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invpacktree_int Class Reference

Inverse wavelet packet transform. More...

#include <invpacktree_int.h>

List of all members.

Public Methods
	invpacktree_int (packdata_list< int > &list, liftbase< packcontainer_int, int > *w)
	This constructor calculates the inverse wavelet packet transform. More...
	~invpacktree_int ()
	The destructor does nothing. More...
const int*	getData ()
	Get the result of the inverse packet transform. More...
void	pr ()
	print the result of the inverse wavelet packet transform. More...
Private Methods
	invpacktree_int (const invpacktree_int &rhs)
	disallow the copy constructor. More...
void	new_level (packdata< int > *elem)
	Allocate a new level in the wavelet packet tree that is being constructed. More...
void	add_elem (packdata< int > *elem)
	Add a packdata element to the inverse wavelet packet transform calculation. More...
void	reduce ()
	At this point the Top Of Stack (TOS) packcontainer_int object should have both a right and a left array. More...
Private Attributes
liftbase<packcontainer_int, int>*	waveObj
	wavelet transform object. More...
LIST<packcontainer_int *>	stack
	inverse wavelet packet transform calculation stack. More...
const int*	data
	pointer to the inverse transform result. More...
size_t	N
	length of data. More...

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Detailed Description

Inverse wavelet packet transform.

The invpacktree_int constructor is passed a packdata_list object and a wavelet transform object. It calculates the inverse wavelet packet transform, using the data in the packdata_list object and the inverse wavelet transform step function of the wavelet transform object. The best basis data is destroyed in calculating the inverse transform.

The packdata_list object contains the "best basis" result from a wavelet packet transform. The wavelet packet transform should have been calculated with the same wavelet transform as the object passed to this constructor.

After the constructor completes, the data result can be obtained by calling the getData() function.

The wavelet transforms used by this object are all derived from the liftbase class and are "lifting scheme" wavelet transforms.

I have found the wavelet literature difficult, in general. When it comes to the wavelet packet transform I have found most of it impossible to understand. Impossible, that it until I got the book Ripples in Mathematics by Jensen and la Cour-Harbo, Springer Verlag, 2001. The wavelet packet transform, for which this class is the inverse, is heavily based on Chapter 8 of Ripples in Mathematics.

I have found very little material on the actual implementation of the inverse wavelet packet transform. This algorithm is my own design.

Definition at line 81 of file invpacktree_int.h.

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Constructor & Destructor Documentation

invpacktree_int::invpacktree_int ( const invpacktree_int & rhs ) [inline, private]

disallow the copy constructor. Definition at line 86 of file invpacktree_int.h. {}

invpacktree_int::invpacktree_int ( packdata_list< int > & list, liftbase< packcontainer_int, int > * w )

This constructor calculates the inverse wavelet packet transform. The constructor is passed a packdata_list object, which contains the "best basis" result of the wavelet packet transform. The liftbase template argument is a pointer to a wavelet transform function. This wavelet transform must be the same function that was used to calculate the packet transform. Definition at line 203 of file invpacktree_int.cpp. { data = 0; N = 0; waveObj = w; // Traverse the "best basis" list and calculate the inverse // wavelet packet transform. packdata_list<int>::handle h; for (h = list.first(); h != 0; h = list.next( h )) { packdata<int> *elem = list.get_item( h ); add_elem( elem ); } // for LIST<packcontainer_int *>::handle tosHandle; tosHandle = stack.first(); packcontainer_int *tos = stack.get_item( tosHandle ); if (tos != 0) { size_t len = tos->length(); N = len/2; data = tos->lhsData(); stack.remove(); } } // invpacktree_int

invpacktree_int::~invpacktree_int ( ) [inline]

The destructor does nothing. Definition at line 105 of file invpacktree_int.h. {}

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Member Function Documentation

void invpacktree_int::add_elem ( packdata< int > * elem ) [private]

Add a packdata element to the inverse wavelet packet transform calculation. A packdata element contains the wavelet packet data items from one level of the wavelet packet transform tree. The inverse wavelet packet transform calculation uses a stack. Each level in the stack consists of a packcontainer_int object. This object consists of left and right hand size arrays. When both these arrays are present, they can be treated as one contiguous array (courtesy of C++ operator overloading). The size of the packcontainer_int object is twice the size of its left and right hand size arrays. If the stack is empty, a new level is created. A packetcontainer object can be viewed as a binary tree element. The left hand size is filled in first. If the stack is not empty and the packcontainer_int object on the top of stack (TOS) is twice the size of the elem argument, then the array contained in the elem argument is added to the TOS element and reduce is called to calculate a step of the inverse wavelet transform. If the TOS element is greater than twice the size of elem then a new level is added. Definition at line 165 of file invpacktree_int.cpp. Referenced by invpacktree_int(). { assert( elem != 0 ); if (stack.first() == 0) { new_level( elem ); } else { size_t half = elem->length(); size_t n = half * 2; LIST<packcontainer_int *>::handle h; h = stack.first(); packcontainer_int *tos = stack.get_item( h ); if (tos->length() == n) { assert( tos->rhsData() == 0); tos->rhsData( (int *)elem->getData() ); reduce(); } else if (tos->length() > n) { new_level( elem ); } else { printf("add_elem: the size of the TOS elem is wrong\n"); } } // else } // add_elem

const int * invpacktree_int::getData ( ) [inline]

Get the result of the inverse packet transform. Definition at line 108 of file invpacktree_int.h. Referenced by packet_calc(). { return data; }

void invpacktree_int::new_level ( packdata< int > * elem ) [private]

Allocate a new level in the wavelet packet tree that is being constructed. The new "level" is built from a packcontainer_int object. The left child will be the elem argument. The length of the data in the new level will be twice that of lower level (of which elem is half). Definition at line 55 of file invpacktree_int.cpp. Referenced by add_elem(). { size_t half = elem->length(); size_t n = half * 2; packcontainer_int *container = new packcontainer_int( n ); container->lhsData( (int *)elem->getData() ); stack.add( container ); } // new_level

void invpacktree_int::pr ( )

print the result of the inverse wavelet packet transform. Definition at line 235 of file invpacktree_int.cpp. { if (data != 0) { for (int i = 0; i < N; i++) { printf("%7.4f ", data[i] ); } printf("\n"); } } // pr

void invpacktree_int::reduce ( ) [private]

At this point the Top Of Stack (TOS) packcontainer_int object should have both a right and a left array. Calculate an inverse wavelet transform step on the packcontainer_int object. The packcontainer_int object allows the right and left hand side arrays to be treated as one array If the current top of stack is twice the size of the inverse wavelet transform step result, the result becomes the right hand size of top of stack packcontainer_int and reduce is called recursively. If the TOS is empty or it is not twice the size of the inverse transform result, a new packcontainer_int will be pushed on the stack. The left hand size will be the transform result. Definition at line 84 of file invpacktree_int.cpp. Referenced by add_elem(). { LIST<packcontainer_int *>::handle h; h = stack.first(); packcontainer_int *tos = stack.get_item( h ); assert( tos->lhsData() != 0 && tos->rhsData() != 0 ); stack.remove(); size_t n = tos->length(); // calculate the inverse wavelet transform step waveObj->inverseStep( (*tos), n ); // copy the result of the inverse wavelet transform // into a new data array. block_pool mem_pool; int *vec = (int *)mem_pool.pool_alloc( n * sizeof( int ) ); for (int i = 0; i < n; i++) { vec[i] = (*tos)[i]; } if (stack.first() != 0) { h = stack.first(); packcontainer_int *tos = stack.get_item( h ); if (tos->length() == n*2) { tos->rhsData( vec ); reduce(); } else { assert( tos->length() > n*2 ); packcontainer_int *container = new packcontainer_int( n*2 ); container->lhsData( vec ); stack.add( container ); } // else } else { // the stack is empty packcontainer_int *container = new packcontainer_int( n*2 ); container->lhsData( vec ); stack.add( container ); } } // reduce

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Member Data Documentation

size_t invpacktree_int::N [private]

length of data. Definition at line 94 of file invpacktree_int.h.

const int * invpacktree_int::data [private]

pointer to the inverse transform result. Definition at line 92 of file invpacktree_int.h.

LIST< packcontainer_int *> invpacktree_int::stack [private]

inverse wavelet packet transform calculation stack. Definition at line 89 of file invpacktree_int.h.

liftbase< packcontainer_int, int > * invpacktree_int::waveObj [private]

wavelet transform object. Definition at line 84 of file invpacktree_int.h.

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

• invpacktree_int.h
• invpacktree_int.cpp

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