Blue Screen & Green Screen Photography

Introduction:

The technology of compositing blue screen and green screen has improved to the point where you can pull a chroma key matte off of almost anything. However, the better the original photography and set-up, the better the matte extraction and composite.

Concept of Blue / Green Screen:

Blue Screen was originally invented as a film technique to separate the actors and composite them over another background. But why blue? Blue may have been chosen because it is least prominent in skin tone. Skin tone is made of a combination of red and green with a little blue.

Basic Blue Screen & Green Screen Photography by: Peter Kuran

Should I shoot Blue Screen or Green Screen?

The choice can be subjective as well as technical. If you are shooting on film and plan on doing the composite through traditional optical methods, you must shoot blue screen.

Subjective Considerations:

Is there one overall, overriding theme that would exclude one or the other? i.e. A sequence of Army personel wearing green fatigues and green camouflage paint would have an overall green bias and might be better shot blue screen for better separation.

Technical Considerations:

On film, the green layer has the finest grain structure. On NTSC video, the green channel has the highest sampling rate.

The blue layer of film is sharpest but is also the grainiest layer. In video, it is the noisiest channel. If you are shooting DV Video (4:1:1), it is probably best to stick with green screen.

Sources of Blue Screen & Green Screen:

Materials: Best materials for blue or green screen for rent and sale are the Digital Green or Digital Blue spandex material available from Composite Components. This provides the best reflectance of the desired color.

The "economy" method is the old "Chroma" Green and "Chroma" Blue or Tempo screen which is a spongy material available for rental and sale. This type of material is NOT preferred over Composite Components spandex material.

Lighting packages are available from: Flo-Co and KinoFlo. In our DVD Program, we used three basic set ups:

Composite Components Digital Blue Screen (12x12) with their blue spike tubes and FloCo lighting units
Composite Components Digital Green Screen with Kino Flo Image 80s (Tungsten 3200K
Composite Components Video Blue Paint on a cove with Kino Flo Images 80s (Tungsten 3200K)

Paints: Digital Green and Digital Blue Paints are available from Composite Components. Paints can also be purchased from Rosco as Rosco Ulitimatte brand or Rosco Chroma Key paint. Questions about Rosco Scenic Paint, email scenepaint@rosco.com.

Support Materials:

Support materials can be purchased from a Rosco Dealer or on line from places such as FilmTools or Studio Depot. When laid flat or perpendicular to the blue/green screen, Rosco 3931 Rigid Silver can add "extra" screen without the addition of more screen, space or lights by reflecting the blue/green screen. Rigid Silver can be positioned under an actor against a blue/green screen providing a blue/green walking surface. This type of set up gives you the best separation of the foreground and the blue or green background. However, there is no interaction with the ground and reflections will have to be rotoscoped out. When shooting in a cove environment, the lighting must be consistent (such as all tungsten Kinoflos) and cannot create the same degree of separation. One benefit the cove has is that the shadows and floor interaction you wind up with may be useful for the composite.

Shooting on a Blue or Green Screen cove:

The object of the cove is to present a shooting environment where you can photograph the subject walking around on the floor and avoid a sharp line or edge where the floor meets the wall.

Special thanks to Ultimate for the use of their stage and Ultimate Advantage Software.

Blue & Green Screen tutorial book.

Now available on DVD documents the photographic aspects of chroma key photography and videography and answers many of the following questions:

What Resolution should I use?
Tracing Markers?
Set up Procedures?
Shooting Video Blue or Green Screen?
Pre Production Check list?
Storyboards? Sequences that require blue or green screen need more detailed boarding and choreography.
Costumes - Are the costumes shiny? Sheer? Frizzy? The SAME COLOR or close match to the Blue or Green Screen Color? Blue jeans?
What type of lighting and how much is needed?

Two versions are available: The Basic Program for $24.95 or the PLUS version ($99.95) which includes Standard Rez and HD Quicktime Blue Screen and Green Screen movies you can composite with as well as pdf manual and resources.

Even if you are a PRO at shooting blue screen or green screen, your clients, associates or crew can all benefit from this new teaching aid available now in our ONLINE STORE for a special introductory price.