JPEGGenerator Class Reference
#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.
Public Types | |
| 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 | |
| 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; | |
| jpeg_compress_struct | cinfo |
| used to interface with libjpeg - holds compression parameters and state | |
| 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 JPEGGenerator & | operator= (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.
Member Function Documentation
| void JPEGGenerator::calcImage | ( | unsigned int | layer, | |
| unsigned int | chan | |||
| ) | [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 | chan | |||
| ) | 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().
| 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.
| 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.
| 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.
| 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().
The documentation for this class was generated from the following files:
