1,721,164 research outputs found
Block-Run Run-Length Coding of Handwriting and Bilevel Graphics Based on Quadtree Segmentation
No full textAn efficient off-line coding scheme for handwriting and bilevel graphics based on quadtree segmentation and block-run run-length coding (RLC) is presented. By segmenting a captured handwriting or graphic image into variable size blocks according to the image activity inside the blocks and run-length coding on a block-run basis, the new scheme is able to achieve higher coding efficiency than the conventional one-dimensional RLC and its bit rate is close to that of on-line dynamographical chain coding
Robust differential chain coding scheme
No full textIn differential chain coding (DCC), the bandwidth efficient relative vector is sensitive to channel errors, resulting in error propagation and corruption of the decoding process. A robust differential chain coding scheme is presented for stopping error propagation in the relative vector without increasing its bandwidth or using an additional forward error correction code. In this scheme, the relative vector is combined with the previous absolute vector to form a new error-resistant channel codeword. Experiments showed that, compared to DCC, the new scheme notably improves subjective quality when subject to transmission errors
Wireless Multi-Level Graphical Correspondence
No full textAn adaptive fixed-length differential chain coding (FL-DCC) scheme is proposed for the transmission of line graphics, which can be re-configured as a lower rate, lower resolution or higher rate, higher resolution source codec. The dual-rate re-configurable FL-DCG codec is embedded in a voice, video multimedia communicator system, which allocates the FL-DCC graphics packets to idle speech packets with the aid of the Packet Reservation Multiple Access (PRMA) multiplexer. In a bandwidth of 200 kHz, which is characteristic of he Pan-European GSM system, nine speech, video and graphics multimedia users can be accommodated using bandwidth efficient 16-level Quadrature Amplitude Modulation (16QAM) over Benign microcellular channels. In the diversity-aided and automatic repeat request (ARQ) assisted 16QAM mode of operation the multimedia user bandwidth becomes 22.2 kHz and the minimum required channel signal to noise ratio (SNR) over AWGN and Rayleigh channels is about 11 and 15 dB, respectively. Indexing terms: Graphical communications, Image processing, Chain coding, Multimedia communications, Intelligent multimode terminals
Adaptive fixed-length differential chain coding for transmission of line graphics
No full textAn adaptive fixed-length differential chain coding (FL-DCC) scheme is introduced for transmission of line graphics. Compared to differential chain coding(DCC), which uses vectors with different lengths, FL-DCC has a lower coding rate and a more uniform data syntax while maintaining a comparable subjective graphical quality
A Novel Coding Scheme for the Transmission of On-line Handwriting
No full textThe proposed adaptive fix-length differential chain coding (FL-DCC) scheme can be configured as a lower rate, lower resolution or higher rate, higher resolution source codec. The programmable-rate FL-DCC codec is embedded in an adaptive transceiver invoking more bandwidth efficient 16-level Quadrature Amplitude Modulation (16QAM) over benign microcellular channels, while employing more robust 4QAM in more hostile propagation scenarios. The minimum required channel signals to noise ratio (SNR) over AWGN and Rayleigh channels in its 16QAM mode is about 11 and 15 dB, respectively and the low-rate graphical stream can be accommodated during silent speech spurts
Robust Programmable-Rate Wireless Graphical Correspondence
No full textAn adaptive fixed-length differential chain coding (FL-DCC) scheme is proposed for the transmission of line graphics, which can be re-configured as a lower rate, lower resolution or higher rate. higher resolution source codec. Compared to Differential Chain Coding (DCC), the proposed FL-DCC codec has a lower coding rate in both of its lower- and higher-rate operating modes, while maintaining a similar subjective graphical quality. The dual-rate reconfigurable FL-DCC codec is embedded in a voice, video multimedia communicator system, which allocates the FL-DCC graphics packets to idle speech packets with the aid of the Packet Reservation Multiple Access (PRMA) multiplexer. In a bandwidth of 200 kHz, which is characteristic of the Pan-European GSM system, nine speech, video and graphics multimedia users can be accommodated using bandwidth efficient 16-level Quadrature Amplitude Modulation (16QAM) over benign microcellular channels. Under less favourable propagation conditions the more robust, but less bandwidth efficient 3QAM mode of operation can be invoked. In the diversity-aided and automatic repeat request (ARQ) assisted I6QAM mode of operation the multimedia user bandwidth becomes 22.2 kHz and the minimum required channel signal to noise ratio (SNR) over AWCN and Rayleigh channels is about 11 and 15 dB, respectively. The most salient system features are summarised in Table 2
Efficient Variable Rate Vector Quantisation using Quadtree Segmentation
No full textVariable rate vector quantization (VQ) using greedy tree growing algorithm has been used in image compression. In previous work, images have been partitioned into fixed size blocks and therefore correlation existing in large variable size blocks can not be exploited. In this paper, a new and efficient variable rate vector quantization scheme using variable block sizes is introduced. Simulation results show that the proposed scheme which is based on variable block size quadtree segmentation can achieve better performance than the fixed block size variable rate VQ
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