摘要 :
Two new coding schemes for bit-rate reduction of digital images are proposed. Both coding schemes are based on a new model which makes use of the conditional statistical properties of the image signals. These statistics are used t...
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Two new coding schemes for bit-rate reduction of digital images are proposed. Both coding schemes are based on a new model which makes use of the conditional statistical properties of the image signals. These statistics are used to construct codebooks for the encoding and decoding of the digital images. In the first scheme, the code words are assigned in such a way as to provide a signal with long bit runs. Such a signal is then efficiently run-length coded using CCITT codes. In the second scheme, each picture element (PEL) value is coded by variable-length code words according to the values of previously transmitted PELs. The performance of both schemes in terms of entropy and bit-rate are compared with an optimum predictive coder. The simulation results indicate that the proposed schemes have a significant advantage over standard predictive encoders. A method to reduce the storage requirement for the encoder and decoder codebooks is also proposed.
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Distortion caused by digital video coding appears locally strongly content dependent and picture quality is time varying. Picture quality assessment methods for digitally coded image are becoming more important as digital audio-vi...
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Distortion caused by digital video coding appears locally strongly content dependent and picture quality is time varying. Picture quality assessment methods for digitally coded image are becoming more important as digital audio-visual systems are widely being used. In this paper, the procedure of subjective testing used for the assessment, mainly the Double Stimulus Continuous Quality Scale (DSCQS) method, is illustrated. Following that, the status of the new technology for criticality measure and objective quality assessment is described.
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Picture quality assessment technique for digital coded video evokes much interest as digital audio-visual systems are widely being used. Picture quality of digital video should be assessed carefully considering characteristics of ...
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Picture quality assessment technique for digital coded video evokes much interest as digital audio-visual systems are widely being used. Picture quality of digital video should be assessed carefully considering characteristics of distortions caused by digital coding, which appear locally and time varying, are much different from analog systems. This paper describes procedures of subjective picture quality assessment tests and the trend of the new technology of criticality and objective quality assessment of video.
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Due to the advances in visual technology three dimensional (3D) imaging systems are becoming popular. One way of stimulating 3D perception is to use stereo pairs, a pair of images of the same scene acquired from different perspect...
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Due to the advances in visual technology three dimensional (3D) imaging systems are becoming popular. One way of stimulating 3D perception is to use stereo pairs, a pair of images of the same scene acquired from different perspectives. Since there is an inherent redundancy between the images of a stereo pair, data compression algorithms should be employed to efficiently represent stereo pairs. Disparity estimation of stereoscopic image is an important stage for the stereo image compression. We propose a new disparity estimation method using a directional regularization technique to preserve edges well for stereoscopic image coding. This method smooths disparity vectors in smooth regions and preserves edges in object boundaries without over-smoothing problem. The experimental results show that the proposed method achieves close matches between a left image and a right image as well as the improved coding efficiency. We use DPCM technique followed by Huffman entropy coding for disparity map coding. In addition, the proposed disparity estimation method can be applied to the high-quality intermediate view reconstruction.
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The characteristics required for a studio format digital recorder are considered and variable-speed operation for the Type B and C systems is described. The implication of the picture-in-shuttle techniques are considered and also ...
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The characteristics required for a studio format digital recorder are considered and variable-speed operation for the Type B and C systems is described. The implication of the picture-in-shuttle techniques are considered and also the reasons for adopting a helical rather than transverse format. Coding systems are then compared in some detail with special reference to error detection and correction and it is concluded that the Miller Squared code is superior to the 8/10 code. Brief comment is made on the adoption of a broadcast digital standard.
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We have developed a 3D player using a high density optical disc (CD-ROM) as the storage medium. Two video channels are compressed by MPEG2 technology while the audio signal is compressed by MPEG1 technology. The player is controll...
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We have developed a 3D player using a high density optical disc (CD-ROM) as the storage medium. Two video channels are compressed by MPEG2 technology while the audio signal is compressed by MPEG1 technology. The player is controlled by our newly developed real time OS. This OS allows the video and audio MPEG streams to be synchronized during playback. The 2 channels video data and audio data are interleaved during recording on the disc. We also have developed a unique disc recording format. The 3D data recorded with this format are exactly synchronized during playback.
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Digital images have become an important source of information in the modern world of communication systems. In their raw form, digital images require a tremendous amount of memory. Many research efforts have been devoted to the pr...
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Digital images have become an important source of information in the modern world of communication systems. In their raw form, digital images require a tremendous amount of memory. Many research efforts have been devoted to the problem of image compression in the last two decades. Two different compression categories must be distinguished: lossless and lossy. Lossless compression is achieved if no distortion is introduced in the coded image. Applications requiring this type of compression include medical imaging and satellite photography. For applications such as video telephony or multimedia applications, some loss of information is usually tolerated in exchange for a high compression ratio. In this two-part paper, the major building blocks of image coding schemes are overviewed. Part I covers still image coding, and Part II covers motion picture sequences. In this first part, still image coding schemes have been classified into predictive, block transform, and multiresolution approaches. Predictive methods are suited to lossless and low-compression applications. Transform-based coding schemes achieve higher compression ratios for lossy compression but suffer from blocking artifacts at high-compression ratios. Multiresolution approaches are suited for lossy as well for lossless compression. At lossy high-compression ratios, the typical artifact visible in the reconstructed images is the ringing effect. New applications in a multimedia environment drove the need for new functionalities of the image coding schemes. For that purpose, second-generation coding techniques segment the image into semantically meaningful pairs. Therefore, parts of these methods have been adapted to work for arbitrarily shaped regions. In order to add another functionality, such as progressive transmission of the information, specific quantization algorithms must he defined. A final step in the compression scheme is achieved by the codeword assignment. Finally, coding results are presented which compare state-of-the-art techniques for lossy and lossless compression. The different artifacts of each technique are highlighted and discussed. Also, the possibility of progressive transmission is illustrated.
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In digital television networks, where the bitrates used for the transmission of video signals are variable, the issue of quality of service is of great importance. The QoS parameter of concern in this paper is the quality of MPEG-...
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In digital television networks, where the bitrates used for the transmission of video signals are variable, the issue of quality of service is of great importance. The QoS parameter of concern in this paper is the quality of MPEG-2 compressed video. Objective video quality assessment methods that can be used for continuous picture quality monitoring of digital encoding equipment at the entrance of the DVB network will be surveyed, along with parameters that can be extracted and transmitted to other parts of the network. The main objective of the contribution is to give an overview of the possibilities that exist and the progress that has been made so far
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A dynamic load balancing method is proposed that uses a multistage switching network to solve the problem of load concentration on certain processors for video coding in multiprocessor digital signal processors. (DSPs) This method...
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A dynamic load balancing method is proposed that uses a multistage switching network to solve the problem of load concentration on certain processors for video coding in multiprocessor digital signal processors. (DSPs) This method balances the processing load by distributing the total load among the processor elements having smaller loads. The load distribution is performed by the multistage switching network, which transmits the load quantity information within the network. A scheduling method for a motion picture coding algorithm using multiprocessor DSPs is also proposed. This scheduling method takes full advantage of the multistage switching network functions when distributing the processing load and sorting the processed results. By using computer simulation, multiprocessor DSP performance with the proposed method is shown to be double that of a conventional multiprocessor DSP when an initially unbalanced load is allocated to the processors, as in picture coding for TV conferences.
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A new approach for digital video enhancement is proposed in order to achieve optimal picture quality for MPEG encoded video. It takes account of the special characteristics of the encoded video by defining a usefulness metric for ...
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A new approach for digital video enhancement is proposed in order to achieve optimal picture quality for MPEG encoded video. It takes account of the special characteristics of the encoded video by defining a usefulness metric for enhancement (UME). This metric is calculated based on coding information and local spatial features to quantify how much a pixel can be enhanced without boosting coding artifacts. Motion estimation and scene change detection are integrated in the proposed algorithm to improve the temporal consistency. The idea proposed here can be applied to improve the performance of video enhancement algorithms for digital compressed sources. To demonstrate the potential of the new approach, the UME is applied to a spatial-domain sharpness enhancement algorithm. Experimental results show significant improvement with respect to the algorithm without the UME for various video sequences containing coding artifacts. This new approach can be incorporated into future digital video products (e.g. DVD recorders, set-top boxes, digital TVs, etc) in order to achieve superior picture quality for encoded video.
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