The Digital Fact Book - Quantel

PerfShort for perforations. It is a way to describe some information about the format of imageson 35mm film by how many of the perforations, or sprocket holes, are used per image.For example, Full Frame is 4 perf.P-framesSee MPEG-2Photo-realVideo and film effects that are constructed in such a way that they look totally real andnot synthetic are referred to as photo-real effects. This use of effects has increased rapidlyand has changed the way many productions are shot and post produced – leading to lowerbudgets and better looking results.Achieving photo-real results requires careful planning from the shoot and computer imagerythrough to compositing in post production. Excellence in keying, so there are no telltales of bluescreen haloes or color spill, are among the many techniques required for successful results.See also: Compositing, Digital keyingPPixel (or Pel)A shortened version of ‘Picture cell’ or ‘Picture element’. The name given to one sampleof picture information. Pixel can refer to an individual sample of R, G, B, luminance orchrominance, or sometimes to a collection of such samples if they are co-sited and togetherproduce one picture element.See also: Aspect ratio – of pixels, Sub-pixelPLDProgrammable Logic Device. This is a family of devices that has included PROMs(Programmable Read Only Memories), PLAs (Programmable Logic Arrays) and PALs(Programmable Array Logic). Today FPGAs (Field Programmable Gate Arrays) are the maininterest. These range in size and complexity from a few dozen up to millions of gatesto provide a compact and efficient means of implementing complex non-standard logicfunctions. They are widely used in Quantel equipment where FPGAs also offer a fast trackfor the implementation of new improvements and ideas.See also: Moore’s LawPlug-inSoftware, usually from a third party, that brings added functionality to a computerapplication. For post production this may add highly specialized aspects to digital effects.140