DJCodecDecoder Class Reference

abstract codec class for JPEG decoders. More...

Inheritance diagram for DJCodecDecoder:

List of all members.

Public Member Functions
	DJCodecDecoder ()
	default constructor
virtual	~DJCodecDecoder ()
	destructor
virtual OFCondition	decode (const DcmRepresentationParameter *fromRepParam, DcmPixelSequence *pixSeq, DcmPolymorphOBOW &uncompressedPixelData, const DcmCodecParameter *cp, const DcmStack &objStack) 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) 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) 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 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 decode.
Private Member Functions
virtual DJDecoder *	createDecoderInstance (const DcmRepresentationParameter *toRepParam, const DJCodecParameter *cp, Uint8 bitsPerSample, OFBool isYBR) const =0
	creates an instance of the compression library to be used for decoding.
Static Private Member Functions
static Uint8	scanJpegDataForBitDepth (const Uint8 *data, const Uint32 fragmentLength)
	scans the given block of JPEG data for a Start of Frame marker and returns the number of bits per pixel stored in the Start of Frame block.
static Uint16	readUint16 (const Uint8 *data)
	reads two bytes from the given array of little endian 16-bit values and returns the value as Uint16 in local byte order.
static OFCondition	createPlanarConfigurationByte (Uint8 *imageFrame, Uint16 columns, Uint16 rows)
	converts an RGB or YBR frame with 8 bits/sample from color-by-pixel to color-by-plane planar configuration.
static OFCondition	createPlanarConfigurationWord (Uint16 *imageFrame, Uint16 columns, Uint16 rows)
	converts an RGB or YBR frame with 16 bits/sample from color-by-pixel to color-by-plane planar configuration.
static OFBool	requiresPlanarConfiguration (const char *sopClassUID, EP_Interpretation photometricInterpretation)
	examines if a given image requires color-by-plane planar configuration depending on SOP Class UID (DICOM IOD) and photometric interpretation.

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Detailed Description

abstract codec class for JPEG decoders.

This abstract class contains most of the application logic needed for a dcmdata codec object that implements a JPEG decoder using the DJDecoder interface to the underlying JPEG implementation. This class only supports decompression, it neither implements encoding nor transcoding.

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Member Function Documentation

virtual OFBool DJCodecDecoder::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.

virtual DJDecoder* DJCodecDecoder::createDecoderInstance	(	const DcmRepresentationParameter *	toRepParam,
		const DJCodecParameter *	cp,
		Uint8	bitsPerSample,
		OFBool	isYBR
	)		const [private, pure virtual]

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

Parameters:

toRepParam	representation parameter passed to decode()
cp	codec parameter passed to decode()
bitsPerSample	bits per sample for the image data
isYBR	flag indicating whether DICOM photometric interpretation is YCbCr

Returns:

pointer to newly allocated decoder object

Implemented in DJDecoderExtended, DJDecoderLossless, DJDecoderProgressive, DJDecoderSpectralSelection, DJDecoderP14SV1, and DJDecoderBaseline.

static OFCondition DJCodecDecoder::createPlanarConfigurationByte	(	Uint8 *	imageFrame,
		Uint16	columns,
		Uint16	rows
	)		[static, private]

converts an RGB or YBR frame with 8 bits/sample from color-by-pixel to color-by-plane planar configuration.

Parameters:

imageFrame	pointer to image frame, must contain at least 3*columns*rows bytes of pixel data.
columns	columns
rows	rows

Returns:

EC_Normal if successful, an error code otherwise

static OFCondition DJCodecDecoder::createPlanarConfigurationWord	(	Uint16 *	imageFrame,
		Uint16	columns,
		Uint16	rows
	)		[static, private]

converts an RGB or YBR frame with 16 bits/sample from color-by-pixel to color-by-plane planar configuration.

Parameters:

imageFrame	pointer to image frame, must contain at least 3*columns*rows words of pixel data.
columns	columns
rows	rows

Returns:

EC_Normal if successful, an error code otherwise

virtual OFCondition DJCodecDecoder::decode	(	const DcmRepresentationParameter *	fromRepParam,
		DcmPixelSequence *	pixSeq,
		DcmPolymorphOBOW &	uncompressedPixelData,
		const DcmCodecParameter *	cp,
		const DcmStack &	objStack
	)		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.

Returns:

EC_Normal if successful, an error code otherwise.

Implements DcmCodec.

virtual OFCondition DJCodecDecoder::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.

virtual OFCondition DJCodecDecoder::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.

virtual OFCondition DJCodecDecoder::encode	(	const Uint16 *	pixelData,
		const Uint32	length,
		const DcmRepresentationParameter *	toRepParam,
		DcmPixelSequence *&	pixSeq,
		const DcmCodecParameter *	cp,
		DcmStack &	objStack
	)		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.

Returns:

EC_Normal if successful, an error code otherwise.

Implements DcmCodec.

virtual OFCondition DJCodecDecoder::encode	(	const E_TransferSyntax	fromRepType,
		const DcmRepresentationParameter *	fromRepParam,
		DcmPixelSequence *	fromPixSeq,
		const DcmRepresentationParameter *	toRepParam,
		DcmPixelSequence *&	toPixSeq,
		const DcmCodecParameter *	cp,
		DcmStack &	objStack
	)		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.

Returns:

EC_Normal if successful, an error code otherwise.

Implements DcmCodec.

static Uint16 DJCodecDecoder::readUint16

(

const Uint8 *

data

)

[static, private]

reads two bytes from the given array of little endian 16-bit values and returns the value as Uint16 in local byte order.

Parameters:

data	pointer to array, must not be NULL, must at least 2 bytes large

Returns:

Uint16 read from array

static OFBool DJCodecDecoder::requiresPlanarConfiguration	(	const char *	sopClassUID,
		EP_Interpretation	photometricInterpretation
	)		[static, private]

examines if a given image requires color-by-plane planar configuration depending on SOP Class UID (DICOM IOD) and photometric interpretation.

All SOP classes defined in the 2003 edition of the DICOM standard or earlier are handled correctly.

Parameters:

sopClassUID	SOP Class UID
photometricInterpretation	decompressed photometric interpretation

Returns:

true if color-by-plane is required, false otherwise.

static Uint8 DJCodecDecoder::scanJpegDataForBitDepth	(	const Uint8 *	data,
		const Uint32	fragmentLength
	)		[static, private]

scans the given block of JPEG data for a Start of Frame marker and returns the number of bits per pixel stored in the Start of Frame block.

Parameters:

data	pointer to array, must not be NULL
fragmentLength	size of array

Returns:

bit depth of JPEG data, 0 if no SOF marker found or parse error

virtual E_TransferSyntax DJCodecDecoder::supportedTransferSyntax

(

)

const [pure virtual]

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

Returns:

supported transfer syntax

Implemented in DJDecoderExtended, DJDecoderLossless, DJDecoderProgressive, DJDecoderSpectralSelection, DJDecoderP14SV1, and DJDecoderBaseline.

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

• dcmjpeg/include/dcmtk/dcmjpeg/djcodecd.h