A lossy data conversion

Data conversion

Data conversion is the conversion of computer data from one format to another. Throughout a computer environment, data is encoded in a variety of ways. For example, computer hardware is built on the basis of certain standards, which requires that data contains, for example, parity bit checks....

method is one where converting data between one storage format and another displays data in a form that is "close enough" to be useful, but may differ in some ways from the original. This type of conversion is used frequently between software packages that rely on different storage techniques. In many cases, a software package such as Microsoft Word

Microsoft Word

Microsoft Word is a word processor designed by Microsoft. It was first released in 1983 under the name Multi-Tool Word for Xenix systems. Subsequent versions were later written for several other platforms including IBM PCs running DOS , the Apple Macintosh , the AT&T Unix PC , Atari ST , SCO UNIX,...

 will enable a document stored in one format to be saved as another, in particular HTML

HTML

HyperText Markup Language is the predominant markup language for web pages. HTML elements are the basic building-blocks of webpages....

. The document saved in the lossy format may look identical, but the conversion can also cause some loss of fidelity or functionality.

Types of lossy conversion

There are three basic types of lossy data conversion:

• With in-place lossy data conversion, software packages such as IBM
  IBM
  International Business Machines Corporation or IBM is an American multinational technology and consulting corporation headquartered in Armonk, New York, United States. IBM manufactures and sells computer hardware and software, and it offers infrastructure, hosting and consulting services in areas...
  
  's Lotus Domino transform a proprietary rich text format into a web standard HTML
  HTML
  HyperText Markup Language is the predominant markup language for web pages. HTML elements are the basic building-blocks of webpages....
  
   as the page is requested. Because the page is served up just in time
  Just In Time
  Just in time is a production strategy that strives to improve a business return on investment by reducing in-process inventory and associated carrying costs. Just-in-time production method is also called the Toyota Production System...
  
  , it can rely on the existence of the software package to handle specialized data features that may not be available in the new format natively. On the other hand, the converted data may not be usable outside of the in-place context.

• With file export lossy data conversion, software packages allow either a File Export to the new data storage format, or a File Save to the new data storage format. The former leaves the original content in its original format and creates a new lossy version in the named file. The latter changes the format of the existing file.

• With extraction lossy data conversion, software packages take content stored by a different software package and extract out the content to the desired format. This may allow data to be extracted in a format not recognized by the original software package.

Other types of data

Graphic data (images) is often converted from one data storage format to another. Such conversions are usually described separately as either lossy data compression

Lossy data compression

In information technology, "lossy" compression is a data encoding method that compresses data by discarding some of it. The procedure aims to minimize the amount of data that need to be held, handled, and/or transmitted by a computer...

 or lossless data compression

Lossless data compression

Lossless data compression is a class of data compression algorithms that allows the exact original data to be reconstructed from the compressed data. The term lossless is in contrast to lossy data compression, which only allows an approximation of the original data to be reconstructed, in exchange...

.

See also

• Round-trip format conversion
  Round-trip format conversion
  The term round-trip is commonly used in document conversion particularly involving markup languages such as XML and SGML. A successful round-trip consists of converting a document in format A to one in format B and then back again to format A . If docA and docA′ are identical then there has been...
  
  
• Transcoding