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  • Mon, Mar 17 2008 12:15 AM

    Grain Matching in Avid using BCC Match Grain

    Grain Matching in Avid using BCC Match Grain

    Match and apply authentic film grain to your Avid media using BCC AVX MatchGrain

    By John Lafauce

    Boris Continuum Complete AVX 4.2’s Match Grain filter takes a snapshot of film-to-video (“telecined”) media and generates a grain signature which is than applied to a destination clip that has very little or no grain. A common application of this filter is adding grain to computer-generated imagery to lend to a more realistic composite. Match Grain can also be used to grain footage shot on video so it edits more seamlessly into a sequence with telecined media.

    To demonstrate how BCC Match Grain’s automatic grain sampling is used, I will borrow grain from a clip of a surfboard surfacing from the ocean depths. Then, I will apply that
    grain to a computer-generated sphere I composited onto the tip of the surfboard.

    Click here to view the ungrained video
    (Please allow a moment for the movie to load)

    Media

    • Beauty Sphere.mov – A 3D sphere rendered as a premultiplied, processed foreground that has been tracked and color balanced using BCC AVX Match Move and BCC AVX Color Match respectively.
      • Frames Size – NTSC 720x486 @ 30fps
      • Format – Apple Quicktime
      • Compression – Apple Animation
      • Field Rendering – Progressive
      • Duration – 8;21

    Beauty Sphere

    • SUR135.mov – Provided by Artbeats - Underwater footage of a surfer on his surfboard.
      • Frame Size – NTSC 720x486 @ 30fps
      • Format – Apple Quicktime
      • Compression – Photo JPEG, high quality setting
      • Field Rendering – Progressive
      • Source – 16mm Film
      • Video Source – Phillips Spirit Datacine to D1
      • Duration – 8;21

    Sur135

     

    Host Application

    • Avid Xpress Pro 5.7 running on Windows XP Pro.

    Plug-in

    • Boris Continuum Complete AVX 4.2 – BCC Match Grain filter

    Getting right to it

    1. Import SUR135.mov followed by Beauty Sphere.mov and add them to your Sequence in the Timeline - with the Beauty Sphere clip above the SUR135 clip.

      Timeline
    1. Advance to 2 secs. in the Timeline so the sphere is lit and plainly visible.

    Sphere composite

    1. In the Avid Effect Palette, navigate to the BCC Effects category, select BCC Match Grain and drag it to the Beauty Sphere.mov clip in your timeline to apply it. BCC 4.2 supports AVX 1.5 and AVX 2.0 on Windows, so either version of the plug-in can be used. (This tutorial was written using AVX 1.5)

      Effect Palette
    1. You should see the alpha channel of the image. (Note: If your Alpha Import Image Settings’ preferences was set to ‘Invert Existing’, you should see a black sphere on white)

      Invert Existing
    1. Under the Title/Matte parameter group of your BCC Match Grain controls (located in your Avid Effect Editor), select ‘Apply to Title-Matte’ to allow the effect to be applied to the sphere only.

    Filter applied

    * Don’t be alarmed by the appearance of the sphere at this point. The grain hasn’t been applied yet.

    Working with BCC Match Grain

    1. In the BCC Match Grain parameters, set ‘Grain’ to RGB (if we were matching to black and white film, we would choose Monochrome).

      BCC Match Grain
    1. Make sure ‘Match Contrast’ is checked so you can generate grain with the same contrast as the source image.

      Match Contrast
    1. In the Sample Controls parameter group, change ‘Sample Layer’ to 1st Below so the SUR135.mov clip gets sampled.

      Sample Layer

      You should see grain appear on the sphere.

    Grain applied

    More about Sample Controls

    To capture the most convincing grain match that will “sell your shot”, finesse the
    ‘Sample Controls’ explained below:

    • Sample Frame # - Sets the frame from the sample layer that is used to create the grain. The default is frame 0.
    • Sample Size – Controls the size or region of the sampled area in pixels. The default is an area 32 pixels wide.
    • Sample CenterPosition control sets the center point for the sample area on the X and Y axis

    Generally, the larger the sample region = better results.

    How accurate is the grain match?

    Once the Sample Layer is assigned, BCC AVX Match Grain conveniently copies the grain pattern from that clip, creates a grain signature and automatically applies it to your ungrained image. To show you the power and accuracy of the match grain algorithm, I’ve provided screen shots of the grain when viewed through each color channel.

    The Red and Green Channels contain fine grain that is not so obvious. Notice how the grain on the sphere matches the background grain pretty well.

    Red Channel

    Green Channel

    Even the very grainy Blue Channel is accurately mirrored on the sphere.

    Blue Channel

    Why so grainy?

    CCDs used in scanners are famous for being noisier in the blue channel when scanning color negative film. This is because the transmittance through the film is lowest in that channel. For an explanation see: http://www.aim-dtp.net/aim/technology/sensitometry/

    Viewing the grain

    1. To view the grain that was generated from your sample, go to the View menu and change it to ‘Generated Grain’.

      Generated Grain View

    Loading and saving Grain Presets is easy

    Just say you have a whole edit sequence that needed this fabulous grain you just sampled. You can save your generated grain as a preset that can be loaded and used on your other clips.

    1. Go to the Grain Presets pull down menu and load or save as you wish.

      Grain Presets

    Kodak 35mm Film Stock presets

    Since our Artbeats media was shot in 16mm, we couldn’t take advantage of the many 35mm motion picture stock presets that come standard with the BCC AVX Match Grain filter. Each preset was designed to emulate the grain found in processed 35 mm color negative film.

    Kodak Presets

    The finished result

    Click here to view the rendered composite with the grain applied.
    (Please allow a moment for the movie to load)

    About the author

    John LafauceJohn Lafauce is a visual effects artist and lead compositor who has worked on over thirty feature films in Hollywood for such companies as Sony Pictures Imageworks, Rhythm & Hues and Pacific Title. He currently works in software quality assurance for Boris FX in Massachusetts. Away from work, John writes about digital effects and compositing for various online communities, and spends time with his wife, twin sons and parrot, Layla.


    Look for BCC AVX 5 in Summer 2007

    • BCC Match Grain will also be included in soon-to-be released version 5 of BCC AVX.
    • To get your free upgrade to BCC AVX 5, click here: http://artel-software.stores.yahoo.net/concomavx1.html

     

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