the file type with the codec - it often surprises people to
know you can have a "MPEG Layer-3" encoded ".wav" file. Some file types just contain the audio. But other file types can
contain additional header information which can contain other information about the file (eg .dct files have information about the sender, priority, notes and other data in the file itself).

Below is a description of audio formats supported by Scratch:

MP3
The most popular audio format, a lossy format playable in almost any device and program. Some open-source programs cannot play it due to patent issues, however.

WAV
The default uncompressed audio format on Windows, also playable in most programs.

Most Common Types of Video Files and Containers

Container and Codecs

A digital video file usually consists of two parts. These two parts are called the “Container” and the “Codec”. The container refers to what the actual file type or extension is, for example: .AVI or .MOV. Now, within each of these containers there is a codec which is like a set of instructions that specifies the specific coding and settings of how the video plays on your player. A few popular codecs you may have seen before are: DV NTSC, DivX, Sony YUV. There are much fewer video file containers than codecs, and each container can have hundreds of codecs within them. Most of the popular computer video software is actually preloaded with several of the most popular and most used codec and container decoders to properly playback popular file formats. Odd or proprietary types of codecs may require downloading specialty made codec packs from external sources in order to play correctly.

A Multitude of Formats

There are literally hundreds of video codecs of video formats. Because there are so many possibilities, we may not be able to convert all video files into some of the less popular or proprietary video formats. There are also some video codecs out there that require expensive licensing that we currently cannot offer. Just like .doc indicates a word file, .mov indicates a QuickTime move file; .wmv stands for windows media video and so forth. Here are the most common video file formats, in alphabetical order:

3GP File Extension (.3gp)

The 3gp format is both an audio and video format that was designed as a multimedia format for transmitting audio and video files between 3G cell phones and the internet. It is most commonly used to capture video from your cell phone and place it online. This format supports both Mac and windows applications and can be commonly played in the following:

•            Apple QuickTime Player

•            RealNetworks RealPlayer

•            VideoLAN VLC media player

•            MPlayer

•            MIKSOFT Mobile 3GP Converter (Windows)

Advances Streaming Format (.asf)

ASF is a subset of the wmv format and was developed by Microsoft. It is intended for streaming and is used to support playback from digital media and HTTP servers, and to support storage devices such as hard disks. It can be compressed using a variety of video codecs. The most common files types that are contained within an ASF file are Windows Media Audio, and Windows Media video.

AVCHD (Advanced Video Codec High Definition)

AVCHD (.mts) is a high end, high-definition (HD) format which was originally developed by Sony and Panasonic for high definition home theaters. It’s not really suitable for sharing due to the excessive file sizes, but the format is becoming more and more popular due to HD camcorders using this format. Video in this format would be best suited as the master copy of your video project and serves as a great piece to edit with. AVCHD is still in its early life as a video format and since it’s still fairly new, compatibility with certain video editing programs may be an issue. Some video editing software applications have begun to support this format but many of can not fully handle it quite yet. Additionally, playback of AVCHD files requires speedy CPUs and a sufficient amount of RAM. That alone makes this format more difficult to work with but, on the other hand, it maintains high quality. As time goes by, it will no doubt become easier to use and be more integrated with editing applications.

.AVI (Audio Video Interlaced)

AVI format is a long-time standard developed by Microsoft and has been around as long as digital video has. AVI files (particularly when uncompressed) tend to be HUGE, way too big for the internet or uploading to someone. AVI is more for the beginning of a video project using it as something to edit off of, not the end. In that sense, it is not really a sharing format. They’ll slide into just about any video editing program and the quality is still high enough to be a master clip. AVI is windows-based and is virtually universal. The problem is, not all AVIs are created equally and you can still run into compatibility issues due to different codecs on the videos. The important thing to know is that whatever streams inside the container (AVI) is not necessarily the same from one AVI video to the next because the codecs used for compression can vary from file to file. This is because AVI is what’s known as a “container format”, which basically means it contains multiple streams of different type data, including a control track and separate video and audio streams.

.FLV (Flash Video Format)

Flash video (FLV) is the single most common sharing format on the web today. You’ll see the .FLV file extension on videos encoded by Adobe Flash software to play within the Adobe Flash Player. Virtually everyone (99%) has the adobe player installed in their browser and so this has fast become the most common online video viewing platform. Almost all the video sharing sites stream video in flash. You can upload formats other than flash, and those sites will convert it into flash for streaming to the end user. Notable users of the Flash Video format include YouTube, Yahoo! Video, MySpace, and many others. Many television news operations are also now using Flash Video on their websites as a way to keep viewers up to date at all times. Most of those sites accept uploads in a handful of formats like QuickTime, mpeg4, or wmv, and then they convert it to flash or MP4 before actually putting it out on the net for viewing. In addition to the nearly universal flash video player, FLV is popular because it gives one of the smallest file sizes after compression yet it retains fairly good quality. This means that the videos load quickly on the internet, and won’t spend a lot of time using up your bandwidth. If you self-host your own videos, you should convert them to flash for greatest compatibility with the highest percentage of Internet viewers. Although FLV’s are the most common format found on the web today, the standard is moving towards the use of using MP4 H.264 files within flash players as it is compatible with both online and mobile (iPhone), not to mention some HTML5 browser support (Safari, Chrome).

.MPEG (Motion Picture Experts Group)

MPEGwas developed by the Motion Picture Experts Group. This international group was established in 1988 to develop standards for digital audio and video formats. However, they’re just one of many groups looking to standardize and develop new technologies for digital video.

MPEG-4 (.MP4)

MPEG-4 is another great sharing format for the internet. It’s a small file size, but looks fairly clean in comparison with other video codecs of the same file size. It’s the video format employed by a growing number of camcorders and cameras and it is highly recommended this day and age. In fact, YouTube actually recommends that users upload using MP4 format. YouTube accepts multiple formats, and then converts them all to .flv or .mp4 in their back-end for distribution. As mentioned earlier, more and more online video publishers are moving to MP4 (with H.264 as the video compression codec) as the standard internet sharing format with use within both Flash players as well as HTML5 and most mobile devices. This is the format that we recommend for online delivery of your media.

.WMV (Windows Media Video)

A .WMV file indicates a windows media video file. Windows Media Video is used for both streaming and downloading content via the Internet. Microsoft’s Windows Media Player, an application bundled with Windows operating systems, is built for WMV files. WMV files are of a pretty small file size, actually one of the smallest. As a result of the low file sizes, the videos are compressed so much they start to lose their quality in a hurry. In fact, I’d say the resolution is pretty crummy in comparison to modern codecs. But a tiny file size can be a real advantage in some situations. If you get an email with an actual video attached instead of just a link to a video, it is probably a wmv file. They are the only ones small enough to attach to an email.

.MOV

.MOV is the file extension used to identify an Apple Quick Time Movie. .MOV is an extremely common sharing format, especially among Mac users. It is considered one of the best looking file formats. While MOV files do look great, the files sizes are extremely big. Due to the fact that QuickTime has not been a Mac-only program for quite some time, QuickTime versions and players exist on almost all PCs. The vast majority of the videos we personally upload to the web are QuickTime format, followed by MPEG4. If you see a video file on your computer labeled MSWMM, be aware that this is a windows movie maker project file and not a video or movie file designed for sharing. MSWMM will only play within Movie Maker. When you want to save your movie to share it, use Movie Maker to convert it into a sharing format, such as .mpeg4 or .wmv. The difference between sharing formats and project file formats confuses many people. No matter what video editing software you use, a project file is designed for working on within the editing program. You must convert the project file to watch it on any other player. Now, what streams inside the container is not necessarily the same from one avi video to the next as the codecs used for compression can vary. At DVD Your Memories, when you opt for a video to hard drive transfer, we give you your video tapes as video files in AVI format.

Real Media Format (.rm)

RealMedia is a format which was created my RealNetworks. It contains both audio and video data and typically used for streaming media files over the internet. Realmedia can play on a wide variety of media players for both Mac and Windows platforms. The real player is the most compatible.

Flash Movie Format (.swf)

The Flash movie format was developed my Macromedia. This format can include text, graphics and animation. In order to play in Web Browsers, they must have the Flash Plug-In Installed. The flash plug in comes preinstalled in the latest version of many popular Web Browsers.

Charged Coupled Device

A charge coupled device (CCD) is an integrated circuit etched onto a silicon surface forming light sensitive elements called pixels. Photons incident on this surface generate charge that can be read by electronics and turned into a digital copy of the light patterns falling on the device. CCDs come in a wide variety of sizes and types and are used in many applications from cell phone cameras to high-end scientific applications.

The function of a CCD can be visualized as an array of buckets(pixels) collecting rainwater (photons). Each bucket in the array is exposed for the same amount of time to the rain. The buckets fill up with a varying amount of water, and the CCD is then read one bucket at a time. This process is initiated by pouring water into the adjacent empty column. The buckets in this column transfer their ‘water’ down to a final pixel where the electronics of the camera read-out this pixel (the computer measuring the bucket) and turn it into a number that can be understood and stored by a computer.

CCDs are sensors used in digital cameras and video cameras to record still and moving images. The CCD captures light and converts it to digital data that is recorded by the camera. For this reason, a CCD is often considered the digital version of film. The quality of an image captured by a CCD depends on the resolution of the sensor. In digital cameras, the resolution is measured in Megapixels (or thousands of or pixels. Therefore, an 8MP digital camera can capture twice as much information as a 4MP camera. The result is a larger photo with more detail.

CCDs in video cameras are usually measured by physical size. For example, most consumer digital cameras use a CCD around 1/6 or 1/5 of an inch in size. More expensive cameras may have CCDs 1/3 of an inch in size or larger. The larger the sensor, the more light it can capture, meaning it will produce better video in low light settings. Professional digital video cameras often have three sensors, referred to as "3CCD," which use separate CCDs for capturing red, green, and blue hues.

HTML

What is HTML?

Hypertext Markup Language (HTML) is a syntax used to format a text document on the web. These documents are interpreted by web browsers such as Internet Explorer and Netscape Navigator.

HTML can be created as standard ASCII text with "tags" included to pass on extra information about character formatting and page layout to a web browser. The fact that HTML is, in essence, ASCII text is what makes it so universally compatible. This fact also makes it easy to edit: almost all computers are equipped with a text editor that can be used to edit HTML.

What are Tags?

Tags are what we use to structure an HTML page. Tags start with a '<', then the command, and end with a '>'. For example, the center tag is '<center>'. To stop centering something, we need an ending, or closing tag. Closing tags look exactly like opening tags, except after the first '<' there is a '/'. In other words, the closing tag for center is '</center>'.

HTML Structure

An HTML document has a definite structure that must be specified to the browser. The HTML's beginning and end must be defined, as well as the document's HEAD (which contains information for the browser that does not appear in the browser's main window) and its BODY (which contains the text that will appear in the browser's main window). The use and order of tags that define the HTML structure are described below.

<html>                      Marks the beginning of your HTML
  <head>                  Begins the heading section of an HTML document
    <title> ... </title>Gives an HTML document a title that appears on the browser menu bar, also will appear on search engines or bookmarks referencing your site (must appear between the <HEAD> ... </HEAD> tags; should be straight text, no tags
  </head>                  Defines the end of the heading
  <body>                    Defines the body of an HTML document (text contained within the <BODY> … </BODY> tags appears in the main browser window). Can be used with "BGCOLOR", "TEXT", "LINK", and "VLINK" attributes
</html>                   Defines the end of your HTML document.