hdiutil syntax

convert image -format format -o outfile
convert image to type format and write the result to outfile.

Formats:
                      UDRW - UDIF read/write image
                      UDRO - UDIF read-only image
                      UDCO - UDIF ADC-compressed image
                      UDZO - UDIF zlib-compressed image
                      UDBZ - UDIF bzip2-compressed image (OS X 10.4+ only)
                      UFBI - UDIF entire image with MD5 checksum
                      UDRo - UDIF read-only (obsolete format)
                      UDCo - UDIF compressed (obsolete format)
                      UDTO - DVD/CD-R master for export
                      UDxx - UDIF stub image
                      UDSP - SPARSE (grows with content)
                      RdWr - NDIF read/write image (deprecated)
                      Rdxx - NDIF read-only image (Disk Copy 6.3.3 format)
                      ROCo - NDIF compressed image (deprecated)
                      Rken - NDIF compressed (obsolete format)
                      DC42 - Disk Copy 4.2 image