#include <invpacktree.h>
Public Methods | |
| invpacktree (packdata_list< double > &list, liftbase< packcontainer, double > *w) | |
| This constructor calculates the inverse wavelet packet transform. More... | |
| ~invpacktree () | |
| The destructor does nothing. More... | |
| const double* | 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 (const invpacktree &rhs) | |
| disallow the copy constructor. More... | |
| void | new_level (packdata< double > *elem) |
| Allocate a new level in the wavelet packet tree that is being constructed. More... | |
| void | add_elem (packdata< double > *elem) |
| Add a packdata element to the inverse wavelet packet transform calculation. More... | |
| void | reduce () |
| At this point the Top Of Stack (TOS) packcontainer object should have both a right and a left array. More... | |
Private Attributes | |
| liftbase<packcontainer, double>* | waveObj |
| wavelet transform object. More... | |
| LIST<packcontainer *> | stack |
| inverse wavelet packet transform calculation stack. More... | |
| const double* | data |
| pointer to the inverse transform result. More... | |
| size_t | N |
| length of data. More... | |
The invpacktree 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 83 of file invpacktree.h.
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disallow the copy constructor.
Definition at line 88 of file invpacktree.h. 00088 {}
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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.cpp. 00205 {
00206 data = 0;
00207 N = 0;
00208 waveObj = w;
00209
00210 // Traverse the "best basis" list and calculate the inverse
00211 // wavelet packet transform.
00212 packdata_list<double>::handle h;
00213 for (h = list.first(); h != 0; h = list.next( h )) {
00214 packdata<double> *elem = list.get_item( h );
00215 add_elem( elem );
00216 } // for
00217
00218 LIST<packcontainer *>::handle tosHandle;
00219 tosHandle = stack.first();
00220 packcontainer *tos = stack.get_item( tosHandle );
00221
00222 if (tos != 0) {
00223 size_t len = tos->length();
00224 N = len/2;
00225
00226 data = tos->lhsData();
00227 stack.remove();
00228 }
00229 } // invpacktree
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The destructor does nothing.
Definition at line 107 of file invpacktree.h. 00107 {}
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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 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 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 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.cpp. Referenced by invpacktree().
00166 {
00167 assert( elem != 0 );
00168
00169 if (stack.first() == 0) {
00170 new_level( elem );
00171 }
00172 else {
00173 size_t half = elem->length();
00174 size_t n = half * 2;
00175 LIST<packcontainer *>::handle h;
00176 h = stack.first();
00177 packcontainer *tos = stack.get_item( h );
00178
00179 if (tos->length() == n) {
00180 assert( tos->rhsData() == 0);
00181 tos->rhsData( (double *)elem->getData() );
00182 reduce();
00183 }
00184 else if (tos->length() > n) {
00185 new_level( elem );
00186 }
00187 else {
00188 printf("add_elem: the size of the TOS elem is wrong\n");
00189 }
00190 } // else
00191 } // add_elem
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Get the result of the inverse packet transform.
Definition at line 110 of file invpacktree.h. 00110 { return data; }
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Allocate a new level in the wavelet packet tree that is being constructed. The new "level" is built from a packcontainer 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.cpp. Referenced by add_elem().
00056 {
00057 size_t half = elem->length();
00058 size_t n = half * 2;
00059
00060 packcontainer *container = new packcontainer( n );
00061 container->lhsData( (double *)elem->getData() );
00062 stack.add( container );
00063 } // new_level
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print the result of the inverse wavelet packet transform.
Definition at line 235 of file invpacktree.cpp. Referenced by main().
00236 {
00237 if (data != 0) {
00238 for (int i = 0; i < N; i++) {
00239 printf("%7.4f ", data[i] );
00240 }
00241 printf("\n");
00242 }
00243 } // pr
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At this point the Top Of Stack (TOS) packcontainer object should have both a right and a left array. Calculate an inverse wavelet transform step on the packcontainer object. The packcontainer 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 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 will be pushed on the stack. The left hand size will be the transform result. Definition at line 84 of file invpacktree.cpp. Referenced by add_elem().
00085 {
00086 LIST<packcontainer *>::handle h;
00087 h = stack.first();
00088 packcontainer *tos = stack.get_item( h );
00089
00090 assert( tos->lhsData() != 0 && tos->rhsData() != 0 );
00091
00097 stack.remove();
00098
00099 size_t n = tos->length();
00100 // calculate the inverse wavelet transform step
00101 waveObj->inverseStep( (*tos), n );
00102
00103 // copy the result of the inverse wavelet transform
00104 // into a new data array.
00105 block_pool mem_pool;
00106
00107 double *vec = (double *)mem_pool.pool_alloc( n * sizeof( double ) );
00108 for (int i = 0; i < n; i++) {
00109 vec[i] = (*tos)[i];
00110 }
00111
00112 if (stack.first() != 0) {
00113 h = stack.first();
00114 packcontainer *tos = stack.get_item( h );
00115
00116 if (tos->length() == n*2) {
00117 tos->rhsData( vec );
00118 reduce();
00119 }
00120 else {
00121 assert( tos->length() > n*2 );
00122 packcontainer *container = new packcontainer( n*2 );
00123 container->lhsData( vec );
00124 stack.add( container );
00125 } // else
00126 }
00127 else {
00128 // the stack is empty
00129 packcontainer *container = new packcontainer( n*2 );
00130 container->lhsData( vec );
00131 stack.add( container );
00132 }
00133 } // reduce
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length of data.
Definition at line 96 of file invpacktree.h. |
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pointer to the inverse transform result.
Definition at line 94 of file invpacktree.h. |
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inverse wavelet packet transform calculation stack.
Definition at line 91 of file invpacktree.h. |
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wavelet transform object.
Definition at line 86 of file invpacktree.h. |
1.2.8.1 written by Dimitri van Heesch,
© 1997-2001