An adaptive transform coding algorithm using a quadtree-based variable blocksize DCT (discrete cosine transform) is introduced to achieve a better tradeoff between bit rate and image quality. The choice of appropriate...
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An adaptive transform coding algorithm using a quadtree-based variable blocksize DCT (discrete cosine transform) is introduced to achieve a better tradeoff between bit rate and image quality. The choice of appropriate blocksize is determined by a mean-based decision rule that can discriminate various image contents for better visual quality. Some simulation results are given. It is found that the same or better image quality can be obtained with lower average bit rate.
An efficient coding scheme for progressive transmission of gray-scale images is presented. In the scheme, a rough sketch of an image is transmitted first and the details are added later. At the final stage of transmis...
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An efficient coding scheme for progressive transmission of gray-scale images is presented. In the scheme, a rough sketch of an image is transmitted first and the details are added later. At the final stage of transmission, a receiver can reproduce the exact replica of an original image with high coding efficiency. This kind of presentation is especially desirable for the interactive visual search of large image databases, where a viewer can recognize image content as quickly as possible, halt transmission of unwanted detail, and retry another image. This scheme utilizes subsampling and level-plane coding in a recursive way. Thus, the coding algorithm is simple and can be easily implemented even on a personal computer. Computer simulations show that the scheme achieves the mean code length of 5.24 b/pel for an image, which is almost the same as that of efficient nonprogressive coding schemes.
This paper reports on the authors' recent work in developing a new multirate method for image coding at low bit rates. The method follows the approach which was introduced at ISCAS 89 [1] and is based on a multira...
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ISBN:
(纸本)0819402389
This paper reports on the authors' recent work in developing a new multirate method for image coding at low bit rates. The method follows the approach which was introduced at ISCAS 89 [1] and is based on a multirate maximally decimated filter bank structure. Difficulties and solutions related to the performance of the system are discussed in this paper. The proposed structure attempts to preserve the perceptually significant characteristics of the reconstructed image in the presence of quantization. Methods for coding the new multirate representation are still under development. However, preliminary coding results are shown in this paper using vector quantization and adaptive differential PCM. Results based on a more efficient contour encoding method will be presented at the conference.
An adaptive transform coding algorithm using a quadtree-based variable blocksize DCT (discrete cosine transform) is introduced to achieve a better tradeoff between bit rate and image quality. The choice of appropriate...
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An adaptive transform coding algorithm using a quadtree-based variable blocksize DCT (discrete cosine transform) is introduced to achieve a better tradeoff between bit rate and image quality. The choice of appropriate blocksize is determined by a mean-based decision rule that can discriminate various image contents for better visual quality. Some simulation results are given. It is found that the same or better image quality can be obtained with lower average bit rate.< >
Three keys are suggested for unlocking the broadband future based on an analysis of human and societal communication needs. A framework is adopted that distinguished three categories of communication needs: access to ...
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Three keys are suggested for unlocking the broadband future based on an analysis of human and societal communication needs. A framework is adopted that distinguished three categories of communication needs: access to people, access to information, and access to information processing. Within this framework, it is argued that applications that emphasize shared visual material, that accommodate advertisers as important end-users, and that include effective security provisions may play a crucial role in realizing the broadband future.< >
An approach to data compression for NTSC composite video is introduced that uses run-length coding and concepts of fractal geometry adapted for color image compression. Compression is achieved by sending only the run ...
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An approach to data compression for NTSC composite video is introduced that uses run-length coding and concepts of fractal geometry adapted for color image compression. Compression is achieved by sending only the run lengths with a sign bit. A feedback mechanism is constituted by defining the encoder and decoder as finite-state machines. The edges are preserved by sending the edge information using a separate edge quantizer. The proposed system takes the characteristics of the human visual model into account. The low computational complexity of the algorithm makes it conducive to an easy real-time implementation. Good-quality reconstructed color images are obtained at 1.25 b/pixel.
Recent activity of an ISO/CCITT working group to produce an excellent coding technique for worldwide still-image telecommunication applications is described. The three techniques considered for final selection are dis...
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Recent activity of an ISO/CCITT working group to produce an excellent coding technique for worldwide still-image telecommunication applications is described. The three techniques considered for final selection are discussed: the adaptive discrete cosine transform (ADCT), adaptive binary arithmetic coding (ABAC), and block-separated component progressive coding (BSPC). Particular emphasis is placed on the selected technique, the ADCT.< >
With the availability of a 144 Kbits/sec user's digital access to the integrated service digital network (ISDN), transmission of video data over the telephone network will become a reality. However, the required c...
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With the availability of a 144 Kbits/sec user's digital access to the integrated service digital network (ISDN), transmission of video data over the telephone network will become a reality. However, the required compression is extremely high and improving the visual quality of the decoded image data continues to be a challenge. The authors present a new image coding algorithm which includes a technique for segmenting image sequences and a modified adaptive 3-D arithmetic coder (MAAC). With these enhancements, it will be possible to transmit an image sequence at 30 frames per second over a digital telephone line.< >
Source coding and channel coding are embedded in a video coding algorithm for low bitrates (64 kb/s) to obtain a complete encoder which is resilient against channel errors. The bits retained for the channel coder are ...
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Source coding and channel coding are embedded in a video coding algorithm for low bitrates (64 kb/s) to obtain a complete encoder which is resilient against channel errors. The bits retained for the channel coder are spent for synchronization words, error correction, and update of erroneous parts in the image. The performance of the complete codec is evaluated by simulations in which channels with different characteristics are modeled.< >
An adaptive Kalman filter for restoring noisy images is presented. This filter is initially derived from a stationary causal image model. In order to improve the visual quality of the restored images, a local spatial ...
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An adaptive Kalman filter for restoring noisy images is presented. This filter is initially derived from a stationary causal image model. In order to improve the visual quality of the restored images, a local spatial activity function is proposed and is incorporated in the implementation of the filter. Experiments show that the restored images have better visual quality than an ordinary Kalman filter.
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