DemoBackgroundSubtract Class Reference

Background subtraction to detect moving objects. More...

Inheritance diagram for DemoBackgroundSubtract:

Collaboration diagram for DemoBackgroundSubtract:

Public Member Functions
	DemoBackgroundSubtract (std::string const &instance)
	Constructor.
virtual	~DemoBackgroundSubtract ()
	Virtual destructor for safe inheritance.
virtual void	process (jevois::InputFrame &&inframe, jevois::OutputFrame &&outframe) override
	Processing function.
virtual void	process (jevois::InputFrame &&inframe, jevois::GUIhelper &helper) override
	Processing function with zero-copy and GUI on JeVois-Pro.
Public Member Functions inherited from jevois::Module
	Module (std::string const &instance)
virtual	~Module ()
virtual void	process (InputFrame &&inframe)
virtual void	sendSerial (std::string const &str)
virtual void	parseSerial (std::string const &str, std::shared_ptr< UserInterface > s)
virtual void	supportedCommands (std::ostream &os)
Public Member Functions inherited from jevois::Component
	Component (std::string const &instance)
virtual	~Component ()
std::shared_ptr< Comp >	addSubComponent (std::string const &instance, Args &&...args)
void	removeSubComponent (std::shared_ptr< Comp > &component)
void	removeSubComponent (std::string const &instance, bool warnIfNotFound=true)
std::shared_ptr< Comp >	getSubComponent (std::string const &instance) const
bool	isTopLevel () const
bool	initialized () const
std::string const &	className () const
std::string const &	instanceName () const
std::vector< std::string >	setParamVal (std::string const &paramdescriptor, T const &val)
void	setParamValUnique (std::string const &paramdescriptor, T const &val)
std::vector< std::pair< std::string, T > >	getParamVal (std::string const &paramdescriptor) const
T	getParamValUnique (std::string const &paramdescriptor) const
std::vector< std::string >	setParamString (std::string const &paramdescriptor, std::string const &val)
void	setParamStringUnique (std::string const &paramdescriptor, std::string const &val)
std::vector< std::pair< std::string, std::string > >	getParamString (std::string const &paramdescriptor) const
std::string	getParamStringUnique (std::string const &paramdescriptor) const
void	freezeParam (std::string const &paramdescriptor, bool doit)
void	freezeAllParams (bool doit)
std::string	descriptor () const
void	setParamsFromFile (std::string const &filename)
std::istream &	setParamsFromStream (std::istream &is, std::string const &absfile)
virtual void	paramInfo (std::shared_ptr< UserInterface > s, std::map< std::string, std::string > &categs, bool skipFrozen, std::string const &cname="", std::string const &pfx="")
void	foreachParam (std::function< void(std::string const &compname, ParameterBase *p)> func, std::string const &cname="")
std::shared_ptr< DynamicParameter< T > >	addDynamicParameter (std::string const &name, std::string const &description, T const &defaultValue, ParameterCategory const &category)
std::shared_ptr< DynamicParameter< T > >	addDynamicParameter (std::string const &name, std::string const &description, T const &defaultValue, ValidValuesSpec< T > const &validValuesSpec, ParameterCategory const &category)
void	setDynamicParameterCallback (std::string const &name, std::function< void(T const &)> cb, bool callnow=true)
void	removeDynamicParameter (std::string const &name, bool throw_if_not_found=true)
void	setPath (std::string const &path)
std::filesystem::path	absolutePath (std::filesystem::path const &path="")
std::shared_ptr< Comp >	addSubComponent (std::string const &instance, Args &&...args)
void	removeSubComponent (std::shared_ptr< Comp > &component)
void	removeSubComponent (std::string const &instance, bool warnIfNotFound=true)
std::shared_ptr< Comp >	getSubComponent (std::string const &instance) const
bool	isTopLevel () const
bool	initialized () const
std::string const &	className () const
std::string const &	instanceName () const
std::vector< std::string >	setParamVal (std::string const &paramdescriptor, T const &val)
void	setParamValUnique (std::string const &paramdescriptor, T const &val)
std::vector< std::pair< std::string, T > >	getParamVal (std::string const &paramdescriptor) const
T	getParamValUnique (std::string const &paramdescriptor) const
std::vector< std::string >	setParamString (std::string const &paramdescriptor, std::string const &val)
void	setParamStringUnique (std::string const &paramdescriptor, std::string const &val)
std::vector< std::pair< std::string, std::string > >	getParamString (std::string const &paramdescriptor) const
std::string	getParamStringUnique (std::string const &paramdescriptor) const
void	freezeParam (std::string const &paramdescriptor, bool doit)
void	freezeAllParams (bool doit)
std::string	descriptor () const
void	setParamsFromFile (std::string const &filename)
std::istream &	setParamsFromStream (std::istream &is, std::string const &absfile)
virtual void	paramInfo (std::shared_ptr< UserInterface > s, std::map< std::string, std::string > &categs, bool skipFrozen, std::string const &cname="", std::string const &pfx="")
void	foreachParam (std::function< void(std::string const &compname, ParameterBase *p)> func, std::string const &cname="")
std::shared_ptr< DynamicParameter< T > >	addDynamicParameter (std::string const &name, std::string const &description, T const &defaultValue, ParameterCategory const &category)
std::shared_ptr< DynamicParameter< T > >	addDynamicParameter (std::string const &name, std::string const &description, T const &defaultValue, ValidValuesSpec< T > const &validValuesSpec, ParameterCategory const &category)
void	setDynamicParameterCallback (std::string const &name, std::function< void(T const &)> cb, bool callnow=true)
void	removeDynamicParameter (std::string const &name, bool throw_if_not_found=true)
void	setPath (std::string const &path)
std::filesystem::path	absolutePath (std::filesystem::path const &path="")
Public Member Functions inherited from jevois::ParameterRegistry
virtual	~ParameterRegistry ()

Protected Attributes
jevois::Timer	itsProcessingTimer
cv::Ptr< cv::BackgroundSubtractor >	bgs

Additional Inherited Members
Protected Member Functions inherited from jevois::Component
virtual void	preInit ()
virtual void	postInit ()
virtual void	preUninit ()
virtual void	postUninit ()
virtual void	preInit ()
virtual void	postInit ()
virtual void	preUninit ()
virtual void	postUninit ()
Protected Member Functions inherited from jevois::ParameterRegistry
void	addParameter (ParameterBase *const param)
void	removeParameter (ParameterBase *const param)
void	callbackInitCall ()

Detailed Description

Background subtraction to detect moving objects.

This background subtraction algorithm learns, over time, a statistical model of the appearance of a scene when the camera is not moving. Any moving object entering the field of view will then be detected as significantly different from the learned pixel model.

You can thus use this module to detect moving objects with a static JeVois camera. This module is quite robust to image noise since it learns a statistical model of the distribution of "normal" values a pixel may take over time, as opposed to more simply subtracting one camera image from the previous one (which would be much noisier).

Trying it out

• Make sure that your JeVois camera is stable and not moving (nor vibrating because of its fan); you may want to mount it securely using screws, zip ties, etc
• When nothing moves, you should see the right side of the video progressively fade to black. This is the result of this module learning the normal range of RGB values that each pixel may take over time, given sensor noise, small variations in lighting, and other environmental factors.
• Now move your hand or some other object in front of JeVois. It should be detected on the right side of the display and should show up in white color.
• Note that the autogain and autoexposure features of the JeVois camera sensor may trip this model. For example if you suddenly present a large white object in front of the JeVois camera that had been looking at an overall dark scene for a while, that bright white object might trigger an automatic reduction in exposure, which will in turn brighten the whole image and make it appear much different from what it used to be (so, everything might briefly turn white color in the right panel of the video display). To avoid this, you may want to use this module with manual settings for gain, white balance, and exposure.

Note that this class has internal state (it learns the statistics of the background over time).

Author

Laurent Itti

Videomapping:

YUYV 640 240 15.0 YUYV 320 240 15.0 JeVois DemoBackgroundSubtract

Videomapping:

YUYV 320 120 30.0 YUYV 160 120 30.0 JeVois DemoBackgroundSubtract

Email:

itti@usc.edu

Address:

University of Southern California, HNB-07A, 3641 Watt Way, Los Angeles, CA 90089-2520, USA

Copyright

Copyright (C) 2016 by Laurent Itti, iLab and the University of Southern California

Main URL:

http://jevois.org

Support URL:

http://jevois.org/doc

Other URL:

http://iLab.usc.edu

License:

GPL v3

Distribution:

Unrestricted

Restrictions:

None

Definition at line 79 of file DemoBackgroundSubtract.C.

Constructor & Destructor Documentation

DemoBackgroundSubtract()

DemoBackgroundSubtract::DemoBackgroundSubtract ( std::string const &  instance )

inline

Constructor.

Definition at line 83 of file DemoBackgroundSubtract.C.

~DemoBackgroundSubtract()

virtual DemoBackgroundSubtract::~DemoBackgroundSubtract ( )

inlinevirtual

Virtual destructor for safe inheritance.

Definition at line 88 of file DemoBackgroundSubtract.C.

Member Function Documentation

process() [1/2]

virtual void DemoBackgroundSubtract::process ( jevois::InputFrame &&  inframe, jevois::GUIhelper &  helper  )

inlineoverridevirtual

Processing function with zero-copy and GUI on JeVois-Pro.

Reimplemented from jevois::Module.

Definition at line 140 of file DemoBackgroundSubtract.C.

References bgs, jevois::GUIhelper::drawImage(), jevois::GUIhelper::drawInputFrame(), jevois::GUIhelper::endFrame(), jevois::GUIhelper::iinfo(), jevois::GUIhelper::itext(), jevois::Timer::start(), jevois::GUIhelper::startFrame(), and jevois::Timer::stop().

process() [2/2]

virtual void DemoBackgroundSubtract::process ( jevois::InputFrame &&  inframe, jevois::OutputFrame &&  outframe  )

inlineoverridevirtual

Processing function.

Reimplemented from jevois::Module.

Definition at line 91 of file DemoBackgroundSubtract.C.

References jevois::async(), bgs, jevois::rawimage::convertToCvBGR(), h, jevois::RawImage::height, itsProcessingTimer, jevois::rawimage::paste(), jevois::rawimage::pasteGreyToYUYV(), jevois::RawImage::require(), jevois::Timer::start(), jevois::Timer::stop(), jevois::yuyv::White, jevois::RawImage::width, and jevois::rawimage::writeText().

Member Data Documentation

bgs

cv::Ptr<cv::BackgroundSubtractor> DemoBackgroundSubtract::bgs

protected

Definition at line 180 of file DemoBackgroundSubtract.C.

Referenced by process(), and process().

itsProcessingTimer

jevois::Timer DemoBackgroundSubtract::itsProcessingTimer

protected

Definition at line 179 of file DemoBackgroundSubtract.C.

Referenced by process().

---

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

• src/Modules/DemoBackgroundSubtract/DemoBackgroundSubtract.C