background image
ISO/IEC 10918-1 : 1993(E)
For progressive processes, a scan contains a partial encoding of all data units from one or more image components.
Components shall not be interleaved in progressive mode, except for the DC coefficients in the first scan for each
component of a progressive frame.
4.11
Summary of coding processes
Table 1 provides a summary of the essential characteristics of the various coding processes specified in this Specification.
The full specification of these processes is contained in Annexes F, G, H, and J.
Table 1 Summary: Essential characteristics of coding processes
Baseline process (required for all DCT-based decoders)
DCT-based process
Source image: 8-bit samples within each component
Sequential
Huffman coding: 2 AC and 2 DC tables
Decoders shall process scans with 1, 2, 3, and 4 components
Interleaved and non-interleaved scans
Extended DCT-based processes
DCT-based process
Source image: 8-bit or 12-bit samples
Sequential or progressive
Huffman or arithmetic coding: 4 AC and 4 DC tables
Decoders shall process scans with 1, 2, 3, and 4 components
Interleaved and non-interleaved scans
Lossless processes
Predictive process (not DCT-based)
Source image: P-bit samples (2
P
16)
Sequential
Huffman or arithmetic coding: 4 DC tables
Decoders shall process scans with 1, 2, 3, and 4 components
Interleaved and non-interleaved scans
Hierarchical processes
Multiple frames (non-differential and differential)
Uses extended DCT-based or lossless processes
Decoders shall process scans with 1, 2, 3, and 4 components
Interleaved and non-interleaved scans
22
CCITT Rec. T.81 (1992 E)
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