ISO/IEC 10918-1 : 1993(E)
INTERNATIONAL STANDARD
ISO/IEC 10918-1 : 1993(E)
CCITT Rec. T.81 (1992 E)
CCITT RECOMMENDATION
INFORMATION TECHNOLOGY – DIGITAL COMPRESSION
AND CODING OF CONTINUOUS-TONE STILL IMAGES –
REQUIREMENTS AND GUIDELINES
1 Scope
This CCITT Recommendation | International Standard is applicable to continuous-tone – grayscale or colour – digital still
image data. It is applicable to a wide range of applications which require use of compressed images. It is not applicable to
bi-level image data.
This Specification
– specifies processes for converting source image data to compressed image data;
– specifies processes for converting compressed image data to reconstructed image data;
– gives guidance on how to implement these processes in practice;
– specifies coded representations for compressed image data.
NOTE – This Specification does not specify a complete coded image representation. Such representations may include
certain parameters, such as aspect ratio, component sample registration, and colour space designation, which are application-
dependent.
2 Normative references
The following CCITT Recommendations and International Standards contain provisions which, through reference in this
text, constitute provisions of this CCITT Recommendation | International Standard. At the time of publication, the
editions indicated were valid. All Recommendations and Standards are subject to revision, and parties to agreements
based on this CCITT Recommendation | International Standard are encouraged to investigate the possibility of applying
the most recent edition of the Recommendations and Standards listed below. Members of IEC and ISO maintain registers
of currently valid International Standards. The CCITT Secretariat maintains a list of currently valid CCITT
Recommendations.
– CCITT Recommendation T.80 (1992), Common components for image compression and communication –
Basic principles.
3 Definitions, abbreviations and symbols
3.1 Definitions and abbreviations
For the purposes of this Specification, the following definitions apply.
3.1.1 abbreviated format: A representation of compressed image data which is missing some or all of the table
specifications required for decoding, or a representation of table-specification data without frame headers, scan headers,
and entropy-coded segments.
3.1.2 AC coefficient: Any DCT coefficient for which the frequency is not zero in at least one dimension.
3.1.3 (adaptive) (binary) arithmetic decoding: An entropy decoding procedure which recovers the sequence of
symbols from the sequence of bits produced by the arithmetic encoder.
3.1.4 (adaptive) (binary) arithmetic encoding: An entropy encoding procedure which codes by means of a recursive
subdivision of the probability of the sequence of symbols coded up to that point.
3.1.5 application environment: The standards for data representation, communication, or storage which have been
established for a particular application.
CCITT Rec. T.81 (1992 E) 1
