留学生论文代写:3000万套指纹

Keywords:留学生论文代写

1924至今天，美国联邦调查局收集了约3000万套指纹。档案主要由纸卡片上的墨水印模组成。印象的传真扫描分布在执法机构，但数字化质量往往低。因为许多地区正在尝试打印的数字存储之间的数据格式不兼容，成为了最近的一个问题。这个问题导致了在刑事司法界的数字化和压缩标准的需求。1993，联邦调查局的刑事司法信息服务部开发与国家标准与技术研究院合作指纹数字化和压缩标准，洛斯阿拉莫斯国家实验室，商业供应商，与刑事司法社区。让我们把数据存储问题透视。指纹图像数字化的分辨率为每英寸500像素，每个像素的灰度信息的256个级别。一个单一的指纹是700000像素，需要0.6字节的存储。一双手，然后，约6兆字节的存储要求。所以数字化的FBI档案将导致约200百万兆字节数据。（注意，在硬盘存储，约900美元每千兆字节的今天的价格存储这些压缩图像的成本大约是2亿美元。）显然，数据压缩是把这些数字记下重要。
留学生论文代写:3000万套指纹
Between 1924 and today, the US Federal Bureau of Investigation has collected about 30 million sets of fingerprints. The archive consists mainly of inked impressions on paper cards. Facsimile scans of the impressions are distributed among law enforcement agencies, but the digitization quality is often low. Because a number of jurisdictions are experimenting with digital storage of the prints, incompatibilities between data formats have recently become a problem. This problem led to a demand in the criminal justice community for a digitization and a compression standard. In 1993, the FBI's Criminal Justice Information Services Division developed standards for fingerprint digitization and compression in cooperation with the National Institute of Standards and Technology, Los Alamos National Laboratory, commercial vendors, and criminal justice communities. Let's put the data storage problem in perspective. Fingerprint images are digitized at a resolution of 500 pixels per inch with 256 levels of gray-scale information per pixel. A single fingerprint is about 700,000 pixels and needs about 0.6 Mbytes to store. A pair of hands, then, requires about 6 Mbytes of storage. So digitizing the FBI's current archive would result in about 200 terabytes of data. (Notice that at today's prices of about $900 per Gbyte for hard-disk storage, the cost of storing these uncompressed images would be about 200 million dollars.) Obviously, data compression is important to bring these numbers down.