ISO/IEC 10918-1 : 1993(E)
B.2.4.4
Restart interval definition syntax
Figure B.9 specifies the marker segment which defines the restart interval.
DRI
Ri
TISO0910-93/d027
Lr
Define restart interval segment
Figure B.9 Restart interval definition syntax
Figure B.9 [D27], = 2.5 cm = 98.%
The marker and parameters shown in Figure B.9 are defined below. The size and allowed values of each parameter are
given in Table B.7.
DRI:
Define restart interval marker Marks the beginning of the parameters which define the restart interval.
Lr:
Define restart interval segment length Specifies the length of the parameters in the DRI segment shown in
Figure B.9 (see B.1.1.4).
Ri:
Restart interval Specifies the number of MCU in the restart interval.
In Table B.7 the value n is the number of rows of MCU in the restart interval. The value MCUR is the number of MCU
required to make up one line of samples of each component in the scan. The SOI marker disables the restart intervals. A
DRI marker segment with Ri nonzero shall be present to enable restart interval processing for the following scans. A DRI
marker segment with Ri equal to zero shall disable restart intervals for the following scans.
Table B.7 Define restart interval segment parameter sizes and values
Values
Parameter
Size (bits)
Sequential DCT
Progressive DCT
Lossless
Baseline
Extended
Lr
16
4
Ri
16
0-65 535
n
×
MCUR
B.2.4.5
Comment syntax
Figure B.10 specifies the marker segment structure for a comment segment.
COM
Lc
TISO00920-93/d028
Cm
1
. . . Cm
Lc-2
Comment segment
Figure B.10 Comment segment syntax
Figure B.10 [D28], = 2.8cm = 98.%
CCITT Rec. T.81 (1992 E)
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