Exiv2

    bool iptc_;                    //!< Iptc option flag.

    bool exif_;                    //!< Exif option flag.

    bool comment_;                 //!< JPEG comment option flag.

    bool preserve_;                //!< Preserve existing metadata option flag.

    std::string read_;             //!< Source file

    std::string write_;            //!< Destination file

               iptc_(false),

               exif_(false),

               comment_(false),

               preserve_(false)

        {}

    if (params.comment_) {

        writeImg->setComment(readImg->comment());

    }

    try {

        writeImg->writeMetadata();

    case 'i': iptc_ = true; break;

    case 'e': exif_ = true; break;

    case 'c': comment_ = true; break;

    case 'p': preserve_ = true; break;

    case 'a':

        iptc_ =true;

        exif_ =true;

        comment_ =true;

        break;

    case ':':

        std::cerr << progname() << ": Option -" << static_cast<char>(optopt)

            std::cerr << progname() << ": Write file must be specified\n";

            rc = 1;

        }

            std::cerr << progname() << ": Option -p has no effect when all metadata types are specified.\n";

            rc = 1;

        }

       << "   -i      Read Iptc data from readfile and write to writefile.\n"

       << "   -e      Read Exif data from readfile and write to writefile.\n"

       << "   -c      Read Jpeg comment from readfile and write to writefile.\n"

       << "   -a      Read all metadata from readfile and write to writefile.\n"

       << "   -p      Preserve existing metadata in writefile if not replaced.\n"

       << "   -h      Display this help and exit.\n\n";