the art of compositing 01 pertemuan 06 matakuliah : uo666 / dkv visual fx tahun : 2009
TRANSCRIPT
The Art Of Compositing 01 Pertemuan 06
Matakuliah : UO666 / DKV Visual FXTahun : 2009
Bina Nusantara
Keying is such a vital area of visual effects,
research continues to both improve the
quality of the key and easy of use of
the module.While it is not strictly keying
in the greenscreen sense - there are a
host of new matte generating tools that
extract mattes via a range of different
technologies.
Digital Keying
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The age old question is should one shoot against
blue or green screen. Many factors influence
the decision, the most obvious being what
colours are represented in the foreground
subject. For a while prior to the Vision 2
stocks - the film stock itself was grainier in the
blue channel, and hence green screen grew
in popularity. One urban myth is that human
skin contains a lot more green than blue and
so blue screen should be better, in fact this is
only true of blond hair - which is often better
shot against blue - but human skin while not
equally balanced in its green and blue
components - easily keys from either blue or
green screen.
Green or Blue?
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Zmatte
The standalone Zbig Software was available on the market since 1998 as a chroma key/compositing program and as a plug-in for many standard programs, (Fusion, Illusion and others)
A unique feature of Zbig Software is the automatic and dynamic application of background color reflections onto the composed foreground, resulting in an extremely convincing composition.
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Keylight
The keyer is effectively a colour difference keyer, so it works better on primary colour, and according to the Foundry's Bruno Nicoletti "to work well it needs a high primary saturation" in the keying background. Keylight's strength comes from the algorithm that allow the spill removal to become an intrinsic part of the process. Recently, it has been upgraded to a full float implementation on Shake, but this is only currently as a plugin. The version shipping with Shake 4 now respects Float and no longer clamps to 16 bit. Even with Keylight's great foreground colour correct, in a floating pipeline in Shake, it is often only used for key or matte generation and not for the key & comp of the foreground and background. The work of CFC in pioneering their compositing pipeline caused them to get a technical achievement award in 1996. Keylight anecdotally is thought to be best on transparent items such as sheer fabric - glass ware and say soft hair. There is now Linux & Burn support for Keylight. When using the Keylight controls fg bias work best with near neutral colours. Nicoletti has also written a great new 64 bit version of Keylight for Discreet (A M&E) products which also has improvements to the matte processing and colour correction tools.
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Primatte
Primatte today runs on a wide variety of OS - LINUX, OSX, NT IRIX etc. Primatte is one of the most widely available plugin keyers, from Flame, Smoke to Fusion, Shake, Quantel, AE, Photoshop, Nuke and others. When using Primatte's controls the fgbias effect the f/g colour & Matte opacity, the key controls are the shadow gain, mid gain and highlight gain.
For a full discussion of Primatte listen to our fxpodcast with Scott Gross of IMAGICA Corporation of America by clicking the links at the top of this page. Scott has been involved with Primatte from the beginning and he explains not only the keyer's approach but much of its history.
The State of the Art Technology by
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Ultra Keyer (Fusion keyer)
- Five modes of spill suppression to eliminate difficult reflection halos.- Animated garbage mattes for isolating rigging and set elements.- Adjustable edge gamma and fringe color correction.- Matte thresholding for semi-transparent region replacement.- Matte blur, gamma, and contrast control for post key processing of the
matte.- Advanced color selection includes a more varied range than traditional
"select" and "soften" style keyers
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