de.unihalle.informatik.MiToBo.enhance

Class HistogramEqualization

java.lang.Object

de.unihalle.informatik.Alida.operator.ALDOperator

de.unihalle.informatik.MiToBo.core.operator.MTBOperator

de.unihalle.informatik.MiToBo.enhance.HistogramEqualization

All Implemented Interfaces:

de.unihalle.informatik.Alida.datatypes.ALDConfigurationValidator, de.unihalle.informatik.Alida.operator.events.ALDOperatorExecutionProgressEventListener, EventListener

@ALDAOperator(genericExecutionMode=ALL,
              level=APPLICATION,
              allowBatchMode=true)
public class HistogramEqualization
extends MTBOperator

Histogram linearization by entropy maximization.

Basically, the cumulative distribution of the normalized intensity histogram is calculated and used as transfer function to linearize the histogram. In theory this yields an entropy maximization, but due to discretization in practice the histogram entropy might at best remain constant and most of the time slightly decreases. Anyway, the contrast of the histogram and the underlying image is increased applying this approach.

Author:

moeller

Nested Class Summary

Nested classes/interfaces inherited from class de.unihalle.informatik.Alida.operator.ALDOperator

de.unihalle.informatik.Alida.operator.ALDOperator.HidingMode, de.unihalle.informatik.Alida.operator.ALDOperator.HistoryConstructionMode

Field Summary

Fields

Modifier and Type	Field and Description
protected MTBImage	inImg Input image to process.
protected double	inputEntropy Initial Shannon entropy of the input image.
private int	maxVal Maximal value of intensity range, depending on input image type.
protected double	outputEntropy Final Shannon entropy of the output image.
protected MTBImage	resultImg Result image with improved contrast.

Fields inherited from class de.unihalle.informatik.Alida.operator.ALDOperator

completeDAG, name, operatorExecutionEventlistenerList, portHashAccess, verbose, versionProvider

Constructor Summary

Constructors

Constructor and Description
HistogramEqualization() Default constructor.
HistogramEqualization(MTBImage img) Constructor with default image.

Method Summary

Modifier and Type	Method and Description
private static double	calcEntropy(MTBImageHistogram histo) Calculates the Shannon entropy for the given (normalized!)
private void	equalizeImageHisto(MTBImage ip) Apply histogram equalization to the given image.
MTBImage	getResultImage() Returns the result image.
private int[]	getTransferFunktion(MTBImageHistogram histo) Get the discrete transfer function for the histogram.
protected void	operate() This method does the actual work.

Methods inherited from class de.unihalle.informatik.MiToBo.core.operator.MTBOperator

readResolve

Methods inherited from class de.unihalle.informatik.Alida.operator.ALDOperator

addOperatorExecutionProgressEventListener, addParameter, addParameter, addParameterUnconditioned, fieldContained, fireOperatorExecutionProgressEvent, getALDPortHashAccessKey, getConstructionMode, getDocumentation, getHidingMode, getInactiveParameterNames, getInInoutNames, getInInoutNames, getInNames, getInOutNames, getMissingRequiredInputs, getName, getNumParameters, getOutInoutNames, getOutNames, getParameter, getParameterDescriptor, getParameterDescriptorUnconditioned, getParameterNames, getParameterUnconditioned, getSupplementalNames, getVerbose, getVersion, handleOperatorExecutionProgressEvent, hasInOutParameters, hasParameter, isAnnotatedParameter, isConfigured, print, print, print, printInterface, printInterface, readHistory, reinitializeParameterDescriptors, removeOperatorExecutionProgressEventListener, removeParameter, runOp, runOp, runOp, setConstructionMode, setConstructionMode, setConstructionMode, setHidingMode, setName, setParameter, setParameterUnconditioned, setVerbose, toStringVerbose, unconfiguredItems, validate, validateCustom, validateGeneric, writeHistory, writeHistory, writeHistory

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

inImg

@Parameter(label="Input Image",
           required=true,
           dataIOOrder=0,
           direction=IN,
           description="Input image.")
protected MTBImage inImg

Input image to process.

resultImg

@Parameter(label="Result Image",
           dataIOOrder=0,
           direction=OUT,
           description="Result image.")
protected MTBImage resultImg

Result image with improved contrast.

inputEntropy

@Parameter(label="Entropy of Input Image",
           dataIOOrder=1,
           direction=OUT,
           description="Input image entropy.")
protected double inputEntropy

Initial Shannon entropy of the input image.

outputEntropy

@Parameter(label="Entropy of Output Image",
           dataIOOrder=2,
           direction=OUT,
           description="Output image entropy.")
protected double outputEntropy

Final Shannon entropy of the output image.

maxVal

private int maxVal

Maximal value of intensity range, depending on input image type.

Constructor Detail

HistogramEqualization

public HistogramEqualization()
                      throws de.unihalle.informatik.Alida.exceptions.ALDOperatorException

Default constructor.

Throws:

de.unihalle.informatik.Alida.exceptions.ALDOperatorException - Thrown in case of failure.

HistogramEqualization

public HistogramEqualization(MTBImage img)
                      throws de.unihalle.informatik.Alida.exceptions.ALDOperatorException

Constructor with default image.

Parameters:

img - Image to enhance.

Throws:

de.unihalle.informatik.Alida.exceptions.ALDOperatorException - Thrown in case of failure.

Method Detail

getResultImage

public MTBImage getResultImage()

Returns the result image.

Returns:

Result image.

operate

protected void operate()

This method does the actual work.

Specified by:

operate in class de.unihalle.informatik.Alida.operator.ALDOperator

equalizeImageHisto

private void equalizeImageHisto(MTBImage ip)

Apply histogram equalization to the given image.

Parameters:

ip - Input image to normalize.

getTransferFunktion

private int[] getTransferFunktion(MTBImageHistogram histo)

Get the discrete transfer function for the histogram.

Parameters:

histo - (Normalized!) histogram to transfer.

Returns:

Array containing discrete transfer function.

calcEntropy

private static double calcEntropy(MTBImageHistogram histo)

Calculates the Shannon entropy for the given (normalized!) histogram.

Parameters:

histo - Input histogram.

Returns:

Shannon entropy value.