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com.xinapse.multisliceimage
Class Histogram

java.lang.Object
  extended by com.xinapse.multisliceimage.Histogram
All Implemented Interfaces:
java.lang.Cloneable
public class Histogram
extends java.lang.Object
implements java.lang.Cloneable

A convenience class for creating and finding statistics about arrays of pixel intensities, histograms of pixel intensities, and statistics about those histograms.

Field Summary
 double[] count
          The array that contains the numbers of values in each bin.
 
Constructor Summary
Histogram(double[] count, double histoMin, double binWidth)
          Creates a Histogram of intensities from pre-computed values.
Histogram(java.lang.Object pixelValues, int offset, int nPixels, PixelDataType dataType)
          Creates a Histogram of intensities from an array of values.
Histogram(java.lang.Object pixelValues, int offset, int nPixels, PixelDataType dataType, ComplexMode complexMode)
          Creates a Histogram of intensities from an array of values, with an option to specifiy the mode of calculation for PixelDataType.COMPLEX, or PixelDataType.DOUBLECOMPLEX images.
Histogram(java.lang.Object pixelValues, int offset, int nPixels, PixelDataType dataType, double min, double max, ComplexMode complexMode)
          Creates a Histogram of intensities from an array of values over a specified intensity range.
Histogram(java.lang.Object pixelValues, int offset, int nPixels, PixelDataType dataType, double min, double max, double binWidth, ComplexMode complexMode)
          Creates a Histogram of intensities from an array of values over a specified intensity range.
Histogram(java.lang.Object pixelValues, PixelDataType dataType)
          Creates a Histogram of intensities from an array of values.
Histogram(java.lang.Object pixelValues, PixelDataType dataType, ComplexMode complexMode)
          Creates a Histogram of intensities from an array of values.
 
Method Summary
 Histogram add(Histogram histo)
          Adds the counts from a Histogram to this Histogram to produce a new Histogram that spans the data range of both.
 void addValues(java.lang.Object pixelValues, int offset, int nPixels, PixelDataType dataType, ComplexMode complexMode)
          Adds some pixel values to this Histogram.
static double calcBinWidth(double min, double max, PixelDataType dataType, ComplexMode complexMode)
          Calculates a suitable bin width for given type of pixels over the given intensity range.
static int calcNBins(double min, double max, PixelDataType dataType, ComplexMode complexMode, double binWidth)
          Calculates a suitable number of bins for a histogram, given the for given type of pixels over the given intensity range, and a given bin width.
 java.lang.Object clone()
          Creates a copy of this Histogram.
 double getAreaUnder()
          Returns the total area under this histogram.
 double getAreaUnder(boolean excludeZero)
          Returns the area under this histogram, optionally excluding any zero-intensity pixels.
 double getAreaUnder(double threshold)
          Returns the number of pixels in this histogram that are above the supplied threshold.
 double getBinWidth()
          Returns the bin width for this Histogram.
 Histogram getCumulativeHistogram()
          Return a new Histogram that is the cumulative histogram of this one.
 double getCumulativeIntensity(float fraction, boolean excludeZero)
          Returns an intensity value such that the specified fraction of pixels is below the returned intensity; zero-valued pixels are optionally excluded from the calculation.
 double getEntropy()
          Returns the entropy of this Histogram.
 double getHistoMax()
          Returns the maximum bin value of this Histogram.
 double getHistoMin()
          Returns the minimum bin value of this Histogram.
static Histogram getInstance(LoadableImage image)
          Creates a Histogram of intensities from a com.xinapse.loadableimage.LoadableImage.
 double getMean()
          Returns the mean intensity value of this Histogram.
 double getMean(boolean excludeZero)
          Returns the mean intensity value of this Histogram, optionally excluding all pixel intensities that are zero.
 double getMedian()
          Returns the median value of this Histogram.
 double getMedian(boolean excludeZero)
          Returns the median value of this Histogram, optionally excluding all pixel intensities that are zero.
static double[] getMinMax(java.lang.Object pixelValues, int offset, int nPixels, PixelDataType dataType, ComplexMode complexMode)
          Returns the minimum and maximum intensity values present in a part of an array of pixel values.
static double[] getMinMax(java.lang.Object pixelValues, PixelDataType dataType, ComplexMode complexMode)
          Returns the minimum and maximum intensity values present in an array of pixel values.
 double getPeakHeight(boolean excludeZero)
          Returns the number of pixels with the most common pixel intensity in this Histogram, optionally excluding the pixel intensities that are zero-valued.
 double getPeakPosition(boolean excludeZero)
          Returns the most common pixel intensity in this Histogram, optionally excluding the pixel intensities that are zero-valued.
 double getSD()
          Returns the standard deviation of intensity values of this Histogram.
 double getSD(boolean excludeZero)
          Returns the standard deviation of intensity values of this Histogram, optionally excluding all pixel intensities that are zero from the calculation.
 void normalise()
          Normalises this Histogram, so that the sum of all the counts is unity.
 java.lang.String toString()
          Returns a String that lists the min, max, bin width and count values of this Histogram.
 
Methods inherited from class java.lang.Object
equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
 

Field Detail

count

public double[] count
The array that contains the numbers of values in each bin.

Constructor Detail

Histogram

public Histogram(double[] count,
                 double histoMin,
                 double binWidth)
Creates a Histogram of intensities from pre-computed values.

Parameters:
count - the number of pixels in each bin of the Histogram.
histoMin - the intensity corresponding to the first bin of the Histogram.
binWidth - the histogram bin width in intensity units.

Histogram

public Histogram(java.lang.Object pixelValues,
                 PixelDataType dataType)
          throws MultiSliceImageException
Creates a Histogram of intensities from an array of values.
For PixelDataType.BINARY images, the histogram always has two bins with the first bin showing the number of pixel values that are false and the second bin showing the number of pixel values that are true.
For RGB-type images (PixelDataType.RGB_BY_PLANE, PixelDataType.RGB_INTERLACED and PixelDataType.COLOURPACKED), the Histogram is a histogram of the luminance of the colour, where the luminance is (0.299 * Red) + (0.587 * Green) + (0.114 * Blue).
Do not use this method for PixelDataType.COMPLEX or PixelDataType.DOUBLECOMPLEX images.

Parameters:
pixelValues - an array of pixel values for which the Histogram will be created.
dataType - the type of pixel value stored in the pixelValues.
Throws:
MultiSliceImageException - if a Histogram cannot be created for the supplied pixel data type, or if the intensity range in the pixels overflows that which can be stored in the Histogram.

Histogram

public Histogram(java.lang.Object pixelValues,
                 PixelDataType dataType,
                 ComplexMode complexMode)
          throws MultiSliceImageException
Creates a Histogram of intensities from an array of values.
For PixelDataType.BINARY images, the histogram always has two bins with the first bin showing the number of pixel values that are false and the second bin showing the number of pixel values that are true.
For RGB-type images (PixelDataType.RGB_BY_PLANE, PixelDataType.RGB_INTERLACED and PixelDataType.COLOURPACKED), the Histogram is a histogram of the luminance of the colour, where the luminance is (0.299 * Red) + (0.587 * Green) + (0.114 * Blue).

Parameters:
pixelValues - an array of pixel values for which the Histogram will be created.
dataType - the type of pixel value stored in the pixelValues.
complexMode - the ComplexMode for complex data types.
Throws:
MultiSliceImageException - if a Histogram cannot be created for the supplied pixel data type, or if the intensity range in the pixels overflows that which can be stored in the Histogram.

Histogram

public Histogram(java.lang.Object pixelValues,
                 int offset,
                 int nPixels,
                 PixelDataType dataType)
          throws MultiSliceImageException
Creates a Histogram of intensities from an array of values.
For PixelDataType.BINARY images, the histogram always has two bins with the first bin showing the number of pixel values that are false and the second bin showing the number of pixel values that are true.
For RGB-type images (PixelDataType.RGB_BY_PLANE, PixelDataType.RGB_INTERLACED and PixelDataType.COLOURPACKED), the Histogram is a histogram of the luminance of the colour, where the luminance is (0.299 * Red) + (0.587 * Green) + (0.114 * Blue).

Parameters:
pixelValues - an array of pixel values for which the Histogram will be created.
offset - an offset (in pixels) into the array for the first pixel to be included in the Histogram.
nPixels - the number of pixels to be included in the Histogram.
dataType - the type of pixel value stored in the pixelValues.
Throws:
MultiSliceImageException - if a Histogram cannot be created for the supplied pixel data type, or if the intensity range in the pixels overflows that which can be stored in the Histogram.

Histogram

public Histogram(java.lang.Object pixelValues,
                 int offset,
                 int nPixels,
                 PixelDataType dataType,
                 ComplexMode complexMode)
          throws MultiSliceImageException
Creates a Histogram of intensities from an array of values, with an option to specifiy the mode of calculation for PixelDataType.COMPLEX, or PixelDataType.DOUBLECOMPLEX images.
For PixelDataType.BINARY images, the histogram always has two bins with the first bin showing the number of pixel values that are false and the second bin showing the number of pixel values that are true.
For RGB-type images (PixelDataType.RGB_BY_PLANE, PixelDataType.RGB_INTERLACED and PixelDataType.COLOURPACKED), the Histogram is a histogram of the luminance of the colour, where the luminance is (0.299 * Red) + (0.587 * Green) + (0.114 * Blue).

Parameters:
pixelValues - an array of pixel values for which the Histogram will be created.
offset - an offset (in pixels) into the array for the first pixel to be included in the Histogram.
nPixels - the number of pixels to be included in the Histogram.
dataType - the type of pixel value stored in the pixelValues.
complexMode - mode for calculation of the histogram of Complex images. For all other types of image, the complexMode is ignored.
Throws:
MultiSliceImageException - if a Histogram cannot be created for the supplied pixel data type, or if the intensity range in the pixels overflows that which can be stored in the Histogram.

Histogram

public Histogram(java.lang.Object pixelValues,
                 int offset,
                 int nPixels,
                 PixelDataType dataType,
                 double min,
                 double max,
                 ComplexMode complexMode)
          throws MultiSliceImageException
Creates a Histogram of intensities from an array of values over a specified intensity range. Intensity values that are outside the supplied min/max range are not included in the histogram. The bin width is calculated automatically.
For PixelDataType.BINARY images, the histogram always has two bins with the first bin showing the number of pixel values that are false and the second bin showing the number of pixel values that are true.
For RGB-type images (PixelDataType.RGB_BY_PLANE, PixelDataType.RGB_INTERLACED and PixelDataType.COLOURPACKED), the Histogram is a histogram of the luminance of the colour, where the luminance is (0.299 * Red) + (0.587 * Green) + (0.114 * Blue).
For PixelDataType.COMPLEX or PixelDataType.DOUBLECOMPLEX images, the Histogram depends on the ComplexMode which determines whether the magnitude, real, imaginary or phase histogram is produced.

Parameters:
pixelValues - an array of pixel values for which the Histogram will be created.
dataType - the type of pixel value stored in the pixelValues.
min - the intensity of the lowest-intensity bin of the Histogram. Pixel intensities below the minimum are not included in the Histogram. For PixelDataType.BINARY images this value must be 0.
max - the intensity of the highest-intensity bin of the Histogram. Pixel intensities above the maximum are not included in the Histogram. For PixelDataType.BINARY images this value must be 1.
complexMode - mode for calculation of the histogram of Complex images. For all other types of image, the complexMode is ignored.
Throws:
MultiSliceImageException - if a Histogram cannot be created for the supplied pixel data type, or if the intensity range in the pixels overflows that which can be stored in the Histogram.

Histogram

public Histogram(java.lang.Object pixelValues,
                 int offset,
                 int nPixels,
                 PixelDataType dataType,
                 double min,
                 double max,
                 double binWidth,
                 ComplexMode complexMode)
          throws MultiSliceImageException
Creates a Histogram of intensities from an array of values over a specified intensity range. Intensity values that are outside the supplied min/max range are not included in the histogram.
For RGB-type images (PixelDataType.RGB_BY_PLANE, PixelDataType.RGB_INTERLACED and PixelDataType.COLOURPACKED), the Histogram is a histogram of the luminance of the colour, where the luminance is (0.299 * Red) + (0.587 * Green) + (0.114 * Blue).
For PixelDataType.COMPLEX or PixelDataType.DOUBLECOMPLEX images, the Histogram is a histogram of the magnitudes of the complex numbers.

Parameters:
pixelValues - an array of pixel values for which the Histogram will be created.
offset - an offset (in pixels) into the array at which to start counting the pixel values.
nPixels - the number of pixels in the array from which the Histogram is created.
dataType - the type of pixel value stored in the pixelValues.
min - the intensity of the lowest-intensity bin of the Histogram. Pixel intensities below the minimum are not included in the Histogram. For PixelDataType.BINARY images this value must be 0.
max - the intensity of the highest-intensity bin of the Histogram. Pixel intensities above the maximum are not included in the Histogram. For PixelDataType.BINARY images this value must be 1.
binWidth - the width of a histogram bin.
complexMode - for calculation of the histogram for Complex images. For all other types of image, the complexMode is ignored.
Throws:
MultiSliceImageException - if a Histogram cannot be created for the supplied pixel data type, or if the intensity range in the pixels overflows that which can be stored in the Histogram.
Method Detail

getInstance

public static Histogram getInstance(LoadableImage image)
                             throws InvalidImageException
Creates a Histogram of intensities from a com.xinapse.loadableimage.LoadableImage.
For PixelDataType.BINARY images, the histogram always has two bins with the first bin showing the number of pixel values that are false and the second bin showing the number of pixel values that are true.
For PixelDataType.BYTE, and Colour images, the histogram always has 255 bins with the intensities from 0 to 255.
For PixelDataType.UBYTE, and Colour images, the histogram always has 255 bins with the intensities from -128 to 127.
For RGB-type images (PixelDataType.RGB_BY_PLANE, PixelDataType.RGB_INTERLACED and PixelDataType.COLOURPACKED), the Histogram is a histogram of the luminance of the colour, where the luminance is (0.299 * Red) + (0.587 * Green) + (0.114 * Blue).
Do not use this method for PixelDataType.COMPLEX or PixelDataType.DOUBLECOMPLEX images.

Parameters:
image - the image for which to find the Histogram.
Throws:
InvalidImageException - if a Histogram cannot be created for the supplied image, or if the intensity range in the pixels overflows that which can be stored in the Histogram.

addValues

public void addValues(java.lang.Object pixelValues,
                      int offset,
                      int nPixels,
                      PixelDataType dataType,
                      ComplexMode complexMode)
               throws MultiSliceImageException
Adds some pixel values to this Histogram. Any pixels whose intensity under- or overflows the range of the Histogram are ignored.

Parameters:
pixelValues - an array of pixel values to add to the Histogram.
offset - an offset (in pixels) into the array at which to start adding the pixel values.
nPixels - the number of pixels in the array to add.
dataType - the type of pixel values to be added to this Histogram.
complexMode - for calculation of the histogram for Complex images. For all other types of image, the complexMode is ignored.
Throws:
MultiSliceImageException - if pixels of this PixelDataType cannot be added to this Histogram.

getBinWidth

public double getBinWidth()
Returns the bin width for this Histogram. For Histograms constructed from integer data types, this method always returns 1.0.

Returns:
the bin width for this Histogram.

calcBinWidth

public static double calcBinWidth(double min,
                                  double max,
                                  PixelDataType dataType,
                                  ComplexMode complexMode)
                           throws MultiSliceImageException
Calculates a suitable bin width for given type of pixels over the given intensity range.

Parameters:
min - the minimum intensity value.
max - the maximum intensity value.
dataType - the PixelDataType of the intensities.
complexMode - the ComplexMode complex display mode for complex images.
Returns:
a suitable bin width for this type of pixel, with the given intensity range. For integer data types, the bin width returned will be 1.0, unless this would result in an exceessively large number of bins. Excessively large for our purposes means more than 65535, which could arise for integer, or long data types with a large data range; in these cases the bin width is increased by powers of two until the number of bins needed for the histogram is less than 65535. For floating point images (including complex real, imaginary and magnitude images), the bin width will always be a power of 10, with the number of bins being as close to 100 as this constraint will allow. For complex phase images, the bin width will always be Pi/180 (1 degree).
Throws:
MultiSliceImageException - if the bin width cannot be calculated for pixels with the given minimum and maximum intensities (typically if the intensity range is infinite).

calcNBins

public static int calcNBins(double min,
                            double max,
                            PixelDataType dataType,
                            ComplexMode complexMode,
                            double binWidth)
                     throws MultiSliceImageException
Calculates a suitable number of bins for a histogram, given the for given type of pixels over the given intensity range, and a given bin width.

Parameters:
min - the minimum intensity value.
max - the maximum intensity value.
dataType - the PixelDataType of the intensities.
complexMode - the ComplexMode complex display mode for complex images.
binWidth - the width of each bin in the histogram.
Returns:
a suitable number of bins for this type of pixel, with the given intensity range.
Throws:
MultiSliceImageException - if this method has been supplied with unsuitable arguments.

getMinMax

public static double[] getMinMax(java.lang.Object pixelValues,
                                 PixelDataType dataType,
                                 ComplexMode complexMode)
                          throws MultiSliceImageException
Returns the minimum and maximum intensity values present in an array of pixel values.
For PixelDataType.BINARY, the values returned are always 0 and 1.
For RGB-type images (PixelDataType.RGB_BY_PLANE, PixelDataType.RGB_INTERLACED and PixelDataType.COLOURPACKED), the intensity values returned are always 0 and 255.
For PixelDataType.COMPLEX and PixelDataType.DOUBLECOMPLEX, the minimum and maximum depend of the complexMode. If complexMode is ComplexMode.PHASE, the minimum and maximum returned are always -PI and +PI. For all other ComplexModes, the minimum is the minimum real or imaginary value, and the maximum is the maximum magnitude value.

Parameters:
pixelValues - an array of pixel values for which to find the minimum and maximum values.
dataType - the type of pixel value stored in the pixelValues.
complexMode - mode for the calculation of the minimum and maximum values for Complex images. For all other types of image, the complexMode is ignored.
Returns:
the minimum and maximim intensity values in a double[] of length 2.
Throws:
MultiSliceImageException - if a the minimum and maximum values cannot be found for the supplied data type

getMinMax

public static double[] getMinMax(java.lang.Object pixelValues,
                                 int offset,
                                 int nPixels,
                                 PixelDataType dataType,
                                 ComplexMode complexMode)
                          throws MultiSliceImageException
Returns the minimum and maximum intensity values present in a part of an array of pixel values.
For PixelDataType.BINARY, the values returned are always 0 and 1.
For RGB-type images (PixelDataType.RGB_BY_PLANE, PixelDataType.RGB_INTERLACED and PixelDataType.COLOURPACKED), the intensity values returned are always 0 and 255.
For PixelDataType.COMPLEX PixelDataType.DOUBLECOMPLEX, the minimum and maximum depend of the complexMode. If complexMode is ComplexMode.PHASE, the minimum and maximum returned are always -PI and +PI. For all other ComplexModes, the minimum is the minimum real or imaginary value, and the maximum is the maximum magnitude value.

Parameters:
pixelValues - an array of pixel values for which to find the minimum and maximum values.
offset - an offset (in pixels) into the array for the first pixel to be included in the calculation of min/max.
nPixels - the number of pixels to be included in the calculation of min/max.
dataType - the type of pixel value stored in the pixelValues.
complexMode - mode for the calculation of the minimum and maximum values for Complex images. For all other types of image, the complexMode is ignored.
Returns:
the minimum and maximim intensity values in a double[] of length 2.
Throws:
MultiSliceImageException - if a the minimum and maximum values cannot be found for the supplied data type

getCumulativeHistogram

public Histogram getCumulativeHistogram()
Return a new Histogram that is the cumulative histogram of this one.

Returns:
a new Histogram that is the cumulative histogram of this one.

getHistoMin

public double getHistoMin()
Returns the minimum bin value of this Histogram.

Returns:
the minimum bin value of this Histogram.

getHistoMax

public double getHistoMax()
Returns the maximum bin value of this Histogram.

Returns:
the maximum bin value of this Histogram.

getPeakHeight

public double getPeakHeight(boolean excludeZero)
Returns the number of pixels with the most common pixel intensity in this Histogram, optionally excluding the pixel intensities that are zero-valued. This is useful when an image has a background of zero, and you want to exclude this.

Parameters:
excludeZero - true if the zero-valued background is to be excluded from the search for the most common intensity.
Returns:
the number of pixels with the most common pixel intensity in this Histogram, optionally excluding the zero-valued background. If the Histogram has multiple peaks all of the same height, then the first one encountered is returned.

getPeakPosition

public double getPeakPosition(boolean excludeZero)
Returns the most common pixel intensity in this Histogram, optionally excluding the pixel intensities that are zero-valued. This is useful when an image has a background of zero, and you want to exclude this. If the histogram has two or more peaks of equal height, then the position of the lowest-intensity peak will be returned.

Parameters:
excludeZero - true if the zero-valued background is to be excluded from the search for the most common intensity.
Returns:
the most common pixel intensity in this Histogram, optionally excluding the zero-valued background. If the Histogram has multiple peaks all of the same height, then the first one encountered is returned.

getMedian

public double getMedian()
Returns the median value of this Histogram.

Returns:
the median pixel intensity of this Histogram.

getMedian

public double getMedian(boolean excludeZero)
Returns the median value of this Histogram, optionally excluding all pixel intensities that are zero. This is useful when an image has a background of zero, and you want to exclude the effect of the background on the median value.

Parameters:
excludeZero - true if the zero-valued background is to be excluded from the calculation of the median.
Returns:
the median pixel intensity of this Histogram, optionally excluding the zero-valued background.

getMean

public double getMean()
Returns the mean intensity value of this Histogram.

Returns:
the mean pixel intensity of this Histogram.

getMean

public double getMean(boolean excludeZero)
Returns the mean intensity value of this Histogram, optionally excluding all pixel intensities that are zero. This is useful when an image has a background of zero, and you want to exclude the effect of the background on the mean value.

Parameters:
excludeZero - true if the zero-valued background is to be excluded from the calculation of the mean.
Returns:
the mean pixel intensity of this Histogram, optionally excluding the zero-valued background.

getSD

public double getSD()
Returns the standard deviation of intensity values of this Histogram.

Returns:
the standard deviation of pixel intensity values of this Histogram.

getSD

public double getSD(boolean excludeZero)
Returns the standard deviation of intensity values of this Histogram, optionally excluding all pixel intensities that are zero from the calculation. This is useful when an image has a background of zero, and you want to exclude the effect of the background on the SD value.

Parameters:
excludeZero - true if the zero-valued background is to be excluded from the calculation of the standard deviation.
Returns:
the standard deviation of pixel intensity values of this Histogram, optionally excluding the zero-valued background.

getCumulativeIntensity

public double getCumulativeIntensity(float fraction,
                                     boolean excludeZero)
Returns an intensity value such that the specified fraction of pixels is below the returned intensity; zero-valued pixels are optionally excluded from the calculation.

Parameters:
fraction - the intensity value returned is such that this fraction of pixels is below the returned intensity. Normally fraction would be between 0.0 and 1.0. If fraction is less than or equal to 0.0, the minimum intensity is returned. If fraction is greater than or equal to 1.0, the maximum intensity is returned.
excludeZero - true if the zero-valued background is to be excluded from the calculation of the intensity.

add

public Histogram add(Histogram histo)
Adds the counts from a Histogram to this Histogram to produce a new Histogram that spans the data range of both.

Parameters:
histo - the Histogram from which to add the counts.
Returns:
a new Histogram compiled by adding this Histogram to the argument.

getAreaUnder

public double getAreaUnder()
Returns the total area under this histogram.

Returns:
the area under this Histogram. The area is the sum of the counts in all the bins multiplied by the bin width. For integer data types, the area returned equals the number of pixels used to compute the Histogram.

getAreaUnder

public double getAreaUnder(boolean excludeZero)
Returns the area under this histogram, optionally excluding any zero-intensity pixels. This is useful when an image has a background of zero, and you want to exclude the background from the calculation of the area.

Parameters:
excludeZero - true if the zero-valued background is to be excluded from the calculation of the area.
Returns:
the area under this Histogram, optionally excluding the zero-valued background. The area is the sum of the counts in all the bins (optionally excluding zero) multiplied by the bin width. For integer data types, the area returned equals the number of pixels used to compute the Histogram (optionally excluding zero-intensity pixels).

getAreaUnder

public double getAreaUnder(double threshold)
Returns the number of pixels in this histogram that are above the supplied threshold.

Parameters:
threshold - pixel intensity values that are below the threshold will be excluded from the calculation of the area.
Returns:
the area under this Histogram, excluding the intensities that are below the threshold.

getEntropy

public double getEntropy()
Returns the entropy of this Histogram. The entropy is calculated as Sum(-p(i) log(p(i))), where p(i) is the probability (normalised frequency) of intensity i, and the sum is performed over all intensities.

Returns:
the entropy of this Histogram.

normalise

public void normalise()
Normalises this Histogram, so that the sum of all the counts is unity. If all bins have zero entries, then this method does nothing.

clone

public java.lang.Object clone()
Creates a copy of this Histogram.

Overrides:
clone in class java.lang.Object
Returns:
a clone of this Histogram instance.

toString

public java.lang.String toString()
Returns a String that lists the min, max, bin width and count values of this Histogram.

Overrides:
toString in class java.lang.Object
Returns:
a String that lists the min, max, bin width and count values of this Histogram.
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