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Low Bit Image Coding, IEE Colloquium on

Date 6 Jun 1995

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  • IEE Colloquium `Low Bit Image Coding' (Digest No.1995/154)

    Publication Year: 1995
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (16 KB)  

    The following topics were dealt with: video codecs; neural networks for image vector quantisation; interframe coding; motion and deformation estimation; VLSI device; H.263 video coding recommendation for PSTN videophone and multimedia View full abstract»

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  • Performance assessment of five neural networks and architecture design for image vector quantization

    Publication Year: 1995 , Page(s): 2/1 - 2/6
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (208 KB)  

    Various neural network algorithms have previously been introduced to implement vector quantisation for image compression. These include competitive learning VQ, a self-organizing feature map, frequency sensitive learning, an LBG neural network and general learning VQ etc. The first three neural networks are members of the LVQ family. The present paper presents a performance assessment based on experimental results for the above five typical neural networks. The second part of the paper contributes to computing an architecture design for a batch mode GLVQ algorithm which shows the best potential for further development View full abstract»

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  • An ASBVQ codec for VLBR video coding

    Publication Year: 1995 , Page(s): 1/1 - 1/5
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (232 KB)  

    A new adaptive subband vector quantisation (ASBVQ) codec for the encoding of video sequences at very low bit rates is presented. The block diagram of the complete system is shown. Overlapped block motion compensation (OBMC) is employed to generate a prediction of the current frame from the previously decoded frame. The OBMC method generates a prediction error signal which can be compressed more efficiently when a subband based coder is used. A 2D discrete wavelet transform is applied to decompose the prediction error frame into 7 subbands. An adaptive subband VQ scheme is employed to quantize the wavelet coefficients and distribute the available bit budget among the subband vector quantizers. For applications where constant bit rate is required this is provided by the adaptive VQ algorithm, eliminating the need for a buffer View full abstract»

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  • H.263-video coding recommendation for PSTN videophone and multimedia

    Publication Year: 1995 , Page(s): 6/1 - 6/9
    Cited by:  Papers (6)  |  Patents (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (380 KB)  

    Presents an overview of JTU-T Recommendation H.263. In particular, the operation and impact on quality and bit-rate of the four H.263 Annexes (D, E, F and G) which specify optional enhanced modes of operation are discussed, with supporting results. The effectiveness of the various options is seen to depend upon the type of sequence and the frame rate, making it clear that for optimum performance a real codec must include means to make appropriate decisions about which options to invoke for maximum performance under given operating conditions. Finally, comparisons with H.261 indicate a significant performance gain for H.263, of the order of 2 to 3 dB View full abstract»

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  • Classified subregion motion estimated interframe coding

    Publication Year: 1995 , Page(s): 3/1 - 3/6
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (224 KB)  

    Introduces the framework of a novel algorithm for the detection, classification and identification of image subregions. It is shown that an efficient technique can be implemented for the representation of interframe motion in a video sequence. The authors suggest that the method can be realised as an original approach to motion vector coding in a simple, low-resolution video codec View full abstract»

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  • A VLSI device for low bit rate coding

    Publication Year: 1995 , Page(s): 5/1 - 5/6
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (296 KB)  

    The pitfalls of designing algorithms without reference to future hardware implications have been illustrated with respect to the implementation of H.261 and MPEG in VLSI systems. The wavelet transform has been shown to be better suited to hardware implementation than MPEG and H.261 by an order of magnitude and achieves higher compression ratios for a given quality. A new mapping onto a VLSI architecture of the wavelet transform is described. A single device can process images at a frame rate of over 30 QCIF frames per second (8 bit pixels) and the compressed bit stream on average 33 kbits per second at an image quality of 32 dB (PSNR) View full abstract»

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  • Object oriented motion and deformation estimation using composite image segmentation

    Publication Year: 1995 , Page(s): 4/1 - 4/6
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (292 KB)  

    A novel object oriented motion estimation algorithm is presented. The algorithm provides the means for highly efficient moving image encoding by fully exploiting the temporal redundancy among the objects of successive frames. Two-dimensional segmentation is performed on a composite image synthesised from two consecutive frames. The object correspondence problem is removed implicitly by virtue of the fact that the generated composite segments correspond to successive versions of the same objects. Thus the scheme not only solves the problem of the correspondence between successive versions of the same object, but it also guarantees well matched segments in the presence of noise and varying illumination. Moreover, it preserves motion or deformation information. Progressive motion estimation is achieved within the segmentation process which adapts to the assumed translational or affine model. Motion compensated extrapolation is performed on uncovered background and overlapping regions of the predicted frame. Simulation results prove the efficiency of the predictive scheme even in the case that only motion and deformation parameters need to be transmitted View full abstract»

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