Bimage_iomodule Spec : sig ... endmodule Input : sig ... endmodule Output : sig ... endval read : 
  ( 'a, 'b ) Bimage.Type.t ->
  'c Bimage.Color.t ->
  string ->
  ( ( 'a, 'b, 'c ) Bimage.Image.t, error ) Stdlib.resultval write : 
  string ->
  ( 'a, 'b, [< `Rgba | `Rgb | `Gray ] ) Bimage.Image.t ->
  ( unit, error ) Stdlib.result