ISO/IEC 10918-1 : 1993(E)
3.1.59
frame:
A group of one or more scans (all using the same DCT-based or lossless process) through the data of one
or more of the components in an image.
3.1.60
frame header:
A marker segment that contains a start-of-frame marker and associated frame parameters that are
coded at the beginning of a frame.
3.1.61
frequency:
A two-dimensional index into the two-dimensional array of DCT coefficients.
3.1.62
(frequency) band:
A contiguous group of coefficients from the zig-zag sequence (in progressive mode coding).
3.1.63
full progression:
A process which uses both spectral selection and successive approximation (in progressive
mode coding).
3.1.64
grayscale image:
A continuous-tone image that has only one component.
3.1.65
hierarchical:
A mode of operation for coding an image in which the first frame for a given component is
followed by frames which code the differences between the source data and the reconstructed data from the previous
frame for that component. Resolution changes are allowed between frames.
3.1.66
hierarchical decoder:
A sequence of decoder processes in which the first frame for each component is followed
by frames which decode an array of differences for each component and adds it to the reconstructed data from the
preceding frame for that component.
3.1.67
hierarchical encoder:
The mode of operation in which the first frame for each component is followed by frames
which encode the array of differences between the source data and the reconstructed data from the preceding frame for
that component.
3.1.68
horizontal sampling factor:
The relative number of horizontal data units of a particular component with respect
to the number of horizontal data units in the other components.
3.1.69
Huffman decoder:
An embodiment of a Huffman decoding procedure.
3.1.70
Huffman decoding:
An entropy decoding procedure which recovers the symbol from each variable length code
produced by the Huffman encoder.
3.1.71
Huffman encoder:
An embodiment of a Huffman encoding procedure.
3.1.72
Huffman encoding:
An entropy encoding procedure which assigns a variable length code to each input symbol.
3.1.73
Huffman table:
The set of variable length codes required in a Huffman encoder and Huffman decoder.
3.1.74
image data:
Either source image data or reconstructed image data.
3.1.75
interchange format:
The representation of compressed image data for exchange between application
environments.
3.1.76
interleaved:
The descriptive term applied to the repetitive multiplexing of small groups of data units from each
component in a scan in a specific order.
3.1.77
inverse discrete cosine transform; IDCT:
A mathematical transformation using cosine basis functions which
converts a block of dequantized DCT coefficients into a corresponding block of samples.
3.1.78
Joint Photographic Experts Group; JPEG:
The informal name of the committee which created this
Specification. The "joint" comes from the CCITT and ISO/IEC collaboration.
3.1.79
latent output:
Output of the arithmetic encoder which is held, pending resolution of carry-over (in arithmetic
coding).
3.1.80
less probable symbol; LPS:
For a binary decision, the decision value which has the smaller probability.
3.1.81
level shift:
A procedure used by DCT-based encoders and decoders whereby each input sample is either
converted from an unsigned representation to a two's complement representation or from a two's complement
representation to an unsigned representation.
4
CCITT Rec. T.81 (1992 E)