STV-974/552S-R01 STMicroelectronics, STV-974/552S-R01 Datasheet - Page 17

• Manufacturer Part Number: STV-974/552S-R01
• Description: KIT DEMO W/VS6552
• Manufacturer: STMicroelectronics

Specifications of STV-974/552S-R01

• Sensor Type: CMOS Imaging, Color (RGB)
• Sensing Range: VGA
• Interface: I²C
• Sensitivity: 30 fps
• Embedded: No
• Utilized Ic / Part: STV0974E, VS6552
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: 497-3891

4.4.4
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Functional description
Quantization block
This block applies a uniform quantizer on all DCT coefficients, in ZigZag sequence. It is compliant
with ISO DIS 10918-1 Annex A - Section A.3.4.
The quantizer step size for each DCT coefficient S
from the quantization table Q’.
Where uv is the index of the zigzag coefficient.
Table Q’ is a scaled quantization table calculated for table Q as follows:
where Squeeze is a parameter value.
Table Q is represented in
Figure 9: Luminance and chrominance quantization tables
Table 6
Table 6: VGA image size - YUV 4: 2: 2 - Example of image size after JPEG compression
Squeeze
Squeeze
quantization table
factor (Squeeze/8)
File size (Kbyte)
Bit per pixel
a. No compression
shows an example of VGA image when different squeeze values are applied by the user.
Q
=
Quantization table for Y blocks
16 11 10 16 24 40 51 61
12 12 14 19 26 58 60 55
14 13 16 24 40 57 69 56
14 17 22 29 51 87 80 62
18 22 37 56 68 109 103 77
24 35 55 64 81 104 113 92
49 64 78 87 103 121 120 101
72 92 95 98 112 100 103 99
614
a
Figure 9
0.12
2.13
~80
2
, as described in ISO DIS 10918-1 Annex K.
Squv
Q '
=
0.25
1.39
~51
=
4
Squeeze
-------------------------
round
32
⎛
⎝
0.85
~32
------------
Q ' uv
0.5
Suv
uv
8
×
Q
is the value of the corresponding element Q’
⎞
⎠
0.62
0.72
~27
10
Quantization table for U and V blocks
Q
=
17 18 24 47 99 99 99 99
18 21 26 66 99 99 99 99
24 26 56 99 99 99 99 99
47 66 99 99 99 99 99 99
99 99 99 99 99 99 99 99
99 99 99 99 99 99 99 99
99 99 99 99 99 99 99 99
99 99 99 99 99 99 99 99
1.25
0.56
~21
20
1.87
0.32
~12
30
3.12
0.24
50
~9
STV0974
4.19
0.24
67
~9
uv