dcmicmp - Man Page

  -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 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

modality LUT transformation:

  +M    --use-modality
          use modality LUT transformation (default)

  -M    --no-modality
          ignore stored modality LUT transformation

VOI LUT transformation:

  -W    --no-windowing
          no VOI windowing (default)

  +Wi   --use-window  [n]umber: integer
          use the n-th VOI window from image file

  +Wl   --use-voi-lut  [n]umber: integer
          use the n-th VOI look up table from image file

  +Wm   --min-max-window
          compute VOI window using min-max algorithm
          on both images separately

  +Wn   --min-max-window-n
          compute VOI window using min-max algorithm
          on both images separately, ignoring extremes

  +Wr   --min-max-ref
          compute VOI window using min-max algorithm
          and use same window for the test image

  +Wq   --min-max-n-ref
          compute VOI window using min-max algorithm,
          ignoring extreme values
          and use same window for the test image

  +Ww   --set-window  [c]enter [w]idth: float
          compute VOI window using center c and width w

  +Wfl  --linear-function
          set VOI LUT function to LINEAR

  +Wfs  --sigmoid-function
          set VOI LUT function to SIGMOID

presentation LUT transformation:

  +Pid  --identity-shape
          set presentation LUT shape to IDENTITY

  +Piv  --inverse-shape
          set presentation LUT shape to INVERSE

  +Pod  --lin-od-shape
          set presentation LUT shape to LIN OD

  +ce   --check-error  [l]imit: integer
          check if max absolute error <= limit

  # Return exit code EXITCODE_LIMIT_EXCEEDED_MAX_ERROR if the computed
  # maximum absolute error is larger than the given limit.

  +cm   --check-mae  [l]imit: float
          check if mean absolute error <= limit

  # Return exit code EXITCODE_LIMIT_EXCEEDED_MAE if the computed
  # mean absolute error is larger than the given limit.

  +cr   --check-rmse  [l]imit: float
          check if root mean square error <= limit

  # Return exit code EXITCODE_LIMIT_EXCEEDED_RMSE if the computed
  # root mean square error is larger than the given limit.

  +cp   --check-psnr  [l]imit: float
          check if PSNR >= limit

  # Return exit code EXITCODE_LIMIT_EXCEEDED_PSNR if the computed
  # peak signal to noise ratio is smaller than the given limit
  # (for PSNR, higher values mean better image quality)

  +cs   --check-snr  [l]imit: float
          check if SNR >= limit

  # Return exit code EXITCODE_LIMIT_EXCEEDED_PSNR if the computed
  # signal to noise ratio is smaller than the given limit
  # (for SNR, higher values mean better image quality)

  +sd   --save-diff  [f]ilename: string
          write secondary capture difference image

  # Create a Multiframe Secondary Capture image that contains a
  # difference image between reference and test image. For monochrome
  # images, one difference frame is created for each frame in the reference
  # image. For color images, three monochrome frames are created for each
  # frame in the reference image, corresponding to the differences in the
  # red, green and blue color plane. The difference image will have
  # BitsStored 8 or 16, depending on the properties of the reference image.

  +a    --amplify  [f]actor: float
          multiply diff image pixel values by f

  # This option can be used to amplify the grayscale values in the
  # difference image by multiplying each value with the given factor.
  # Alternatively, a DICOM VOI LUT window may be used when visualizing
  # the difference image.

Monochrome DICOM images require that a multi-stage display pipeline is executed in order to convert the raw pixel values to the so-called presentation values (p-values) that are sent to the (possibly calibrated) display. When comparing the similarity of images before and after post-processing, it can be relevant to activate some stages of this display pipeline before calculating the difference image and metrics. The image processing options allow the caller to either activate or deactivate the Modality LUT, VOI LUT and Presentation LUT transformations. In any case, the same transformation is applied to both images, although possibly with different parameters if for example the 'first VOI LUT window' stored in each image is applied. This assumes that the post-processing algorithm (e.g. compression algorithm) has adapted the values of such windows during compression such that the image display after applying the window is as close as possible to the reference. For images with more than 8 bits/sample it may be important to known which VOI LUT transformation will be applied by the user when viewing the image, because this may affect the perceived image quality. Therefore, absolute Window parameters can also be given with the --set-window option, which will then be applied to both images.

The user should also note that the metrics computed by this tool cannot predict or estimate the suitability of lossy compressed image for diagnostic purposes. Much more complex image processing and an understanding of the image content (e.g. body part) would be needed for this purpose. The metrics computed provide an estimation of the level of distortion caused by the post-processing - no more and no less.

EXITCODE_NO_ERROR                         0
EXITCODE_COMMANDLINE_SYNTAX_ERROR         1

EXITCODE_INVALID_INPUT_FILE              22
EXITCODE_CANNOT_WRITE_OUTPUT_FILE        40

EXITCODE_INITIALIZE_DIFF_IMAGE           80
EXITCODE_DISPLAY_PIPELINE                81
EXITCODE_IMAGE_COMPARISON                82

EXITCODE_LIMIT_EXCEEDED_MAX_ERROR        90
EXITCODE_LIMIT_EXCEEDED_MAE              91
EXITCODE_LIMIT_EXCEEDED_RMSE             92
EXITCODE_LIMIT_EXCEEDED_PSNR             93
EXITCODE_LIMIT_EXCEEDED_SNR              94