Calculate Bitmap Negativ

function InvertBmp(SourceBitmap: TBitmap): TBitmap;
var
  iFor, iFor2: LongInt;
  TempBitmap: TBitmap;
  bRed, bGreen, bBlue: Byte;
  PixelColor: LongInt;
begin
  TempBitmap := TBitmap.Create;
  TempBitmap.Width := SourceBitmap.Width;
  TempBitmap.Height := SourceBitmap.Height;
  for iFor := 0 to SourceBitmap.Width -1 do
  begin
    for iFor2 := 0 to SourceBitmap.Height -1 do
    begin
      PixelColor := ColorToRGB(SourceBitmap.Canvas.Pixels[iFor, iFor2]);
      bRed := PixelColor;
      bGreen := PixelColor shr 8;
      bBlue := PixelColor shr 16;
      bRed := 255 -bRed;
      bGreen := 255 -bGreen;
      bBlue := 255 -bBlue;
      TempBitmap.Canvas.Pixels[iFor, iFor2] := (bRed shl 8 +bGreen) shl 8 +bBlue;
    end;
  end;
  Result := TempBitmap;
end;

Beispiel :

procedure TForm1.Button1Click(Sender: TObject);
begin
  Image1.Picture.Bitmap.Assign(InvertBmp(Image1.Picture.Bitmap));
end;