// pattern for use in texture/pigment/normal/density
// takes the color of an image file to calculate the pattern value
  image_pattern {
    png "plasma3.png"   // image file to read (iff/tga/gif/png/jpeg/tiff/sys)
    //use_color         // use pixel color gray scale (default)
    //use_alpha         // use alpha value
    //use_index         // use palette index
  }

