JPEGGenerator Class Reference

Generates FilterBankEvents containing JPEG compressed images. More...

#include <JPEGGenerator.h>

Inheritance diagram for JPEGGenerator:

Detailed Description

Generates FilterBankEvents containing JPEG compressed images.

There's only one channel per resolution layer, which holds the compressed data. This is mostly intended for being sent over wireless, but if you know how JPEG works, you may be able to interpret the compressed data directly and glean useful information from it. After all, compression is all about throwing away unimportant details and storing the salient information.

The generated events use 0 for their event source IDs. The row skip and row stride are 0. (they don't really apply here)

This can either compress a greyscale image or an interleaved YUV image. If the source generator's type is not InterleavedYUVGenerator, it will assume greyscale. Call setSource() to override this.

The InterleavedYUVGenerator is separated from this because it wouldn't really make things much faster to combine the algorithms, and others might find the interleaved format handy for passing to other libraries which expect that format, such as what happened with libjpeg.

This class shares a lot of non-JPEG specific code with PNGGenerator, so you may want to replicate any changes made in that class as well.

Todo:

possible speedup by using jpeg_write_raw_data

create a common super class with PNGGenerator to hold common setup code

Definition at line 38 of file JPEGGenerator.h.

List of all members.

Public Types
enum	src_mode_t { SRC_AUTO, SRC_GRAYSCALE, SRC_COLOR }
	defines how to interpret the source images (see srcMode and curMode) More...
Public Member Functions
	JPEGGenerator (unsigned int mysid, FilterBankGenerator *fbg, EventBase::EventTypeID_t tid)
	constructor
	JPEGGenerator (unsigned int mysid, JPEGGenerator::src_mode_t sMode, FilterBankGenerator *fbg, EventBase::EventTypeID_t tid)
	constructor
virtual	~JPEGGenerator ()
	destructor
virtual void	setSourceMode (src_mode_t mode)
	set srcMode and curMode as well if mode==SRC_AUTO
virtual src_mode_t	getSourceMode () const
	returns srcMode
virtual src_mode_t	getCurrentSourceFormat () const
	returns curMode
virtual void	doEvent ()
	should receive FilterBankEvents from a RawCameraGenerator (or a subclass thereof)
virtual unsigned int	getBinSize () const
	if we don't already know bytesUsed, let's assume the size will be smaller than the original uncompressed. If we fail this assumption, probably better to fail anyway.
virtual unsigned int	loadBuffer (const char buf[], unsigned int len, const char *filename=NULL)
virtual unsigned int	saveBuffer (char buf[], unsigned int len) const
	you probably don't want to be calling this to access the JPEG -- use getImage() instead (saveBuffer will prepend some header information before the actual image data)
virtual unsigned int	getQuality () const
	returns quality
virtual void	setQuality (unsigned int q)
	sets quality; this will invalidate the cache if q does not equal current quality
virtual size_t	getImageSize (unsigned int layer, unsigned int chan) const
	returns the number of bytes used for the image returned by getImage() - will return 0 if the image hasn't been calculated yet (so call it after getImage())
Static Public Member Functions
static std::string	getClassDescription ()
	Gives a short description of what this class of behaviors does... you should override this (but don't have to).
Static Public Attributes
static const unsigned int	JPEG_HEADER_PAD = 500
	add a bit to the expected size in getBinSize just to leave a little extra room for small images
Protected Member Functions
virtual void	setNumImages (unsigned int nLayers, unsigned int nChannels)
	resizes the filter bank information storage area, you should override this to do your setup and call it from your constructor
virtual unsigned char *	createImageCache (unsigned int layer, unsigned int chan) const
	create new image data storage area for the cache - this called by getImage() only when the corresponding entry in images is NULL
virtual void	calcImage (unsigned int layer, unsigned int chan)
	should calculate new image data, called by getImage() only when imageValids indicates the image being requested is dirty (and only after getImage() has already called createImageCache())
virtual void	destruct ()
	deletes the arrays
Protected Attributes
src_mode_t	srcMode
	how to interpret source channel of next filter bank event
src_mode_t	curMode
	how to interpret getImage's current image
unsigned int **	bytesUsed
	number of bytes used per image to actually store data;
struct jpeg_compress_struct	cinfo
	used to interface with libjpeg - holds compression parameters and state
struct jpeg_error_mgr	jerr
	used to interface with libjpeg - gives us access to error information
unsigned int	quality
	quality level to pass to libjpeg; -1U causes Config::vision_config::RawCam::compress_quality to be used
Private Member Functions
	JPEGGenerator (const JPEGGenerator &fbk)
	don't call
const JPEGGenerator &	operator= (const JPEGGenerator &fbk)
	don't call

Member Enumeration Documentation

enum JPEGGenerator::src_mode_t

defines how to interpret the source images (see srcMode and curMode)

Enumerator:

SRC_AUTO	if src is not a InterleavedYUVGenerator, SRC_GREYSCALE, otherwise SRC_COLOR
SRC_GRAYSCALE	indicates each channel of source should be compressed individually as grayscale images
SRC_COLOR	indicates first channel should be in an interleaved layout which can be compressed into a "color" image

Definition at line 43 of file JPEGGenerator.h.

Constructor & Destructor Documentation

JPEGGenerator::JPEGGenerator	(	unsigned int	mysid,
		FilterBankGenerator *	fbg,
		EventBase::EventTypeID_t	tid
	)

constructor

Definition at line 12 of file JPEGGenerator.cc.

JPEGGenerator::JPEGGenerator	(	unsigned int	mysid,
		JPEGGenerator::src_mode_t	sMode,
		FilterBankGenerator *	fbg,
		EventBase::EventTypeID_t	tid
	)

constructor

Definition at line 33 of file JPEGGenerator.cc.

JPEGGenerator::~JPEGGenerator ( ) [virtual]

destructor

Definition at line 56 of file JPEGGenerator.cc.

JPEGGenerator::JPEGGenerator ( const JPEGGenerator & fbk ) [private]

don't call

Member Function Documentation

void JPEGGenerator::calcImage	(	unsigned int	layer,
		unsigned int	channel
	)			`[protected, virtual]`

should calculate new image data, called by getImage() only when imageValids indicates the image being requested is dirty (and only after getImage() has already called createImageCache())

This is where you'll want to put your user-specific code for calculating the image data

Implements FilterBankGenerator.

Definition at line 195 of file JPEGGenerator.cc.

unsigned char * JPEGGenerator::createImageCache	(	unsigned int	layer,
		unsigned int	channel
	)			const `[protected, virtual]`

create new image data storage area for the cache - this called by getImage() only when the corresponding entry in images is NULL

You should return the pointer you want stored in images to be returned by any calls to getFirstRow. Interpretation of the data it points to is dependant on the the generator which creates it

Implements FilterBankGenerator.

Definition at line 190 of file JPEGGenerator.cc.

Referenced by loadBuffer().

void JPEGGenerator::destruct ( ) [protected, virtual]

deletes the arrays

Reimplemented from FilterBankGenerator.

Definition at line 226 of file JPEGGenerator.cc.

Referenced by ~JPEGGenerator().

void JPEGGenerator::doEvent ( ) [virtual]

should receive FilterBankEvents from a RawCameraGenerator (or a subclass thereof)

The const casts in this function are regretable but necessary since the corresponding OPEN-R functions require mutable arguments, even though they shouldn't be modifying the data

Reimplemented from FilterBankGenerator.

Definition at line 68 of file JPEGGenerator.cc.

unsigned int JPEGGenerator::getBinSize ( ) const [virtual]

if we don't already know bytesUsed, let's assume the size will be smaller than the original uncompressed. If we fail this assumption, probably better to fail anyway.

Reimplemented from FilterBankGenerator.

Definition at line 86 of file JPEGGenerator.cc.

static std::string JPEGGenerator::getClassDescription ( ) [static]

Gives a short description of what this class of behaviors does... you should override this (but don't have to).

If you do override this, also consider overriding getDescription() to return it

Reimplemented from BehaviorBase.

Definition at line 64 of file JPEGGenerator.h.

virtual src_mode_t JPEGGenerator::getCurrentSourceFormat ( ) const [virtual]

returns curMode

Definition at line 62 of file JPEGGenerator.h.

Referenced by calcImage(), getBinSize(), loadBuffer(), and saveBuffer().

virtual size_t JPEGGenerator::getImageSize	(	unsigned int	layer,
		unsigned int	chan
	)			const `[virtual]`

returns the number of bytes used for the image returned by getImage() - will return 0 if the image hasn't been calculated yet (so call it after getImage())

Reimplemented from FilterBankGenerator.

Definition at line 88 of file JPEGGenerator.h.

Referenced by CameraBehavior::doEvent(), and LGmixin::uploadCameraImage().

virtual unsigned int JPEGGenerator::getQuality ( ) const [virtual]

returns quality

Definition at line 78 of file JPEGGenerator.h.

Referenced by CameraBehavior::doEvent().

virtual src_mode_t JPEGGenerator::getSourceMode ( ) const [virtual]

returns srcMode

Definition at line 60 of file JPEGGenerator.h.

Referenced by doEvent().

unsigned int JPEGGenerator::loadBuffer	(	const char	buf[],
		unsigned int	len,
		const char *	filename = `NULL`
	)			`[virtual]`

The loadBuffer() functions of the included subclasses aren't tested, so don't assume they'll work without a little debugging...

Reimplemented from FilterBankGenerator.

Definition at line 106 of file JPEGGenerator.cc.

const JPEGGenerator& JPEGGenerator::operator= ( const JPEGGenerator & fbk ) [private]

don't call

unsigned int JPEGGenerator::saveBuffer	(	char	buf[],
		unsigned int	len
	)			const `[virtual]`

you probably don't want to be calling this to access the JPEG -- use getImage() instead (saveBuffer will prepend some header information before the actual image data)

Reimplemented from FilterBankGenerator.

Definition at line 138 of file JPEGGenerator.cc.

void JPEGGenerator::setNumImages	(	unsigned int	nLayers,
		unsigned int	nChannels
	)			`[protected, virtual]`

resizes the filter bank information storage area, you should override this to do your setup and call it from your constructor

In general, it isn't expected that FilterBankGenerator's should necessarily be dynamically resizeable (although it would be nice), which is why this isn't public. If yours is, just add some pubic accessor functions which call this. In general, the included subclasses should be able to handle being resized, but there's no reason to do so since the system won't be changing its available resolutions at run time.

The default implementation is a no-op if(numLayers==nLayers && numChannels==nChannels)

Reimplemented from FilterBankGenerator.

Definition at line 174 of file JPEGGenerator.cc.

Referenced by JPEGGenerator().

virtual void JPEGGenerator::setQuality ( unsigned int q ) [virtual]

sets quality; this will invalidate the cache if q does not equal current quality

Definition at line 80 of file JPEGGenerator.h.

Referenced by CameraBehavior::doEvent().

virtual void JPEGGenerator::setSourceMode ( src_mode_t mode ) [virtual]

set srcMode and curMode as well if mode==SRC_AUTO

Definition at line 58 of file JPEGGenerator.h.