A lossy
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 tha ...
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 is a word processing software developed by Microsoft. It was first released on October 25, 1983, under the name ''Multi-Tool Word'' for Xenix systems. Subsequent versions were later written for several other platforms includin ...
will enable a document stored in one format to be saved as another, in particular
HTML
The HyperText Markup Language or HTML is the standard markup language for documents designed to be displayed in a web browser. It can be assisted by technologies such as Cascading Style Sheets (CSS) and scripting languages such as JavaScri ...
. 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's
Lotus Domino
HCL Notes (formerly IBM Notes and Lotus Notes; see Branding below) and HCL Domino (formerly IBM Domino and Lotus Domino) are the client and server, respectively, of a collaborative client-server software platform formerly sold by IBM, now by ...
transform a proprietary rich text format into a web standard
HTML
The HyperText Markup Language or HTML is the standard markup language for documents designed to be displayed in a web browser. It can be assisted by technologies such as Cascading Style Sheets (CSS) and scripting languages such as JavaScri ...
as the page is requested. Because the page is served up
just in time, 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
In information technology, lossy compression or irreversible compression is the class of data compression methods that uses inexact approximations and partial data discarding to represent the content. These techniques are used to reduce data size ...
or
lossless data compression
Lossless compression is a class of data compression that allows the original data to be perfectly reconstructed from the compressed data with no loss of information. Lossless compression is possible because most real-world data exhibits statistic ...
.
See also
*
Round-trip format conversion {{noref, date=January 2019
The term round-trip is 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 (docA) to one in format B (docB) and ...
*
Transcoding
Transcoding is the direct digital-to-digital conversion of one encoding to another, such as for video data files, audio files (e.g., MP3, WAV), or character encoding (e.g., UTF-8, ISO/IEC 8859). This is usually done in cases where a target devic ...
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Computer file formats
Data compression