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dcmconv(1) OFFIS DCMTK dcmconv(1)


dcmconv - Convert DICOM file encoding


dcmconv [options] dcmfile-in dcmfile-out


The dcmconv utility reads a DICOM file (dcmfile-in), performs an encoding conversion and writes the converted data to an output file (dcmfile-out).


dcmfile-in   DICOM input filename to be converted
dcmfile-out  DICOM output filename to write to


general options

-h --help
print this help text and exit
print version information and exit
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
-l --log-level [l]evel: string constant
(fatal, error, warn, info, debug, trace)
use level l for the logger
-l --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 parsing of file meta information:
+ml --use-meta-length
use file meta information group length (default)
-ml --ignore-meta-length
ignore file meta information group length parsing of odd-length attributes:
+ao --accept-odd-length
accept odd length attributes (default)
+ae --assume-even-length
assume real length is one byte larger handling of explicit VR:
+ev --use-explicit-vr
use explicit VR from dataset (default)
-ev --ignore-explicit-vr
ignore explicit VR (prefer data dictionary) handling of non-standard VR:
+vr --treat-as-unknown
treat non-standard VR as unknown (default)
-vr --assume-implicit
try to read with implicit VR little endian TS handling of undefined length UN elements:
+ui --enable-cp246
read undefined len UN as implicit VR (default)
-ui --disable-cp246
read undefined len UN as explicit VR handling of defined length UN elements:
-uc --retain-un
retain elements as UN (default)
+uc --convert-un
convert to real VR if known handling of private max-length elements (implicit VR):
-sq --maxlength-dict
read as defined in dictionary (default)
+sq --maxlength-seq
read as sequence with undefined length handling of wrong delimitation items:
-rd --use-delim-items
use delimitation items from dataset (default)
+rd --replace-wrong-delim
replace wrong sequence/item delimitation items handling of illegal undefined length OB/OW elements:
-oi --illegal-obow-rej
reject dataset with illegal element (default)
+oi --illegal-obow-conv
convert undefined length OB/OW element to SQ handling of VOI LUT Sequence with OW VR and explicit length:
-vi --illegal-voi-rej
reject dataset with illegal VOI LUT (default)
+vi --illegal-voi-conv
convert illegal VOI LUT to SQ handling of explicit length pixel data for encaps. transfer syntaxes:
-pe --abort-expl-pixdata
abort on explicit length pixel data (default)
+pe --use-expl-pixdata
use explicit length pixel data general handling of parser errors:
+Ep --ignore-parse-errors
try to recover from parse errors
-Ep --handle-parse-errors
handle parse errors and stop parsing (default) other parsing options:
+st --stop-after-elem [t]ag: "gggg,eeee" or dictionary name
stop parsing after element specified by t automatic data correction:
+dc --enable-correction
enable automatic data correction (default)
-dc --disable-correction
disable automatic data correction bitstream format of deflated input:
+bd --bitstream-deflated
expect deflated bitstream (default)
+bz --bitstream-zlib
expect deflated zlib bitstream

processing options

specific character set:

# the following options require support from an underlying character
# encoding library (see output of --version on which one is available)
+U8 --convert-to-utf8
convert all element values that are affected
by Specific Character Set (0008,0005) to UTF-8
+L1 --convert-to-latin1
convert affected element values to ISO 8859-1
+A7 --convert-to-ascii
convert affected element values to 7-bit ASCII
+C --convert-to-charset [c]harset: string
convert affected element values to the character
set specified by the DICOM defined term c
-Ct --transliterate
try to approximate characters that cannot be
represented through similar looking characters
-Cd --discard-illegal
discard characters that cannot be represented
in destination character set other processing options:
-ig --no-invalid-groups
remove elements with invalid group number

output options

output file format:

+Fm --write-new-meta-info
write file format with new meta information (default)
+F --write-file
write file format
-F --write-dataset
write data set without file meta information output transfer syntax:
+t= --write-xfer-same
write with same TS as input (default)
+te --write-xfer-little
write with explicit VR little endian TS
+tb --write-xfer-big
write with explicit VR big endian TS
+ti --write-xfer-implicit
write with implicit VR little endian TS
+td --write-xfer-deflated
write with deflated explicit VR little endian TS
+tg --write-xfer-ge
write private GE implicit VR little endian
with big endian pixel data TS (non-standard) post-1993 value representations:
+u --enable-new-vr
enable support for new VRs (UN/UT) (default)
-u --disable-new-vr
disable support for new VRs, convert to OB group length encoding:
+g= --group-length-recalc
recalculate group lengths if present (default)
+g --group-length-create
always write with group length elements
-g --group-length-remove
always write without group length elements length encoding in sequences and items:
+e --length-explicit
write with explicit lengths (default)
-e --length-undefined
write with undefined lengths
+eo --write-oversized
write oversized explicit length sequences
and items with undefined length (default)
-eo --abort-oversized
abort on oversized explicit sequences/items data set trailing padding (not with --write-dataset):
-p= --padding-retain
do not change padding (default if not --write-dataset)
-p --padding-off
no padding (implicit if --write-dataset)
+p --padding-create [f]ile-pad [i]tem-pad: integer
align file on multiple of f bytes
and items on multiple of i bytes deflate compression level (only with --write-xfer-deflated):
+cl --compression-level [l]evel: integer (default: 6)
0=uncompressed, 1=fastest, 9=best compression


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 behavior 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 one to summarize common combinations of options/parameters and avoids longish and confusing command lines (an example is provided in file <datadir>/dumppat.txt).


The dcmconv 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 behavior 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.




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Fri Apr 22 2022 Version 3.6.7