sig
  type composite_operator =
      Undefined
    | Over
    | In
    | Out
    | Atop
    | Xor
    | Plus
    | Minus
    | Add
    | Subtract
    | Difference
    | Multiply
    | Bumpmap
    | Copy
    | CopyRed
    | CopyGreen
    | CopyBlue
    | CopyOpacity
    | Clear
    | Dissolve
    | Displace
    | Modulate
    | Threshold
    | No
    | Darken
    | Lighten
    | Hue
    | Saturate
    | Colorize
    | Luminize
    | Screen
    | Overlay
    | CopyCyan
    | CopyMagenta
    | CopyYellow
    | CopyBlack
    | Divide
    | HardLight
    | Exclusion
    | ColorDodge
    | ColorBurn
    | SoftLight
    | LinearBurn
    | LinearDodge
    | LinearLight
    | VividLight
    | PinLight
    | HardMix
  val to_string : Magick.CompositeOp.composite_operator -> string
  val of_string : string -> Magick.CompositeOp.composite_operator
end