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JPEGGenerator Class Reference

#include <JPEGGenerator.h>

Inheritance diagram for JPEGGenerator:

List of all members.


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

Definition at line 38 of file JPEGGenerator.h.


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 processEvent (const EventBase &event)
 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)
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 unsigned int 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::RawCamBehavior::compress_quality to be used

Private Member Functions

 JPEGGenerator (const JPEGGenerator &fbk)
 don't call
const JPEGGeneratoroperator= (const JPEGGenerator &fbk)
 don't call

Member Enumeration Documentation

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 11 of file JPEGGenerator.cc.

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

constructor

Definition at line 32 of file JPEGGenerator.cc.

JPEGGenerator::~JPEGGenerator (  )  [virtual]

destructor

Definition at line 55 of file JPEGGenerator.cc.

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

don't call


Member Function Documentation

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

set srcMode and curMode as well if mode==SRC_AUTO

Definition at line 58 of file JPEGGenerator.h.

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

returns srcMode

Definition at line 60 of file JPEGGenerator.h.

Referenced by processEvent().

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

returns curMode

Definition at line 62 of file JPEGGenerator.h.

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

static std::string JPEGGenerator::getClassDescription (  )  [inline, 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.

void JPEGGenerator::processEvent ( const EventBase event  )  [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 67 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.

unsigned int JPEGGenerator::loadBuffer ( const char  buf[],
unsigned int  len 
) [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.

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.

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

returns quality

Definition at line 78 of file JPEGGenerator.h.

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

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

Definition at line 80 of file JPEGGenerator.h.

virtual unsigned int JPEGGenerator::getImageSize ( unsigned int  layer,
unsigned int  chan 
) const [inline, 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())

Definition at line 88 of file JPEGGenerator.h.

Referenced by LGmixin::uploadCameraImage().

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().

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::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.

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

deletes the arrays

Reimplemented from FilterBankGenerator.

Definition at line 226 of file JPEGGenerator.cc.

Referenced by ~JPEGGenerator().

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

don't call


Member Data Documentation

const unsigned int JPEGGenerator::JPEG_HEADER_PAD = 500 [static]

add a bit to the expected size in getBinSize just to leave a little extra room for small images

Definition at line 40 of file JPEGGenerator.h.

Referenced by calcImage(), createImageCache(), and getBinSize().

how to interpret source channel of next filter bank event

Definition at line 96 of file JPEGGenerator.h.

Referenced by getSourceMode(), JPEGGenerator(), and setSourceMode().

how to interpret getImage's current image

Definition at line 97 of file JPEGGenerator.h.

Referenced by getCurrentSourceFormat(), JPEGGenerator(), processEvent(), and setSourceMode().

unsigned int** JPEGGenerator::bytesUsed [protected]

number of bytes used per image to actually store data;

Definition at line 99 of file JPEGGenerator.h.

Referenced by calcImage(), destruct(), getBinSize(), getImageSize(), loadBuffer(), saveBuffer(), and setNumImages().

struct jpeg_compress_struct JPEGGenerator::cinfo [read, protected]

used to interface with libjpeg - holds compression parameters and state

Definition at line 101 of file JPEGGenerator.h.

Referenced by calcImage(), JPEGGenerator(), and ~JPEGGenerator().

struct jpeg_error_mgr JPEGGenerator::jerr [read, protected]

used to interface with libjpeg - gives us access to error information

Definition at line 102 of file JPEGGenerator.h.

Referenced by JPEGGenerator().

unsigned int JPEGGenerator::quality [protected]

quality level to pass to libjpeg; -1U causes Config::vision_config::RawCamBehavior::compress_quality to be used

Definition at line 104 of file JPEGGenerator.h.

Referenced by calcImage(), getQuality(), and setQuality().


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

Tekkotsu v4.0
Generated Thu Nov 22 00:58:27 2007 by Doxygen 1.5.4