adv601lc Analog Devices, Inc., adv601lc Datasheet - Page 7

• Manufacturer Part Number: adv601lc
• Description: Ultralow Cost Video Codec
• Manufacturer: Analog Devices, Inc.

THE PROGRAMMABLE QUANTIZER
This block quantizes the filtered image based on the response
profile of the human visual system. In general, the human eye
cannot resolve high frequencies in images to the same level of
accuracy as lower frequencies. Through intelligent “quantiza-
tion” of information contained within the filtered image, the
ADV601LC achieves compression without compromising the
visual quality of the image. Figure 7 shows the encode and de-
code data formats used by the quantizer.
Figure 8 shows how a typical quantization pattern applies over
Mallat block data. The high frequency blocks receive much
larger quantization (appear darker) than the low frequency
blocks (appear lighter). Looking at this figure, one sees some key
point concerning quantization: (1) quantization relates directly
to frequency in Mallat block data and (2) levels of quantization
range widely from high to low frequency block. (Note that the
fill is based on a log formula.) The relation between actual
ADV601LC bin width factors and the Mallat block fill pattern
in Figure 8 appears in Table II.
REV. 0
40
37
41
38
28
39
29
36
34
31
32
35
19
20
27
25
22
26
33
30
23
18
10
11
13
16
14
21
17
24
9
Cr COMPONENT
Figure 8. Typical Quantization of Mallat Data Blocks (Graphed)
Cb COMPONENT
7
4
8
15
12
5
6
3
1
2
Y COMPONENT
–7–
WAVELET
LOW
NUMBER
15.0 BIN
DATA
9.7
Figure 7. Programmable Quantizer Data Flow
6.10 1/BW
SIGNED
SIGNED
QUANTIZATION OF MALLAT BLOCKS
8.8 BW
UNSIGNED
UNSIGNED
1/BW
BW
QUANTIZER - ENCODE MODE
QUANTIZER - DECODE MODE
SIGNED
SIGNED
0
15.17 DATA
23.8 DEQUANTIZED
WAVELET DATA
0.5
ADV601LC
TRNC
SAT
HIGH
15.0 BIN
NUMBER
9.7
WAVELET
DATA