function TForm1.MouseIsOutsideImage(const X, Y: Integer): Boolean;
begin
  Result := (X < 0) or (Y < 0) or (X > ImageEnView1.IEBitmap.Width) or (Y > ImageEnView1.IEBitmap.Height);
end;

procedure TForm1.ImageEnView1MouseMove(Sender: TObject; Shift: TShiftState; X, Y: Integer);
begin
  var bx := ImageEnView1.XScr2Bmp(X, False);
  var by := ImageEnView1.YScr2Bmp(Y, False);
  if MouseIsOutsideImage(bx, by) then
  begin
    DoSomething;
    EXIT; 
  end;
  var ThisColor: TColor;
  try
    ThisColor := TRGB2TColor(ImageEnView1.IEBitmap.Pixels[bx, by]);
  except
    CodeSite.Send('TForm1.ImageEnView1MouseMove except: bx', bx);
    CodeSite.Send('TForm1.ImageEnView1MouseMove except: by', by);
  end;

  DoSomething(ThisColor);
end;