dcmjpls: a compression/decompression library and utility apps

This module contains classes that convert between uncompressed and JPEG-LS compressed representations (transfer syntaxes) of a DICOM image object. Both lossless and near-lossless JPEG-LS processes are supported. This module implements a family of codecs that are derived from class DcmCodec and can be registered in the codec list maintained in module dcmdata.

The main interface classes are:

• DJLSEncoderRegistration
• DJLSDecoderRegistration
• DJLSEncoderBase
• DJLSDecoderBase

Tools

This module contains the following command line tools:

• dcmcjpls: Encode DICOM file to JPEG-LS transfer syntax
• dcmdjpls: Decode JPEG-LS compressed DICOM file
• dcml2pnm: Convert DICOM images to PGM/PPM, PNG, TIFF or BMP

Examples

The following example shows how to compress a DICOM image file with lossless JPEG-LS:

DJLSEncoderRegistration::registerCodecs(); // register JPEG-LS codecs
DcmFileFormat fileformat;
if (fileformat.loadFile("test.dcm").good())
{
  DcmDataset *dataset = fileformat.getDataset();
  DcmItem *metaInfo = fileformat.getMetaInfo();
  DJLSRepresentationParameter rp(0, OFTrue); // parameters for lossless

  // this causes the lossless JPEG-LS version of the dataset to be created
  dataset->chooseRepresentation(EXS_JPEGLSLossless, &params);

  // check if everything went well
  if (dataset->canWriteXfer(EXS_JPEGLSLossless))
  {
    // force the meta-header UIDs to be re-generated when storing the file
    // since the UIDs in the data set may have changed
    delete metaInfo->remove(DCM_MediaStorageSOPClassUID);
    delete metaInfo->remove(DCM_MediaStorageSOPInstanceUID);

    // store in lossless JPEG-LS format
    fileformat.saveFile("test_jpls.dcm", EXS_JPEGLSLossless);
  }
}
DJLSEncoderRegistration::cleanup(); // deregister JPEG-LS codecs

The following example shows how to decompress a JPEG-LS compressed DICOM image file:

DJLSDecoderRegistration::registerCodecs(); // register JPEG-LS codecs
DcmFileFormat fileformat;
if (fileformat.loadFile("test_jpls.dcm").good())
{
  DcmDataset *dataset = fileformat.getDataset();

  // decompress data set if compressed
  dataset->chooseRepresentation(EXS_LittleEndianExplicit, NULL);

  // check if everything went well
  if (dataset->canWriteXfer(EXS_LittleEndianExplicit))
  {
    fileformat.saveFile("test_decompressed.dcm", EXS_LittleEndianExplicit);
  }
}
DJLSDecoderRegistration::cleanup(); // deregister JPEG-LS codecs

Legal Remark

Please note that Hewlett Packard claims to own patents that apply to JPEG-LS. Hewlett Packard grants free licenses for conformant implementations of JPEG-LS. OFFIS as the author of the DCMTK toolkit has obtained such a license, but depending on your national legislations companies that use DCMTK's JPEG-LS codec may need to also acquire a license. Read more at http://www.hpl.hp.com/loco/ if you intend to use this module for commercial purposes.