Jason Dunn
12-18-2006, 05:43 AM
<div class='os_post_top_link'><a href='http://en.wikipedia.org/wiki/Aspect_ratio_%28image%29' target='_blank'>http://en.wikipedia.org/wiki/Aspect_ratio_%28image%29</a><br /><br /></div>"Multiple aspect ratios create additional burdens on filmmakers, consumers and confusion among TV broadcasters. It is not uncommon for a widescreen film to be presented in an altered format (cropped or expanded beyond the Original Aspect Ratio). It is also not uncommon for a 16:9 broadcast to embed a 4:3 commercial within the 16:9 image area. A viewer watching on a standard 4:3 (non-widescreen) television would see an 4:3 image of the commercial with 2 sets of black stripes, vertical and horizontal (matchboxing). A similar scenario may also occur for a widescreen set owner when viewing 16:9 material embedded in a 4:3 frame. It is also not uncommon that a 4:3 image is stretched horizontally to fit a 16:9 screen and avoid pillarboxing.<br /><br />This is not a problem in countries where the 625 line television standard is used (usually with PAL colour), because this standard has provision for a pair of pulses contained within the video signal. This pair of pulses is detected by television sets that have widescreen displays and cause the television to automatically switch to 16:9 display mode. When 4:3 material is included (such as the aforementioned commercial), the pulses are removed and the television switches to a 4:3 display mode to correctly display the material. Where a video signal is transmitted via a European SCART conection, one of the status lines is used to signal 16:9 material instead. The NTSC video standard contains no provision for widescreen mode switching.<br /><br />Wikipedia is such an awesome resource, at least for the mostly factual entries that is - I never knew about this PAL/NTSC signal issue for instance.