Class that provides median filter abilities . More...

#include <MedianOp.h>

Inheritance diagram for icl::filter::MedianOp:

Public Member Functions
	MedianOp (const utils::Size &maskSize)
	Constructor that creates a median filter object, with specified mask size. More...

void	apply (const core::ImgBase poSrc, core::ImgBase *ppoDst)
	applies the median operation on poSrc and stores the result in poDst More...

virtual utils::Size	adaptSize (const utils::Size &size)
	ensures that mask width and height are odd More...

Public Member Functions inherited from icl::filter::NeighborhoodOp
virtual	~NeighborhoodOp ()
	Destructor. More...

bool	computeROI (const core::ImgBase *poSrc, utils::Point &oROIoffset, utils::Size &oROIsize)
	compute neccessary ROI offset and size More...

virtual void	applyMT (const core::ImgBase operand1, core::ImgBase *dst, unsigned int nThreads)
	NEW apply function for multithreaded filtering (reimplemented here for special roi handling!) More...

const utils::Size &	getMaskSize () const

const utils::Point &	getAnchor () const

const utils::Point &	getROIOffset () const

virtual void	apply (const core::ImgBase operand1, core::ImgBase *dst)=0
	Import unaryOps apply function without destination image. More...

virtual const core::ImgBase *	apply (const core::ImgBase *src)
	Import unaryOps apply function without destination image. More...

Public Member Functions inherited from icl::filter::UnaryOp
	UnaryOp ()
	Explicit empty constructor. More...

	UnaryOp (const UnaryOp &other)
	Explicit copy constructor. More...

UnaryOp &	operator= (const UnaryOp &other)
	Explicit declaration of the assignment operator. More...

virtual	~UnaryOp ()
	Destructor. More...

virtual const core::ImgBase *	apply (const core::ImgBase *src)
	applys the filter usign an internal buffer as output image More...

void	operator() (const core::ImgBase src, core::ImgBase *dst)
	function operator (alternative for apply(src,dst) More...

const core::ImgBase *	operator() (const core::ImgBase *src)
	function operator for the implicit destination apply(src) call More...

const core::ImgBase &	operator() (const core::ImgBase &src)
	reference based function operator More...

void	setClipToROI (bool bClipToROI)
	sets if the image should be clip to ROI or not More...

void	setCheckOnly (bool bCheckOnly)
	sets if the destination image should be adapted to the source, or if it is only checked if it can be adapted. More...

bool	getClipToROI () const
	returns the ClipToROI status More...

bool	getCheckOnly () const
	returns the CheckOnly status More...

virtual void	setPropertyValue (const std::string &propertyName, const utils::Any &value)
	sets value of a property (always call call_callbacks(propertyName) or Configurable::setPropertyValue) More...

Public Member Functions inherited from icl::utils::Configurable
virtual	~Configurable ()
	virtual destructor More...

	Configurable (const Configurable &other)
	Copy constructor. More...

Configurable &	operator= (const Configurable &other)
	Assignment operator. More...

void	setConfigurableID (const std::string &ID)
	sets the ID of this configurable More...

const std::string &	getConfigurableID () const
	returns the configurables static ID More...

bool	isOrderedFlagSet () const
	returns whether the ordered flag is set More...

void	deactivateProperty (const std::string &pattern)
	adds an additional deativation pattern More...

void	deleteDeactivationPattern (const std::string &pattern)
	removed a formerly added deactivation pattern More...

std::vector< std::string >	getPropertyListWithoutDeactivated () const
	this returns a filtered list of properties (using all filters added by deactivateProperty) More...

virtual void	adaptProperty (const std::string &name, const std::string &newType, const std::string &newInfo, const std::string &newToolTip)
	this function can be used to adapt a specific property afterwards More...

void	registerCallback (const Callback &cb)
	add a callback for changed properties More...

void	removedCallback (const Callback &cb)
	removes a callback that was registered before More...

void	syncChangesTo (Configurable *others, int num=1)
	this can be used to let this instance also apply property changes to others More...

virtual std::vector< std::string >	getPropertyList () const
	returns a list of All properties, that can be set using setProperty More...

virtual bool	supportsProperty (const std::string &propertyName) const
	base implementation for property check (seaches in the property list) More...

virtual void	saveProperties (const std::string &filename, const std::vector< std::string > &propertiesToSkip=EMPTY_VEC) const
	writes all available properties into a file More...

virtual void	loadProperties (const std::string &filename, const std::vector< std::string > &propertiesToSkip=EMPTY_VEC)
	reads a camera config file from disc More...

virtual std::string	getPropertyType (const std::string &propertyName) const
	get type of property More...

virtual std::string	getPropertyInfo (const std::string &propertyName) const
	get information of a properties valid values More...

virtual Any	getPropertyValue (const std::string &propertyName) const
	returns the current value of a property or a parameter More...

virtual std::string	getPropertyToolTip (const std::string &propertyName) const
	returns the tooltip description for a given property More...

virtual int	getPropertyVolatileness (const std::string &propertyName) const
	Returns whether this property may be changed internally. More...

Additional Inherited Members
Public Types inherited from icl::utils::Configurable
typedef Function< void, const Property & >	Callback
	Function type for changed properties. More...

Static Public Member Functions inherited from icl::filter::UnaryOp
static UnaryOp *	fromString (const std::string &definition)
	Creates a UnaryOp instance from given string definition. More...

static std::string	getFromStringSyntax (const std::string &opSpecifier)
	gives a string syntax description for given opSpecifier More...

static std::vector< std::string >	listFromStringOps ()
	returns a list of all supported OP_SPEC values for the fromString function More...

static void	applyFromString (const std::string &definition, const core::ImgBase src, core::ImgBase *dst)
	creates, applies and releases a UnaryOp defined by given definition string More...

Static Public Member Functions inherited from icl::utils::Configurable
static std::string	create_default_ID (const std::string &prefix)
	this function can be used in subclasses to create a default ID More...

static Configurable *	get (const std::string &id)
	returns configurable by given ID More...

static void	register_configurable_type (const std::string &classname, Function< Configurable * > creator)
	registers a configurable type More...

static std::vector< std::string >	get_registered_configurables ()
	returns a list of all registered configurable classnames More...

static Configurable *	create_configurable (const std::string &classname)
	creates a configurable by given name More...

Static Public Attributes inherited from icl::utils::Configurable
static const std::vector< std::string >	EMPTY_VEC
	used as shortcut – just an empty vector of std::strings More...

Protected Member Functions inherited from icl::filter::NeighborhoodOp
	NeighborhoodOp ()

	NeighborhoodOp (const utils::Size &size)

void	setMask (const utils::Size &size)

void	setMask (const utils::Size &size, const utils::Point &anchor)

void	setROIOffset (const utils::Point &offs)

virtual bool	prepare (core::ImgBase *ppoDst, const core::ImgBase poSrc)
	prepare filter operation: ensure compatible image format and size More...

virtual bool	prepare (core::ImgBase *ppoDst, const core::ImgBase poSrc, core::depth eDepht)
	prepare filter operation: as above, but with depth parameter More...

Protected Member Functions inherited from icl::filter::UnaryOp
bool	prepare (core::ImgBase **ppoDst, core::depth eDepth, const utils::Size &imgSize, core::format eFormat, int nChannels, const utils::Rect &roi, utils::Time timestamp=utils::Time::null)

Protected Member Functions inherited from icl::utils::Configurable
void	addProperty (const std::string &name, const std::string &type, const std::string &info, const Any &value=Any(), const int volatileness=0, const std::string &tooltip=std::string())
	This can be used by derived classes to store supported properties in the internal list. More...

void	addChildConfigurable (Configurable *configurable, const std::string &childPrefix="")
	This adds another configurable as child. More...

void	removeChildConfigurable (Configurable *configurable)
	removes the given child configurable More...

Property &	prop (const std::string &propertyName)
	this CAN be used e.g. to store a property value in internal property-list More...

const Property &	prop (const std::string &propertyName) const
	this CAN be used e.g. to store a property value in internal property-list More...

	Configurable (const std::string &ID="", bool ordered=true)
	create this configurable with given ID More...

void	call_callbacks (const std::string &propertyName, const Configurable *caller) const
	calls all registered callbacks More...

Protected Attributes inherited from icl::filter::NeighborhoodOp
utils::Size	m_oMaskSize
	TODO: later private with getter and setter functions. More...

utils::Point	m_oAnchor
	anchor of filter mask More...

utils::Point	m_oROIOffset
	to-be-used ROI offset for source image More...

Protected Attributes inherited from icl::filter::UnaryOp
utils::MultiThreader *	m_poMT

Protected Attributes inherited from icl::utils::Configurable
std::vector< Callback >	callbacks
	internally managed list of callbacks More...

Detailed Description

Class that provides median filter abilities .

The median class provides the ability for arbitrary mask sizes. Although the functionality of the IPP-optimized implementation and the fallback C++-implementation is identical, the performances are of different orders of magnitude. Fallback-functions for masks with dimensions 3x3 and 5x5 are optimizied with SSE-instructions, but the computation time for images of types Img8u and Img16s is still greater than the one of IPP-implementations. However SSE-implementations show a better performance for the type icl32f. Here the algorithm just takes the median using min and max functions. Images of the type Img8u and Img16s with other mask sizes are processed by the algorithm, that was introduced by Thomas S. Huang. With the help of a histogram the algorithm runs in O(n). For all other types a trivial implementation was designed to calculate the median values. It uses the naive algorithm of sorting all N pixel values inside the median mask, and setting the destination pixel value to the mid-element of the sorted pixel list. This algorithm runs in O(w*h*N*log(N)) where (w,h) is the size of source images ROI, and N=n*n is the mask size used. The following code extract explains the operation of the fallback algorithm in Img-style notation for a single channel image, and Img8u type (the real implementation uses some special optimizations, that are not mentioned further):

  void channel_median_8u(Img8u &src, Img8u &dst, int w, int h, int c)
  {
      std::vector<icl8u> list;

      for(Img8u::iterator s=src.begin(c), d=dst.begin(c); s.inRegion() ; s++, d++ )
      {
          for(Img8u::iterator sR(s,w,h); sR.inRegion(); sR++)
          {
             list.push_back(*sR);
          }
          std::sort(list.begin(),list.end());
          *d = list[w*h/2];
          list.clear();
      }
  }

The IPP implementation uses a fast median algorithm that estimates the median not by sorting a list, but by working on a histogram. Look at the IPPI manual for more detail.

IPP for floats

Currently the IPP implementation of 2D-median filtering for Ipp32f type is slower than the C++-implementation, so the C++-fallback is always used then.

Mask-Sizes

Although the fallback C++ implementation can work with arbitrary mask sizes, the Median will internally use odd mask dimension like 3x3 or 5x7. If an even width or height parameter is given to the Median constructor, the next higher odd value is used.

Benchmarks

table

	3x3	5x5	51x51	51x3	3x51
icl8u, ipp	~1.8ms	~2.6ms	~292ms	~32.4ms	~328ms
icl8u, c++	~2.6ms	~11.7ms	~323ms	~350ms	~47ms
icl16s, ipp	~2.7ms	~4ms	~21100ms	~338ms	~420ms
icl16s, c++	~4.2ms	~16.2ms	~370ms	~384ms	~90ms
float, ipp	~25ms	~257ms	~?ms	~52000ms	~49000ms
float, c++	~11.6ms	~39ms	~217000ms	~8700ms	~8700ms

Details

Test A 1000x1000 icl8u-image with IPP

mask size 3x3 ~1.8ms (highly optimized)
mask size 5x5 ~2.6ms
mask size 51x51 ~292ms (still usable!)
mask size 51x3 ~32.4ms
mask size 3x51 ~328ms (mask height specifies time usage)

Test B 1000x1000 icl8u-image no IPP

mask size 3x3 ~2.6ms (less than 1.5 times slower)
mask size 5x5 ~11.7ms (about 4 times slower)
mask size 51x51 ~323ms (IPP is not much faster)
mask size 51x3 ~350ms (mask width specifies time usage)
mask size 3x51 ~47ms

Test A 1000x1000 icl8u-image with IPP

mask size 3x3 ~2.7ms (highly optimized)
mask size 5x5 ~4ms
mask size 51x51 ~21100ms (unusable!)
mask size 51x3 ~338ms
mask size 3x51 ~420ms

Test B 1000x1000 icl16s-image no IPP

mask size 3x3 ~4.2ms (1.5 times slower)
mask size 5x5 ~16.2ms ( 4 times slower)
mask size 51x51 ~370ms (IPP is not much faster)
mask size 51x3 ~384ms (mask width specifies time usage)
mask size 3x51 ~90ms

Test C 1000x1000 icl32f-image with IPP

mask size 3x3 ~25ms
mask size 5x5 ~257ms
mask size 51x51 ~?ms (calculation time is to great)
mask size 51x3 ~52000ms (unusable!)
mask size 3x51 ~49000ms (unusable!)

Test C 1000x1000 icl32f-image no IPP

mask size 3x3 ~11.6ms (sse optimization)
mask size 5x5 ~39ms (sse optimization)
mask size 51x51 ~217000ms (unusable!)
mask size 51x3 ~8700ms
mask size 3x51 ~8700ms

Example

Here is an examle, how to use the Median object.

// create source and destination image
Img8u src(640,480,3), *poDst=0;

// acquire some image data
...

// create the median object
Median m(Size(5,5));

// apply the median on the images - first call (slow)
// destination image is renewed to 640x480x3 (memory allocation)
m.apply(&src,&poDst);

// enter iteration loop
while(1)
{
    // aquire some new image data
    ...

    // apply the median filter (now fast, as no memory
    // allocation must be performed)
    m.apply(&src,&poDst);

    // further processing steps
    ...
}

Constructor & Destructor Documentation

◆ MedianOp()

icl::filter::MedianOp::MedianOp ( const utils::Size & maskSize )

inline

Constructor that creates a median filter object, with specified mask size.

Parameters

maskSize of odd width and height Even width or height is increased to next higher odd value.

Member Function Documentation

◆ adaptSize()

virtual utils::Size icl::filter::MedianOp::adaptSize ( const utils::Size & size )

inlinevirtual

ensures that mask width and height are odd

This is a workaround, necessary because of an ipp Bug that allows no even mask sizes here!

Parameters

size	size to adjust

Returns: adjusted size (width and height are rounded up to the next higher odd value

Reimplemented from icl::filter::NeighborhoodOp.

◆ apply()

void icl::filter::MedianOp::apply	(	const core::ImgBase *	poSrc,
		core::ImgBase **	ppoDst
	)

virtual

applies the median operation on poSrc and stores the result in poDst

The depth, channel count and size of poDst is adapted to poSrc' ROI:

Parameters

poSrc	source image
ppoDst	pointer to destination image

Implements icl::filter::UnaryOp.

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

/Users/alneuman/vm/icl/ICLFilter/src/ICLFilter/MedianOp.h

Public Member Functions

Additional Inherited Members

Detailed Description

IPP for floats

Mask-Sizes

Benchmarks

table

Details

Test A 1000x1000 icl8u-image with IPP

Test B 1000x1000 icl8u-image no IPP

Test A 1000x1000 icl8u-image with IPP

Test B 1000x1000 icl16s-image no IPP

Test C 1000x1000 icl32f-image with IPP

Test C 1000x1000 icl32f-image no IPP

Example

Constructor & Destructor Documentation

◆ MedianOp()

Member Function Documentation

◆ adaptSize()

◆ apply()