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- Vitor Silva, Luis de Sa
- IEEE Trans. Signal Processing
- 1999

A general approach to the non-expansive M band decomposition of finite length signals is presented. The technique is based on linear signal extensions and can be applied to all types of linear and non-linear phase M band perfect reconstruction filter banks. The signal expansion is described by a linear transformation on the input signal and the extended… (More)

- Vitor Silva, Luis de Sa
- IEEE Trans. Signal Processing
- 1996

The optimization of subband filter banks for signal and image coding is normally dealt with by numerical means. It will be shown that this optimization can be done analytically in the case of the 4-tap CQF prototype filter. Coding gain and aliasing energy were considered in the optimization. Using parametrizations of the prototype filter coefficients it was… (More)

- João Silvestre, Luís de Sá
- 1999

Para resolver este problema surgiram várias soluções, entre as quais se encontra a mais simples e evidente, que é a extensão periódica. Outro tipo de extensão que se aplica a bancos de filtros de fase linear é a extensão simétrica dos dados [3]. Outros tipos de extensão usados são a extensão com zeros [2] e a replicação dos valores das fronteiras. Na… (More)

- Vitor Silva, Luís de Sá
- 1998

A new approach to the non-expansive two band decomposition of finite length signals is introduced. The technique is based on the time-varying perfect reconstruction filter banks concept. In this approach the main analysis filter bank is instantaneously switched, at the signal boundaries, to a shorter filter bank: the D 1 or Haar filter bank. The technique… (More)

One efficient way to compress digital images is subband coding. Subband coding using vector quantization could be a competitor to DCT-like image compression schemes. In this paper we will describe an image sequence compression algorithm based on difference image coding techniques, with block motion compensation, difference image segmentation in rectangles… (More)

One key problem in subband and wavelet coding systems, is the decomposition of limited size signals. The Wavelet transform is defined for infinite-length signals. In practice we only have finite-length signals, so signals must be extended before they can be transformed. The question is how to extend the signal to minimize signal end effects, or how to find… (More)

- João Silvestre, Luís de Sá
- 1999

The Wavelet transform is defined for infinite-length signals. In practice we only have finite-length signals, so signals must be extended before they can be transformed. The question is how to extend the signal to minimize signal end effects, or how to find the signal extension that preserves the transform signal length. In this paper we discuss the problem… (More)

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