dcmjpeg: a compression/decompression library and utility apps

This module contains classes that convert between uncompressed and JPEG compressed representations (transfer syntaxes) of a DICOM image object. Both lossless and lossy JPEG 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:

• DJEncoderRegistration
• DJDecoderRegistration
• DJCodecEncoder
• DJCodecDecoder

Tools

This module contains the following command line tools:

• dcmcjpeg: Encode DICOM file to JPEG transfer syntax
• dcmdjpeg: Decode JPEG-compressed DICOM file
• dcmj2pnm: Convert DICOM images to PGM/PPM, PNG, TIFF, JPEG or BMP
• dcmmkdir: Create a DICOMDIR file

Examples

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

DJEncoderRegistration::registerCodecs(); // register JPEG codecs
DcmFileFormat fileformat;
if (fileformat.loadFile("test.dcm").good())
{
  DcmDataset *dataset = fileformat.getDataset();
  DcmItem *metaInfo = fileformat.getMetaInfo();
  DJ_RPLossless params; // codec parameters, we use the defaults

  // this causes the lossless JPEG version of the dataset to be created
  if (dataset->chooseRepresentation(EXS_JPEGProcess14SV1, &params).good() &&
      dataset->canWriteXfer(EXS_JPEGProcess14SV1))
  {
    // 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 format
    fileformat.saveFile("test_jpeg.dcm", EXS_JPEGProcess14SV1);
  }
}
DJEncoderRegistration::cleanup(); // deregister JPEG codecs

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

DJDecoderRegistration::registerCodecs(); // register JPEG codecs
DcmFileFormat fileformat;
if (fileformat.loadFile("test_jpeg.dcm").good())
{
  DcmDataset *dataset = fileformat.getDataset();

  // decompress data set if compressed
  if (dataset->chooseRepresentation(EXS_LittleEndianExplicit, NULL).good() &&
      dataset->canWriteXfer(EXS_LittleEndianExplicit))
  {
    fileformat.saveFile("test_decompressed.dcm", EXS_LittleEndianExplicit);
  }
}
DJDecoderRegistration::cleanup(); // deregister JPEG codecs