What is the three major' adverse side effects of scan conversion? 

Subject Computer Graphics and Multimedia
NU Year Set: 3.(d) Marks: 2 Year: 2011
Scan conversion or scan rate converting is a technique for changing the vertical/horizontal scan frequency of video signal for different purposes and applications. The device which performs this conversion is called scan converter. The application of scan conversion is wide and covers video projectors, cinema equipment, TV and video capture cards, standard and HDTV televisions, LCD monitors and many different aspects of picture and video processing.
 
Scan conversion process, not only needs to make changes in synchronization (sync) frequencies, changes in picture information data rate are also mandatory in most cases. There are two distinct methods for doing the process:
 
 
  1. Analog Methods (Nonretentive, memory-less or real-time method) - This conversion is done using large numbers of delay cells and is appropriate for analog video.
  2. Digital Methods (Retentive or buffered method) - In this method, picture is stored in a line or frame buffer with n1 speed (data rate) and is read with n2 speed, several picture processing techniques are applicable when the picture is stored in buffer memory including kinds of interpolation from simple to smart high order comparisons, motion detection and to improve the picture quality and prevent the conversion artifacts.

Scan conversion is essentially a systematic approach to mapping objects that are defined in continuous space to their discrete approximation. The various forms of distortion that result from this operation are collectively referred to as the aliasing effects (side effects) of scan conversion.

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