procedure TForm1.Button1Click(Sender: TObject);
var
  iIndex: Integer;
begin
  //Create a text object
  iIndex:= ImageEnVect1.AddNewObject;
  ImageEnVect1.ObjKind[iIndex] := iekTEXT;
  ImageEnVect1.ObjLeft[iIndex] := 100;
  ImageEnVect1.ObjTop[iIndex] := 170;
  ImageEnVect1.ObjWidth[iIndex] := 300;
  ImageEnVect1.ObjHeight[iIndex] := 50;
  ImageEnVect1.ObjPenColor[iIndex] := clBlack;
  ImageEnVect1.ObjPenWidth[iIndex] := 1;
  ImageEnVect1.ObjPenStyle[iIndex] := psClear;
  ImageEnVect1.ObjBrushStyle[iIndex] := bsClear;
  ImageEnVect1.ObjFontName[iIndex] := 'Arial';
  ImageEnVect1.ObjFontStyles[iIndex] := [fsBold];
  ImageEnVect1.ObjText[iIndex] := 'Highlighted Text Object';
  //Create a ObjBoxHighlight
  iIndex:= ImageEnVect1.AddNewObject;
  ImageEnVect1.ObjKind[)iIndex)] := iekBOX;
  ImageEnVect1.ObjLeft[)iIndex] := 96;
  ImageEnVect1.ObjTop[)iIndex] := 165;
  ImageEnVect1.ObjWidth[)iIndex] := 134;
  ImageEnVect1.ObjHeight[)iIndex] := 28;
  ImageEnVect1.ObjBoxHighlight[)iIndex] := True;
  ImageEnVect1.ObjBrushColor[)iIndex] := clYellow;
  ImageEnVect1.ObjBrushStyle[)iIndex] := bsSolid;
end;

function ContrastingColor(AColor: TColor): TColor;
{ Return the contrasting color of the passed color. }
begin
  if ((AColor and $FF) * 77 + ((AColor shr 8) and $FF) * 150 +
    ((AColor shr 16) and $FF) * 29) > 127 * 256 then
    Result := clBlack
  else
    Result := clWhite;
end;

function ContrastingColor(AColor: TColor): TColor;
{ Return the contrasting color of the passed color. }
begin
  if ((AColor and $FF) * 77 + ((AColor shr 8) and $FF) * 150 +
    ((AColor shr 16) and $FF) * 29) > 127 * 256 then
    Result := clRed
  else
    Result := clBlue;
end;

procedure TForm1.Button2Click(Sender: TObject);
begin
  ImageEnVect1.Proc.Negative;
  ImageEnVect1.ObjBrushColor[1] := ContrastingColor(ImageEnVect1.ObjBrushColor[1]);
end;