When looking into color difference keying background materials, there are many options. Compositing and Keying have a long history, with many different technical advances that each had their own optimal solutions. Some have been optimized for photo-chemical processes and others for digital video.
For most modern color difference keyers, like Previzion’s built-in DvMatte Pro 3, there are specific recommendations that allow for production quality keying in real-time.
Among your material options are:
- Digital or “Digi” Paint – High pigment specialty paint
- Cyc or Professional Cycloramas – Pre-painted seamless floor and wall modules that cast no shadows onto themselves.
- Spandex and Cloths – Portable evenly dyed fabric materials that can be stretched seamlessly over frames.
As explained in the Blue vs Green Screen section, there are major differences between regular Chroma Blue/Green and Digital Blue/Green. Chroma colors are optimized and designed for photochemical processes and work best with negative film. Because of this nature, it is inherently “darker” than its Digital counterpart color.
There are other options for paint, like Rosco’s DigiComp Paints, but we still highly recommend Digital Green and Digital Blue (“Digital Green” and “Digital Blue” is trademark and/or registered under Composite Components Company, or CCC). Another name for these “digital” colors are Component Green and Component Blue.
The difference between using these specialty paints as opposed to a similar shade of these colors from your local hardware store is that not only are these colors consistently been tested and engineered to be within the proper color spectrum that digital cameras “see”, but they are also a very high pigment paint, meaning that one good coat of these paints on a properly treated surface is often sufficient to yield the proper paint coverage. It goes without saying that the sheen of Digital Green and Digital Blue is also a very specific matte finish to, again, yield the proper color spectrum.
- CCC’ Digital Green or Digital Blue – This paint, when applied according to the directions on the pail, with a white underlayer, has a very good separation between the green channel and the red and blue channels.
- Green Kino Flo Tubes – Colored Fluorescent Tubes are usually not necessary nor recommended when working with the CCC Digital Green paint. In most applications, green tubes tend to spill green all over.
- Green Gels – Avoid using green gels over your lights, as they may actually narrow some of the Digital Green/Blue color spectrum.
- Lighting the screen – Lighting the your screen should be around the same f-stop that the foreground subject is set to, which is also what CCC specifies for their paints.
Seamless backgrounds and Cycs (Cycloramas)
For more permanent installations, the most recommended options is to either purchase easy-to-assemble a seamless background or build one yourself. There are experienced construction crews that are very capable of building seamless backgrounds that can be painted green or blue.
As an alternative, there are modular cycs that can be easily assembled and painted on location.
The one area that is always difficult, however, is the occasional compound corner. A company that makes very good off-the-shelf modular cycs is Pro Cyc.
Fabrics and Tape
For temporary installations, fabric is often the best choice. Using frames to stretch the fabric around is usually a faster setup and lighter for travelling productions.
There are a couple of things to know about fabric:
- When using dyed spandex always use the matte side facing the camera. Spandex has a shiny and a matte side. The matte side is the one intended to be facing the camera, whereas the shiny side should always be avoided.
- Green/Blue fabrics don’t generally produce the same separation that paint does.
- Keep your fabric clean and be careful around sharp corners and objects as these can tear your material.
We recommend using CCC’s fabric backings or equivalent, just make sure that the fabric is the correct “lime green” or “smurf blue” that Digital Green and Digital Blue are.
For covering seams, you may use a “magic skirt” of the same material and color and some tape.