Generally, lossy data conversion refers to the conversion of data from one storage format to another in a way that doesn't allow the exact recovery of the original data. In particular, it can refer to lossy
type conversion
In computer science, type conversion, type casting, type coercion, and type juggling are different ways of changing an expression from one data type to another. An example would be the conversion of an integer value into a floating point val ...
, where some values in the original type cannot be represented in the target type,
or to lossy
file conversion, where the target format does not support all the feature of the original format.
Type conversion
File conversion
Such conversions are typically used between incompatible software or as the export target of edition tools. Most of the time, the document saved in the lossy format will look identical, but the conversion can also cause some loss in 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
International Business Machines Corporation (using the trademark IBM), nicknamed Big Blue, is an American Multinational corporation, multinational technology company headquartered in Armonk, New York, and present in over 175 countries. It is ...
's
Lotus Domino transform a proprietary rich text format into a web standard
HTML
Hypertext Markup Language (HTML) is the standard markup language for documents designed to be displayed in a web browser. It defines the content and structure of web content. It is often assisted by technologies such as Cascading Style Sheets ( ...
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 Redundanc ...
.
See also
*
Round-trip format conversion
*
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 ...
References
{{DEFAULTSORT:Lossy Data Conversion
Computer file formats
Data compression