JEITA CP-3451
- 59 -
B. Quantization table definition (DQT: Define Quantization Table)
DQT is a marker code defining a quantization table.
As many as three kinds of tables may be recorded with a precision of 8 bits (Pq=0). All quantization tables shall be
defined in one DQT marker segment; recording of multiple DQT markers is not allowed. The table may have any
values (see Figure 19). DQT, DHT, DRI and SOF may line up in any order, but shall be recorded after APP1 (or
APP2 if any) and before SOS.
Address Offset
Code
Meaning
(Hex)
(Hex)
+00
FF
Marker Prefix
+01
DB
DQT
+02
00
Length of field
C5
2+(1+64)*3=197 (Bytes)
+04
00
Y: Pq=0, Nq=0
+05
:
Quantization table Y:Q0
:
:
:
:
:
Quantization table Y:Q63
+45
01
Cb: Pq=0, Nq=1
+46
:
Quantization table Cb:Q0
:
:
:
:
:
Quantization table Cb:Q63
+86
02
Cr: Pq=0, Nq=1
+87
:
Quantization table Cr:Q0
:
:
:
:
:
Quantization table Cr:Q63
Figure 19 DQT Structure (with three quantization tables)