Section: OFFIS DCMTK (1)
Updated: Thu Nov 29 2018
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dcmscale - Scale DICOM images



dcmscale [options] dcmfile-in dcmfile-out



The dcmscale utility reads a DICOM image, scales it according to the command line settings and writes back the DICOM image. This utility only supports uncompressed and RLE compressed DICOM images.  


dcmfile-in   DICOM input filename to be scaled

dcmfile-out  DICOM output filename to be written




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

  -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


image processing and encoding options


  +a    --recognize-aspect
          recognize pixel aspect ratio (default)

  -a    --ignore-aspect
          ignore pixel aspect ratio when scaling

  +i    --interpolate  [n]umber of algorithm: integer
          use interpolation when scaling (1..4, default: 1)

  -i    --no-interpolation
          no interpolation when scaling

  -S    --no-scaling
          no scaling, ignore pixel aspect ratio (default)

  +Sxf  --scale-x-factor  [f]actor: float
          scale x axis by factor, auto-compute y axis

  +Syf  --scale-y-factor  [f]actor: float
          scale y axis by factor, auto-compute x axis

  +Sxv  --scale-x-size  [n]umber: integer
          scale x axis to n pixels, auto-compute y axis

  +Syv  --scale-y-size  [n]umber: integer
          scale y axis to n pixels, auto-compute x axis

other transformations:

  +C    --clip-region  [l]eft [t]op [w]idth [h]eight: integer
          clip rectangular image region (l, t, w, h)

SOP Instance UID:

  +ua   --uid-always
          always assign new SOP Instance UID (default)

  +un   --uid-never
          never assign new SOP Instance UID


output options

output file format:

  +F    --write-file
          write file format (default)

  -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

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

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



The following preferred interpolation algorithms can be selected using the --interpolate option:

1 = free scaling algorithm with interpolation from pbmplus toolkit
2 = free scaling algorithm with interpolation from c't magazine
3 = magnification algorithm with bilinear interpolation from Eduard Stanescu
4 = magnification algorithm with bicubic interpolation from Eduard Stanescu



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 dcmscale 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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general options
input options
image processing and encoding options
output options