Blue Screen Matting

      n     Composite

      This consists of at least two elements, one or more foreground objects each shot against a special backing color—typically a bright blue or green—and a background.

 

n     The Matting Problem :

     

      Given Cf and Cb, and Ck, and assuming

      Cf = Co + (1 – αo)Ck ,

      determine Co which then gives composite color

      C = Co + (1 – αo)Cb  ,

      for all points that Cf and Cb share in common.

Several Problems of Matting :

blue spill or blue flare

backing shadows on the blue screen

backing impurities

 

 

n     Three equations and four unknowns

     

      Rf = Ro + (1 – αo )Rk ,

      Gf = Go + (1 – αo )Gk ,

      Bf = Bo + (1 – αo )Bk .

Unknown :    Ro , Go , Bo , and αo