Archive for the ‘chromakey’ Category

Blockbuster Movies Without Visual Effects

Friday, March 8th, 2013

Before VFX: Blockbuster movies without visual effects.  The site at the following link has a collection of of behind-the-scenes photos prior to visual effects, hence revealing green screen etc. shots, actors festooned with CGI motion-tracking rigs etc.

Discovered via NoFilmSchool, which I subscribe to and heartily recommend for makers and enthusiasts of movies and videos etc.

It even has some shots from John Carter, in which I was a film Extra, though sadly none of “my” scenes.   I wish I could re-cut it, not only for my bits 🙂  but also to allow its climate catastrophe message to be more dramatically expressed, some of the “cutting-floor” scenes were truly emotional.  Regardless,  “all the world’s a stage” 🙁

Sony EX3 Noise & Bits-Resolution & Green-Screen

Sunday, November 4th, 2012

It has been said ( I believe by Alister Chapman ) that there are only marginal benefits from recording XDCAM-EX to more than 8 bits, due to the relatively high noise of this camera, as compared to more typical broadcast cameras.

In my experience, while it was a wonderful step-up from my Z1, certainly it’s recordings are noisier than I’d like, leading me to pretty-process certain footage (using Neat Video denoising plugin to my NLE).  And as a recent project with reasonably well-lit green-screen illustrated, it’s noise in shadows can be a particularly nuisance (much time in post experimenting to work around this).

So I wondered:

  • Even if marginal, to what extent is 10-bit beneficial to EX3 recording?
  • For the EX3, when recording 10-bit, it is also 4:2:2, surely a benefit to chroma keying and resizing (reframing, stabilising/deshaking/tracking).
  • Could the benefit depend on editing workflow?  For example:
    • What if subsequently de-noising (like I mentioned)?
    • Some NLE’s do bits-dithering, hiding the quantisation/banding that would otherwise be apparent from having only 8 bits.

I need to do my own experiments, but for now, here (below) are some results from web-searching…


Sony EX3 for Green Screen (Greenscreen)

Sunday, November 4th, 2012

 Tips on using an EX3 for chromakey (e.g . Greenscreen) work

Chromakeying in After Effects (e.g. linked to Premiere)

Monday, September 3rd, 2012

  • Put the two layers in Premiere tracks
  • Send it to AE
    • [Replace with AE Composition]
  • In AE use Keylight (offers more control than Premiere’s Ultra vector-keyer)
  • Simply switch back to Premiere, it’s already in the timeline
  • {BUT … does that constitute “Dynamic Linking”, which I have heard is inefficient on cpu/speed?}

Chromakeying (Chroma-Keying) in Boris

Saturday, September 1st, 2012

The following tutorial is great as it shows how to employ not only the chromakey effect itself (including some typical adjustments and settings values) but also a suite of associated ancillary effects, such as choker, pseudo-spill etc.

Cineform and Alpha Channels

Friday, August 31st, 2012

The full (paid) version of GoPro-Cineform Neo (as I have) does support alpha channels.

(A colleague initially thought otherwise – but that impression turned out to be based on info from old forum threads)


Chroma Upsampling (Chroma Interpolation)

Friday, August 31st, 2012

Shooting green-screen onto a 4:2:0 chroma-subsampled format, intending of course to use it for chroma-keying.  Obvious disadvantage is green-ness of green-screen only gets sampled at quarter-resolution.  Not a show-stopper, given my target deliverable is standard definition, but anyhow, towards perfectionism, is there any way to up-sample to 4:4:4 i.e. full definition colour?

It does occur to me that something more sophisticated than chroma blur ought to be possible, broadly along the lines of edge-following methods employed in resizing. What’s out there?

  • Simplest method, that most people seem to use, is chroma-blur.  That’s only the chroma, not the luma.
  • Searching around, Graham Nattress has analysed the problem and seems to have produced a more mathematical approach.  But it’s only available (at time of writing) for Final Cut (which of course is Mac-only at present).

Some tools that “promise” upsampling, but I wonder by what methods:

  • GoPro-CineForm intermediate.  The codec settings include an option to up-sample to 4:4:4
  • Adobe Premiere, but only if a Color Corrector effect employed.
    • But the crucial thing here, regarding the usefulness of this, is whether it uses any better method than chroma blur.

Some questions:

  •  Does Adobe have anything built-in to do something Nattress-like nowadays?
  • DaVinci Resolve?
  • Boris?