#version 3.6;

#declare fp=function{pigment{image_map{png "test.png" interpolate 2}}}

#declare RED = pigment {
  function { fp(x,y,z).red } 
  color_map { [0 rgb 0][1 rgb <1,0,0>] }
}
#declare GREEN = pigment {
  function { fp(x,y,z).green } 
  color_map { [0 rgb 0][1 rgb <0,1,0>] }
}
#declare BLUE = pigment {
  function { fp(x,y,z).blue } 
  color_map { [0 rgb 0][1 rgb <0,0,1>] }
}

box{-.5,.5
  texture{
    pigment{
      average
      pigment_map{
        [1 RED]
        [1 GREEN]
        [1 BLUE]
      }
    }
    finish{
      ambient 3
    }
  }
}