finds the local extrema in an image More...

IPSDKIPLFEATUREDETECTION_API ipsdk::imaproc::attr::Pixels2dPtr	ipsdk::imaproc::fd::extractLocalExtrema2d (const image::ImageConstPtr &pInImg, const ipsdk::ipUInt32 inFeaturesDistX, const ipsdk::ipUInt32 inFeaturesDistY)
	wrapper function for extraction of local extrema (minima, maxima, or both of them) in an image This wrapper must be used with mono slice (sizeZ=sizeC=sizeT=1) input images More...

IPSDKIPLFEATUREDETECTION_API ipsdk::imaproc::attr::Pixels2dPtr	ipsdk::imaproc::fd::extractLocalExtrema2d (const image::ImageConstPtr &pInImg, const ipsdk::ipUInt32 inFeaturesDistX, const ipsdk::ipUInt32 inFeaturesDistY, const ipsdk::imaproc::attr::LocalExtremaConfigConstPtr &localExtremaConfig)
	wrapper function for extraction of local extrema (minima, maxima, or both of them) in an image This wrapper must be used with mono slice (sizeZ=sizeC=sizeT=1) input images More...

IPSDKIPLFEATUREDETECTION_API ipsdk::imaproc::attr::PlanIndexedPixels2dPtr	ipsdk::imaproc::fd::multiSlice_extractLocalExtrema2d (const image::ImageConstPtr &pInImg, const ipsdk::ipUInt32 inFeaturesDistX, const ipsdk::ipUInt32 inFeaturesDistY)
	multi slices version of wrapper function for extraction of local extrema (minima, maxima, or both of them) in an image This wrapper can be used with multi slice input images More...

IPSDKIPLFEATUREDETECTION_API ipsdk::imaproc::attr::PlanIndexedPixels2dPtr	ipsdk::imaproc::fd::multiSlice_extractLocalExtrema2d (const image::ImageConstPtr &pInImg, const ipsdk::ipUInt32 inFeaturesDistX, const ipsdk::ipUInt32 inFeaturesDistY, const ipsdk::imaproc::attr::LocalExtremaConfigConstPtr &localExtremaConfig)
	multi slices version of wrapper function for extraction of local extrema (minima, maxima, or both of them) in an image This wrapper can be used with multi slice input images More...

Detailed Description

finds the local extrema in an image

Given an input 2d gray level image, and depending on the parameters $LocalExtremaConfig$ , set by the user, the algorithm returns:

if value equals to $eLocalExtremumType::eLET\_Max$ , the collection of local maxima of the input image that are greater than the attribute value. A local maximum is a pixel whose value is greater or equal than the values of all its neighbours defined by the half kernel sizes along the x and y directions and . In the case of plateaus, only the first pixel found is selected except for a special case illustrated in the figure below.
if value equals to $eLocalExtremumType::eLET\_StrictMax$ , the collection of strict local maxima of the input image that are greater than the attribute value. A strict local maximum is a pixel whose value is strictly greater than the values of all its neighbours defined by the half kernel sizes along the x and y directions and .
if value equals to $eLocalExtremumType::eLET\_Min$ , the collection of local minima of the input image that are lower than the attribute value. A local minimum is a pixel whose value is lower or equal than the values of all its neighbours defined by the half kernel sizes along the x and y directions and . In the case of plateaus, only the first pixel found is selected except for a special case illustrated in the figure below.
if value equals to $eLocalExtremumType::eLET\_StrictMin$ , the collection of strict local minima of the input image that are lower than the attribute value. A strict local minimum is a pixel whose value is strictly lower than the values of all its neighbours defined by the half kernel sizes along the x and y directions and .

For non strict local extrema calculation, an extremum can belong to a plateau. In this case, the algorithm generally selects the first pixel of the first line of the plateau. However, several local extrema can be found in the same plateau. The following figure illustrates an example of plateau where more than one local extremum is found. The plateau is represented by black pixels and the extrema selected are colored in red in the right figure.

Two wrappers can be called : the extractLocalExtrema2d wrapper is only used to compute the extrema extraction on a grey level 2d images, whereas the multiSlice_extractLocalExtrema2d wrapper must be used for more complex data (volume, sequence and/or color).

The user may handle this behaviour correctly to analyze the obtained results.

Attributes description

Attribute description for algorithm :

Name	ToolTip	Default Initializer
ipsdk::imaproc::attr::InImg	[Input] image for processing operation	X
ipsdk::imaproc::attr::InFeaturesDistX	[Input] distance between detected features along x axis (tchebychev distance)	X
ipsdk::imaproc::attr::InFeaturesDistY	[Input] distance between detected features along y axis (tchebychev distance)	X
ipsdk::imaproc::attr::InOptLocalExtremaConfig	[Input Optional] Attribute for local extrema calculation configuration	X
ipsdk::imaproc::attr::OutPIPixels2d	[Output] plan indexed collection of positions and intensities of 2d pixels	ipsdk::imaproc::fromImage (_pOutPIPixels2d, _pInImg)

Global Rule description

Global rule description for algorithm :
ipsdk::imaproc::matchImagePlans (_pOutPIPixels2d,_pInImg,eImagePlansMatchPolicy::eIPMP_ZCT)

Example of Python code :

Example imports

import PyIPSDK

import PyIPSDK.IPSDKIPLFeatureDetection as fd

Code Example

    # opening of input image
    inImg = PyIPSDK.loadTiffImageFile(inputImgPath)
    
    # half size neighbourhood definition
    halfSizeKnlX = 1
    halfSizeKnlY = 1
    
    # local extrema configuration definition
    threshold = -30
    nbTotPoints = 2000
    localExtremaConfig = PyIPSDK.createLocalExtremaConfig(PyIPSDK.eLocalExtremumType.eLET_StrictMax, threshold, nbTotPoints)
    
    # local extrema computation
    outPixels2d = fd.extractLocalExtrema2d(inImg, halfSizeKnlX, halfSizeKnlY, localExtremaConfig)
    
    # retrieve coordinates of maximum detected extrema
    maxPixel2d = PyIPSDK.toPyDict(outPixels2d)['Coll'][0]
    print("Maximum extrema value " + str(maxPixel2d['Intensity'] ) + " found on coordinates x=" + str(maxPixel2d['X'] ) + " and y=" + str(maxPixel2d['Y'] ))

Example of C++ code :

Example informations

Associated library

IPSDKIPLFeatureDetection

Header file

#include <IPSDKIPL/IPSDKIPLFeatureDetection/Processor/ExtractLocalExtrema2d/ExtractLocalExtrema2d.h>

Code Example

    // ------------ Calculation on a mono-slice grey level image ------------ //
    // Create the local extrema configuration instance, specifying the local extremum type, 
    // the threshold and the number of total points. All these parameters are optional
    LocalExtremaConfigPtr pLocalExtremaConfig = createLocalExtremaConfig(localExtremumType, threshold, nbTotPoints);
    // Load the input image
    ImagePtr pInImg = loadTiffImageFile(inImgFilePath);
    // Extrcat the local extrema, in a given neighbourhood
    Pixels2dPtr pExtremaColl = extractLocalExtrema2d(pInImg, halfKnlSizeX, halfKnlSizeY, pLocalExtremaConfig);
    // Retrieve the extrema collection
    const std::vector< boost::shared_ptr<Pixel2d> > extremaColl = pExtremaColl->getNodeColl<Pixels2d::Coll>();
    const ipUInt64 nbPoints = extremaColl.size();
    // ------------ Calculation on a multi-slice grey level image ------------ //
    // Extrcat the local extrema, in a given neighbourhood
    PlanIndexedPixels2dPtr pExtremaColl_multiSlice = multiSlice_extractLocalExtrema2d(pInImg_multiSlice, halfKnlSizeX, halfKnlSizeY, pLocalExtremaConfig);
    // Retrieve the extrema collection for the frame 2, the channel 0 and the slice 1
    const std::vector< boost::shared_ptr<Pixel2d> > extremaColl_multiSlice = pExtremaColl_multiSlice->getValue(1, 0, 2).getNodeColl<Pixels2d::Coll>();

See also: ExtractLocalExtrema2dLvl1; ExtractLocalExtrema2dLvl2; ExtractLocalExtrema2dLvl3

Function Documentation

◆ extractLocalExtrema2d() [1/2]

IPSDKIPLFEATUREDETECTION_API ipsdk::imaproc::attr::Pixels2dPtr ipsdk::imaproc::fd::extractLocalExtrema2d	(	const image::ImageConstPtr &	pInImg,
		const ipsdk::ipUInt32	inFeaturesDistX,
		const ipsdk::ipUInt32	inFeaturesDistY
	)

wrapper function for extraction of local extrema (minima, maxima, or both of them) in an image This wrapper must be used with mono slice (sizeZ=sizeC=sizeT=1) input images

Exceptions

ipsdk::processor::IPSDKBaseProcessingException on failure

◆ multiSlice_extractLocalExtrema2d() [1/2]

IPSDKIPLFEATUREDETECTION_API ipsdk::imaproc::attr::PlanIndexedPixels2dPtr ipsdk::imaproc::fd::multiSlice_extractLocalExtrema2d	(	const image::ImageConstPtr &	pInImg,
		const ipsdk::ipUInt32	inFeaturesDistX,
		const ipsdk::ipUInt32	inFeaturesDistY
	)

multi slices version of wrapper function for extraction of local extrema (minima, maxima, or both of them) in an image This wrapper can be used with multi slice input images

Exceptions

ipsdk::processor::IPSDKBaseProcessingException on failure

◆ extractLocalExtrema2d() [2/2]

IPSDKIPLFEATUREDETECTION_API ipsdk::imaproc::attr::Pixels2dPtr ipsdk::imaproc::fd::extractLocalExtrema2d	(	const image::ImageConstPtr &	pInImg,
		const ipsdk::ipUInt32	inFeaturesDistX,
		const ipsdk::ipUInt32	inFeaturesDistY,
		const ipsdk::imaproc::attr::LocalExtremaConfigConstPtr &	localExtremaConfig
	)

wrapper function for extraction of local extrema (minima, maxima, or both of them) in an image This wrapper must be used with mono slice (sizeZ=sizeC=sizeT=1) input images

Exceptions

ipsdk::processor::IPSDKBaseProcessingException on failure

◆ multiSlice_extractLocalExtrema2d() [2/2]

IPSDKIPLFEATUREDETECTION_API ipsdk::imaproc::attr::PlanIndexedPixels2dPtr ipsdk::imaproc::fd::multiSlice_extractLocalExtrema2d	(	const image::ImageConstPtr &	pInImg,
		const ipsdk::ipUInt32	inFeaturesDistX,
		const ipsdk::ipUInt32	inFeaturesDistY,
		const ipsdk::imaproc::attr::LocalExtremaConfigConstPtr &	localExtremaConfig
	)

multi slices version of wrapper function for extraction of local extrema (minima, maxima, or both of them) in an image This wrapper can be used with multi slice input images

Exceptions

ipsdk::processor::IPSDKBaseProcessingException on failure