DCMTK: DJCodecEncoder Class Reference

DCMTK Version 3.7.0 OFFIS DICOM Toolkit

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Public Member Functions | Static Protected Member Functions | Private Member Functions | Static Private Member Functions | List of all members
DJCodecEncoder Class Referenceabstract

abstract codec class for JPEG encoders. More...

Inheritance diagram for DJCodecEncoder:

## Public Member Functions
| DJCodecEncoder ()
| default constructor
virtual | ~DJCodecEncoder ()
| destructor
virtual OFCondition | decode (const DcmRepresentationParameter *fromRepParam, DcmPixelSequence *pixSeq, DcmPolymorphOBOW &uncompressedPixelData, const DcmCodecParameter *cp, const DcmStack &objStack, OFBool &removeOldRep) const
| decompresses the given pixel sequence and stores the result in the given uncompressedPixelData element.
virtual OFCondition | decodeFrame (const DcmRepresentationParameter *fromParam, DcmPixelSequence *fromPixSeq, const DcmCodecParameter *cp, DcmItem *dataset, Uint32 frameNo, Uint32 &startFragment, void *buffer, Uint32 bufSize, OFString &decompressedColorModel) const
| decompresses a single frame from the given pixel sequence and stores the result in the given buffer.
virtual OFCondition | encode (const Uint16 *pixelData, const Uint32 length, const DcmRepresentationParameter *toRepParam, DcmPixelSequence *&pixSeq, const DcmCodecParameter *cp, DcmStack &objStack, OFBool &removeOldRep) const
| compresses the given uncompressed DICOM image and stores the result in the given pixSeq element.
virtual OFCondition | encode (const E_TransferSyntax fromRepType, const DcmRepresentationParameter *fromRepParam, DcmPixelSequence *fromPixSeq, const DcmRepresentationParameter *toRepParam, DcmPixelSequence *&toPixSeq, const DcmCodecParameter *cp, DcmStack &objStack, OFBool &removeOldRep) const
| transcodes (re-compresses) the given compressed DICOM image and stores the result in the given toPixSeq element.
virtual OFBool | canChangeCoding (const E_TransferSyntax oldRepType, const E_TransferSyntax newRepType) const
| checks if this codec is able to convert from the given current transfer syntax to the given new transfer syntax
virtual Uint16 | decodedBitsAllocated (Uint16 bitsAllocated, Uint16 bitsStored) const
| determines the effective value of BitsAllocated that a dataset will have after decompression of an image with the given values for bitsAllocated and bitsStored.
virtual OFCondition | determineDecompressedColorModel (const DcmRepresentationParameter *fromParam, DcmPixelSequence *fromPixSeq, const DcmCodecParameter *cp, DcmItem *dataset, OFString &decompressedColorModel) const
| determine color model of the decompressed image
virtual E_TransferSyntax | supportedTransferSyntax () const =0
| returns the transfer syntax that this particular codec is able to encode and decode.
Public Member Functions inherited from DcmCodec
| DcmCodec ()
| default constructor
virtual | ~DcmCodec ()
| destructor

## Static Protected Member Functions
static void | appendCompressionRatio (OFString &arg, double ratio)
| format compression ratio as string and append to given string object.
static OFCondition | togglePlanarConfiguration8 (Uint8 *pixelData, const size_t numValues, const Uint16 samplesPerPixel, const Uint16 oldPlanarConfig)
| toggles Planar Configuration of 8-bit pixel data from "by pixel" to "by plane" and vice versa.
static OFCondition | togglePlanarConfiguration16 (Uint16 *pixelData, const size_t numValues, const Uint16 samplesPerPixel, const Uint16 oldPlanarConfig)
| toggles Planar Configuration of 16-bit pixel data from "by pixel" to "by plane" and vice versa.

## Private Member Functions
virtual OFCondition | encodeColorImage (OFBool YBRmode, DcmItem *dataset, const DcmRepresentationParameter *toRepParam, DcmPixelSequence *&pixSeq, const DJCodecParameter *cp, double &compressionRatio) const
| compresses the given uncompressed DICOM color image and stores the result in the given pixSeq element.
virtual OFCondition | encodeMonochromeImage (DcmItem *dataset, const DcmRepresentationParameter *toRepParam, DcmPixelSequence *&pixSeq, const DJCodecParameter *cp, double &compressionRatio) const
| compresses the given uncompressed monochrome DICOM image and stores the result in the given pixSeq element.
virtual OFCondition | encodeTrueLossless (const DcmRepresentationParameter *toRepParam, DcmPixelSequence *&pixSeq, const DcmCodecParameter *cp, DcmStack &objStack) const
| compresses the given uncompressed DICOM image and stores the result in the given pixSeq element.
virtual OFCondition | updateLossyCompressionRatio (DcmItem *dataset, double ratio) const
| create Lossy Image Compression and Lossy Image Compression Ratio.
virtual OFCondition | updateDerivationDescription (DcmItem *dataset, const DcmRepresentationParameter *toRepParam, const DJCodecParameter *cp, Uint8 bitsPerSample, double ratio) const
| create Derivation Description.
virtual OFCondition | adjustOverlays (DcmItem *dataset, DicomImage &image) const
| for all overlay groups create (60xx,3000) Overlay Data.
virtual OFBool | isLosslessProcess () const =0
| returns true if the transfer syntax supported by this codec is lossless.
virtual void | createDerivationDescription (const DcmRepresentationParameter *toRepParam, const DJCodecParameter *cp, Uint8 bitsPerSample, double ratio, OFString &derivationDescription) const =0
| creates 'derivation description' string after encoding.
virtual DJEncoder * | createEncoderInstance (const DcmRepresentationParameter *toRepParam, const DJCodecParameter *cp, Uint8 bitsPerSample) const =0
| creates an instance of the compression library to be used for encoding/decoding.

## Static Private Member Functions
static OFCondition | correctVOIWindows (DcmItem *dataset, double voiOffset, double voiFactor)
| modifies all VOI window center/width settings in the image.

## Additional Inherited Members
Static Public Member Functions inherited from DcmCodec
static OFCondition | insertStringIfMissing (DcmItem *dataset, const DcmTagKey &tag, const char *val)
| helper function that inserts a string attribute with a given value into a dataset if missing in the dataset.
static OFCondition | convertToSecondaryCapture (DcmItem *dataset)
| helper function that converts a dataset containing a DICOM image into a valid (standard extended) Secondary Capture object by inserting all attributes that are type 1/2 in Secondary Capture and missing in the source dataset.
static OFCondition | newInstance (DcmItem *dataset, const char *purposeOfReferenceCodingScheme=NULL, const char *purposeOfReferenceCodeValue=NULL, const char *purposeOfReferenceCodeMeaning=NULL)
| create new SOP Instance UID and Source Image Sequence referencing the old SOP instance (if present)
static OFCondition | updateImageType (DcmItem *dataset)
| update value of the Image Type element (if needed).
static OFCondition | insertCodeSequence (DcmItem *dataset, const DcmTagKey &tagKey, const char *codingSchemeDesignator, const char *codeValue, const char *codeMeaning)
| insert code sequence into the given dataset
static OFCondition | determineStartFragment (Uint32 frameNo, Sint32 numberOfFrames, DcmPixelSequence *fromPixSeq, Uint32 &currentItem)
| determine the index number (starting with zero) of the compressed pixel data fragment corresponding to the given frame (also starting with zero)

## Detailed Description

abstract codec class for JPEG encoders.

This abstract class contains most of the application logic needed for a dcmdata codec object that implements a JPEG encoder using the DJEncoder interface to the underlying JPEG implementation. This class only supports compression, it neither implements decoding nor transcoding.

## Member Function Documentation

## ◆ adjustOverlays()

virtual OFCondition DJCodecEncoder::adjustOverlays | ( | DcmItem * | dataset,
|  | DicomImage & | image ) const
| privatevirtual

for all overlay groups create (60xx,3000) Overlay Data.

Parameters

  dataset | dataset to be modified
  image | DicomImage object for this dataset

Returns
  EC_Normal if successful, an error code otherwise

## ◆ appendCompressionRatio()

void DJCodecEncoder::appendCompressionRatio | ( | OFString & | arg,
|  | double | ratio )
| staticprotected

format compression ratio as string and append to given string object.

Parameters

  arg | string to append to
  ratio | compression ratio

## ◆ canChangeCoding()

virtual OFBool DJCodecEncoder::canChangeCoding | ( | const E_TransferSyntax | oldRepType,
|  | const E_TransferSyntax | newRepType ) const
| virtual

checks if this codec is able to convert from the given current transfer syntax to the given new transfer syntax

Parameters

  oldRepType | current transfer syntax
  newRepType | desired new transfer syntax

Returns
  true if transformation is supported by this codec, false otherwise.

Implements DcmCodec.

## ◆ correctVOIWindows()

OFCondition DJCodecEncoder::correctVOIWindows | ( | DcmItem * | dataset,
|  | double | voiOffset,
|  | double | voiFactor )
| staticprivate

modifies all VOI window center/width settings in the image.

Modifications are based on the pixel value mapping f(x) = (x+voiOffset)*voiFactor

Parameters

  dataset | dataset to be updated
  voiOffset | offset to be added to each pixel
  voiFactor | factor to be multiplied

Returns
  EC_Normal if successful, an error code otherwise

## ◆ createDerivationDescription()

virtual void DJCodecEncoder::createDerivationDescription | ( | const DcmRepresentationParameter * | toRepParam,
|  | const DJCodecParameter * | cp,
|  | Uint8 | bitsPerSample,
|  | double | ratio,
|  | OFString & | derivationDescription ) const
| privatepure virtual

creates 'derivation description' string after encoding.

Parameters

  toRepParam | representation parameter passed to encode()
  cp | codec parameter passed to encode()
  bitsPerSample | bits per sample of the original image data prior to compression
  ratio | image compression ratio. This is not the "quality factor" but the real effective ratio between compressed and uncompressed image, i. e. 30 means a 30:1 lossy compression.
  derivationDescription | derivation description returned in this parameter which is initially empty

Implemented in DJEncoderBaseline, DJEncoderExtended, DJEncoderLossless, DJEncoderP14SV1, DJEncoderProgressive, and DJEncoderSpectralSelection.

## ◆ createEncoderInstance()

virtual DJEncoder * DJCodecEncoder::createEncoderInstance | ( | const DcmRepresentationParameter * | toRepParam,
|  | const DJCodecParameter * | cp,
|  | Uint8 | bitsPerSample ) const
| privatepure virtual

creates an instance of the compression library to be used for encoding/decoding.

Parameters

  toRepParam | representation parameter passed to encode()
  cp | codec parameter passed to encode()
  bitsPerSample | bits per sample for the image data

Returns
  pointer to newly allocated codec object

Implemented in DJEncoderBaseline, DJEncoderExtended, DJEncoderLossless, DJEncoderP14SV1, DJEncoderProgressive, and DJEncoderSpectralSelection.

## ◆ decode()

virtual OFCondition DJCodecEncoder::decode | ( | const DcmRepresentationParameter * | fromRepParam,
|  | DcmPixelSequence * | pixSeq,
|  | DcmPolymorphOBOW & | uncompressedPixelData,
|  | const DcmCodecParameter * | cp,
|  | const DcmStack & | objStack,
|  | OFBool & | removeOldRep ) const
| virtual

decompresses the given pixel sequence and stores the result in the given uncompressedPixelData element.

Parameters

  fromRepParam | current representation parameter of compressed data, may be NULL
  pixSeq | compressed pixel sequence
  uncompressedPixelData | uncompressed pixel data stored in this element
  cp | codec parameters for this codec
  objStack | stack pointing to the location of the pixel data element in the current dataset.
  removeOldRep | boolean flag that should be set to false before this method call and will be set to true if the codec modifies the DICOM dataset such that the pixel data of the original representation may not be usable anymore.

Returns
  EC_Normal if successful, an error code otherwise.

Implements DcmCodec.

## ◆ decodedBitsAllocated()

virtual Uint16 DJCodecEncoder::decodedBitsAllocated | ( | Uint16 | bitsAllocated,
|  | Uint16 | bitsStored ) const
| virtual

determines the effective value of BitsAllocated that a dataset will have after decompression of an image with the given values for bitsAllocated and bitsStored.

This may differ from the bitsAllocated parameter for example if that value is not a multiple of 8. Returns zero if an image with the given parameters cannot be decoded with this codec.

Parameters

  bitsAllocated | current value of Bits Allocated
  bitsStored | current value of Bits Stored

Returns
  value of BitsAllocated after decompression, 0 if no decompression possible

Implements DcmCodec.

## ◆ decodeFrame()

virtual OFCondition DJCodecEncoder::decodeFrame | ( | const DcmRepresentationParameter * | fromParam,
|  | DcmPixelSequence * | fromPixSeq,
|  | const DcmCodecParameter * | cp,
|  | DcmItem * | dataset,
|  | Uint32 | frameNo,
|  | Uint32 & | startFragment,
|  | void * | buffer,
|  | Uint32 | bufSize,
|  | OFString & | decompressedColorModel ) const
| virtual

decompresses a single frame from the given pixel sequence and stores the result in the given buffer.

Parameters

  fromParam | representation parameter of current compressed representation, may be NULL.
  fromPixSeq | compressed pixel sequence
  cp | codec parameters for this codec
  dataset | pointer to dataset in which pixel data element is contained
  frameNo | number of frame, starting with 0 for the first frame
  startFragment | index of the compressed fragment that contains all or the first part of the compressed bitstream for the given frameNo. Upon successful return this parameter is updated to contain the index of the first compressed fragment of the next frame. When unknown, zero should be passed. In this case the decompression algorithm will try to determine the index by itself, which will always work if frames are decompressed in increasing order from first to last, but may fail if frames are decompressed in random order, multiple fragments per frame and multiple frames are present in the dataset, and the offset table is empty.
  buffer | pointer to buffer where frame is to be stored
  bufSize | size of buffer in bytes
  decompressedColorModel | upon successful return, the color model of the decompressed image (which may be different from the one used in the compressed images) is returned in this parameter.

Returns
  EC_Normal if successful, an error code otherwise.

Implements DcmCodec.

## ◆ determineDecompressedColorModel()

virtual OFCondition DJCodecEncoder::determineDecompressedColorModel | ( | const DcmRepresentationParameter * | fromParam,
|  | DcmPixelSequence * | fromPixSeq,
|  | const DcmCodecParameter * | cp,
|  | DcmItem * | dataset,
|  | OFString & | decompressedColorModel ) const
| virtual

determine color model of the decompressed image

Parameters

  fromParam | representation parameter of current compressed representation, may be NULL
  fromPixSeq | compressed pixel sequence
  cp | codec parameters for this codec
  dataset | pointer to dataset in which pixel data element is contained
  dataset | pointer to DICOM dataset in which this pixel data object is located. Used to access photometric interpretation.
  decompressedColorModel | upon successful return, the color model of the decompressed image (which may be different from the one used in the compressed images) is returned in this parameter

Returns
  EC_Normal if successful, an error code otherwise

Implements DcmCodec.

## ◆ encode() [1/2]

virtual OFCondition DJCodecEncoder::encode | ( | const E_TransferSyntax | fromRepType,
|  | const DcmRepresentationParameter * | fromRepParam,
|  | DcmPixelSequence * | fromPixSeq,
|  | const DcmRepresentationParameter * | toRepParam,
|  | DcmPixelSequence *& | toPixSeq,
|  | const DcmCodecParameter * | cp,
|  | DcmStack & | objStack,
|  | OFBool & | removeOldRep ) const
| virtual

transcodes (re-compresses) the given compressed DICOM image and stores the result in the given toPixSeq element.

Parameters

  fromRepType | current transfer syntax of the compressed image
  fromRepParam | current representation parameter of compressed data, may be NULL
  fromPixSeq | compressed pixel sequence
  toRepParam | representation parameter describing the desired new compressed representation (e.g. JPEG quality)
  toPixSeq | compressed pixel sequence (pointer to new DcmPixelSequence object allocated on heap) returned in this parameter upon success.
  cp | codec parameters for this codec
  objStack | stack pointing to the location of the pixel data element in the current dataset.
  removeOldRep | boolean flag that should be set to false before this method call and will be set to true if the codec modifies the DICOM dataset such that the pixel data of the original representation may not be usable anymore.

Returns
  EC_Normal if successful, an error code otherwise.

Implements DcmCodec.

## ◆ encode() [2/2]

virtual OFCondition DJCodecEncoder::encode | ( | const Uint16 * | pixelData,
|  | const Uint32 | length,
|  | const DcmRepresentationParameter * | toRepParam,
|  | DcmPixelSequence *& | pixSeq,
|  | const DcmCodecParameter * | cp,
|  | DcmStack & | objStack,
|  | OFBool & | removeOldRep ) const
| virtual

compresses the given uncompressed DICOM image and stores the result in the given pixSeq element.

Parameters

  pixelData | pointer to the uncompressed image data in OW format and local byte order
  length | of the pixel data field in bytes
  toRepParam | representation parameter describing the desired compressed representation (e.g. JPEG quality)
  pixSeq | compressed pixel sequence (pointer to new DcmPixelSequence object allocated on heap) returned in this parameter upon success.
  cp | codec parameters for this codec
  objStack | stack pointing to the location of the pixel data element in the current dataset.
  removeOldRep | boolean flag that should be set to false before this method call and will be set to true if the codec modifies the DICOM dataset such that the pixel data of the original representation may not be usable anymore.

Returns
  EC_Normal if successful, an error code otherwise.

Implements DcmCodec.

## ◆ encodeColorImage()

virtual OFCondition DJCodecEncoder::encodeColorImage | ( | OFBool | YBRmode,
|  | DcmItem * | dataset,
|  | const DcmRepresentationParameter * | toRepParam,
|  | DcmPixelSequence *& | pixSeq,
|  | const DJCodecParameter * | cp,
|  | double & | compressionRatio ) const
| privatevirtual

compresses the given uncompressed DICOM color image and stores the result in the given pixSeq element.

Parameters

  YBRmode | true if the source image has YBR_FULL or YBR_FULL_422 photometric interpretation and can thus be compressed without color space conversion.
  dataset | DICOM dataset containing the pixel data as well as descriptive attributes
  toRepParam | representation parameter describing the desired compressed representation (e.g. JPEG quality)
  pixSeq | compressed pixel sequence (pointer to new DcmPixelSequence object allocated on heap) returned in this parameter upon success.
  cp | codec parameters for this codec
  compressionRatio | compression ratio returned in this parameter if successful.

Returns
  EC_Normal if successful, an error code otherwise.

## ◆ encodeMonochromeImage()

virtual OFCondition DJCodecEncoder::encodeMonochromeImage | ( | DcmItem * | dataset,
|  | const DcmRepresentationParameter * | toRepParam,
|  | DcmPixelSequence *& | pixSeq,
|  | const DJCodecParameter * | cp,
|  | double & | compressionRatio ) const
| privatevirtual

compresses the given uncompressed monochrome DICOM image and stores the result in the given pixSeq element.

Parameters

  dataset | DICOM dataset containing the pixel data as well as descriptive attributes
  toRepParam | representation parameter describing the desired compressed representation (e.g. JPEG quality)
  pixSeq | compressed pixel sequence (pointer to new DcmPixelSequence object allocated on heap) returned in this parameter upon success.
  cp | codec parameters for this codec
  compressionRatio | compression ratio returned in this parameter if successful.

Returns
  EC_Normal if successful, an error code otherwise.

## ◆ encodeTrueLossless()

virtual OFCondition DJCodecEncoder::encodeTrueLossless | ( | const DcmRepresentationParameter * | toRepParam,
|  | DcmPixelSequence *& | pixSeq,
|  | const DcmCodecParameter * | cp,
|  | DcmStack & | objStack ) const
| privatevirtual

compresses the given uncompressed DICOM image and stores the result in the given pixSeq element.

No colorspace conversions, modality or windowing transformations are applied to guarantee, that the quality of the source image is fully preserved.

Parameters

  toRepParam | - [in] representation parameter describing the desired
  pixSeq | - [out] compressed pixel sequence (pointer to new DcmPixelSequence object allocated on heap) returned in this parameter upon success
  cp | - [in] codec parameters for this codec
  objStack | - [in/out] stack pointing to the location of the pixel data element in the current dataset.

Returns
  EC_Normal if successful, an error code otherwise.

## ◆ isLosslessProcess()

virtual OFBool DJCodecEncoder::isLosslessProcess | ( |  | ) | const
| privatepure virtual

returns true if the transfer syntax supported by this codec is lossless.

Returns
  lossless flag

Implemented in DJEncoderBaseline, DJEncoderExtended, DJEncoderLossless, DJEncoderP14SV1, DJEncoderProgressive, and DJEncoderSpectralSelection.

## ◆ supportedTransferSyntax()

virtual E_TransferSyntax DJCodecEncoder::supportedTransferSyntax | ( |  | ) | const
| pure virtual

returns the transfer syntax that this particular codec is able to encode and decode.

Returns
  supported transfer syntax

Implemented in DJEncoderBaseline, DJEncoderExtended, DJEncoderLossless, DJEncoderP14SV1, DJEncoderProgressive, and DJEncoderSpectralSelection.

## ◆ togglePlanarConfiguration16()

OFCondition DJCodecEncoder::togglePlanarConfiguration16 | ( | Uint16 * | pixelData,
|  | const size_t | numValues,
|  | const Uint16 | samplesPerPixel,
|  | const Uint16 | oldPlanarConfig )
| staticprotected

toggles Planar Configuration of 16-bit pixel data from "by pixel" to "by plane" and vice versa.

Parameters

  pixelData | - [in/out] Original pixel data (input), contains pixel data with toggled Planar configuration after returning (output).
  numValues | - [in] The number of 16 bit values in pixelData
  samplesPerPixel | - [in] Number of components for one pixel
  oldPlanarConfig | - [in] The old Planar Configuration, that should be toggled. 0 means "by pixel", 1 "by color"

Returns
  EC_Normal, if conversion was successful; error else

## ◆ togglePlanarConfiguration8()

OFCondition DJCodecEncoder::togglePlanarConfiguration8 | ( | Uint8 * | pixelData,
|  | const size_t | numValues,
|  | const Uint16 | samplesPerPixel,
|  | const Uint16 | oldPlanarConfig )
| staticprotected

toggles Planar Configuration of 8-bit pixel data from "by pixel" to "by plane" and vice versa.

Parameters

  pixelData | - [in/out] Original pixel data (input), contains pixel data with toggled Planar configuration after returning (output).
  numValues | - [in] The number of 8 bit values in pixelData
  samplesPerPixel | - [in] Number of components for one pixel
  oldPlanarConfig | - [in] The old Planar Configuration, that should be toggled. 0 means "by pixel", 1 "by color"

Returns
  EC_Normal, if conversion was successful; error else

## ◆ updateDerivationDescription()

virtual OFCondition DJCodecEncoder::updateDerivationDescription | ( | DcmItem * | dataset,
|  | const DcmRepresentationParameter * | toRepParam,
|  | const DJCodecParameter * | cp,
|  | Uint8 | bitsPerSample,
|  | double | ratio ) const
| privatevirtual

create Derivation Description.

Parameters

  dataset | dataset to be modified
  toRepParam | representation parameter passed to encode()
  cp | codec parameter passed to encode()
  bitsPerSample | bits per sample of the original image data prior to compression
  ratio | image compression ratio. This is not the "quality factor" but the real effective ratio between compressed and uncompressed image, i. e. 30 means a 30:1 lossy compression.

Returns
  EC_Normal if successful, an error code otherwise

## ◆ updateLossyCompressionRatio()

virtual OFCondition DJCodecEncoder::updateLossyCompressionRatio | ( | DcmItem * | dataset,
|  | double | ratio ) const
| privatevirtual

create Lossy Image Compression and Lossy Image Compression Ratio.

Parameters

  dataset | dataset to be modified
  ratio | image compression ratio > 1. This is not the "quality factor" but the real effective ratio between compressed and uncompressed image, i. e. 30 means a 30:1 lossy compression.

Returns
  EC_Normal if successful, an error code otherwise

The documentation for this class was generated from the following file:

- dcmjpeg/include/dcmtk/dcmjpeg/djcodece.h

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