An optimized recursive binary nesting (RBN) algorithm for coding true color documents is presented. The RBN compression in which algorithm is a segmentation algorithm in which a picture is subdivided into regions with...
详细信息
An optimized recursive binary nesting (RBN) algorithm for coding true color documents is presented. The RBN compression in which algorithm is a segmentation algorithm in which a picture is subdivided into regions with equal properties and for each region only the relevant information for the human eye is kept. Thus, the compressed image consists of segmentation information and the information of the picture behavior in those regions. The picture is subsampled on a quadtree based lattice (segmentation information). The inner pixels are approximated with the use of four lattice corner pixels (pictorial behavior). The subdivision in blocks has to be a function of the image contents. The size of the initial blocks is 65*65. Each pixel in the block is approximated as a weighted average of the four corner pixels (bilinear interpolation). The efficient VLSI architecture used to implement the algorithm is termed the lowly multiplexed cooperating data-path style. Several other designs under consideration are briefly reviewed.< >
The data compressor decompressor (DCD) IC, a VLSI implementation of a version of the Lempel-Ziv (L-Z) compression algorithm, is discussed. The IC is suitable for high-speed, lossless compression of digital data such a...
详细信息
The data compressor decompressor (DCD) IC, a VLSI implementation of a version of the Lempel-Ziv (L-Z) compression algorithm, is discussed. The IC is suitable for high-speed, lossless compression of digital data such as text and images. The single-pass lossless compression scheme adapts to the statistics of the data being processed. The authors outline the L-Z compression method, illustrate a solution to its search requirement, and discuss the chip architecture and features.< >
During 1987 and 1988, a joint group of ISO and CCITT has worked to create a world standard for data compression of still-frame color continuous-tone images. During this period, the adaptive discrete cosine transform (...
详细信息
During 1987 and 1988, a joint group of ISO and CCITT has worked to create a world standard for data compression of still-frame color continuous-tone images. During this period, the adaptive discrete cosine transform (ADCT) was selected for final refinement from 12 proposed algorithms. Because the standard is required to provide either lossless or lossy compression, subjective image quality testing procedures were used extensively in the selection process. Each algorithm compressed test pictures to predefined bit rates, and the quality of the resulting images was evaluated using a modification of the CCIR 500 television quality evaluation procedures. The authors describe the perceptual test procedures and results which led to selection of the ADCT.< >
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...
详细信息
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.< >
The authors discuss the use of advanced digital signal processing (DSP) algorithms to implement sophisticated audio processing functions and microcontroller tasks on a low-cost digital signal processor, enabling OEM (...
详细信息
The authors discuss the use of advanced digital signal processing (DSP) algorithms to implement sophisticated audio processing functions and microcontroller tasks on a low-cost digital signal processor, enabling OEM (original equipment manufacturer) vendors to build cost-effective solid-state telephone answering devices. Sophisticated data compression algorithms and a low-cost programmable DSP processor were used to develop a powerful set of telephone-answering-machine chips. The DSP-based chip sets have been integrated in devices that offer incoming message recording times from 5 to 25 min, outgoing messages, time/date voice stamping and many other advanced features. A key to the project was finding application areas where DSP software could replace the traditional hardware while providing higher performance at lower cost. Speech processing along with telephony provided that environment. Aspects of hardware and software design are discussed.
Most compression algorithms for motion television require large data storage, usually several television fields, and typically operate on blocks of data. A chip has been built to support both of these features. It gen...
详细信息
Most compression algorithms for motion television require large data storage, usually several television fields, and typically operate on blocks of data. A chip has been built to support both of these features. It generates, from a single clock source, all of the control and address signals required by standard off-the-shelf dynamic RAMs (DRAMs). This includes data packing and unpacking and automatic refresh when required. Counters are provided to address the data into and out of the memories of the form of blocks. The block sizes and field dimensions are programmable and are independent for both read and write operations. Thus, one set of counters can be programmed for sequentially scanned data coming from a camera or going to a television monitor, and other set of counters can be programmed for the block size employed in the compression hardware. Blocks of data can be accessed either continuously or one at a time. When data are read from the memories, a single pel-width pulse marks the start of valid data. Signals marking both end of the block and end of field have also been provided to ease system interfacing.< >
The efficiencies of various data-compression techniques as applied to color maps are compared. These color maps have certain special characteristics, such as large homogeneous regions, and fine detail, such as lines a...
详细信息
The efficiencies of various data-compression techniques as applied to color maps are compared. These color maps have certain special characteristics, such as large homogeneous regions, and fine detail, such as lines and lettering. The color maps are first classified using the K-means clustering algorithm with neighborhood classification. Three techniques are investigated, namely, contour, quadtree, and run-length coding. The run-length coding algorithm is modified to allow wrap-around of runs. A modification of the standard binary image quadtree compression algorithm for color images is introduced. In quadtree coding a modified eldest-son eldest-younger-sibling quadtree is used to reduce the memory requirement for storing the quadtree. Lempel-Ziv compression is applied to the classified and unclassified images as well as to the output of the compression algorithms. The algorithms are compared on the compression ratios achieved. The exponential behavior of the histogram of the runs indicates that runs of short run length have higher probability. Accordingly, Huffman coding of the runs would result in more efficient bit assignment and hence greater compression ratios.< >
暂无评论