---

Histogram Class Reference

A class allowing N-D histograms to be represented, calculated and compared. More...

#include <Histogram.h>

List of all members.

Public Methods
	Histogram (float minimum_data_value, float maximum_data_value, unsigned int bands_per_dimension, unsigned int dimensionality)
	Allocate memory for and initialise histogram. More...
	Histogram (char const *hstFile)
	Constructor to load an existing histogram from a file and allocate appropriate memory.
unsigned int	numBands (void)
void	add_new_data_item (int *data)
	Adds new data to histogram calculation. More...
void	add_new_data_item (float *data)
	Adds new data to histogram calculation. More...
void	reset_histogram ()
	Resets histogram by setting all frequencys to 0 and no_data_items to zero. More...
void	calculate_probabilities ()
	Calculate histogram probabilities (probs) from frequencies (frequency_data).
void	calculate_histogram ()
	Calculate normalised histogram probabilities (probs) from frequencies (frequency_data). More...
float	get_histogram_value (unsigned int *bin)
	Returns bin probability value (from probs). More...
float	get_mapped_value (unsigned int *bin)
	Returns probability associated with bin containing the data 'data'.
float	calculate_difference (Histogram *hist)
	Returns mean absolute difference between histograms. More...
float	get_maximum_prob (void)
	Returns maximum probability over all bins.
void	get_best_bin (unsigned int *bin)
	Returns best bin.
float	calculate_proportion_threshold (float proportion)
	Calculate the probability threshold above which no more than 'proportion' of the training data lie. More...
void	save_histogram (char const *)
	Saves histogram data to an (XML format) file.
void	load_histogram (char const *)
	Loads histogram from a (XML format) file.
Protected Attributes
float*	probs
	Bin relative probabilities.

---

Detailed Description

A class allowing N-D histograms to be represented, calculated and compared.

Definition at line 25 of file Histogram.h.

---

Constructor & Destructor Documentation

Histogram::Histogram ( float minimum_data_value, float maximum_data_value, unsigned int bands_per_dimension, unsigned int dimensionality )

Allocate memory for and initialise histogram. Parameters: minimum_data_value   Minimum data value (e.g. 0 for standard RGB data) maximum_data_value   Maximum data value (e.g. 255 for standard RGB data) bands_per_dimension   No. of bands to divide each dimension into dimensionality   Dimensionality of Histogram/data (e.g. 3 for RGB data) Definition at line 31 of file Histogram.cpp.

---

Member Function Documentation

void Histogram::add_new_data_item ( float * data )

Adds new data to histogram calculation. Dimensionality must match dim. Parameters: data   The data to add (pointer to array of size dim) Definition at line 137 of file Histogram.cpp.

void Histogram::add_new_data_item ( int * data )

Adds new data to histogram calculation. Dimensionality must match dim. Parameters: data   The data to add (pointer to array of size dim) Definition at line 90 of file Histogram.cpp.

float Histogram::calculate_difference ( Histogram * hist )

Returns mean absolute difference between histograms. Histograms must have same dimensionality and bands_per_dim. Parameters: hist   Pointer to Histogram to compare with this object Definition at line 339 of file Histogram.cpp.

void Histogram::calculate_histogram ( )

Calculate normalised histogram probabilities (probs) from frequencies (frequency_data). I.e. max probability set to 1. To calculate true probabilities use calculate_probabilities(). Definition at line 249 of file Histogram.cpp.

float Histogram::calculate_proportion_threshold ( float proportion )

Calculate the probability threshold above which no more than 'proportion' of the training data lie. I.E. if proportion = 1 => threshold = 0 OR if proportion = 0.99999... => threshold = lowest non zero bin prob NOTE: calculate_probabilities() should be called prior to this method. Definition at line 205 of file Histogram.cpp.

float Histogram::get_histogram_value ( unsigned int * bin )

Returns bin probability value (from probs). Parameters: bin   The bin to return. An array of u-ints, one for each dimension. N.B. Numbers are from 0->(bands_per_dim-1) Definition at line 268 of file Histogram.cpp.

void Histogram::reset_histogram ( )

Resets histogram by setting all frequencys to 0 and no_data_items to zero. N.B. This has no effect on probs - calculate_histogram() should ALWAYS be called befor using the probabilities. Definition at line 72 of file Histogram.cpp.

---

The documentation for this class was generated from the following files:

• Histogram.h
• Histogram.cpp

---