Showing papers on "Run-length encoding published in 2006"

A Bit Level Representation for Time Series Data Mining with Shape Based Similarity

Abstract: Clipping is the process of transforming a real valued series into a sequence of bits representing whether each data is above or below the average. In this paper, we argue that clipping is a useful and flexible transformation for the exploratory analysis of large time dependent data sets. We demonstrate how time series stored as bits can be very efficiently compressed and manipulated and that, under some assumptions, the discriminatory power with clipped series is asymptotically equivalent to that achieved with the raw data. Unlike other transformations, clipped series can be compared directly to the raw data series. We show that this means we can form a tight lower bounding metric for Euclidean and Dynamic Time Warping distance and hence efficiently query by content. Clipped data can be used in conjunction with a host of algorithms and statistical tests that naturally follow from the binary nature of the data. A series of experiments illustrate how clipped series can be used in increasingly complex ways to achieve better results than other popular representations. The usefulness of the proposed representation is demonstrated by the fact that the results with clipped data are consistently better than those achieved with a Wavelet or Discrete Fourier Transformation at the same compression ratio for both clustering and query by content. The flexibility of the representation is shown by the fact that we can take advantage of a variable Run Length Encoding of clipped series to define an approximation of the Kolmogorov complexity and hence perform Kolmogorov based clustering.

Drawing processing apparatus and method for compressing drawing data

Abstract: A drawing processing apparatus is provided to solve the problems in which pixels of a drawing primitive with sub-pixel information may have an increased amount of data causing a burden on implementation. A setup processing unit sets up various parameters to allow a digital differential analyzer (DDA) to process the stream of a drawing primitive supplied from a primitive input unit. The DDA performs DDA processing on the drawing primitive supplied from the setup processing unit for conversion into pixel data. The DDA performs the DDA processing on a per rectangular pixel set basis along a scan line to output the pixel data of the drawing primitive on a per rectangular pixel set basis. A compression encoding unit encodes the sub-pixel information of each pixel contained in the rectangular pixel set by run length encoding for output to a FIFO buffer.

Improved Bitmap Indexing Strategy for Data Warehouses

Abstract: Improving the query performance is critical in data warehousing and decision support systems. A lot of methods have been proposed by various researches. Indexing the data warehouse is a common but effective technique. Bitmap indices play a very important role in improving query performance in data warehousing and decision support systems. In this paper we present a new bitmap indexing strategy that can be applied to any existing bitmap compression schemes that are based on run length encoding. The new strategy, in most cases, requires less space and provides performance gains as well. The new strategy is tested on two commonly used bitmap compression schemes namely, word-aligned hybrid (WAH) and byte-aligned bitmap code (BBC) and results are presented graphically. The proposed strategy simply sorts the field on which a bitmap is to be created. Sorting of the field ensures long runs of ones and zeros. These long runs of ones and zeros are desirable for any compression scheme that is based on run length encoding and its variants. The space required to store the bitmap indexes goes down dramatically. The effect of sorting on query response time is studied for equality and range queries and it is found that there is a considerable decrease in the response time of queries. The overheads associated with the proposed strategy are sorting a table on a particular field and maintaining a sorted table. These extra tasks could be easily performed during the ETL process or when the data warehouse is offline. The new strategy concentrates on reducing space requirement for the bitmap index and the response time of queries and achieves both objectives without incurring any processing overheads when the data warehouse is online.

Parallel Algorithm for Run Length Encoding

Abstract: This article describes the development of a parallel variation of the “run length encoding” data compression algorithm. It points out the major difficulties encountered with the creation of the parallel algorithm and introduces a model applicable to the creation of parallel variations of other single-pass algorithm.

Drawing processor and drawing data compression method

Abstract: PROBLEM TO BE SOLVED: To solve the problem that sub-pixel information for pixels of a drawing primitive causes an increased mounting load because of increase in data volume SOLUTION: A setup processing part 14 performs setup of various parameters to process a stream of the drawing primitive given from a primitive input part 12 by a digital differential analyzer (DDA) The DDA 16 converts the drawing primitive supplied from the setup processing part 14 to pixel data by DDA processing The DDA 16 performs the DDA processing in rectangular pixel assembly units along a scan line, and outputs pixel data of the drawing primitive in rectangular pixel group units A compression encoding part 18 compression-encodes sub-pixel information of each pixel contained in each rectangular pixel group by run length encoding, and outputs it to a FIFO buffer 20 COPYRIGHT: (C)2006,JPO&NCIPI

A new spaceborne compression approach for remote sensing imagery

Abstract: After analyzing advantages and disadvantages of these typical encoding methods: SPIHT and VQ, a "DWT+MRLE" approach for spaceborne data compression was proposed in this paper. This approach includes two steps: Discrete Wavelet Transform (DWT) and Modified Run Length Encoding (MRLE). The former used CDF9/7 biorthogonal wavelet filters to powerfully get rid of correlation between pixels in imagery. The later put enlightening information into the lowest bit of some key-position transform coefficients. Consequently, CDF9/7 and MRLE together make hardware platform remain high real-time capability, and help reconstructed images keep good fidelity with PSNR being about 40dB, compared with the original ones. Comparison between experimentations on SPOT4's low-spatial-resolution (10m) imagery and Ikonos2's high-spatial-resolution (1m) imagery, shows this "DWT+MRLE" method having better performance for remote-sensed imagery, especially those of higher resolution. Although inferior to 8:1, Compression Ration (CR) here near 5:1 is greater than France SPOT5's 3:1 and American Ikonos2's 11:2.6 on-board data compression. More important, this method having less computational amount is good for spaceborne capability of real time. The consumed time of different image size is also presented in this paper, based on TI TMSC6416 DSP chip with 600MHz CPU cycle clock.

Method and apparatus for compressing a stream of video data

Abstract: A method of and apparatus for compressing a stream of data, such as video data, are disclosed. First, data in the video stream are classified in accordance with their values. Data with values equal to zero are classified in a first class. Data with values less than a predetermined positive number but greater than a predetermined negative number, and not equal to zero, are classified in a second class. All other data are classified in a third class. Data in the first class are compressed using a run length encoding technique. Data in the second class are compressed by reducing the size of the data value and by adding a constant. Data in the third class are not compressed, but are modified by adding a constant. The data can be decompressed by determining the class of the compressed value and reversing the compression process. The compression method disclosed is easy to implement and results in a significant reduction in the amount of data that needs to be transmitted.

Efficient document rendering with enhanced run length encoding

Abstract: Document imaging and transmission systems (typically MFPs) require both effective and efficient image rendering methods that support standard data formats for a variety of document types, and allow for real time implementation. Since most conventional raster formats (e. g. TIFF, PDF, JPEG) are designed for use with either black and white text, or continuous-tone images, more specialized rendering methods are often required for representing mixed content documents. The baseline TIFF format supports a few binary compression options: PackBits, CCITT G3 and G4. Conventionally, halftoning algorithms, such as error diffusion, can be used to create a binary representation of a document image in the TIFF format. However, PackBits, CCITT G3 and G4 compression generally do not produce desired compression on halftone images. In this paper, we propose an efficient error diffusion algorithm optimized for PackBits compression. This method, which we refer to as POED (PackBits optimized error diffusion), is a form of threshold modulation error diffusion which takes advantage of the byte-oriented run length structure of PackBits compression by encouraging repetition of bytes in the resulting binary image. To maintain the sharpness of text, a binary segmentation algorithm is provided to switch off the adaptive error diffusion procedure and switch on the Floyd Steinberg error diffusion procedure in text regions. The POED method with PackBits compression yields higher compression ratios than the conventional error diffusion method, while maintaining desirable visual quality with low computational and memory requirements. We show experimental results to compare our method with the Floyd Steinberg error diffusion method.

A method of icon compression for mobile station

Abstract: An icon compression method for a mobile communication terminal is provided to reduce a load of the mobile communication terminal and to improve performance by performing the lossless compression of an icon image used in the mobile communication terminal by applying an RLE(Run Length Encoding) method, and enhancing the compression efficiency of the icon image using several colors. A mobile communication terminal calculates color information per one pixel composing an icon image, and obtains a change image for calculating the color information about the entire image(S80). The mobile communication terminal reads the calculated color information, grasps continuous number information of the same color value indicating the same color, and generates compression data(S82). The mobile communication terminal composes a file header by using the compression data, generates a file of the icon image, and compresses the icon image(S84).