protected function tryToMakeTrueColorIfNot(&$image)
    {
        $mustMakeTrueColor = false;
        if (function_exists('imageistruecolor')) {
            if (imageistruecolor($image)) {
                $this->logLn('image is true color');
            } else {
                $this->logLn('image is not true color');
                $mustMakeTrueColor = true;
            }
        } else {
            $this->logLn('It can not be determined if image is true color');
            $mustMakeTrueColor = true;
        }

        if ($mustMakeTrueColor) {
            $this->logLn('converting color palette to true color');
            $success = $this->makeTrueColor($image);
            if (!$success) {
                $this->logLn(
                    'Warning: FAILED converting color palette to true color. ' .
                    'Continuing, but this does NOT look good.'
                );
            }
        }
    }