de.unihalle.informatik.MiToBo.enhance

Class GlobalContrastStretching

java.lang.Object

de.unihalle.informatik.Alida.operator.ALDOperator

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

de.unihalle.informatik.MiToBo.enhance.GlobalContrastStretching

All Implemented Interfaces:

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

@ALDAOperator(genericExecutionMode=ALL,
              level=APPLICATION)
public class GlobalContrastStretching
extends MTBOperator

Global contrast stretching.

This operator performs a linear global contrast stretching on the intensity histogram of the given image. Since outliers may seriously affect the stretching, fractions of outliers at the left and right margins of the histogram can be defined which are then ignored in determining the minimal and maximal intensity values in the image.

The new intensity value of a pixel is calculated by the following equation:

\begin{equation*} I_{new}(x,y) = (I(x,y) - c) \cdot \frac{b-a}{d-c} + a \end{equation*}

where a and b are the minimal and maximal values of the target intensity range (e.g., usually 0 and 255 for 8-bit grayscale images), and c and d are the minimal and maximal intensity values in the given image. c and d are determined considering the outlier fractions.

Note that we always assume positive image intensities here, i.e. a is always 0. In case of negative values being present in the input image the result is undefined.

Target values being larger than b or smaller than a are mapped to b and a, respectively.

More information can be found at Image Processing Learning Resources.

Author:

Birgit 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
private MTBImage	inImg Input grayscale image.
private double	leftOutlierFraction Fraction of outlier pixels at left histogram margin.
private MTBImage	resultImg Result image with stretched contrast.
private double	rightOutlierFraction Fraction of outlier pixels at right histogram margin.

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

completeDAG, name, operatorExecutionEventlistenerList, portHashAccess, verbose, versionProvider

Constructor Summary

Constructors

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

Method Summary

Modifier and Type	Method and Description
MTBImage	getResultImage() Returns the result image.
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.")
private transient MTBImage inImg

Input grayscale image.

leftOutlierFraction

@Parameter(label="Expected Fraction of Left Outliers",
           required=true,
           direction=IN,
           dataIOOrder=1,
           description="Lower Outlier Fraction.")
private double leftOutlierFraction

Fraction of outlier pixels at left histogram margin.

rightOutlierFraction

@Parameter(label="Expected Fraction of Right Outliers",
           required=true,
           direction=IN,
           dataIOOrder=2,
           description="Right Outlier Fraction.")
private double rightOutlierFraction

Fraction of outlier pixels at right histogram margin.

resultImg

@Parameter(label="Result Image",
           required=true,
           direction=OUT,
           description="Result image.")
private transient MTBImage resultImg

Result image with stretched contrast.

Constructor Detail

GlobalContrastStretching

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

Default constructor.

Throws:

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

GlobalContrastStretching

public GlobalContrastStretching(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