Methods of color document compression, processing, and transmission

A mixed content document typically contains a mixture of text, graphics, halftone regions, and pictures. Since the characteristics and spatial behaviors in these regions are dramatically distinct, efficient and accurate representation of a mixed content document becomes very challenging in many document imaging applications. This thesis includes three chapters focusing on three different application areas. ^ In Chapter 1, our objective is to develop an effective and high quality color document coding method based on the mixed raster content (MRC) model. While most MRC based methods can yield very high compression ratios, the binary representation of MRC tends to distort fine document details. To address this problem, we propose a method called resolution enhanced rendering (RER), which works by adaptively dithering the encoded binary mask, and then applying a nonlinear predictor to decode a gray level mask at the same or higher resolution. This method substantially improves the decoded document quality of text and graphics at a fixed bit rate. ^ In Chapter 2, we propose an efficient and flexible solution for binary representation of mixed content documents using CCITT G3/G4 compression. The solution includes two variations which we refer to as FastFax and ReadableFax. Both methods provide accurate binary representation of image content with high compressibility. Based on FastFax, we propose a layer-based compression scheme, MixedPDF, for color document representation in the PDF format. This method includes an efficient segmentation algorithm to separate the document into a text layer and a background layer, which are then separately coded by different compressions. The MixedPDF algorithm substantially outperforms conventional JPEG compression with low computational and memory requirements. ^ In Chapter 3, 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. 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.

Research on Self-Monitoring Method for Anomalies of Satellite Atomic Clock

Atomic clock is the core component of navigation satellite payload, playing a decisive role in the realization of positioning function. So the monitoring for anomalies of the satellite atomic clock is very important. In this paper, a complete autonomous monitoring method for the satellite clock is put forward, which is, respectively, based on Phase-Locked Loop (PLL) and statistical principle. Our methods focus on anomalies in satellite clock such as phase and frequency jumping, instantaneous deterioration, stability deterioration, and frequency drift-rate anomaly. Now, method based on PLL has been used successfully in China’s newest BeiDou navigation satellite

High quality MRC document coding

The mixed raster content (MRC) model can be used to implement highly effective document com-pression algorithms. MRC document coders are typically based on the use of a binary mask layer that efficiently encodes the text and graphic content. However, while many MRC-based methods can yield much higher compression ratios than conventional color image compression methods, the binary representation tends to distort fine document details, such as thin lines and text edges. In this paper, we propose a method for encoding and decoding the binary mask layer that substantially improves the decoded document fidelity of text and graphics at a fixed bit rate. This method, which we call resolution enhanced rendering (RER), works by adaptively dithering the encoded binary mask, and then applying a nonlinear predictor to decode a gray level mask at the same resolution. Both the dithering and nonlinear prediction algorithms are jointly optimized to produce the minimal distortion rendering. In addition, we introduce a second method, interpolative RER (IRER), which incorporates interpolation into the MRC decoder. The IRER method increases the compression ratio by allowing a high resolution document to be coded at lower resolution. We present experimental results illustrating the performance of our RER/IRER methods and comparing them to some existing MRC-based compression algorithms. This work was supported by Xerox Foundation

High quality MRC document coding

The mix raster content (MRC) model can be used to implement highly effective document compression algorithms. However, many MRC based methods which achieve high compression ratio can distort some £ne details of document quality, such as thin lines, and text edges. In this paper, we present a method called resolution enhanced rendering (RER) to achieve high quality rendering of document containing text, pictures and graphics, while maintaining desired compression ratios. The method applies adaptive dithering to the MRC encoder and then performs a nonlinear prediction in the MRC decoder. Both the dithering and nonlinear prediction algorithms are jointly optimized to produce the best quality rendering. We present experimental results illustrating the performance of our method and comparing it to some existing MRC compression algorithms. 1

Study on mechanical properties of traffic pavement materials under fatigue loading

The durability of pavement subgrade materials is the most important indicator for judging their merits as well as their mechanical properties. The durability of pavement subgrade material is mainly reflected in its water stability, because in the actual pavement environment, the subgrade is subjected to the infiltration of groundwater, immersion and the washout of pressure water under the concrete slab. The subgrade is subjected to a series of damage caused by freeze-thaw cycles and wet-dry cycles due to changes in temperature. In view of this, this chapter has targeted. In view of this, this chapter focuses on the frost resistance, water stability, scour resistance, dry shrinkage and sulfate erosion resistance of iron tailings as pavement base material. The study is carried out to simulate the real situation as much as possible to provide more detailed and accurate guidance for the actual engineering application. The study will provide more detailed and accurate guidance for the actual engineering application

A Disruption Tolerant Distributed Routing Algorithm in LEO Satellite Networks

The low earth orbit (LEO) constellation network has become a promising approach to provide global communication services, due to its advantages in wide global coverage, low transmission delay, and convenient networking. However, the instability of the intersatellite laser terminal and the high relative speed between adjacent satellites cause frequent network topology changing problems for data routing. In this paper, a disruption tolerant distributed routing algorithm (DTDR) is proposed, where the satellites calculate the alternate path for transmission when the network topology changes, which improves the performance of packet loss. Specifically, each satellite maintains the intersatellite link (ISL) information within a specified number of hops. When an ISL state changes within the specified number of hops, the corresponding satellite calculates and switches to the detour path. Furthermore, the traffic is balanced through the detour process. Various simulations were constructed and show that the proposed algorithm outperforms the existing algorithm in terms of packet loss ratio and transmission delay