DCMTK Version 3.7.0 OFFIS DICOM Toolkit

dcmscale: Scale DICOM images

# SYNOPSIS

    dcmscale [options] dcmfile-in dcmfile-out

# DESCRIPTION

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.

# PARAMETERS

    dcmfile-in   DICOM input filename to be scaled ("-" for stdin)

    dcmfile-out  DICOM output filename to be written ("-" for stdout)

# OPTIONS

## 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

## image processing and encoding options

    scaling:

      +a    --recognize-aspect
              recognize pixel aspect ratio when scaling (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

# NOTES

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

# LOGGING

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.

# COMMAND LINE

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).

# ENVIRONMENT

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.

# COPYRIGHT

Copyright (C) 2002-2025 by OFFIS e.V., Escherweg 2, 26121 Oldenburg, Germany.

Generated on Mon Dec 15 2025 for DCMTK Version 3.7.0 by Doxygen 1.9.1