Entropy improvement by the Temporal-Window method for Alternating and Non-Alternating 3D wavelet transform over angiographies

Abstract

The three-dimensional wavelet transform (3D-WT) has been proposed for volumetric data coding, since it can provide lossless coding and top-quality reconstruction: two key features highly relevant to medical imaging applications. In this paper, we present experimental results for four new algorithms based on the Classic 3D-WT. The proposed algorithms are capable of obtaining the wavelet coefficients after the spatial and, mainly, the temporal decomposition processes, reducing most redundancies in the video sequence and getting lower entropy values than the Classic algorithm. The new algorithms are based on the Temporal-Window method for carrying out the temporal decomposition. We have conducted a set of experimental evaluations for a representative data set of a modality of intrinsically volumetric medical imaging: angiography sequences.

Parallel Algorithms Based on the Temporal-Window Method for Non-Alternating 3D-WT over Angiographies Using a Multicomputer

“…This section briefly describes the algorithms based on the temporal-window method that were presented in some of our previous works [3][4][5]. The main aim of this method is to improve the efficiency of the decorrelation process.…”

“…The group of frames where the temporal transform is jointly applied is called window, and inside it, the temporal 1D-WT is performed on four frames at a time, and by sliding the 1D-WT over the whole window. In this way, the temporal transformation is applied on all the frames making part of the window [5]. The temporal 1D-WT is applied over the first four frames of the window.…”

“…This avoids changing the context alternatively on each decomposition level. In [5] we presented a study of the alternating and non-alternating versions of the two algorithms, the sequential versions, where its non-alternating implementations exhibited better performance, in terms of the entropy associated to the decorrelated angiography; resulting on a better coding efficiency of the decorrelated sequences.…”

“…The first-order entropy performance improvement of the temporal-window based algorithms versus the classic 3D-WT algorithm was studied in previous works [5].…”

“…In this paper, we evaluate the parallel implementations of image-sequences decorrelation algorithms, having been recently introduced in some of our previous works [3][4][5]. The algorithms have been developed based on the nonalternating wavelet-based transform algorithms [6] that will be explained in the following sections.…”