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Manual Reference Pages  -  DCM2XML (1)


dcm2xml - Convert DICOM file and data set to XML



dcm2xml [options] dcmfile-in [xmlfile-out]


The dcm2xml utility converts the contents of a DICOM file (file format or raw data set) to XML (Extensible Markup Language). The DTD (Document Type Definition) is described in the file dcm2xml.dtd.

If dcm2xml reads a raw data set (DICOM data without a file format meta-header) it will attempt to guess the transfer syntax by examining the first few bytes of the file. It is not always possible to correctly guess the transfer syntax and it is better to convert a data set to a file format whenever possible (using the dcmconv utility). It is also possible to use the -f and -t[ieb] options to force dcm2xml to read a data set with a particular transfer syntax.


dcmfile-in DICOM input filename to be converted

xmlfile-out XML output filename (default: stdout)


    general options

-h --help print this help text and exit

--version print version information and exit

--arguments print expanded command line arguments

-q --quiet quiet mode, print no warnings and errors

-v --verbose verbose mode, print processing details

-d --debug debug mode, print debug information

-ll --log-level [l]evel: string constant (fatal, error, warn, info, debug, trace) use level l for the logger

-lc --log-config [f]ilename: string use config file f for the logger

    input options

input file format:

+f --read-file read file format or data set (default)

+fo --read-file-only read file format only

-f --read-dataset read data set without file meta information

input transfer syntax:

-t= --read-xfer-auto use TS recognition (default)

-td --read-xfer-detect ignore TS specified in the file meta header

-te --read-xfer-little read with explicit VR little endian TS

-tb --read-xfer-big read with explicit VR big endian TS

-ti --read-xfer-implicit read with implicit VR little endian TS

long tag values:

+M --load-all load very long tag values (e.g. pixel data)

-M --load-short do not load very long values (default)

+R --max-read-length [k]bytes: integer (4..4194302, default: 4) set threshold for long values to k kbytes

    processing options

character set:

+Cr --charset-require require declaration of extended charset (default)

+Ca --charset-assume [c]harset: string constant (latin-1 to -5, cyrillic, arabic, greek, hebrew) assume charset c if no extended charset declared

+Cc --charset-check-all check all data elements with string values (default: only PN, LO, LT, SH, ST and UT)

    output options

XML structure:

+Xd --add-dtd-reference add reference to document type definition (DTD)

+Xe --embed-dtd-content embed document type definition into XML document

+Xf --use-dtd-file [f]ilename: string use specified DTD file (only with +Xe) (default: /usr/local/share/dcmtk/dcm2xml.dtd)

+Xn --use-xml-namespace add XML namespace declaration to root element

DICOM data elements:

+Wn --write-element-name write name of the DICOM data elements (default)

-Wn --no-element-name do not write name of the DICOM data elements

+Wb --write-binary-data write binary data of OB and OW elements (default: off, be careful with --load-all)

+Eh --encode-hex encode binary data as hex numbers (default)

+Eb --encode-base64 encode binary data as Base64 (RFC 2045, MIME)


The basic structure of the XML output created from a DICOM image file looks like the following:

<?xml version="1.0" encoding="ISO-8859-1"?> <!DOCTYPE file-format SYSTEM "dcm2xml.dtd"> <file-format xmlns=""> <meta-header xfer="1.2.840.10008.1.2.1" name="LittleEndianExplicit"> <element tag="0002,0000" vr="UL" vm="1" len="4" name="MetaElementGroupLength"> 166 </element> ... <element tag="0002,0013" vr="SH" vm="1" len="16" name="ImplementationVersionName"> OFFIS_DCMTK_353 </element> </meta-header> <data-set xfer="1.2.840.10008.1.2" name="LittleEndianImplicit"> <element tag="0008,0005" vr="CS" vm="1" len="10" name="SpecificCharacterSet"> ISO_IR 100 </element> ... <sequence tag="0028,3010" vr="SQ" card="2" name="VOILUTSequence"> <item card="3"> <element tag="0028,3002" vr="xs" vm="3" len="6" name="LUTDescriptor"> 256\0\8 </element> ... </item> ... </sequence> ... <element tag="7fe0,0010" vr="OW" vm="1" len="262144" name="PixelData" loaded="no" binary="hidden"> </element> </data-set> </file-format>

The ’file-format’ and ’meta-header’ tags are absent for DICOM data sets.

    Character Encoding

The XML encoding is determined automatically from the DICOM attribute (0008,0005) ’Specific Character Set’ (if present) using the following mapping:

ASCII "ISO_IR 6" => "UTF-8" UTF-8 "ISO_IR 192" => "UTF-8" ISO Latin 1 "ISO_IR 100" => "ISO-8859-1" ISO Latin 2 "ISO_IR 101" => "ISO-8859-2" ISO Latin 3 "ISO_IR 109" => "ISO-8859-3" ISO Latin 4 "ISO_IR 110" => "ISO-8859-4" ISO Latin 5 "ISO_IR 148" => "ISO-8859-9" Cyrillic "ISO_IR 144" => "ISO-8859-5" Arabic "ISO_IR 127" => "ISO-8859-6" Greek "ISO_IR 126" => "ISO-8859-7" Hebrew "ISO_IR 138" => "ISO-8859-8"

Multiple character sets are not supported (only the first attribute value is mapped in case of value multiplicity).

    XML Encoding

Attributes with very large value fields (e.g. pixel data) are not loaded by default. They can be identified by the additional attribute ’loaded’ with a value of ’no’ (see example above). The command line option --load-all forces to load all value fields including the very long ones.

Furthermore, binary information of OB and OW attributes are not written to the XML output file by default. These elements can be identified by the additional attribute ’binary’ with a value of ’hidden’ (default is ’no’). The command line option --write-binary-data causes also binary value fields to be printed (attribute value is ’yes’ or ’base64’). But, be careful when using this option together with --load-all because of the large amounts of pixel data that might be printed to the output.

Multiple values (i.e. where the DICOM value multiplicity is greater than 1) are separated by a backslash ’#146; (except for Base64 encoded data). The ’len’ attribute indicates the number of bytes for the particular value field as stored in the DICOM data set, i.e. it might deviate from the XML encoded value length e.g. because of non-significant padding that has been removed. If this attribute is missing in ’sequence’ or ’item’ start tags, the corresponding DICOM element has been stored with undefined length.


The level of logging output of the various command line tools and underlying libraries can be specified by the user. By default, only errors and warnings are written to the standard error stream. Using option --verbose also informational messages like processing details are reported. Option --debug can be used to get more details on the internal activity, e.g. for debugging purposes. Other logging levels can be selected using option --log-level. In --quiet mode only fatal errors are reported. In such very severe error events, the application will usually terminate. For more details on the different logging levels, see documentation of module ’oflog’.

In case the logging output should be written to file (optionally with logfile rotation), to syslog (Unix) or the event log (Windows) option --log-config can be used. This configuration file also allows for directing only certain messages to a particular output stream and for filtering certain messages based on the module or application where they are generated. An example configuration file is provided in <etcdir>/logger.cfg).


All command line tools use the following notation for parameters: square brackets enclose optional values (0-1), three trailing dots indicate that multiple values are allowed (1-n), a combination of both means 0 to n values.

Command line options are distinguished from parameters by a leading ’+’ or ’-’ sign, respectively. Usually, order and position of command line options are arbitrary (i.e. they can appear anywhere). However, if options are mutually exclusive the rightmost appearance is used. This behaviour conforms to the standard evaluation rules of common Unix shells.

In addition, one or more command files can be specified using an ’@’ sign as a prefix to the filename (e.g. @command.txt). Such a command argument is replaced by the content of the corresponding text file (multiple whitespaces are treated as a single separator unless they appear between two quotation marks) prior to any further evaluation. Please note that a command file cannot contain another command file. This simple but effective approach allows to summarize common combinations of options/parameters and avoids longish and confusing command lines (an example is provided in file <datadir>/dumppat.txt).


The dcm2xml utility will attempt to load DICOM data dictionaries specified in the DCMDICTPATH environment variable. By default, i.e. if the DCMDICTPATH environment variable is not set, the file <datadir>/dicom.dic will be loaded unless the dictionary is built into the application (default for Windows).

The default behaviour should be preferred and the DCMDICTPATH environment variable only used when alternative data dictionaries are required. The DCMDICTPATH environment variable has the same format as the Unix shell PATH variable in that a colon (’:’) separates entries. On Windows systems, a semicolon (’;’) is used as a separator. The data dictionary code will attempt to load each file specified in the DCMDICTPATH environment variable. It is an error if no data dictionary can be loaded.


<datadir>/dcm2xml.dtd - Document Type Definition (DTD) file


xml2dcm(1), dcmconv(1)


Copyright (C) 2002-2010 by OFFIS e.V., Escherweg 2, 26121 Oldenburg, Germany.

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Version 3.6.0 DCM2XML (1) 6 Jan 2011

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