[[AgustinOrtu]]

Esta es otra forma similar a la anterior, pero usando metodos estaticos (de clase)

Código Delphi [-]
procedure TForm2.btnToBase64Click(Sender: TObject);
var
  AStringStream: TStringStream;
  ABase64, DecodedBase64: string;
begin
  AStringStream := TStringStream.Create;
  try
    imLoad.Picture.Graphic.SaveToStream(AStringStream);
    AStringStream.Position := 0;
    ABase64 := TIdEncoderMIME.EncodeString(AStringStream.DataString);
  finally
    AStringStream.Free;
  end;

  DecodedBase64 := TIdDecoderMIME.DecodeString(ABase64);
  AStringStream := TStringStream.Create(DecodedBase64);
  try
    AStringStream.Position := 0;
    imBase64.Picture.Bitmap.LoadFromStream(AStringStream);
  finally
    AStringStream.Free;
  end;
end;