Entropy

Measure allowing to compute entropy of intensities for shape. More...

Classes
class	ipsdk::imaproc::shape::analysis::EntropyMsr
	Measurement object for measure Entropy. More...
class	ipsdk::imaproc::shape::analysis::EntropyMsrInfo
	Information object for measure Entropy. More...
class	ipsdk::imaproc::shape::analysis::EntropyMsrParams
	Parameter object for measure Entropy. More...

Detailed Description

Measure allowing to compute entropy of intensities for shape.

This measure computes the entropy of image pixel/voxel intensity values associated to a 2d/3d shape. This is a measure of disorder of the state which value tends to zero for a constant signal and which increase with its unpredictability.

Entropy measure is based on the analysis of shape histogram (see Histogram). Given histogram parameters allowing to determine (among others) number of classes and a global range for histogram, this measure computes shape entropy as :

where is the density of probability associated to bin of histogram :

and :

• is the population for bin of histogram
• is the intensity range (width) for bin of histogram

Here is an example of entropy measurement in 2d case :

See also

https://en.wikipedia.org/wiki/Entropy_(information_theory)

Author

E.Noirfalise

Date

2017/02/06

Copyright

2017 Reactiv'IP, all right reserved.

Measure allowing to compute entropy of intensities for shape

Measure synthesis :

Measure Type	Measure Unit Type	Parameter Type	Result Type	Shape Requirements
Generic	None	EntropyMsrParams	Value (ipsdk::ipReal64)	None

See Shape measurement for additional information on these pictograms

Measure Type :

This is a generic measure

• it does not directly use shape or image data
• it can use dependencies to other measures to compute a result (see Measure Dependencies section)

This measure can be used in 2d and 3d case

Measure Unit Type:

Measure Entropy is not associated to any unit [ipsdk::shape::analysis::eMsrUnitFormat::eMUF_NoUnit]

Measure Parameter Type :

Measure Entropy is associated to EntropyMsrParams parameters

Measure Result Type :

Measure Entropy is associated to ipsdk::shape::analysis::ValueMeasureResult<ipsdk::ipReal64> results

Measure Shape Requirements :

Measure Entropy does not requires anything from shape data

Measure Dependencies :

Measure Entropy depends on following measures :

Measure Mode	Measure Name	Measure Type	Measure Parameters
eMVP_2d3d	Histogram	Histogram	createHistogramMsrParams(_pMsrParams->getNode<EntropyMsrParams::HistoParams>())

Note

See Shape Analysis 2d for more information on general shape 2d analysis and measurement usage.

See Shape Analysis 3d for more information on general shape 3d analysis and measurement usage.

Example of Python code :

Generic example in 2d case :

import PyIPSDK
import PyIPSDK.IPSDKIPLShapeAnalysis as shapeanalysis

    # Create the infoset
    inMeasureInfoSet2d = PyIPSDK.createMeasureInfoSet2d()
    PyIPSDK.createMeasureInfo(inMeasureInfoSet2d, "EntropyMsr")
    
    #Perform the analysis
    outMeasureSet = shapeanalysis.labelAnalysis2d(inGreyImg, inLabelImg2d, inMeasureInfoSet2d)
    
    # save results to csv format
    PyIPSDK.saveCsvMeasureFile(os.path.join(tmpPath,  "shape_analysis_results.csv"), outMeasureSet)
    
    # retrieve measure results
    outMsr = outMeasureSet.getMeasure("EntropyMsr")
    
    # retrieve measure values
    outMsrValues = outMsr.getMeasureResult().getColl(0)
    print("First label measurement equal " + str(outMsrValues[1]))

Generic example in 3d case :

import PyIPSDK
import PyIPSDK.IPSDKIPLShapeAnalysis as shapeanalysis

    # Create the infoset
    inMeasureInfoSet3d = PyIPSDK.createMeasureInfoSet3d()
    PyIPSDK.createMeasureInfo(inMeasureInfoSet3d, "EntropyMsr")
    
    #Perform the analysis
    outMeasureSet = shapeanalysis.labelAnalysis3d(inGreyImg, inLabelImg, inMeasureInfoSet3d)
    
    # save results to csv format
    PyIPSDK.saveCsvMeasureFile(os.path.join(tmpPath,  "shape_analysis_results.csv"), outMeasureSet)
    
    # retrieve measure results
    outMsr = outMeasureSet.getMeasure("EntropyMsr")
    
    # retrieve measure values
    outMsrValues = outMsr.getMeasureResult().getColl(0)
    print("First label measurement equal " + str(outMsrValues[1]))

Example of C++ code :

Example informations

Associated library

IPSDKIPLShapeAnalysis

Code Example

    // opening grey level input image
    ImagePtr pInGreyImg2d = loadTiffImageFile(inputGreyImgPath);

    // read entity shape 2d collection used for processing
    Shape2dCollPtr pShape2dColl = boost::make_shared<Shape2dColl>();
    IPSDK_REQUIRE(readFromXmlFile(inputShape2dCollPath, *pShape2dColl) == true);

    // define a measure info set
    MeasureInfoSetPtr pMeasureInfoSet = MeasureInfoSet::create2dInstance();
    createMeasureInfo(pMeasureInfoSet, "EntropyMsr");
    
    // compute measure on shape 2d collection
    MeasureSetPtr pOutMeasureSet = shapeAnalysis2d(pInGreyImg2d, pShape2dColl, pMeasureInfoSet);

    // retrieve associated results
    const MeasureConstPtr& pEntropyOutMsr = pOutMeasureSet->getMeasure("EntropyMsr");
    const ipsdk::shape::analysis::ValueMeasureResult<ipsdk::ipReal64>& outResults = static_cast<const ipsdk::shape::analysis::ValueMeasureResult<ipsdk::ipReal64>&>(pEntropyOutMsr->getMeasureResult());