Frequent Asked Questions
How do I clean the chroma key fabric?
Can I walk on the Chroma key fabric?
How should I light the chroma key screen?
Will the seam cause a problem?
How is the fabric shipped? Will it be folded?
How should I store my chroma key fabric?
What makes a larger chroma key screen better?
What color is better for my chroma key screen (BLUE or GREEN)?
I only have access to a mini-DV camera, what can I do to make the
composite look better?
How to creating better looking green screen composites?
I’m interested in buying a professional video camera, what features are
best for color keying?
How do I clean the chroma key fabric?
Yes, you can wash the chroma key fabric in the washing machine and hang
or tumble dry. For larger backdrops (too big for a washing machine),
put a little soap on a cotton rag (mild soap or laundry detergent) then
run the rag under water to dilute the soap (if the soap is not diluted,
it may be hard to rinse completely). Use the rag to spot clean the
fabric. If the spots are bad, you can also use stain remover
or spray it down with a water hose.
After you are done, hang out to dry or use a hair blow-dryer
for spot drying. The important thing is to clean away any excess soap
and let it dry completely before using. If the backdrop is not dry,
dirt might attract to the wet spots. Don’t be scared to use soap if
necessary but don’t use any chemicals that will harm
synthetics (bleach, Tilex, etc).
CanI walk on the Chroma key fabric?
The fabric is very durable and will not rip or tear when walking on it.
The Chroma key fabric is made of very strong nylon/polyester that is
very difficult to rip. It is also very difficult to cut. You would need
sharp scissors or a matte knife to cut it.
When walking on it I would recommend to clean any loose mud or dirt off
your shoes and use anti-slip mats under the screen if the floor is
slippery.
How should I light the chroma key screen?
The best way to successfully pull a key is to evenly light the entire
chroma key screen. Eliminate any hot spots inside the frame. Light the
screen from the sides at 45 degree angles and Place equal amounts
of lights on each side.
The quantity of lights you need is completely dependent on
screen size. If the backdrop is fairly wide, roof mounted lights across
the length are very helpful. Place your actor 7ft – 10ft away from the
backdrop to eliminate most shadowing problems and color bleed. This
also makes it easier to light them separately.
The way you light your subject/talent depends a lot on the
scene you’re compositing them in. A backlight or hair rim light can
help give you more separation also helps minimize color bleed issues.
Will the seam cause a problem?
The seam is so small it should not effect your color key. For most
productions, the camera will also be at least 8 feet away, making it
hard to notice the seam. It is not large enough to effect the keying.
How is the fabric shipped? Will it be folded?
The chroma key fabric is rolled up then folded to fit in an optimally
sized box. This saves you money on shipping. If you want the chroma key
fabric shipped rolled instead of folded, it will be considered over
sized and can cost 2-3x more to ship.
If you’re worried about wrinkling, you should be happy to hear
that there is foam-cored for backdrops that bounce back amazingly well.
For storage, fold the fabric at the seam, then roll up on a
pole or on itself. Another option is to loosely and fold it up. Remove
every month or two and refold differently each time to eliminate
creasing.
How should I store my chroma key fabric?
The best method would be to fold the chroma key fabric at the seam,
then roll the fabric up on a pole or on itself. Another option is to
loosely and fold it up. Unroll it every month or so and refold
differently each time to eliminate any creasing.
How do I remove wrinkles?
Let chroma key fabric hang up for a day or so, depending on the extent
of the wrinkles and the wrinkles should disappear. If you need
them out faster, fill up a spray bottle with water and spray the back
side (in the area with wrinkles). The water will speed up the foam
expansion process and remove wrinkles within 30-45Min’s. Use a hair
blow drier if you need to dry the fabric quickly.
What makes a larger chroma key screen better?
When the chroma key screen is smaller, the actor has to stand closer to
the screen. If your subject is to close to the screen, you may have
problems due to the chroma key color reflecting off the screen and
bouncing onto your subject.
This is called “color bleed”. Too much bleed can cause the
subject to become transparent where the green hits their skin and
clothes. Bleed can be removed by bouncing white light into
the problematic areas or by moving your actor further away from the
screen. This is one reason why a large backdrop is extremely beneficial
for a successful color key. The larger the chroma key screen is, the
further you can pull your actor away from it.
Having a larger backdrop also makes it easier to light the
backdrop separate from the subject. With more space between the
backdrop and the model, you can easily light the backdrop without
casting dark shadows on the back of the screen. We recommend placing
the subject at least 8′-10′ away.
A larger screen will also give you more range of camera
movement. If you plan on shooting multiple angles make sure your screen
is large enough for its application.
What color is better for my chroma key screen (BLUE or GREEN)?
Both blue and green work very well for color keying. Green
tends to be more popular for DV because the camera’s CCD is more
sensitive to the frequencies in the green color spectrum and requires
slightly less light.
However, blue can be easier to work with when color bounces
onto the subject (bleed). Most people purchase green, but both colors
are industry standard.
Keep in mind that the Chroma key screen shouldn’t resemble
colors in your scene. For example, if you are taking photos of a person
wearing green clothes, then Chroma key Green may not be your best
choice. Photography studios often buy multiple colors so they have a
keying screen for any situation.
I only have access to a mini-DV camera, what can I do to make the
composite look better?
It is a common mistake to assume Mini-DV is uncompressed because it is
a digital format. In reality, the video is compressed the moment it is
recorded to tape. Mini-DV cameras record to tape at a 4:1:1 color space.
For every scan-line (720 total NTSC) every group of 4 pixels
are sampled down to a single pixel. The color channel on a mini-DV tape
is actually only 180×480 chroma samples and not 720×480. The reason the
color channel doesn’t appear to be a lower resolution is because the
luminance channel is recorded at a higher sample rate, which gives the
illusion of color shift.
This can be minimized significantly by using a good keying
plug-in. Some of the color keying programs has built-in settings to
reduce mini-DV compression artifacts. If possible, you should use a
3CCD camera for color keying.
If a 3CCD camera is not available, we recommend using a green
screen instead of a blue screen. Since the blue chroma channel on a DV
camera is inherently grainy and noisy, shooting green screen will have
less artifacts from noise and grain.
How to creating better looking green screen composites?
It is always a good idea for your subject to take up as much of the
frame as possible. Afterwards, you can scale them down to fit inside
your composite.
For example, if you were working on visual effects shot with a
final output resolution of 720, you would shoot the green screen
footage at 1080. The footage would then be keyed and scaled down to 720.
The more you are able to scale your footage down, the cleaner
the edging will look in your final composite. You rarely ever want to
frame your subject as small as they will be in the final shot. We also
don’t recommend zooming or pushing into chroma key footage after it has
been shot.
I am interested in buying a professional video camera, what features are
best for color keying?
Cameras that record to memory cards or directly to hard drives are
preferred because they are not limited to the NTSC 4:1:1 DV tape
compression. Some can record at 4:2:2 (1/2 color space samples) or
4:4:4 (Uncompressed color space).
The color pixel information on a 4:2:2 camera has twice as
many color pixels as a 4:1:1 DV camera. The color keying artifacts due
to color compression will be minimized on a 4:2:2 camera or eliminated
with a 4:4:4 camera.
When shooting digital video, we recommend a 3CCD 4:2:2 (1/2
compressed chroma channels) or a high-end 3CCD 4:4:4 (uncompressed
chroma channels) camera.
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