MULTIMEDIA TUTORIAL-II

SHASHI BHUSHANSOCIS, IGNOU

Hardware and Software Capturing & displaying image

Graphics AdaptorsScannersDigital CamerasPhoto CDMonitors

Hardware and Software for Capturing & Displaying Image

Refresh RateResolutionMagnetic Fields

Graphics Adaptors

Also called video cards are limiting factors in displayTwo standard VGA Super VGA (S-VGA)

Graphics Adapters

VGA Standard provides 16 colours at 640 x 480 or 256 columns at 320 x 200.VGA standard is insufficient for multi-media applicationSVGA is generally used for multimedia application (640 x 480 in the 64 k colours)

Graphics Adapters

SVGA is not a standard and different drivers are needed for each card.Colour depth of a card depends upon the amount of memory

Graphics Adapters

Graphics cards are usually supported with 1024 x 764 with 16 million colours and 2 M memory.Many cards claim to be graphics accelerators having an extra IC which does the calculation necessary to determine what parts of video memory need updating.

Digital Cameras

Digital camera, also known as still video cameras, take still photographs and put them directly into digital media without using film. The images are usually saved to a floppy or hard disk and can then be downloaded into your computer.

Refresh Rate

Minimum refresh rate of a monitor should be 60 Hz (I.e. the screen is redrawn 60 times a second)Preferable 70-75 Hz in order to prevent any flicker

Computer Colour Models

RGB (Red, green blue)HSB (Hue, Saturation, Brightness)HSL (hue, Saturation, lightness)CMYKCIE

RGB

In RGB, colour is specified by setting the amount of red, green and blue in the range of 0 to 65535.

HSB and HSL

In the HSB and HSL models, you specify hue or colour as an angle from 0 to 360 degree on a colour wheel and saturation, brightness and lightness as percentage

HSB and HSL

A lightness of 100% - White colour

A lightness of 0% - Black colourA lightness of 50% - Pure colour

HSB and HSL

Saturation is the intensity of the colour. At 100% saturation, the colour is pure; at 0 percent saturation, the colour is white, black or gray.

Location of Colour in colour wheel

Colour DegreeRed 0Yellow 60ºGreen 120ºCyan 180ºBlue 240ºMagnets 300º

Video

Of all the multimedia elements, video places the higher performance demands on your computer and its memory.

Video : Storage Requirement

Requirement of a still colour image - 1 M Byte (Assumption)

For Appearance of motion multiply by 30 (30 times/sec.) – 30 x1 M Byte (to play video per second)To play video per minute – 60x30 MB = 1.8 GBTo play video per hour –1.8 GB x60 =108GB/h

Broadcast video standards : Analog

Three analog broadcast and video standards and recording formats are in use around the world.NTSCPALSECAMHDTV

Broadcast Video Standards

Each system is based on a different standard that defines the manner in which information is encoded to produce the electronic signal that ultimately creates a television picture.

National Television Standard Committee (NTSC)

Used in Japan, USA for broadcasting and displaying video.Defines methods for encoding information into the electronic signal

NTSC

As specified by the NTSC standard, a single frame of video is made up of 525 horizontal scan lines drawn into the inside face of a phosphors coated picture tube of every 1/30 of a second by a fast moving electron beam.

NTSC

The picture is laid down on the screen in two passes, first odd numbered lines and then even of 60 passes/second or 60 Hz. Using two passes like this is known as interlacing and helps prevent flicker. Remember that computer monitors draws the lines of an entire frame in one scan, without interlacing.

PAL (Phase Alternate Line)

Used in UK, Europe, Australia and South Africa.Uses 625 lines in the frame rate of 25 frames/sLike NTSC it is interlaced at 50 Hz.

SECAM (Sequential Colour and Memory)

Used in France, Russia and other countriesUses 625 lines and 50 Hz. SystemDiffers from NTSC and PAL in basic technology and broadcast method

HDTV (High Definition TV)

Going to be the Next StandardProvides 1200 lines3, different standards available, two of which are analog and the third digital.

Digital Video

Variety of digital video formatsVideo files are very large, all formats include some kind of compression.Formats such as AVI – Microsoft's video for windows and Apples Quick time use several different kinds of compression.

Video Colour

Colour reproduction and display is different between television and computer monitors. Computer use RGB component video (they split colours into red, green and blue signals) Their colours are purer and more accurate then those seen on a television monitor.

Video Colour

NTSC television uses a limited colour palette and restricted luminance (brightness) levels and black levels (the richness of the blocks). Some colour generated by a computer that display fine on RGB monitor may be illegal for display on an NTSC television.

Video Recording Formats

Several video recording formats existingFormats represent different means of putting the video signal onto tape.

Video Recording Formats

S-VHSHi-8 (High Band 8 mm)Betacam

S-VHS and Hi-8

S-VHS video keeps the colour and luminance information on two separate tracks, which gives better quality.Hi-8 is better quality than S-VHS and one can make unlimited VHS copies without the degradation when copying from VHS to VHS.

Principles of Animation

Animation is possible because of a biological phenomenon known as persistence of vision. An object seen by the human eye remains mapped on the eye’s retina for a brief time after viewing.

Principles of Animation

If the location and shape of an object is changed rapidly, the eye will perceive change

Animation

Television video builds 30 entire frames a picture every second; the speed with which each frame is replaced by the next one, makes the images appear to blend smoothly into movement.Movies are shot at 24 frames per second.

Animation

To make an object travel across the screen while it changes its shape, just change the shape and also move it a few pixels for each frame. Then, you play the frames back at a faster speed, the changes blend together and you have motion and animation.

COMPUTER ANIMATION

One can usually set your own frames rates on the computer, but the rate at which changes are computed and screens are refreshed which will depend on the speed and power of Hardware.

Animation File Formats

Director (MMM)Animator P & D (FLI & FLC)Super Card, Director, Super DBD (PICS)Window Audio Video Interfered format (AVI)Macintosh Time-Based Data Format (Quick Time)

Making Animation that work

Multimedia Authoring Systems typically provide tools to simplify creating animation within that authoring system. And they often have a mechanism for playing the special animation files created by dedicated Software.