NRG

ISO Master which is claimed to be the best ISO editing tool is a graphical editor for ISO images. ISO Master is useful for extracting, deleting, or adding files and directories to or from an ISO image. ISO Master can read .ISO files (ISO9660, Joliet, RockRidge, and El Torito), most .NRG files, and some single-track .MDF files and can save and only save as .ISO.