Monthly Archives: March 2012

Multimedia technology – what we’ve learnt so far!

For the past few weeks the class has been studying the final topic of the course, multimedia technology. Here is a summary of what we’ve learnt so far.

Creating a multimedia solution/applications.

A multimedia application is the use of media types within the program. Multimedia applications are most of the time interactive. There are three types of multimedia applications:

  • A stand-alone application.
  • A web page.
  • A Presentation.
These applications are created using the same waterfall model used in the software development stage but are applied slightly differently. 
ANALYSIS:  Get specification/ aims of application
                   Who will use it
                   Where will it be shown/distributed.
DESIGN:      The program structure
                   How the HCI (human computer interface) works
                   How each screen will look (if there is multiple screens)
                   Which media elements will be used(video, audio and/or images)
IMPLEMENTATION: Create the application.
                               What software will be used to import/export/embed media elements.
                               What is the most appropriate authoring software.

TESTING: Make sure everything works as expected (multiple windows, links, videos/audio streaming etc)

DOCUMENTATION: Hardware requirements and where the user will find help with application.

EVALUATION: Evaluate robustness of application.

MAINTENANCE: Perform corrective, adaptive and perfective maintenance.

Fix bugs (corrective)  Add additional features/ make changes (perfective)  Improve application by external software/hardware (adaptive)

Bitmap Graphics

The two main devices used for capturing still graphic data are a scanner and a digital camera.

CCD(Charged Coupled Device): This is used to capture the light.

ADC(Analogue-Digital Converter): As light is an analogue signal, the ADC converts the light signal captured by the CCD into a digital signal.

There are 4 different file storage types:

  • Bitmap (.BMP)
  • Joint pictures expert group (.JPG/JPEG)
  • Graphic interchange format (.GIF)
  • Portable network graphics (PNG)
Features within Bitmap Graphics

GIF TRANSPARENCY: When a GIF is made transparent, the background of the GIF is made the same colour as the background of the document the user is placing it into. for example, a GIF that is made transparent and is placed on a blue background. The GIF’s background will become blue.
GIF ANIMATION: This allows a number of still pictures (frames) to be compressed together to create a moving picture (animation) 
RLE(Run Length Encoding): is a compression technique that runs of data. This means that sequences with the same value are stored as a single element, rather than the original run.
CLUT(Colour Look Up Table): This is a table of colours which is used to change a set of preset colours. they are found in graphic software packages. e.g. paint.
Calculating Bitmap graphic storage requirements
Firstly we must calculate the number of pixels in the image
number of pixels = image width x resolution x image height x resolution 
example: How many pixels are there in an image 5 inches by 6 inches and with 700 dpi(dots per inch)
number of pixels = 5 x 700 x 6 x 700
                         =14700000 pixels
Calculating File Size
to calculate the file size we must multiply the number of pixels by the colour depth. To get the answer into bytes, we must divide by 8. 
File size(in bytes) = total number of pixels x the colour depth of each pixel / 8
example: an image 5 inches by 6 inches with 700 dpi uses 16 bit colour depth. calculate the file size.
Number of pixels = 5 x 700 x 6 x 700
                         = 14700000 pixels 
File Size = 14700000 x 16 /8
              = 29400000 bytes 
                 29400000/1024 = 28710.9 KB
                 28710.9/ 1024 = 28.04 MB
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Posted by on March 17, 2012 in Computing