Is blue or green best for chroma key?

Discussion in 'Amateur Video Production' started by tobeok, Jan 20, 2007.

  1. tobeok

    tobeok Guest

    I'm about to purchase a chroma key backdrop system and would enjoy
    hearing opinions on choosing blue or green before my order is placed.
    BTW editing is on an Intel iMac employing FCE HD with footage shot on
    HDR-FX1.

    Thanks ...
     
    tobeok, Jan 20, 2007
    #1
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  2. tobeok

    Ken Maltby Guest

    It depends on whether the subject wears blue or green ties.

    There are reversible backdrops available, blue/green.

    Luck;
    Ken
     
    Ken Maltby, Jan 20, 2007
    #2
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  3. With zero information about what you are shooting and
    what kind of effects, etc. you want to do, might as well
    flip a coin.

    OTOH, if you wish to fill in the missing information, there
    may be some people here who can share some valuable
    experience.

    For several reasons that are relevant to my situations, I
    would go with green, but we have no idea if any of them
    apply to your case?
     
    Richard Crowley, Jan 20, 2007
    #3
  4. tobeok

    S. Whitmore Guest

    FWIW, I went with green -- but just as a seamless chroma green paper
    roll. I can always pick up a chroma blue paper roll if the need
    arises. I like the reversible options but the seamless paper seemed
    less expensive up front, plus I can cut off pieces for smaller needs
    than a complete backdrop.
     
    S. Whitmore, Jan 20, 2007
    #4
  5. Shoot against red/grey/black ;-)
    --
     
    Martin Heffels, Jan 21, 2007
    #5
  6. tobeok

    theDVshow Guest

    What you are trying to achieve is to provide your keyer with a color
    channel that is as distinct as possible. Since human skin tones and
    lips tend to be red, that leaves blue and green. So which one to
    choose? That depends on a couple of things...

    Green chroma screens have become more and more popular in recent years,
    largely because green provides a brighter color channel that tends to
    have less noise than the blue channel. The relative brightness of green
    makes it a bad choice for shooting blonde hair though, which is a lot
    easier to key against blue backgrounds.

    The bluescreen has some distinct advantages. When you can't avoid a lot
    of spill (for example when you have to put the foreground very close to
    the chroma material) you can take advantage of the fact that we tend to
    find blue casts less disturbing than people walking around looking
    sea-sick with green faces. Also, when shooting for something that will
    be composited on to outdoor backgrounds and water, a slight blueish
    cast won't be a problem.

    So if you are shooting a blonde with jeans, you'll have to settle for a
    compromise!


    Brian Alves

    Listen to the new podcast
    for DV creators- The DV Show!
    http://www.thedvshow.com
     
    theDVshow, Jan 21, 2007
    #6
  7. Or make her remove the jeans....
     
    Ashton Crusher, Jan 21, 2007
    #7
  8. tobeok

    Ray S Guest

    Green paper roll! (smacks head) Thats a darn fine idea! At least for
    studio work.

    Sometimes local cable access stations have a green screen, and often
    enough lights to use them decently.

    I bought from Ebay a small 8ft blue/green reversible fold up screen that
    can go anywhere. Its not recommended for really critical chroma work
    cause it has creases in the fabric, but a garbage matte helps gets good
    results.
     
    Ray S, Jan 22, 2007
    #8
  9. tobeok

    Mike Kujbida Guest


    And if you're looking for another cheap way to do it, go to your local
    discount flooring store and buy the cheapest roll of linoleum you can find.
    Flip it over, prime the back side and apply a coat or two or very bright
    green paint (flat, please). The advantage to this is that it can (if it's
    long enough) be rolled out onto a floor. It can be hung by stapling it to a
    2 x 4 and, when you're done the shoot, roll it back up and store it.

    Mike
     
    Mike Kujbida, Jan 22, 2007
    #9
  10. tobeok

    David McCall Guest

    In my opinion green works a little better because a lot of the
    "green" information is in the "Y" part of the signal so it
    doesn't mush up quite as badly as red and blue. Green is
    easier than blue to keep out of a wardrobe. However there
    are issues with green too.

    As was mentioned by the other poster, the spill from green can
    cause more problems with the "look" of the image than blue.
    Spill being the light that bounces off of the colored surface.
    It tends to wind up lighting your subject with the background color,
    and green just doesn't look very nice, especially on people, but then
    neither does blue. Modern chroma keyers (hardware and software)
    have what they refer to as spill supression. It looks for green in the
    subject and tries to filter it out. If you do very much of it you bet
    black and white in areas that have spill. Blue is farther from flesh tones
    than green is. Flesh tones will start to go transparent if you usee too
    much.
    Putting as much distance between the subject and the background will
    help a bit.

    Blue is a more pleasant color to be imersed in than is green.

    There is no win/win solution.

    David
     
    David McCall, Jan 23, 2007
    #10
  11. All of which are quite valid. But in the absense of ANY
    deails from the OP, we have no idea whether ANY of
    them apply to his situation.
     
    Richard Crowley, Jan 23, 2007
    #11
  12. tobeok

    tobeok Guest

    OP checking in ...

    Thanks for all the discussion, my primary projects are life sketch
    recordings enhanced with an 24" iMac displaying photos shot in wide
    screen. The talent controls the picture flow in Keynote (think
    PowerPoint on a PC).

    Anyway, considering your posts as well as some advise on "help" on the
    iMac, I ordered a 10X15 GREEN backdrop with support frame for $200 from
    http://www.backdropsource.com/ as well as a non-key 2nd drop as well.
    As one previous post points out, being immersed in blue is tolerable
    while the green basically forces you to go with chroma key.

    BTW, the iMac's light output (even turned low) is so high that the
    talent must be flooded as too not be lost in shadows, for this purpose
    two 24X32 light boxes w/eggshell grids are employed. Keeping the iMac
    in square-plumb alignment plus the lighting are the biggest challenges.
    Vortex Media's "Setup, Light, & Shoot Interviews" is a great resource
    but messing with the background is just too much grief so I personally
    take the easy cop-out route with a huge bed sheet (bed sheet routine
    ends once backdrop order arrives).

    Thanks again for all the input ...
     
    tobeok, Jan 23, 2007
    #12
  13. A piece of neutral-density gray gel over the screen
    would seem to be a lot easier and cheaper than
    dumping so much light on the talent?
     
    Richard Crowley, Jan 23, 2007
    #13
  14. tobeok

    theDVshow Guest

    theDVshow, Jan 23, 2007
    #14
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