unit Unit2;

interface

uses
  Windows, Classes, Graphics;

type
  TMyThread = class(TThread)
  private
    { private-Deklarationen }
  protected
    procedure Execute; override;
  end;

type
  TFarbe = record
    Red : Integer;
    Green : Integer;
    Blue : Integer;
  end;

implementation

{ TMyThread }

procedure TMyThread.Execute;
  var Bitmap : TBitmap;
      x, y : Integer;
      Farbe : TFarbe;
      Arith : Integer;
begin
  for x:=0 to Bitmap.Width do
    begin
      for y:=0 to Bitmap.Height do
        begin
          with Farbe do
            begin
              Red:=GetRValue(Bitmap.Canvas.Pixels[x, y]);
              Green:=GetGValue(Bitmap.Canvas.Pixels[x, y]);
              Blue:=GetBValue(Bitmap.Canvas.Pixels[x, y]);

              Arith:=Round((Red + Green + Blue) / 3);
            end;
          Bitmap.Canvas.Pixels[x, y]:=RGB(Arith, Arith, Arith);
        end;
    end;
end;

end.