Scan conversion

Scan conversion involves changing the picture information data rate and wrapping the new picture in appropriate synchronization signals. There are two distinct methods for changing a picture's data rate: ;Analog Methods (Non retentive, memory-less or real time method) This conversion is done using large numbers of delay cells and is appropriate for analog video. It may also be performed using a specialized scan converter vacuum tube. == How to realize ==

The process in practice is applicable only using integrated circuits in LSI and VLSI scales. Timing, interference between digital and analog signals, clocks, noise and exact synchronization have important roles in the circuit. Digital conversion method needs the analog video signal to be converted to digital data at the first step. A scan converter can be made in its basic structure using some high speed integrated circuits as a circuit board however there are some integrated circuits which perform this function plus other picture processing functions like scissoring, change of aspect ratio and … an easy-to-use example was SDA9401. == Some examples ==

Up conversion (interpolation): • In many LCD monitors there is a native picture mode, however the monitor can display different graphical modes using a scan converter. • In a 100 Hz/120 Hz analog TV, there is a scan converter circuit which converts the vertical frequency (refresh rate) from standard 50/60 Hz to 100/120 Hz to achieve a low level of flicker which is important in large screen (high inch) TVs. • An external TV card receives the TV signals and converts them to VGA or SVGA format to display on monitor. Down conversion (decimation): • Many graphic cards have output for standard-definition television. Here there is a conversion from computer graphical modes to TV standard formats. • Other graphic cards lack an SDTV output, but their VGA outputs can still be connected to an SDTV through an external scan converter (pictured). Scan conversion serves as a bridge between TV and computer graphics technology. ==See also==