Encontrados 9 documentos, a visualizar página 1 de 1
A simple lossy audio coding scheme based on the DWT
Vikas K., Gupta; Khevariya, Prashant K.; Salvado, JoséThis paper proposes a simple scheme for audio coding that does not use perceptual models. The audio coder is based on the discrete wavelet transform to decorrelate signals, computed through the lifting scheme, and followed by Huffman coding. The evaluation of the coding scheme is presented by using some .wav audio test files, coded for different conditions, and also includes subjective evaluation. Experimental ...
Engineering graduation projects in a transdisciplinary approach
Oliveira, Joaquim; Salvado, JoséThis paper presents some project themes proposed by the authors and the methodology adopted in its supervision, in a transdisciplinary approach. We describe the projects and discuss the most relevant aspects of this approach, from the technical and pedagogical points of view. The stronger points of this methodology are some similarities with the environment that recent graduated students might find in the emplo...
Evaluation of transform based image coders, using different transforms and tech...
Salvado, José; Roque, BrunoThis paper addresses the most relevant aspects of lossy image coding techniques, and presents an evaluation study on this subject, using several transforms and different methods in the transform domain. We developed different transform based image coders/decoders (codecs) using different transforms, such as the discrete cosine transform, the discrete wavelet transform and the S transform. Besides JPEG Baseline,...
A comparative study on JPEG-Like and EZW based image Coders
Bruno, Roque; Salvado, JoséThis paper presents a comparative study on image coders using the discrete cosine transform and the discrete wavelet transform, addressing in particular the JPEG-like and the EZW based image coders. We compare and evaluate the JPEG Baseline Image coder (using the DCT), a JPEG-like image coder based on the DWT, and an EZW coder, which is also based on the DWT. Taking into account the differences on the architect...
Video coding by applying the extension of EZW to 3D and the lifting scheme
Salvado, José; Sousa, LeonelThis paper proposes a video codec based on the discrete wavelet transform (DWT). The video sequences are first splitted in groups of frames(GOF). Each GOF is then decomposed in the time domain, and in the spatial domain (for each frame) by applying the DWT. We use the lifting scheme to compute the DWT coefficients. The coefficients of the 3D structure resulting from both DWT (in time and space domain) are than ...
Codificador de vídeo baseado na transformada de ôndulas 3D
Salvado, José; Sousa, LeonelNeste artigo apresenta-se um codificador de vídeo baseado na transformada de ôndulas, com interface do tipo Windows®, desenvolvido em Borland C++ Builder v5.0. O codificador tira partido das características da estrutura hierárquica 3D de coeficientes da DWT, resultante da sua aplicação no domínio do tempo e do espaço. O utilizador escolhe a sequência a codificar (armazenada em ficheiro), o número de tramas, o n...
Ferramenta de síntese e implementação de filtros em DSPs
Gonçalves, João; Marques, Libânia; Salvado, José; Sousa, LeonelNeste artigo apresenta-se uma ferramenta computacional para síntese automática de filtros digitais, com interface do tipo Windows®, desenvolvida em MATLAB™. Os filtros sintetizados podem ser posteriormente implementados em DSPs da família TMS320 da Texas Instruments, nomeadamente, nos DSPs TMS320C50 e TMS320C6201. Os filtros foram testados num sistema baseado no DSP C6201, recorrendo a sinais áudio digitais arm...
Codificação de vídeo por decomposição 3-D baseada na transformada de ôndulas
Salvado, José António da CostaNeste trabalho foi desenvolvido um codificador/descodificador (CoDec) de vídeo de ritmo binário variável, baseado na decomposição 3D por transformada de ôndulas, sendo o cálculo das transformadas de ôndulas, e das transformadas inversas, realizado através do esquema progressivo (lifting scheme). Analisa-se a aplicação à codificação de vídeo da decomposição de sinais 1D e 2D por bancos de filtros de ôndulas...
Applying matrix decomposition techniques to edge detection operators
Sousa, Leonel; Salvado, JoséIn this paper decomposition techniques are applied to derivative operators, used for image edge detection. It is shown that the application of decomposition techniques to common edge detectors can result in substantial savings in computing time. For a 25x25 Laplacian of Gaussian, mask, an improvement of six times less arithmetic operations is achieved when decomposition techniques are applied.We also show that ...
| Financiadores do RCAAP | |||||||
|
|
|
|
|
|
||