Image Component Library (ICL)
Public Member Functions | List of all members

Class that provides median filter abilities . More...

#include <MedianOp.h>

Inheritance diagram for icl::filter::MedianOp:
icl::filter::NeighborhoodOp icl::filter::UnaryOp icl::utils::Configurable

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::SizegetMaskSize () const
const utils::PointgetAnchor () const
const utils::PointgetROIOffset () const
- Public Member Functions inherited from icl::filter::UnaryOp
 UnaryOp ()
 Explicit empty constructor. More...
 UnaryOp (const UnaryOp &other)
 Explicit copy constructor. More...
UnaryOpoperator= (const UnaryOp &other)
 Explicit declaration of the assignment operator. More...
virtual ~UnaryOp ()
 Destructor. More...
virtual const core::ImgBaseapply (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::ImgBaseoperator() (const core::ImgBase *src)
 function operator for the implicit destination apply(src) call More...
const core::ImgBaseoperator() (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) throw (utils::ICLException)
 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...
Configurableoperator= (const Configurable &other)
 Assignment operator. More...
void setConfigurableID (const std::string &ID) throw (ICLException)
 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) throw (ICLException)
 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 UnaryOpfromString (const std::string &definition) throw (utils::ICLException)
 Creates a UnaryOp instance from given string definition. More...
static std::string getFromStringSyntax (const std::string &opSpecifier) throw (utils::ICLException)
 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) throw (utils::ICLException)
 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 Configurableget (const std::string &id)
 returns configurable by given ID More...
static void register_configurable_type (const std::string &classname, Function< Configurable * > creator) throw (ICLException)
 registers a configurable type More...
static std::vector< std::string > get_registered_configurables ()
 returns a list of all registered configurable classnames More...
static Configurablecreate_configurable (const std::string &classname) throw (ICLException)
 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()) throw (ICLException)
 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...
Propertyprop (const std::string &propertyName) throw (ICLException)
 this CAN be used e.g. to store a property value in internal property-list More...
const Propertyprop (const std::string &propertyName) const throw (ICLException)
 this CAN be used e.g. to store a property value in internal property-list More...
 Configurable (const std::string &ID="", bool ordered=true) throw (ICLException)
 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
- Protected Attributes inherited from icl::utils::Configurable
std::vector< Callbackcallbacks
 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++)
          *d = list[w*h/2];

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.


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.



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


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


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)
// enter iteration loop 
    // aquire some new image data
    // apply the median filter (now fast, as no memory
    // allocation must be performed)
    // further processing steps

Constructor & Destructor Documentation

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

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

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

Member Function Documentation

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

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!

sizesize to adjust
adjusted size (width and height are rounded up to the next higher odd value

Reimplemented from icl::filter::NeighborhoodOp.

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

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:

poSrcsource image
ppoDstpointer to destination image

Implements icl::filter::UnaryOp.

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