CHAPTER 11 SUMMARYDIGITAL MEDIADigital media refers to the processing of digital data in the forms of text, audio, animation and video. Data is represented digitally because it can be fast processed and also used with information technology.

Types of Digital Media E-music refers to audio compressed from the Internet. It has been made possible through the usage of

compressed file formats such MP3 and MIDI files. This form of digital media has allowed the download of music from the Internet, and also create digital copies of a CD (called ripping), by copying onto the hard-drive.

Digital newspapers are the online versions of newspapers, and newspaper articles. They provide information on stories of special interest from the Internet. They constantly are updated and provide the latest news. Digital newspapers can email subscribers a page of news headlines on the areas they nominate. Each item of text is linked to the full story contained on a website.

Digital television provides interactive television. It merges communication with television and communication technologies. Digital television offers more channel choices, a higher resolution screen and greater control over the program the user is watching.

Electronic games are played using a game machine (game console) which is displayed on a television, or using gaming software on the computer. The latest games have different levels, and are closer to becoming realistic. Games have also been designed for multiple players, who can interact and compete with each other. The Internet is sometimes used to play games, including multiplayer games.

Digital Media Products Desktop publishing magazines are created using desktop publishing software (DTP). This is specialised software

to combine text and graphics on the screen. DTP software such as Microsoft Publisher enables the user to have precise control over objects on the page. Desktop publishing software is object based and uses algorithms to represent objects in binary code. It can easily create magazines and newspapers using layout tools such as multiple columns and wrapping text around images. DTP documents are often saved in the PDF format (Portable Digital Format) and transmitted via the Internet.

Bit-mapped graphics are created and edited using a painting program. It stores each pixel as a value and manipulates each pixel, rather than the objects of desktop publishing software. It also stores the colour of the pixel as a value as well. Bit-mapped graphics produce good quality images where shading and fine detail are needed such as in photographs. Common file formats for bit-mapped software include: BMP, JPEG, GIF, TIFF and PICT.

Vector graphics are created and editing using a drawing program. This stores pictures as a collection of objects such as shapes and lines. Each object is defined by its characteristic such as position, line width, length, and pattern. These characteristics are stored as mathematic expression and are displayed on the screen as pixels. Some common file formats include PNG, CDR, WMF, EPS and PICT and are editing Adobe Illustrator.

Audio is captured using a microphone. Sound travels through air in waves, with a particular amplitude, wavelength and frequency. Editing a sound wave involves the modification of one or more of these characteristics. A short piece of sound is often referred to as a sequence. Some common file formats for audio include WAV, MP3 and WMA. Common audio editing programs include Audacity and GoldWave.

MIDI sequence is a file which contains the note information and not the details of the sound wave. (MIDI stands for Musical Instrument Digital Interface and is pronounced ‘middy’). It is a standard connection for computers and electronic music instruments. MIDI allows (usually) up to 16 instruments to play simultaneously. A musician uses a MIDI instrument such as a keyboard to play the music, which is stored and edited in the computer. MIDI sequences require less storage than audio files as they only contain the note information, and therefore are easier to edit. They can also be easily converted to audio formats, which have better quality, but use more space in the hard-drive. MIDI editing programs include Sibelius and Finale.

Animation sequences are the movement of an object, or several objects. It is the result of a series of graphics or frames presented in rapid succession. When creating an animation sequence, the user needs to consider the size and speed of the graphic as well as the speed of the movement. Some common file formats include SWF, MOV and animated GIF. They are edited using software such as Adobe Flash.

Video productions are created using video clips (or sequences) from a digital video camera and video editing software. It involves adding video clips, audio or pictures to a timeline (or storyline). Each video clip is composed of many frames that contain individual images. When the video is played, the frames are displayed in sequence. These frames are played at a fast rate, so to the viewer it appears that there is only one movement. Common file formats for video include MPEG, AVI, DivX, WMV and MOV. They are edited using software such as Adobe Premier Elements, and Windows Live Movie Maker.

Manipulation TechniquesDigital media involves the processing of digital data. Processing involves editing the data using manipulation techniques for each data type.

GraphicsGraphics are created using a graphics program or captured using a scanner, digital camera or video camera. The two types of graphics are bit-mapped graphics and vector graphics. Editing a graphic involves the following techniques: Cropping refers to the process where unwanted parts on the edge of the image are removed. In some

programs, the parts of the picture which are cropped are permanently deleted. Other programs simply hide them from view, so that the picture can be restored to its original state.

Resizing refers to the process of making a graphic smaller or bigger. It can keep the proportions the same so that the picture will not be distorted. Resizing a bit-mapped graphic at an object level is often a problem, because it is difficult to select an object in a bit-mapped graphic. Enlarging the graphic enlarges every pixel and creates a staircase pattern along what appeared to be a diagonal or curved lines (called jaggies)

Size and position refers to the process of moving the graphic or object to another location. It also including processes of rotating, flipping, and moving objects forwards and backwards.

Rendering refers to the process of converting the graphic into a more realistic image. This involves adding 3D qualities such as shadows and textures to surfaces. A common technique for rendering is ray tracing. Ray tracing sends a ray of light to each pixel on the screen. The ray is deflected depending on the surface and colour of an object.

Colour effects change the colour properties of a graphic, such as colour, brightness and contrast. Adjusting the brightness and contrast makes a dull object lighter and a bright object darker. The colour of a graphic is edited using a palette of colours and also patterns. Another use for colour effects is the removal of red eye which is a common problem in photographs.

Special effects change the proportions of a graphic. This includes distortion, transparency, blurring and sharpening the focus.

AudioAudio signals from a computer are converted into analog sound waves for transmission through speakers. Each sound wave has an amplitude, wavelength and frequency. The amplitude is the height of the wave. It gives the sound its volume (or dynamics). The wavelength is the distance between the ends of one complete cycle of a wave. It gives the sound its pitch

or note. The frequency (pitch) of the wave is the number of wavelengths per second, and is measured in hertz (Hz).

The editing of these characteristics of the wave can be done multiple ways: Amplify refers to the process of changing the amplitude of the way, effectively this increases or decreases the

volume of the sound. Amplifying is a useful process in order to make sure that the audio will be clearly heard or not heard. Mute does not play the audio.

Equalisers (or filters) are used to make adjustments to the strength of sounds at different frequencies. Stretch (or time warp) changes the frequency (pitch) and duration of the audio signal. For example, you can use

this to change a song to higher key. This effect usually distorts voices. Some programs can change just the frequency or duration of the audio signal, but this usually reduces the quality of the sound.

Noise removal refers to the process of removing unwanted or background noise, without little reduction in quality. It is used to remove the background noise of a microphone.

Delete silence is used to remove periods of silence between words or other sounds. Add silence adds silence between two sounds.

Echo is used to add an echo to a sound. Fading refers to the process of gradually increasing or decreasing the audio volume. Fade in refers to the

increase from one volume, to a louder volume, while fade out refers to the decrease from one volume, to a softer volume. It is used to mix more than one song together, or if the song is unfinished at the end.

AnimationAnimation is created using path-based and cell-based animation. Cell-based animation (cell short for celluloid) creates an animation by using a sequence of individual still

images each displayed in a frame (or cell). Path-based animation creates an animation by displaying the movement of an animated object onto a fixed

background in a particular sequence or path.

Some techniques used by animation software to edit an animation: Tweening refer to the process of creating of an intermediate frames between two objects that are to be

animated. The animation software enables the user to identify specific objects in an image and define how they should move and change during the tweening process. The computer then processes the data to calculate what should be displayed in each intermediate frame.

Morphing is the smooth change between two different images. It involves the transforming the shape, size, dimension and colour of one image so it appears to merge into another image. Morphing programs work by marking the main points of the before and after image. These points are used to calculate the movements from one image to the other. Morphing requires large amounts of memory and fast processing speeds.

VideoVideo is captured using a digital video camera and edited using video editing software. After each clip is captured, it is displayed as a thumbnail. Creating the video production involves adding video clips, audio or pictures to a timeline (or storyline). A timeline is an area that shows the timing and arrangement of clips or files that make up a video production. Editing a video involves the following techniques. Trimming (or splicing) a clip, changes the start and the end point of the video clip. It allows the user to hide

unwanted material. Trimming does not usually remove the information. The user can delete the trim points and return the clip to its original state if required.

Splitting refers to the process of dividing a video clip in two clips. It is often used to insert a picture or transition in the middle of a clip, or remove a section from the middle that it unwanted (by trimming each of the two clips).

Combining refers to the process of joining two or more clips into one. It is useful when there are several small clips involved, and the user wishes to view and edit them as one clip.

Video effects are special effects which can be added to a video. Such changes include changing colour, speed and quality of a clip, as well as distortion.

Transitions are special effects used to change from one video or picture to another. Before one clip ends, the other clip will play. There are many types of transitions such as dissolves, fades and cuts.

Adding a picture involves importing a graphic file or capturing a picture from a video clip. The graphic file is displayed as a thumbnail and is dragged onto the timeline. The user determines the duration of the picture.

Adding audio involves a narration or background music. A narration is added by talking into a microphone, when viewing the timeline of the video. Background music is added by the process of importing, and then is dragged onto the timeline that specifies audio.

Titles and credits add the finishing touches to your video by the addition of text. Information displayed includes the title of the video production, the date, and the author of the video. Text can be formatted and animated in different ways.

DigitisationDigitisation is the process of general digital data, represented using the binary system. In fact all data can be represented in the binary system, means the computer can organise and transmit data of any type. It deals with the binary code (0s and 1s – bits) irrespective of the original format of the data. There are different processes involved to digitise each data type.

TextText is digitised using a standard method of conversion such as ASCII. It works by assigning each character with a decimal number and converting this number into binary code.

A scanner creates digital data from any printed page of text. However, unless instructed otherwise it will represent this text as an image. Optical character recognition (OCR) software converts text on paper into digital data that can be edited. This is done by matching it with the shape of the letter. Characters it cannot read are marked with a tilde (~).

GraphicsGraphics are digitised using a process called bit-mapping. Bit-mapping is the relationship between the graphic on screen and the bits in memory.

All graphics are made up of pixels, and each of these is assigned one or more bits. The number of bits per pixel is called the bit depth (or colour depth). At the simplest level, a graphic with a bit depth of one would have 2 colours. The 0 bit would be white, and the 1 bit would be black.

The file size of a graphic can be calculated using this formula:

File ¿¿KB¿=Horizontal pixels×Vertical pixels×Bit depth8×1024

The file size is affected by the resolution of the graphic. The resolution is the total number of pixels on the screen. It is calculating by multiplying the horizontal and vertical dimensions in pixels. The division in the above formula converts it from bits to bytes (8 bits = 1 byte), and to kilobytes (1 kilobyte = 1024 bytes).

Colour and greyscale (shades or tones) increase the number of bits per pixel and require more storage. If two bits represent one pixel, four shades are possible, since two bits results in four binary numbers: 00, 01, 10, and 11. Colour graphics are obtained from an RGB (red-green-blue) screen that uses a combination of red, green and blue colours. The minimum number of colours is eight: red only, green only, blue only, red and green (yellow), red and blue (magenta), blue and green (cyan), red, green and blue (white) and no colour (black). The relationship between the bit depth and number of colours or tones:Number of colours∧tones=2Bit Depth

These apply to raw image. Compression formats such as JPEG (Joint Photographic Experts Group) can be used to reduce file size.

AudioSound is digitised using a method called sampling. Sampling converts a sound wave to audio. It has three important characteristics called the sampling rate, bit resolution and the number of channels. Sampling rate is the number of times a sample (slice) is taken from the sound wave. During a sample the

amplitude of the wave is measured and converted to a number. The higher the sampling rate, the better the sound, but the larger the file is.

Bit resolution (or sample size) is the number of bits per sample. The most common sampling sizes are 8 bit, 16 bit and 24 bit sound. The larger the bit resolution the better the quality of sound. Voice is often produced using 8 bit sound, while CD quality stereo requires 16 bit resolution and larger file sizes.

Channels used by the sound. Mono uses one channel and stereo uses two channels (left and right) of sound. Stereo sound results in better sound.

Sampling rates and their uses:Sampling Rate Bit Resolution Best use for audio files

11.025 Hz 8-bit Low quality – acceptable for voice22.05 Hz 8-bit Acceptable quality with low file sizes44.1 Hz 16-bit CD quality – minimum for serious audio protection.48 Hz 16-bit Standard for most digital systems such as DAT recorders.96 Hz 24-bit Serious music production – present recording standard.192 Hz 32-bit Standard under development

The file size of audio can be calculated using this formula:

File ¿(¿KB¿)=Sample rate×Bit resolution×Time (s )×Channels

8×1024

VideoVideo is made up of frames that contain individual images. To satisfactory play a video, we need to consider the speed at which the image can be shown. The speed of a video or animation is called the frame rate and is measured in frames per second (fps). The higher the frame rate, the smoother the video or animation is.

Sampling rates and their uses:Frame Rate Examples

30+ Screen refresh rate of monitors.25 Video speed for the PAL system.24 Film speed for motion pictures.12 Cartoon animation speed.8 Minimum speed for the illusion of motion.

In order to calculate the file size of a video the total number of frames is needed (frame rate × length is seconds) and the formula for a graphic. This formula is:

File ¿(KB¿)=Frame rate×Time (s )×Horizontal Pixels×VerticalPixels×Bit Depth

8×1024

A frame grabber captures and digitises graphics from a video. If a video has a frame rate of 25 fps then the freeze

frame operates by grabbing an image that lasts for 125

of a seconds.

Data compressionData compression reduces the number of bits required to represent the information. It allows the user to store more data and makes data transmission faster. The amount a file is compressed is measured by the compression ratio, which compares how much larger the uncompressed file is to the compressed file. If the compression file is half the size of the uncompressed file, then the compression ratio is 2 to 1 (2:1). A higher compression ratio indicates greater compression of data. High compression ratios can be achieved with graphic, audio and video files, but often result in downgrade of quality. Some compression formats include JPEG, WMA, MP3 and MPEG.

Displaying and distributionDisplaying and distributing digital media products involves the presentation of that product using a range of devices.

DisplayingThe media used to display digital media products is dependent on the data type, the audience and the hardware requirements of the product. Display devices include screens, printers and speakers. A screen is a display surface that provides immediate feedback about what the computer is doing. It can

display text, graphics, animation and video data. The screen uses pixels to display data. Screens that allow more pixels to be displayed and have a smaller dot pitch have clearer images. The most common type of screen is a monitor, which mainly use CRT (cathode-ray tubes). Other screens use LCD (liquid crystal display) technology. Data projectors use LCD technology to project images and videos onto a larger screen.

A printer is an output device that produces a paper copy of the required data. The two types of printers are inkjet and laser printers, which use ink and toner (or cartridge) respectfully, to create the data on the paper.

A speaker is a device used to present sounds and audio. A small speaker is usually located in most personal computers inside the system unit. However, high quality stereo speakers are often connected to the computer using a port and a sound card. A speaker generates sounds electromagnetically. A core of wire is attached to a core. The coil is magnetised and causes the cone to vibrate. The movement of the cone makes the air near the cone vibrate and this creates sound waves.

DistributionThe media used to store distribute digital media products is also dependent on the data type, the audience and the hardware requirements of the product. Distribution involves optical disks, the Internet and streaming.

Optical discs are a storage medium used to distribute digital media. Data is read and written using laser technology. Optical discs have the capacity to store large amounts of data. Some types of optical discs include CDs and DVDs:

CD (compact disc) is a polycarbonate disc whose surface is coated with a reflective layer of metal. The standard CD is 12 centimetres in diameter and can store up to 800 MB. There are many kinds of CDs such as CD-ROM, CD-R and CD-RW.

DVD (digital versatile disc) is similar in appearance to a CD and can store in excess of 17 GB. There are many types of DVDs such as DVD-ROM, DVD-RAM, DVD-R and DVD-RW. DVD-ROM drives can play DVD movies, read DVD data discs, play audio CDS and read computer CDs.

The Internet is a network of computers used to display and distribute digital media. Websites present information using all of the data types. A user visits a website and digital media is displayed from powerful computers called servers. Websites are available on a range of topics and display text, graphics, animation, audio and video. The Internet also allows digital media products to be distributed.

Streaming is a method of displaying audio and video across a network. It occurs when a computer begins to receive content from a server and plays the content before the entire file has been transferred. Streaming uses the bandwidth efficiently as it sends data at the speed the computer can play the content. The bandwidth is the quantity of information that can be send through a transmission medium. Streaming is widely used on the Web. A streamed video is played within a few seconds, but the data is not permanently stored on the computer.

Further Summary of CHAPTER 11Comparison between Bitmap and VectorBitmap Vector

Every Pixel represented in memory Algorithms representing OBJECTS Editing:

Eraser Pixel by Pixel editing

Layers

Manipulation: Paint over Erase

Manipulation: By handles:

Stretch Shrink Reshape Move

When zooming in:Pixilation, Stair-casing

When zooming in: keep accuracy

File TypesBitmap Graphics JPEG (joint photographic expert group) – compressed data type by using pixel averaging by collectively groups

describe a group of pixels with a similar colour. BMP (bitmap) – uncompressed data type

Vector GraphicsAudio WAV – uncompressed data type MP3 (MPEG audio layer III) – compressed data type, 11:1 compression rate.

MIDIMIDI stands for Musical Instrument Digital Interface, and only describes notes.

AnimationFlash – multiple frames that give moving images.

SWF – flash GIF – compressed format, where only 256 colours are used.

VideoMPEG (moving pictures expert group)

Methods of Compression File formats such as JPEG, MPEG and MP3 use a compression method called lossy compression where the

original file and data cannot be retrieved. File formats such GIF uses loss less compression where the original file can be retrieved.

Animation Types Cell-based animation uses a separate image for each frame. Path-based animation uses a moving object on a fixed background.